Grafting study of polysulfone polymeric membranes by gamma ray irradiation

International Nuclear Information System (INIS)

Furtado Filho, Acacio A.M.; Gomes, Ailton de S.

2011-01-01

Radiation-induced grafting of styrene poli sulfone films were investigated by simultaneous method in solution using gamma-ray from a radio nuclide 60 Co source. The gamma-ray energy of high intensity induced breaking of chemical bonds leading to free radical formation. The radical start a conventional polymerization sequence comparable with that obtained with a chemical catalyst acting as initiator. The effects of grafting conditions such as irradiation total dose, dose rate and addition of cross linking agent, were studied by means of morphology analysis, thermal degradation and crystallinity. After the grafting reaction, the membranes were submitted to an exhaustive extraction with solvent to remove the polystyrene homopolymer formed. The degree of grafting (DOG) was analyzed by percentage of weight increase. As a result, the reaction always follows the same pattern: DOG increases rapidly initially whilst propagation is the main reaction, then more slowly as termination becomes more frequent. (author)

Proton-Conducting Sulfonated Ionomers by Chemical Modification and Atom Transfer Radical Polymerization

DEFF Research Database (Denmark)

Nielsen, Mads Møller

The cornerstone in this dissertation is made up by three individual assessments of the diversity in the macromolecular landscape that can be obtained by applying relatively few efficient chemical tools. The intention is to gain deeper knowledge on the chemical tuning of proton exchange membranes...... of hydrocarbon macromolecular architectures, PSU with postsulfonated polystyrene (PS) grafts are investigated. Here, IEC is controlled through the degree of substitution, the graft length and DS. The grafting is performed with atom transfer radical polymerization (ATRP). The third assessment is dedicated...... of control by ATRP and click chemistry enables a wide selection of polymer structures with the handles: degree of substitution (DS), polymerization and sulfonation, and blending....

Surface-initiated Atom Transfer Radical Polymerization - a Technique to Develop Biofunctional Coatings

DEFF Research Database (Denmark)

Fristrup, Charlotte Juel; Jankova Atanasova, Katja; Hvilsted, Søren

2009-01-01

The initial formation of initiating sites for atom transfer radical polymerization (ATRP) on various polymer surfaces and numerous inorganic and metallic surfaces is elaborated. The subsequent ATRP grafting of a multitude of monomers from such surfaces to generate thin covalently linked polymer...

Synthesis of Environmentally Responsive Polymers by Atom Transfer Radical Polymerization: Generation of Reversible Hydrophilic and Hydrophobic Surfaces

Directory of Open Access Journals (Sweden)

Vikas Mittal

2010-05-01

Full Text Available Environmentally responsive poly(N-isopropylacrylamide brushes were grafted from the surface of polymer particles or flat surfaces in order to generate reversible hydrophilic and hydrophobic surfaces. The use of atom transfer radical polymerization was demonstrated for the grafting of polymer brushes as it allows efficient control on the amount of grafted polymer. The polymer particles were generated with or without surfactant in the emulsion polymerization and their surface could be modified with the atom transfer radical polymerization (ATRP initiator. The uniform functionalization of the surface with ATRP initiator was responsible for the uniform grafting of polymer brushes. The grafted brushes responded reversibly with changes in temperature indicating that the reversible responsive behavior could be translated to the particle surfaces. The particles were observed to adsorb and desorb protein and virus molecules by changing the temperatures below or higher than 32 °C. The initiator functionalized particles could also be adsorbed on the flat surfaces. The adsorption process also required optimization of the heat treatment conditions to form a uniform layer of the particles on the substrate. The grafted polymer brushes also responded to the changes in temperatures similar to the spherical particles studied through water droplets placed on the flat substrates.

Halloysite nanotubes grafted hyperbranched (co)polymers via surface-initiated self-condensing vinyl (co)polymerization

International Nuclear Information System (INIS)

Mu Bin; Zhao Mingfei; Liu Peng

2008-01-01

Halloysite nanotubes (HNTs) grafted hyperbranched polymers were prepared by the self-condensing vinyl polymerization (SCVP) of 2-((bromoacetyl)oxy)ethyl acrylate (BAEA) and the self-condensing vinyl copolymerization of n-butyl acrylate (BA) and BAEA with BAEA as inimer (AB*) respectively, from the surfaces of the 2-bromoisobutyric acid modified halloysite nanotubes (HNTs-Br) via atom transfer radical polymerization (ATRP) technique. The halloysite nanotubes grafted hyperbranched polymer (HNTs-HP) and the halloysite nanotubes grafted hyperbranched copolymer (HNTs-HCP) were characterized by elemental analysis (EA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscope (TEM). The grafted hyperbranched polymers were characterized with Nuclear magnetic resonance (NMR) and the molecular ratio between the inimer AB* and BA in the grafted hyperbranched copolymers was found to be 3:2, calculated from the TGA and EA results

Halloysite nanotubes grafted hyperbranched (co)polymers via surface-initiated self-condensing vinyl (co)polymerization

Energy Technology Data Exchange (ETDEWEB)

Mu Bin; Zhao Mingfei; Liu Peng [Lanzhou University, State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering (China)], E-mail: pliu@lzu.edu.cn

2008-05-15

Halloysite nanotubes (HNTs) grafted hyperbranched polymers were prepared by the self-condensing vinyl polymerization (SCVP) of 2-((bromoacetyl)oxy)ethyl acrylate (BAEA) and the self-condensing vinyl copolymerization of n-butyl acrylate (BA) and BAEA with BAEA as inimer (AB*) respectively, from the surfaces of the 2-bromoisobutyric acid modified halloysite nanotubes (HNTs-Br) via atom transfer radical polymerization (ATRP) technique. The halloysite nanotubes grafted hyperbranched polymer (HNTs-HP) and the halloysite nanotubes grafted hyperbranched copolymer (HNTs-HCP) were characterized by elemental analysis (EA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscope (TEM). The grafted hyperbranched polymers were characterized with Nuclear magnetic resonance (NMR) and the molecular ratio between the inimer AB* and BA in the grafted hyperbranched copolymers was found to be 3:2, calculated from the TGA and EA results.

Metal-catalyzed living radical polymerization and radical polyaddition for precision polymer synthesis

Energy Technology Data Exchange (ETDEWEB)

Mizutani, M; Satoh, K [Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kamigaito, M, E-mail: kamigait@apchem.nagoya-u.ac.j

2009-08-01

The metal-catalyzed radical addition reaction can be evolved into two different polymerization mechanisms, i.e.; chain- and step-growth polymerizations, while both the polymerizations are based on the same metal-catalyzed radical formation reaction. The former is a widely employed metal-catalyzed living radical polymerization or atom transfer radical polymerization of common vinyl monomers, and the latter is a novel metal-catalyzed radical polyaddition of designed monomer with an unconjugated C=C double bond and a reactive C-Cl bond in one molecule. The simultaneous ruthenium-catalyzed living radical polymerization of methyl acrylate and radical polyaddition of 3-butenyl 2-chloropropionate was achieved with Ru(Cp*)Cl(PPh{sub 3}){sub 2} to afford the controlled polymers, in which the homopolymer segments with the controlled chain length were connected by the ester linkage.

Crystalline TiO2 grafted with poly(2-methacryloyloxyethyl phosphorylcholine) via surface-initiated atom-transfer radical polymerization

International Nuclear Information System (INIS)

Zhao Yuancong; Tu Qiufen; Wang Jin; Huang Qiongjian; Huang Nan

2010-01-01

Crystalline TiO 2 films were prepared by unbalanced magnetron sputtering and the structure was confirmed by XRD. An organic layer of 11-hydroxyundecylphosphonic acid (HUPA) was prepared on the TiO 2 films by self-assembling, and the HUPA on TiO 2 films was confirmed by FTIR analysis. Simultaneously, hydroxyl groups were introduced in the phosphonic acid molecules to provide a functionality for further chemical modification. 2-Methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, was chemically grafted on the HUPA surfaces at room temperature by surface-initiated atom-transfer radical polymerization. The surface characters of TiO 2 films modified by poly-MPC were confirmed by FTIR, XPS and SEM analysis. Platelet adhesion experiment revealed that poly-MPC modified surface was effective to inhibit platelet adhesion in vitro.

Crystalline TiO 2 grafted with poly(2-methacryloyloxyethyl phosphorylcholine) via surface-initiated atom-transfer radical polymerization

Science.gov (United States)

Zhao, Yuancong; Tu, Qiufen; Wang, Jin; Huang, Qiongjian; Huang, Nan

2010-12-01

Crystalline TiO 2 films were prepared by unbalanced magnetron sputtering and the structure was confirmed by XRD. An organic layer of 11-hydroxyundecylphosphonic acid (HUPA) was prepared on the TiO 2 films by self-assembling, and the HUPA on TiO 2 films was confirmed by FTIR analysis. Simultaneously, hydroxyl groups were introduced in the phosphonic acid molecules to provide a functionality for further chemical modification. 2-Methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, was chemically grafted on the HUPA surfaces at room temperature by surface-initiated atom-transfer radical polymerization. The surface characters of TiO 2 films modified by poly-MPC were confirmed by FTIR, XPS and SEM analysis. Platelet adhesion experiment revealed that poly-MPC modified surface was effective to inhibit platelet adhesion in vitro.

Preparation of polystyrene brush film by radical chain-transfer polymerization and micromechanical properties

Energy Technology Data Exchange (ETDEWEB)

Zhao Jing [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Chen Miao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: miaochen99@yahoo.com; An Yanqing [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Liu Jianxi [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Yan Fengyuan [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)], E-mail: fyyan@lzb.ac.cn

2008-12-30

A radical chain-transfer polymerization technique has been applied to graft-polymerize brushes of polystyrene (PSt) on single-crystal silicon substrates. 3-Mercapto-propyltrimethoxysilane (MPTMS), as a chain-transfer agent for grafting, was immobilized on the silicon surface by a self-assembling process. The structure and morphology of the graft-functionalized silicon surfaces were characterized by the means of contact-angle measurement, ellipsometric thickness measurement, Fourier transformation infrared (FTIR) spectroscopy, and atomic force microscopy (AFM). The nanotribological and micromechanical properties of the as-prepared polymer brush films were investigated by frictional force microscopy (FFM), force-volume analysis and scratch test. The results indicate that the friction properties of the grafted polymer films can be improved significantly by the treatment of toluene, and the chemically bonded polystyrene film exhibits superior scratch resistance behavior compared with the spin-coated polystyrene film. The resultant polystyrene brush film is expected to develop as a potential lubrication coating for microelectromechanical systems (MEMS)

Preparation of antifouling ultrafiltration membranes via irradiation induced graft polymerization technique

International Nuclear Information System (INIS)

Deng Bo; Liu Zhognying; Lu Xiaofeng; Li Jingye; Yang Xuanxuan; Yu Ming; Zhang Bowu

2010-01-01

PVDF powders were irradiated in air at dose of 15 kGy by using gamma-rays. Macromolecular peroxides transformed from free radicals in the irradiated PVDF powders in air can be preserved for long-term at appropriate temperature stably. By mixing acrylic monomers with irradiated PVDF powders then the graft polymerization can be initiated by heating. Then a series of hydrophilic ultrafiltration (UF) membranes were fabricated by dissolving the PVDF-g-PAAc powders in the NMP under phase inversion method. The antifouling performances of UF membranes cast from virgin and grafted PVDF powders were compared. (authors)

Development of deodorizing materials by radiation graft polymerization

International Nuclear Information System (INIS)

Sugo, Takanobu; Okamoto, Jiro; Fujiwara, Kunio; Sekiguchi, Hideo.

1989-01-01

With the development of society, the countermeasures for service water and sewerage in large cities and the environment preservation in industrial districts become difficult as their scale becomes larger. There are many unsolved problems, for example photochemical smog due to harmful gases, exhaust gas from automobiles, and smell of toilets and home waste water. The deodorizing materials used so far are mainly inorganic substances, and their ability of adsorbing harmful gases is very low. Besides, those are mostly granular, and limited in the formability. Therefore, it is expected to develop the fibrous adsorbent which has large adsorbing surface area and is easy to make filters. The chemical structures of the compounds having smell are shown. Eight legal bad smell substances which exert large influence to environment even in very small amount are designated. In this paper, the method of introducing functional radicals into existing fiber materials by the application of radiation graft polymerization process and the test of removing smelling compositions by using the obtained resin are reported. The experimental method, and the results of radiation graft polymerization, the adsorption of basic gases and acid gases, and gas flow test are described. (K.I.)

Crystalline TiO{sub 2} grafted with poly(2-methacryloyloxyethyl phosphorylcholine) via surface-initiated atom-transfer radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Zhao Yuancong; Tu Qiufen; Wang Jin; Huang Qiongjian [Key Lab. of Advanced Technology for Materials, Education Ministry, School of Material Science and Technology of Southwest Jiaotong University, Chengdu, Sichuan (China); Huang Nan, E-mail: zhaoyc7320@163.com [Key Lab. of Advanced Technology for Materials, Education Ministry, School of Material Science and Technology of Southwest Jiaotong University, Chengdu, Sichuan (China)

2010-12-15

Crystalline TiO{sub 2} films were prepared by unbalanced magnetron sputtering and the structure was confirmed by XRD. An organic layer of 11-hydroxyundecylphosphonic acid (HUPA) was prepared on the TiO{sub 2} films by self-assembling, and the HUPA on TiO{sub 2} films was confirmed by FTIR analysis. Simultaneously, hydroxyl groups were introduced in the phosphonic acid molecules to provide a functionality for further chemical modification. 2-Methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, was chemically grafted on the HUPA surfaces at room temperature by surface-initiated atom-transfer radical polymerization. The surface characters of TiO{sub 2} films modified by poly-MPC were confirmed by FTIR, XPS and SEM analysis. Platelet adhesion experiment revealed that poly-MPC modified surface was effective to inhibit platelet adhesion in vitro.

Electron-beam-induced post-grafting polymerization of acrylic acid onto the surface of Kevlar fibers

Science.gov (United States)

Xu, Lu; Hu, Jiangtao; Ma, Hongjuan; Wu, Guozhong

2018-04-01

The surface of Kevlar fibers was successfully modified by electron beam (EB)-induced post-grafting of acrylic acid (AA). The generation of radicals in the fibers was confirmed by electron spin resonance (ESR) measurements, and the concentration of radicals was shown to increase as the absorbed dose increased, but decrease with increasing temperature. The influence of the synthesis conditions on the degree of grafting was also investigated. The surface microstructure and chemical composition of the modified Kevlar fibers were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The SEM images revealed that the surface of the grafted fibers was rougher than those of the pristine and irradiated fibers. XPS analysis confirmed an increase in C(O)OH groups on the surface of the Kevlar fibers, suggesting successful grafting of AA. These results indicate that EB-induced post-grafting polymerization is effective for modifying the surface properties of Kevlar fibers.

Functionalization of lanthanum hydroxide nanowires by atom transfer radical polymerization

International Nuclear Information System (INIS)

Zhou Mi; Yuan Jinying; Yuan Weizhong; Yin Yingwu; Hong Xiaoyin

2007-01-01

Atom transfer radical polymerization (ATRP) has been used to prepare a core-shell hybrid nanostructure successfully: a hard core of single-crystalline lanthanum hydroxide nanowires and a soft shell of polystyrene (PS) brushes. Transmission electron microscopy (TEM) images indicated that the resulting products presented special structures and different thicknesses of polymer layers. The chemical components and grafted PS quantities of the samples were measured by Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The polymers showed narrow polydispersity, which proved that the lanthanum hydroxide nanowires initiated the 'living'/controlled polymerization of styrene. With the modifiability of lanthanum hydroxide nanowires, the solubility increased, which affords a new way to functionalize nanowires

Graft polymerization of acrylic acid onto chitin nanofiber to improve dispersibility in basic water.

Science.gov (United States)

Ifuku, Shinsuke; Iwasaki, Masayoshi; Morimoto, Minoru; Saimoto, Hiroyuki

2012-09-01

Graft copolymerization of acrylic acid (AA) on chitin nanofibers was carried out with potassium persulfate as a free radical initiator in an aqueous medium. The molar ratio of grafted AA increased with the AA concentration. The grafted chitin nanofibers were characterized by FT-IR, FE-SEM, UV-vis, XRD, and TGA. After polymerization, the characteristic morphology of chitin nanofibers was maintained. Chitin nanofibers grafted with AA were efficiently dissociated and dispersed homogeneously in basic water because of the electrostatic repulsion effect between nanofibers. AA was grafted on the surface and amorphous part of chitin nanofibers, and the original crystalline structure of α-chitin was maintained. At 330 °C, the weight residue of the graft copolymer increased with the grafted AA content. Copyright © 2012 Elsevier Ltd. All rights reserved.

The role of hydroperoxides as a precursor in the radiation-induced graft polymerization of methyl methacrylate to ultra-high molecular weight polyethylene

Energy Technology Data Exchange (ETDEWEB)

Enomoto, Ichiro, E-mail: enomoto.ichiro@iri-tokyo.j [Tokyo Metropolitan Industrial Technology Research Institute, KFC bldg., 12F, 1-6-1, Yokoami, Sumida-ku, Tokyo 130-0015 (Japan); School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Katsumura, Yosuke [School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Kudo, Hisaaki [School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Sekiguchi, Masayuki [Tokyo Metropolitan Industrial Technology Research Institute, KFC bldg., 12F, 1-6-1, Yokoami, Sumida-ku, Tokyo 130-0015 (Japan)

2010-06-15

A graft polymerization of methyl methacrylate (MMA) to ultra-high molecular weight polyethylene (UHMWPE) with Co-60 gamma-ray irradiation in air at room temperature has been carried out. The grafting yields were measured as a function of the storage time (elapsed time from the end of irradiation to the start of grafting), and it was found that the yields reach at the maximum values at around several days since the end of irradiation. In order to clarify the precursor of the graft polymerization, changes of the radical yields and the carbonyl groups were measured as a function of storage time with ESR and microscopic FT-IR, respectively. From the similarities between the depth profiles of the hydroperoxide formation and the grafting products, it was concluded that the hydroperoxides can be main precursors of the grafting of the radiation-induced polymerization of MMA to UHMWPE under the given conditions.

The role of hydroperoxides as a precursor in the radiation-induced graft polymerization of methyl methacrylate to ultra-high molecular weight polyethylene

International Nuclear Information System (INIS)

Enomoto, Ichiro; Katsumura, Yosuke; Kudo, Hisaaki; Sekiguchi, Masayuki

2010-01-01

A graft polymerization of methyl methacrylate (MMA) to ultra-high molecular weight polyethylene (UHMWPE) with Co-60 γ-ray irradiation in air at room temperature has been carried out. The grafting yields were measured as a function of the storage time (elapsed time from the end of irradiation to the start of grafting), and it was found that the yields reach at the maximum values at around several days since the end of irradiation. In order to clarify the precursor of the graft polymerization, changes of the radical yields and the carbonyl groups were measured as a function of storage time with ESR and microscopic FT-IR, respectively. From the similarities between the depth profiles of the hydroperoxide formation and the grafting products, it was concluded that the hydroperoxides can be main precursors of the grafting of the radiation-induced polymerization of MMA to UHMWPE under the given conditions.

Hydrophilization of poly(ether ether ketone) films by surface-initiated atom transfer radical polymerization

DEFF Research Database (Denmark)

Fristrup, Charlotte Juel; Jankova Atanasova, Katja; Hvilsted, Søren

2010-01-01

Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP) has been exploited to hydrophilize PEEK. The ketone groups on the PEEK surface were reduced to hydroxyl groups which were converted to bromoisobutyrate initiating sites for SI-ATRP. The modification steps were followed by contact...... angle measurements and XPS. Moreover, ATR FTIR has been used to confirm the formation of initiating groups. Grafting of PEGMA from PEEK was performed in aqueous solution. The presence of the PPEGMA grafts on PEEK was revealed by the thermograms from TGA whereas investigations with AFM rejected changes...

Poly(N-4-vinylbenzyl-1,4,7-triazacyclononane Copper Complex Grafted Solid Catalyst for Oxidative Polymerization of 2,6-Dimethylphenol

Directory of Open Access Journals (Sweden)

Kei Saito

2016-01-01

Full Text Available A new solid phase catalyst, poly(N-4-vinylbenzyl-1,4,7-triazacyclononane copper(I complex, grafted onto polystyrene particles, has been employed for the oxidative polymerization of 2,6-dimethylphenol using an aqueous biphasic (water/toluene solvent system. The solid catalyst was synthesized by first grafting N-(4-vinylbenzyl-1,4,7-triaza-cyclononane onto polystyrene particles using a radical mediated polymerization method and next by creating the polymer-metal complex of copper-triazacyclononane with these modified particles. Poly(2,6-dimethyl-1,4-phenylene oxide was successfully obtained from the polymerization of 2,6-dimethylphenol using this new metal-organic solid phase catalyst.

Efficient Functionalization of Polyethylene Fibers for the Uranium Extraction from Seawater through Atom Transfer Radical Polymerization

Energy Technology Data Exchange (ETDEWEB)

Neti, Venkata S. [Chemical; Das, Sadananda [Chemical; Brown, Suree [Department; Janke, Christopher J. [Materials; Kuo, Li-Jung [Marine; Gill, Gary A. [Marine; Dai, Sheng [Chemical; Department; Mayes, Richard T. [Chemical

2017-09-14

Brush-on-brush structures are proposed as one method to overcome support effects in grafted polymers. Utilizing glycidyl methacrylate (GMA) grafted on polyethylene (PE) fibers using radiation-induced graft polymerization (RIGP) provides a hydrophilic surface on the hydrophobic PE. When integrated with atom transfer radical polymerization (ATRP), the grafting of acrylonitrile (AN) and hydroxyethyl acrylate (HEA) can be controlled and manipulated more easily than with RIGP. Poly(acrylonitrile)-co-poly(hydroxyethyl acrylate) chains were grown via ATRP on PE-GMA fibers to generate an adsorbent for the extraction of uranium from seawater. The prepared adsorbents in this study demonstrated promise (159.9 g- U/kg of adsorbent) in laboratory screening tests using a high uranium concentration brine and 1.24 g-U/Kg of adsorbent in the filtered natural seawater in 21-days. The modest capacity in 21- days exceeds previous efforts to generate brush-on-brush adsorbents by ATRP while manipulating the apparent surface hydrophilicity of the trunk material (PE).

Graft polymerization of vynil monomers at carbon black surface (1)

International Nuclear Information System (INIS)

Haryono Arumbinang.

1976-01-01

Effect of aromatic condensates containing functional group on carbon black surface, effect of pH condensates on carbon black chemisorption, analysis and configuration of functional group, the crystal structure, property measurement standard, particle diameter measurement, oil adsorption, colour capacity, volatile acid content, electric resistence and the volume of the granular or carbon black dust, are given. Electron paramagnetic resonance determination of the amount of free radicals on carbon black surface, its oxidation and effects on the surface and inner structure of carbon black, and graft polymerization by radiation copolymerization, are discussed. Experiments on radiation graft copolymerization by acrylic acid, methacrylate, and glycidol methacrylate, in a vacuum condition, have been carried out. It is concluded that further research on the modification and configuration of carbon black should be developed. (author)

Radiation-Induced Graft Polymerization: Gamma Radiation and Electron Beam Technology for Materials Development

International Nuclear Information System (INIS)

Madrid, Jordan F.; Cabalar, Patrick Jay; Lopez, Girlie Eunice; Abad, Lucille V.

2015-01-01

The formation of functional hybrid materials by attaching polymer chains with advantageous tailored properties to the surface of a base polymer with desirable bulk character is an attractive application of graft copolymerization. Radiation-induced graft polymerization (RIGP) has been a popular approach for surface modification of polymers because of its merits over conventional chemical processes. RIGP, which proceeds primarily via free radical polymerization process, has the advantages such as simplicity, low cost, control over process and adjustment of the materials composition and structure. RIGP can be performed using either electron beam or gamma radiation and it can be applied to both synthetic and natural polymers. These merits make RIGP a popular research topic worldwide. Moreover, the materials synthesized and produced via RIGP has found applications, and were proposed to produce continuous impact, in the fields of medicine, agriculture, pollution remediation, rare earth and valuable metals recovery, fuel cell membrane synthesis and catalysis to name a few. From 2012 our group has performed electron beam and gamma radiation-induced graft polymerization of various monomers onto polymers of natural and synthetic origins (e.g. monomers - glycidyl methacrylate, styrene, acrylonitrile, N,N-dimethylaminoethyl methacrylate; base polymers – polyethylene/polypropylene nonwoven fabric, polypropylene nonwoven fabric pineapple fibers, cellulose nonwoven fabric microcrystalline cellulose). We tested these grafted materials for heavy metals (Pb, Ni, Cu) and organic molecule removal from aqueous solutions and E. coli activity (using reversible addition fragmentation chain transfer RAFT mediated grafting). The results clearly showed the success of materials modified via FIGP in these applications. Currently, we are studying the applications of grafted materials on treatment of waste waters from tanning industry, value addition to abaca nonwoven fabrics cell sheet

Pre-irradiation induced emulsion graft polymerization of acrylonitrile onto polyethylene nonwoven fabric

International Nuclear Information System (INIS)

Liu Hanzhou; Yu Ming; Deng Bo; Li Linfan; Jiang Haiqing; Li Jingye

2012-01-01

Acrylonitrile has been widely used in the modification of polymers by graft polymerization. In the present work, pre-irradiation induced emulsion graft polymerization method is used to introduce acrylonitrile onto PE nonwoven fabric instead of the traditional reaction in organic solvents system. The degree of grafting (DG) is measured by gravimetric method and the kinetics of the graft polymerization is studied. The existence of the graft chains is proven by Fourier transform infrared spectroscopy (FT-IR) analysis. Thermal stability of the grafted polymer is measured by Thermogravimetric analysis (TGA). - Highlights: → Acrylonitrile is grafted onto pre-irradiated polyethylene (PE) nonwoven fabrics. → Emulsion system is applied, for the graft polymerization avoids organic solvent. → Kinetic of the pre-irradiation induced graft polymerization is studied. → Optimal condition is determined at the temperature below the b.p. of acrylonitrile.

High fluorescence emission silver nano particles coated with poly (styrene-g-soybean oil) graft copolymers: Antibacterial activity and polymerization kinetics.

Science.gov (United States)

Hazer, Baki; Kalaycı, Özlem A

2017-05-01

Autoxidation of poly unsaturated fatty acids makes negative effect on foods. In this work, this negative effect was turned to a great advantage using autoxidized soybean oil as a macroperoxide nanocomposite initiator containing silver nano particles in free radical polymerization of vinyl monomers. The synthesis of soybean oil macro peroxide was carried out by exposing soybean oil to air oxygen with the presence of silver nanoparticles (Ag NPs) at room temperature. Autoxidized soybean oil macroperoxide containing silver nanoparticles (Agsbox) successfully initiated the free radical polymerization of styrene in order to obtain Polystyrene (PS)-g-soybean oil graft copolymer containing Ag NPs. Both autoxidized soybean oil and PS-g-sbox with Ag NPs showed a surface plasmon resonance and high fluorescence emission. Overall rate constant (K) of styrene polymerization initiated by autoxidized soybean oil macroperoxide with Ag NPs was found to be K=1.95.10 -4 Lmol -1 s -1 at 95°C. Antibacterial efficiency was observed in the PS-g-soybean oil graft copolymer film samples containing Ag NPs. 1 H NMR and GPC techniques were used for the structural analysis of the fractionated polymeric oils. Copyright © 2016 Elsevier B.V. All rights reserved.

Constructing Functional Ionic Membrane Surface by Electrochemically Mediated Atom Transfer Radical Polymerization

Directory of Open Access Journals (Sweden)

Fen Ran

2016-01-01

Full Text Available The sodium polyacrylate (PAANa contained polyethersulfone membrane that was fabricated by preparation of PES-NH2 via nonsolvent phase separation method, the introduction of bromine groups as active sites by grafting α-Bromoisobutyryl bromide, and surface-initiated electrochemically atom transfer radical polymerization (SI-eATRP of sodium acrylate (AANa on the surface of PES membrane. The polymerization could be controlled by reaction condition, such as monomer concentration, electric potential, polymerization time, and modifier concentration. The membrane surface was uniform when the monomer concentration was 0.9 mol/L, the electric potential was −0.12 V, the polymerization time was 8 h, and the modifier concentration was 2 wt.%. The membrane showed excellent hydrophilicity and blood compatibility. The water contact angle decreased from 84° to 68° and activated partial thromboplastin increased from 51 s to 84 s after modification of the membranes.

Grafting of polymer onto silica surface in the presence of γ-ray irradiated silica

International Nuclear Information System (INIS)

Tsuchida, A.; Yokoyama, R.; Takami, M.; Chen, J.; Ohta, M.; Tsubokawa, N.

2002-01-01

Complete text of publication follows. We have reported the graft polymerization of vinyl monomers initiated by surface radicals formed by the decomposition of azo and peroxide groups previously introduced onto the surface. In addition, the grafting of polymers onto carbon black has been reported by the reaction of polymer radicals with the surface. On the other hand, it is well known that the relatively stable radicals are generated on the surface by the γ-ray irradiation. In this paper, the grafting of polystyrene onto silica surface during the thermal polymerization of styrene in the presence of γ-ray irradiated silica, grafting mechanism and thermal stability of grafted polymer will be discussed. The grafting of polymers onto silica surface by irradiation of polymer-adsorbed silica was also investigated. Silica obtained from Mitsubishi Chemical Co., Japan was used after pulverization: the particle size was 0.037-0.088 mm. Irradiation was performed in Cs-137 source at room temperature. The silica was irradiated at 50 Gy with dose rate of 3.463 Gy/min. Into a polymerization tube, styrene and irradiated silica was charged and the polymerization was carried out under argon under stirring. The percentage of polystyrene grafting was determined from weight loss when polystyrene-grafted silica was heated at 600 deg C by a thermal analyzer. Untreated silica did not affect the thermal polymerization of styrene. On the contrary, the thermal polymerization of styrene was remarkably retarded in the presence of the irradiated silica at 60 deg C. Similar tendency was reported during the polymerization of vinyl monomers in the presence of carbon black. In the initial stage of the polymerization in the presence of the irradiated silica below 50 deg C, the polymerization was accelerated. During the polymerization in the presence of irradiated silica, polystyrene was grafted onto the surface: the percentage of grafting was 5-11%. The amount of polystyrene grafted onto silica

Cotton fibers encapsulated with homo- and block copolymers: synthesis by the atom transfer radical polymerization grafting-from technique and solid-state NMR dynamic investigations.

Science.gov (United States)

Castelvetro, Valter; Geppi, Marco; Giaiacopi, Simone; Mollica, Giulia

2007-02-01

Cotton fibers were modified by surface-initiated atom transfer radical polymerization of ethyl acrylate (EA) followed by copolymerization with styrene. Either ethyl 2-bromopropionate as a sacrificial free initiator or Cu(II) as a deactivator was used to optimize the EA grafting yield and to preserve the livingness of the chain ends for the subsequent growth of a poly(styrene) (PSty) block from the poly(ethyl acrylate) (PEA) grafts. The polymer-encapsulated cotton fibers were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, and solid-state NMR (high-resolution 13C cross-polarization magic angle spinning, 1H spin-lattice relaxation times, and 1H free induction decay analysis NMR). The latter allowed the detection of the dynamic modifications associated with the presence of homo- and block copolymer grafts. In particular, the results of the DSC and NMR investigations suggest a heterogeneous morphology of the g-PEA-b-PSty grafted skin, which could be described as an inner layer of g-PEA sandwiched between the semicrystalline cellulose of the core fiber and the high glass transition temperature PSty of the covalently linked outer layer. Such morphology results in a reduced molecular mobility of the PEA chains.

prepared via atom transfer radical polymerization, reverse atom

Indian Academy of Sciences (India)

Synthesis and characterization of poly(2-ethylhexyl acrylate) prepared via atom transfer radical polymerization, reverse atom transfer radical polymerization and ... Zydex Industries, 25-A Gandhi Oil Mill Compound, Gorwa, Vadodara 390 016, India; Rubber Technology Centre, Indian Institute of Technology Kharagpur, ...

Functionalization and Polymerization on the CNT Surfaces

KAUST Repository

Albuerne, Julio

2013-07-01

In this review we focus on the current status of using carbon nanotube (CNT) as a filler for polymer nanocomposites. Starting with the historical background of CNT, its distinct properties and the surface functionalization of the nanotube, the three different surface polymerization techniques, namely grafting "from", "to" and "through/in between" were discussed. Wider focus has been given on "grafting from" surface initiated polymerizations, including atom transfer radical polymerization (ATRP), reversible addition fragmentation chain-transfer (RAFT) Polymerization, nitroxide mediated polymerization (NMP), ring opening polymerization (ROP) and other miscellaneous polymerization methods. The grafting "to" and "through / in between" also discussed and compared with grafting from polymerization. The merits and shortcomings of all three grafting methods were discussed and the bottleneck issue in grafting from method has been highlighted. Furthermore the current and potential future industrial applications were deliberated. Finally the toxicity issue of CNTs in the final product has been reviewed with the limited available literature knowledge. © 2013 Bentham Science Publishers.

Fluoropolymer materials and architectures prepared by controlled radical polymerizations

DEFF Research Database (Denmark)

Hansen, Natanya Majbritt Louie; Jankova Atanasova, Katja; Hvilsted, Søren

2007-01-01

This review initially summarizes the mechanisms, merits and limitations of the three controlled radical polymerizations: nitroxide mediated polymerization (NMP), atom transfer radical polymerization (ATRP) or metal catalyzed living radical polymerization, and reversible addition–fragmentation chain...... transfer (RAFT) polymerization. This is followed by two parts, one dealing with homo- and copolymerizations of fluorinated methacrylates and acrylates, and a second where fluorinated styrenes, alone or in combination with other monomers, are the main issues. In these parts, initiators (including...... properties and functionalities that can be obtained from these novel fluorinated materials and architectures are especially emphasized. Thus, various amphiphilic, biocompatible or low energy materials, fluorinated nanoparticles and nanoporous films/membranes as well as materials for submicron and nanolevel...

TRANSITION METAL CATALYSIS IN CONTROLLED RADICAL POLYMERIZATION: ATOM TRANSFER RADICAL POLYMERIZATION. (R826735)

Science.gov (United States)

Novel and diversified macromolecular structures, which include polymers with designed topologies (top), compostions (middle), and functionalities (bottom), can be prepared by atom transfer radical polymerization processes. These polymers can be synthesized from a large variety of...

Preparation of Mg(OH)_2 hybrid pigment by direct precipitation and graft onto cellulose fiber via surface-initiated atom transfer radical polymerization

International Nuclear Information System (INIS)

Wang, Xiao; Zhang, Yue; Lv, Lihua; Cui, Yongzhu; Wei, Chunyan; Pang, Guibing

2016-01-01

Graphical abstract: - Highlights: • Adsorbed anionic dye molecules are conducive to preferential growth of (0 0 1) plane of Mg(OH)_2 crystal for Mg(OH)_2 pigments. • Uniform coverage of nanosized Mg(OH)_2 pigments on fiber surface is achieved via surface-initiated ATRP. • About 4 wt% of Mg(OH)_2 pigment on fiber surface shortens nearly half of burning time of cellulose. - Abstract: Mg(OH)_2 flame retardant hybrid pigment is synthesized through simultaneous solution precipitation and adsorption of anionic dyes (C.I. Acid Red 6). The Mg(OH)_2 hybrid pigment bearing vinyl groups after surface silane modification is immobilized onto the surface of bromo end-functional cellulose fiber by atom transfer radical polymerization (ATRP). The morphology and structure of Mg(OH)_2 pigments and cellulose fibers grafted with modified pigments are characterized. The thermal properties, flammability and color fastness of cellulose fibers grafted with modified pigments are measured. The results reveal that anionic dye molecules are adsorbed onto Mg(OH)_2 crystals and affect the formation of lamella-like Mg(OH)_2 crystals. The cellulose fiber grafted with modified Mg(OH)_2 hybrid pigment absorbs about four times heat more than original cellulose fiber with about 4% immobilization ratio of pigment, which shortens nearly half of afterflame time and afterglow time.

Preparation of polymer brushes grafted graphene oxide by atom transfer radical polymerization as a new support for trypsin immobilization and efficient proteome digestion.

Science.gov (United States)

Guo, Cong; Zhao, Xinyuan; Zhang, Wanjun; Bai, Haihong; Qin, Weijie; Song, Haifeng; Qian, Xiaohong

2017-08-01

Highly efficient protein digestion is one of the key issues in the "bottom-up" strategy-based proteomic studies. Compared with the time-consuming solution-based free protease digestion, immobilized protease digestion offers a promising alternative with obviously improved sample processing throughput. In this study, we proposed a new immobilized protease digestion strategy using two kinds of polymer-grafted graphene oxide (GO) conjugated trypsin. The polymer brush grafted GO was prepared using in situ polymer growth on initiator-functionalized GO using surface-initiated atom transfer radical polymerization (SI-ATRP) and characterized by AFM, TEM, TGA, and XPS. The polymer brush grafted GO supports three-dimensional trypsin immobilization, which not only increases the loading amount but also improves accessibility towards protein substrates. Both of the two types of immobilized trypsin provide 700 times shorter digestion time, while maintaining comparable protein/peptide identification scale compared with that of free trypsin digestion. More interestingly, combined application of the two types of immobilized trypsin with different surface-grafted polymers leads to at least 18.3/31.3% enhancement in protein/peptide identification compared with that obtained by digestion using a single type, indicating the potential of this digestion strategy for deeper proteome coverage using limited mass spectrometer machine hour. We expect these advantages may find valuable application in high throughput clinical proteomic studies, which often involve processing of a large number of samples. Graphical abstract Preparation of polymer brushes grafted and trypsin immobilized graphene oxide and its application in proteome digestion and mass spectrometry identification.

Allylthioketone Mediated Free Radical Polymerization of Methacrylates

Directory of Open Access Journals (Sweden)

Feng Zhong

2017-11-01

Full Text Available By combination of high trapping free radical efficiency of the thioketone and resonance of the allylic radical, a new type of mediating agent, 1,3,3-triphenylprop-2-ene-1-thione (TPPT has been successfully synthesized, and then is used to study controlled free radical polymerization of methacrylates. Very stable TPPT radicals at the end of poly(methyl methacrylate (PMMA are detected in the polymerization of MMA using TPPT and AIBN as the control agent and initiator. The MALDI-TOF MS spectra are used to identify terminal groups of the resultant poly(glycidyl methacrylate (PGMA, and major component of the obtained polymer has the structure, (CH32(CNC-PGMA-C7H9O3. Chain extension reaction tests ascertain formation of the dead polymers during the polymer storage and purification process of the polymers. Owing to very slow fragmentation reaction of the TPPT-terminated polymethacrylate radical and addition reaction of this radical with a primary radical, the growing chain radicals are difficult to be regenerated, leading to an unobvious change of the molecular weight with monomer conversion. The molecular weights of polymers can be controlled by the ratios of monomer/initiator and TPPT/initiator. However, the first order kinetics of the polymerization and the polymers with narrow polydispersity are obtained, and these phenomena are discussed. This study provides useful information on how to design a better controlling agent.

Preparation of Dimethylaminoethylmethacrylate Grafted Polymeric Adsorbent by Using Radiation-Induced Grafting Technique for Removal of Anions

International Nuclear Information System (INIS)

Kavakli, P. A.

2006-01-01

The development of efficient separation and purification techniques is very important from industrial, environmental and economic points of view. Polymeric materials having polyfunctional groups such as carboxylic, amide, nitrile, iminodiacetic acid, amidoxime, and ammonium groups, etc., not only possess good hydrophilic properties, but also have good ion exchange properties which make them suitable for metal recovery from aqueous solutions. Radiation induced grafting is a powerful technique capable of controlling the introduction of various functional groups to the polymeric materials, keeping the original properties and especially the mechanical strength of the base material, and thus, allowing the synthesis of more stable polymeric adsorbents. The main objective of this study was to develop special polymeric adsorbents to remove NOx and PO 4 anions from aqueous systems. For this purpose, a novel nonwoven fabric was prepared by radiation-induced graft polymerization of imethylaminoethylmethacrylate (DMAEMA) onto polypropylene coated polyethylene nonwoven fabric. The trunk polymer was irradiated by electron beam at a voltage of 2 MeV and a current of 3 mA in a nitrogen atmosphere at dry-ice temperature at different doses. The degree of grafting was determined as a function of the total dose, monomer concentration, temperature, and reaction time. It was found that the degree of grafting of grafted polymer was greatly affected by reaction conditions. Grafting conditions were optimized, and about 150 % degree of grafting samples was used for further experiments. DMAEMA grafted polymer was later protonated by using acid solution to prepare adsorbent for the removal of anions. Adsorption experiments were performed in column mode for removal of phosphate. Approximately 2000 bed volumes of phosphate-free water can be produced from 10 ppb phosphate solution at high space velocity

Simulating Controlled Radical Polymerizations with mcPolymer—A Monte Carlo Approach

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Georg Drache

2012-07-01

Full Text Available Utilizing model calculations may lead to a better understanding of the complex kinetics of the controlled radical polymerization. We developed a universal simulation tool (mcPolymer, which is based on the widely used Monte Carlo simulation technique. This article focuses on the software architecture of the program, including its data management and optimization approaches. We were able to simulate polymer chains as individual objects, allowing us to gain more detailed microstructural information of the polymeric products. For all given examples of controlled radical polymerization (nitroxide mediated radical polymerization (NMRP homo- and copolymerization, atom transfer radical polymerization (ATRP, reversible addition fragmentation chain transfer polymerization (RAFT, we present detailed performance analyses demonstrating the influence of the system size, concentrations of reactants, and the peculiarities of data. Different possibilities were exemplarily illustrated for finding an adequate balance between precision, memory consumption, and computation time of the simulation. Due to its flexible software architecture, the application of mcPolymer is not limited to the controlled radical polymerization, but can be adjusted in a straightforward manner to further polymerization models.

Neutral hydrophilic coatings for capillary electrophoresis prepared by controlled radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Navarro, Fabián H.; Gómez, Jorge E.; Espinal, José H.; Sandoval, Junior E., E-mail: junior.sandoval@correounivalle.edu.co

2016-12-15

In the present study, porous silica particles as well as impervious fused-silica wafers and capillary tubes were modified with hydrophilic polymers (hydroxylated polyacrylamides and polyacrylates), using a surface-confined grafting procedure based on atom transfer radical polymerization (ATRP) which was also surface-initiated from α-bromoisobutyryl groups. Initiator immobilization was achieved by hydrosilylation of allyl alcohol on hydride silica followed by esterification of the resulting propanol-bonded surface with α-bromoisobutyryl bromide. Elemental analysis, IR and NMR spectroscopies on silica micro-particles, atomic force microscopy, ellipsometry and profilometry on fused-silica wafers, as well as CE on fused-silica tubes were used to characterize the chemically modified silica substrate at different stages. We studied the effect of monomer concentration as well as cross-linker on the ability of the polymer film to reduce electroosmosis and to prevent protein adsorption (i. e., its non-fouling capabilities) and found that the former was rather insensitive to both parameters. Surface deactivation towards adsorption was somewhat more susceptible to monomer concentration and appeared also to be favored by a low concentration of the cross-linker. The results show that hydrophilic polyacrylamide and polyacrylate coatings of controlled thickness can be prepared by ATRP under very mild polymerization conditions (aqueous solvent, room temperature and short reaction times) and that the coated capillary tubes exhibit high efficiencies for protein separations (0.3–0.6 million theoretical plates per meter) as well as long-term hydrolytic stability under the inherently harsh conditions of capillary isoelectric focusing. Additionally, there was no adsorption of lysozyme on the coated surface as indicated by a complete recovery of the basic enzyme. Furthermore, since polymerization is confined to the inner capillary surface, simple precautions (e.g., solution

Surface modification of cation exchange membranes by graft polymerization of PAA-co-PANI/MWCNTs nanoparticles

International Nuclear Information System (INIS)

Nemati, Mahsa; Hosseini, Sayed Mohsen; Bagheripour, Ehsan; Madaeni, Sayed Siavash

2016-01-01

Surface modification of polyvinylchloride based heterogeneous cation exchange membrane was performed by graft polymerization of PAA and PAA-co-PANI/MWCNTs nanoparticles. The ion exchange membranes were prepared by solution casting technique. Spectra analysis confirmed graft polymerization clearly. SEM images illustrated that graft polymerization covers the membranes by simple gel network entanglement. The membrane water content was decreased by graft polymerization of PAA-co-PANI/MWCNTs nanoparticles on membrane surface. Membrane transport number and selectivity declined initially by PAA graft polymerization and then began to increase by utilizing of composite nanoparticles in modifier solution. The sodium and barium flux was improved sharply by PAA and PAAco- 0.01%wt PANI/MWCNTs graft polymerization on membrane surface and then decreased again by more increase of PANI/MWCNTs nanoparticles content ratio in modifier solution. The electrodialysis experiment results in laboratory scale showed higher dialytic rate in heavy metals removal for grafted-PAA and grafted-PAA-co-PANI/MWCNTs modified membrane compared to pristine one. Membrane areal electrical resistance was also decreased by introducing graft polymerization of PAA and PAA-co-PANI/MWCNTs NPs on membrane surface.

Survey Study of Trunk Materials for Direct ATRP Grafting

Energy Technology Data Exchange (ETDEWEB)

Saito, Tomonori [ORNL; Chatterjee, Sabornie [ORNL; Johnson, Joseph C. [ORNL; Dai, Sheng [ORNL; Brown, Suree [ORNL

2015-02-01

In previous study, we demonstrated a new method to prepare polymeric fiber adsorbents via a chemical-grafting method, namely atom-transfer radical polymerization (ATRP), and identified parameters affecting their uranium adsorption capacity. However, ATRP chemical grafting in the previous study still utilized conventional radiation-induced graft polymerization (RIGP) to introduce initiation sites on fibers. Therefore, the objective of the present study is to perform survey study of trunk fiber materials for direct ATRP chemical grafting method without RIGP for the preparation of fiber adsorbents for uranium recovery from seawater.

Fabrication of ultrahydrophobic poly(lauryl acrylate) brushes on silicon wafer via surface-initiated atom transfer radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Oztuerk, Esra; Turan, Eylem [Department of Chemistry, Faculty of Art and Science, Gazi University, 06500 Besevler, Ankara (Turkey); Caykara, Tuncer, E-mail: caykara@gazi.edu.tr [Department of Chemistry, Faculty of Art and Science, Gazi University, 06500 Besevler, Ankara (Turkey)

2010-11-15

In this report, ultrahydrophobic poly(lauryl acrylate) [poly(LA)] brushes were synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) of lauryl acrylate (LA) in N,N-dimethylformamide (DMF) at 90 deg. C. The formation of ultrahydrophobic poly(LA) films, whose thickness can be turned by changing polymerization time, is evidenced by using the combination of ellipsometry, X-ray photoelectron spectroscopy (XPS), grazing angle attenuated total reflectance-Fourier transform infrared spectroscopy (GATR-FTIR), atomic force microscopy (AFM), gel permeation chromatography (GPC), and water contact angle measurements. The SI-ATRP can be conducted in a well-controlled manner, as revealed by the linear kinetic plot, linear evolution of number-average molecular weights (M-bar{sub n}) versus monomer conversions, and the relatively narrow PDI (<1.28) of the grafted poly(LA) chains. The calculation of grafting parameters from experimental measurements indicated the synthesis of densely grafted poly(LA) films and allowed us to predict a 'brushlike' conformation for the chains in good solvent. The poly(LA) brushes exhibited high water contact angle of 163.3 {+-} 2.8{sup o}.

RADIOCHEMICAL YIELDS OF GRAFT POLYMERIZATION REACTIONS OF CELLULOSE

Energy Technology Data Exchange (ETDEWEB)

Arthur, Jr, J C; Blouin, F A

1963-12-15

The preparation of radioinduced graft polymers of cotton cellulose, while retaining the fibrous nature and high molecular weight of the cellulose, depended primarily on the radiochemical yields of cellulose reactions and of graft polymerization reactions. Yields of the initial major molecular changes in cellulosic polymer indicated that, in the case of scission of the molecule and carboxyl group formation, chain reactions were not initiated by radiation; however, in the case of carbonyl group formation chain reactions were initiated but quickly terminated. Generally, experimental procedures, used in graft polymerization reactions, were: simultaneous irradiation reactions, that is, application of monomers or solutions of monomers to cellulose or chemically modified celluloses, then irradiation; and post-irradiation reactions, that is, irradiation of cellulose or chemically modified celluloses, then after removal from the field of radiation, contacting the irradiated cellulose with monomer. Some of the most important factors influencing the radiochemical yields of graft polymerization reactions, of styrene and acrylonitrile onto cellulose were: concentration of monomer in treating solution; solvent; ratio of monomer solution to cellulose; prior chemical modification of cellulose; and absence of oxygen, particularly in post-irradiation reactions. Experimental data are presented, and the direct and indirect effects of Co/sup 60/ gamma radiation on these reactions are discussed. (auth)

Effects of Molecular Iodine and 4-tert-Butylcatechol Radical Inhibitor on the Radical Polymerization of Styrene

Directory of Open Access Journals (Sweden)

Mojtaba Bozorg

2017-05-01

Full Text Available The presence of molecular iodine was studied in relation the molecular weight and molecular weight distribution of polystyrene, produced by radical poly merization. Radical polymerization of styrene initiated by 2,2׳-azobisisobutyronitrile (AIBN was performed at 70°C in the presence of molecular iodine. The synthesized polymers were characterized by gel permeation chromatography (GPC and proton- nuclear magnetic resonance (1H NMR techniques. The results of these reactions including conversion data, number-average molecular weight and molecular weight distribution were compared with those obtained for styrene radical polymerization initiated by AIBN at the same temperature in the absence of molecular iodine. It was found that the presence of iodine had a profound effect on the molecular weight and its distribution in the produced polystyrene. This was attributed to the ability of iodine to control the polymerization of styrene initiated by AIBN via reverse iodine transfer polymerization (RITP mechanism. The polymer produced by this method had a molecular weight of 10600 g/mol with a molecular weight polydispersity index of 1.3. Due to the importance of induction period in reverse iodine transfer radical polymerization, increasing the temperature to 120°C during the induction period resulted in shorter induction periods and the produced species led to better control of the molecular weight. Also, due to the role of iodine molecules as a radical inhibitor, the presence of a secondary radical inhibitor, i.e. 4-tert-butylcatechol, along with the iodine was investigated in radical polymerization of polystyrene initiated by AIBN. It was observed that the secondary radical inhibitor prevented the consumption of the iodine molecules by the radicals produced from decomposition of the AIBN initiator; therefore, alkyl halides were not produced during the induction period.

Study on non-ionic membrane prepared by radiation-induced graft polymerization

International Nuclear Information System (INIS)

Hegazy, E.-S.A.; Mokhtar, S.M.; Osman, M.B.S.; Mostafa, A.E.-K.B.

1990-01-01

The preparation of good hydrogel supported on polymeric material was carried out by means of direct radiation-induced graft polymerization of N-vinyl-2-pyrrolidone (NVP) onto low density polyethylene films (LDPE). The optimum conditions were determined, at which the grafting process occurred and suitable degrees of grafting were obtained with a homogeneous distribution of the graft chains throughout the polymer. The effect of different inhibitors, addition of ZnCl 2 and monomer concentration on the grafting yield was also studied. Some investigations and characterization on the prepared graft copolymer were investigated and the possibility of its practical use was discussed. Mechanical properties, thermal and chemical stability and hydrophilic properties of such prepared grafted films showed a great promise in some practical applications. (author)

Improving the organic and biological fouling resistance and removal of pharmaceutical and personal care products through nanofiltration by using in situ radical graft polymerization.

Science.gov (United States)

Lin, Yi-Li; Tsai, Chia-Cheng; Zheng, Nai-Yun

2018-09-01

In this study, an insitu radical graft polarization technique using monomers of 3-sulfopropyl methacrylate potassium salt (SPM) and 2-hydroxyethyl methacrylate (HEMA) was applied to a commercial nanofiltration membrane (NF90) to improve its removal of six commonly detected pharmaceutical and personal care products (PPCPs) and mitigate organic and biological fouling by humic acid (HA) and sodium alginate (SA). Compared with the virgin membrane, the modified NF90 membrane exhibited considerably improved fouling resistance and an increased reversible fouling percentage, especially for SA+HA composite fouling Moreover, the PPCP removal of the modified NF90 membrane was higher than that of the virgin membrane after SA and SA+HA fouling, respectively. Triclosan and carbamazepine, which are poorly rejected, could be effectively removed by modified membrane after SA or SA+HA fouling. Both monomers modified the membrane surface by increasing the hydrophilicity and decreasing the contact angle. The degree of grafting was quantified using attenuated total reflection Fourier-transform infrared spectroscopy. The mitigation in the fouling was evident from the low quantity of deposit formed on the modified membrane, as observed using scanning electron microscopy. A considerable amount of highly hydrophobic triclosan was adsorbed on the SA-fouled virgin membrane and penetrated through it. By contrast, the adsorption of triclosan was substantially lower in the SPM-modified membrane. After membrane modification, the fouling mechanism changed from solely intermediate blocking to both intermediate blocking and complete blocking after membrane modification. Thus, the in situ radical graft polymerization method effectively reduces organic and biological fouling and provides high PPCP removal, which is beneficial for fouling control and produces permeate of satisfactory quality for application in the field of membrane technology. Copyright © 2018 Elsevier B.V. All rights reserved.

Copper-mediated homogeneous living radical polymerization of acrylamide with waxy potato starch-based macroinitiator.

Science.gov (United States)

Fan, Yifei; Cao, Huatang; van Mastrigt, Frank; Pei, Yutao; Picchioni, Francesco

2018-07-15

Cu 0 -mediated living radical polymerization (Cu 0 -mediated LRP) was employed in this research for the synthesis of starch-g-polyacrylamide (St-g-PAM). The use of a controlled radical grafting technique is necessary, as compared to the traditional free-radical polymerization methods, in order to obtain a well-defined structure of the final product. This is in turn essential for studying the relationship between such structure and the end-properties. Waxy potato starch-based water-soluble macroinitiator was first synthesized by esterification with 2-bromopropionyl bromide in the mixture of dimethylacetamide and lithium chloride. With the obtained macroinitiator, St-g-PAM was homogeneously synthesized by aqueous Cu 0 -mediated LRP using CuBr/hexamethylated tris(2-aminoethyl)amine (Me 6 Tren) as catalyst. The successful synthesis of the macroinitiator and St-g-PAM was proved by NMR, FT-IR, SEM, XRD and TGA analysis. The molecular weight and polydispersity of PAM chains were analyzed by gel permeation chromatography (GPC) after hydrolyzing the starch backbone. Monomer conversion was monitored by gas chromatography (GC), on the basis of which the kinetics were determined. A preliminarily rheological study was performed on aqueous solutions of the prepared materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

Synthesis and characterization of TiO2/Ag/polymer ternary nanoparticles via surface-initiated atom transfer radical polymerization

International Nuclear Information System (INIS)

Park, Jung Tae; Koh, Joo Hwan; Seo, Jin Ah; Cho, Yong Soo; Kim, Jong Hak

2011-01-01

We report on the novel ternary hybrid materials consisting of semiconductor (TiO 2 ), metal (Ag) and polymer (poly(oxyethylene methacrylate) (POEM)). First, a hydrophilic polymer, i.e. POEM, was grafted from TiO 2 nanoparticles via the surface-initiated atom transfer radical polymerization (ATRP) technique. These TiO 2 -POEM brush nanoparticles were used to template the formation of Ag nanoparticles by introduction of a AgCF 3 SO 3 precursor and a NaBH 4 aqueous solution for reduction process. Successful grafting of polymeric chains from the surface of TiO 2 nanoparticles and the in situ formation of Ag nanoparticles within the polymeric chains were confirmed using transmission electron microscopy (TEM), UV-vis spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). FT-IR spectroscopy also revealed the specific interaction of Ag nanoparticles with the C=O groups of POEM brushes. This study presents a simple route for the in situ synthesis of both metal and polymer confined within the semiconductor, producing ternary hybrid inorganic-organic nanomaterials.

Monte Carlo simulation of non-linear free radical polymerization using a percolation kinetic gelation model (I): free radical homo polymerization

International Nuclear Information System (INIS)

Ghiass, M.; Dabir, B.; Nikazar, M.; Rey, A.D.; Mirzadeh, H.

2001-01-01

A kinetic gelation model that incorporates the kinetics of free radical homo polymerization is implemented to determine the effects of kinetics on polymerization statistics and microstructures. The simulation is performed on a simple cubic lattice that has 100 sites in each direction. A new algorithm for random selecting of the next step in a self-avoiding random walk and very efficient mechanisms of mobility of components are introduced to improve the generality of the predictions by removing commonly accruing deficiencies due to early trapping of radicals. A first order kinetics is considered for decomposition of initiator that enables us to consider the effect of temperature on polymerization reaction. Better understanding of microstructural evolution during polymerization and providing a framework to produce a realistic system of highly packed random chains within polymer network are among the benefits of model

Imidazoline and imidazolidine nitroxides as controlling agents in nitroxide-mediated pseudoliving radical polymerization

Science.gov (United States)

Edeleva, M. V.; Marque, S. R. A.; Bagryanskaya, E. G.

2018-04-01

Controlled, or pseudoliving, radical polymerization provides unique opportunities for the synthesis of structurally diverse polymers with a narrow molecular-weight distribution. These reactions occur under relatively mild conditions with broad tolerance to functional groups in the monomers. The nitroxide-mediated pseudoliving radical polymerization is of particular interest for the synthesis of polymers for biomedical applications. This review briefly describes one of the mechanisms of controlled radical polymerization. The studies dealing with the use of imidazoline and imidazolidine nitroxides as controlling agents for nitroxide-mediated pseudoliving radical polymerization of various monomers are summarized and analyzed. The publications addressing the key steps of the controlled radical polymerization in the presence of imidazoline and imidazolidine nitroxides and new approaches to nitroxide-mediated polymerization based on protonation of both nitroxides and monomers are considered. The bibliography includes 154 references.

Experimental study of living free radical polymerization using trifunctional initiator and polymerization mediated by nitroxide

International Nuclear Information System (INIS)

Galhardo, Eduardo; Lona, Liliane M.F.

2009-01-01

Controlled free radical polymerization or living free radical polymerization has received increasing attention as a technique for the production of polymers with microstructure highly controlled. In particular, narrow molecular weight distributions are obtained with polydispersity very close to one. In this research it was investigate the controlled polymerization mediated by nitroxide, using a cyclic trifunctional peroxide. As long as we know, there are only publications in literature dealing with NMRP using mono- and bi-functional initiators. It was believed that the trifunctional peroxide can increase the rate of polymerization, since more free radicals are generated, if compared with initiators with lower functionality. Furthermore, the fact of the initiator be cyclic means that branches are not generated in the chains, which theoretically prevents an increase in polydispersity of the polymer. The effect of the dissociation constant of the trifunctional initiator in the velocity of the reaction was analyzed. (author)

Surface modification of polypropylene membrane by polyethylene glycol graft polymerization

Energy Technology Data Exchange (ETDEWEB)

Abednejad, Atiye Sadat, E-mail: atiyeabednejad@gmail.com [Department of Biomedical Engineering, Faculty of New Sciences and Technologies, University of Tehran, P.O. Box 14395-1561, Tehran (Iran, Islamic Republic of); Amoabediny, Ghasem [Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran, P.O. Box 14395-1561, Tehran (Iran, Islamic Republic of); Research Center for New Technologies in Life Science Engineering, University of Tehran, P.O. Box 63894-14179, Tehran (Iran, Islamic Republic of); Ghaee, Azadeh [Department of Biomedical Engineering, Faculty of New Sciences and Technologies, University of Tehran, P.O. Box 14395-1561, Tehran (Iran, Islamic Republic of)

2014-09-01

Polypropylene hollow fiber microporous membranes have been used in a wide range of applications, including blood oxygenator. The hydrophobic feature of the polypropylene surface causes membrane fouling. To minimize fouling, a modification consisting of three steps: surface activation in H{sub 2} and O{sub 2} plasma, membrane immersion in polyethylene glycol (PEG) and plasma graft polymerization was performed. The membranes were characterized by contact angle measurement, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), tensile test, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Oxygen transfer of modified membranes was also tested. The stability of grafted PEG was measured in water and in phosphate buffer saline (PBS) at 37 °C. Blood compatibility of modified surfaces was evaluated by the platelet adhesion method. Water contact angel reduction from 110° to 72° demonstrates the enhanced hydrophilicity, and XPS results verify the presence of oxygenated functional groups due to the peak existence in 286 eV as a result of PEG grafting. The results clearly indicate that plasma graft-polymerization of PEG is an effective way for antifouling improvement of polypropylene membranes. Also, the results show that oxygen transfer changes in PEG grafted membranes are not significant. - Highlights: • H{sub 2} and O{sub 2} plasma graft polymerization of PEG on polypropylene membrane was carried out. • Changes in surface properties were investigated by FTIR, XPS, SEM, and AFM. • Surface wettability enhanced as a result of poly ethylene glycol grafting. • PEG grafting degree increase causes reduction of fouling and adhesion.

Visible Light-Induced Metal Free Surface Initiated Atom Transfer Radical Polymerization of Methyl Methacrylate on SBA-15

Directory of Open Access Journals (Sweden)

Liang Ma

2017-02-01

Full Text Available Surface-initiated atom transfer radical polymerization (SI-ATRP is one of the most versatile techniques to modify the surface properties of materials. Recent developed metal-free SI-ATRP makes such techniques more widely applicable. Herein photo-induced metal-free SI-ATRP of methacrylates, such as methyl methacrylate, N-isopropanyl acrylamide, and N,N-dimethylaminoethyl methacrylate, on the surface of SBA-15 was reported to fabricate organic-inorganic hybrid materials. A SBA-15-based polymeric composite with an adjustable graft ratio was obtained. The structure evolution during the SI-ATRP modification of SBA-15 was monitored and verified by FT-IR, XPS, TGA, BET, and TEM. The obtained polymeric composite showed enhanced adsorption ability for the model compound toluene in aqueous conditions. This procedure provides a low-cost, readily available, and easy modification method to synthesize polymeric composites without the contamination of metal.

The Synthesis of Cellulose Graft Copolymers Using Cu(0)-Mediated Polymerization

Science.gov (United States)

Donaldson, Jason L.

Cellulose is the most abundant renewable polymer on the planet and there is great interest in expanding its use beyond its traditional applications. However, its hydrophilicity and insolubility in most common solvent systems are obstacles to its widespread use in advanced materials. One way to counteract this is to attach hydrophobic polymer chains to cellulose: this allows the properties of the copolymer to be tailored by the molecular weight, density, and physical properties of the grafts. Two methods were used here to synthesize the graft copolymers: a 'grafting-from' approach, where synthetic chains were grown outward from bromoester moieties on cellulose (Cell-BiB) via Cu(0)-mediated polymerization; and a 'grafting-to' approach, where fully formed synthetic chains with terminal sulfide functionality were added to cellulose acetate with methacrylate functionality (CA-MAA) via thiol-ene Michael addition. The Cell-BiB was synthesized in the ionic liquid 1-butyl-3-methylimidazolium chloride and had a degree of substitution of 1.13. Polymerization from Cell-BiB proceeded at similar but slightly slower rate than an analogous non-polymeric initiator (EBiB). The average graft density of poly(methyl acrylate) chains was 0.71 chains/ring, with a maximum of 1.0 obtained. The graft density when grafting poly(methyl methacrylate) was only 0.15, and this appeared to be due to the slow initiation of BiB groups. Using EBiB to model the reaction and improve the design should allow this to be overcome. Chain extension experiments demonstrated the living behaviour of the polymer. The CA-MAA was synthesized by esterification with methacrylic acid. Reactions of CA-MAA with thiophenol and dodecanethiol resulted in quantitative addition of the thiol to the alkene. The grafts were synthesized by Cu(0)-mediated polymerization from a bifunctional initiator containing a disulfide bond, followed by reduction to sulfides. The synthetic polymers were successfully grafted to CA-MAA but the

Surface modification of thermoplastic poly(vinyl alcohol)/saponite nanocomposites via surface-initiated atom transfer radical polymerization enhanced by air dielectric discharges barrier plasma treatment

International Nuclear Information System (INIS)

Zhen Weijun; Lu Canhui

2012-01-01

To improve the water resistance of thermoplastic poly(vinyl alcohol)/saponite nanocomposites (TPVA), a simple two-step method was developed for the covalent immobilization of atom transfer radical polymerization (ATRP) initiators on the TPVA surfaces enhanced by air dielectric barrier discharges (DBD) plasma treatment, and hydrophobic poly(methyl methacrylate) (PMMA) brushes were then grafted onto the surface of TPVA via surface-initiated atom transfer radical polymerization (SI-ATRP). The chemical composition, morphology and hydrophobicity of the modified TPVA surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The water resistance of the surface-functionalized PMMA was evaluated by the contact angle and water adsorption method. It was shown that air DBD plasma treatment activated the TPVA surface and accelerated the immobilization of ATRP initiator on the TPVA surface. Compared with TPVA control, TPVA modified by SI-ATRP can be grafted well-defined and covalently tethered network PMMA brushes onto the surface and the hydrophobicity of TPVA were significantly enhanced.

The pentafluorostyrene endeavours with atom transfer radical polymerization - quo vadis?

DEFF Research Database (Denmark)

Hvilsted, Søren

2014-01-01

The versatility of the atom transfer radical polymerization (ATRP) of pentafluorostyrene (FS) is comprehensively evaluated. The ATRP of a wide range of monomers derived from FS is likewise discussed with emphasis on the potential polymer applications. A large number of block and star copolymers...... centred around polypentafluorostyrene (PFS) and prepared primarily using the bromomacroinitiator concept is surveyed. Here the main emphasis is on the feasibility of the polymer design, but also the very many different applications are highlighted. The potential grafting onto PFS and PFS block copolymers...... by exploitation of the very labile para-fluorine demonstrates new material architecture possibilities through very mild reaction conditions. Finally the utility of PFS in various conducting materials is elaborated. The amphiphilic nature of PFS in triblock copolymers with polyethers has been exploited for Li+ ion...

Functionalization of nanochannels by radio-induced grafting polymerization on PET track-etched membranes

International Nuclear Information System (INIS)

Soto Espinoza, S.L.; Arbeitman, C.R.; Clochard, M.C.; Grasselli, M.

2014-01-01

The application of swift-heavy ion bombardment to polymers is a well-established technique to manufacture micro- and nanopores onto polymeric films to obtain porous membranes. A few years ago, it was realized that, during ion bombardment, the high energy deposition along the ion path through the polymer reached cylindrical damage regions corresponding to the core trace and the penumbra. After the etching procedure, there are still enough active sites left in the penumbra that can be used to initiate a polymerization process selectively inside the membrane pores. In this study, we report the grafting polymerization of glycidyl methacrylate onto etched PET foils to obtain functionalized nanochannels. Grafted polymers were labeled with a fluorescent tag and analyzed by different fluorescence techniques such as direct fluorescence, fluorescence microscopy and confocal microscopy. These techniques allowed identifying and quantifying the grafted regions on the polymeric foils. - Highlights: • Irradiated PET foils with swift-heavy ions were etched and grafted in a step-by-step process. • Grafting polymerization was performed on the remaining active sites after etching. • Track-etched PET membranes were fluorescently labeled by chemical functionalization. • Functionalized track-etched PET membranes were analyzed by fluorescence and confocal microscopy

The use of radiation-induced graft polymerization for obtaining polymeric biomaterial on the basis of preparation 'Piyavit'

International Nuclear Information System (INIS)

Kudryavtsev, V.N.; Degtyareva, T.V.; Kabanov, V.Ya.

1998-01-01

The purpose of the present study is to obtain hemocompatible polymeric materials. The method of modification of polymer surface have been elaborated using the radiation-induced graft polymerization after which the surface is capable of coupling with the biologically active substances (BAS) produced from the medicinal leeches. At the Biological Department of Lomonosov Moscow State University was created a medicinal preparation 'Piyavit' isolated from the salivary glands secretion of the medicinal leeches (Hirudo medicinalis). It possess a wide spectrum of biological action on the human organism thanks to the presence of an unique complex natural of BAS (enzymes, inhibitors of proteolityc ensymes, prostanoids and et. al) guaranteed the anticoagulating, thrombolytic, antithrombotic, antiphlogistic, antiatherosclerotic, hypotentic effects and et al.. It has several advantages over anticoagulant heparin which is widely used for above mentioned purpose. 'Piyavit' is the multifunctional preparation, has not negative side-effects and is more cheap. The method of obtaining biocompatible polymers (basically polyethylene) with immobilized 'Piyavit' consist of three stages: 1. The modification of polymer surface by the radiation-induced graft polymerization of acrylic acid to obtain grafted chains polyacrylic acid (PAA) with controlled number and length. 2. The treatment of radiation grafted PAA by thionyl chloride that lead to conversion carboxyl groups of PAA in highly reactive acide chloride groups. 3. The covalent immobilization BAS of 'Piyavit' by acylation amino- and hydroxy-groups (functional groups in BAS) by acide chloride of PAA grafted on the polymere. (author)

Corona-induced graft polymerization for surface modification of porous polyethersulfone membranes

International Nuclear Information System (INIS)

Zhu Liping; Zhu Baoku; Xu Li; Feng Yongxiang; Liu Fu; Xu Youyi

2007-01-01

Graft polymerization of acrylic acid (AA) onto porous polyethersulfone (PES) membrane surfaces was developed using corona discharge in atmospheric ambience as an activation process followed by polymerization of AA in aqueous solution. The effects of the corona parameters and graft polymerization conditions on grafting yield (GY) of AA were investigated. The grafting of AA on the PES membranes was confirmed by ATR-FTIR and X-ray photoelectron spectroscopy (XPS) analysis. Porosimetry measurements indicate the average pore diameters and porosities of the modified membranes decrease with the increase of the GY. The hydrophilicity and surface wetting properties of the original and modified membranes were evaluated by observing the dynamic changes of water contact angles. It is found that the grafting of AA occurs not only on the membrane surfaces, but also on the pore walls of the cells inside the membrane. The permeability experiments of protein solution reveal that the grafting of PAA endows the modified membranes with enhanced fluxes and anti-fouling properties. The optimized GY of AA is in the range of 150-200 μg/cm 2 . In addition, the tensile experiments show the corona discharge treatment with the power lower than 150 W yields little damage to the mechanical strength of the membranes

Grafting of antibacterial polymers on stainless steel via surface-initiated atom transfer radical polymerization for inhibiting biocorrosion by Desulfovibrio desulfuricans.

Science.gov (United States)

Yuan, S J; Xu, F J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T

2009-06-01

To enhance the biocorrosion resistance of stainless steel (SS) and to impart its surface with bactericidal function for inhibiting bacterial adhesion and biofilm formation, well-defined functional polymer brushes were grafted via surface-initiated atom transfer radical polymerization (ATRP) from SS substrates. The trichlorosilane coupling agent, containing the alkyl halide ATRP initiator, was first immobilized on the hydroxylated SS (SS-OH) substrates for surface-initiated ATRP of (2-dimethylamino)ethyl methacrylate (DMAEMA). The tertiary amino groups of covalently immobilized DMAEMA polymer or P(DMAEMA), brushes on the SS substrates were quaternized with benzyl halide to produce the biocidal functionality. Alternatively, covalent coupling of viologen moieties to the tertiary amino groups of P(DMAEMA) brushes on the SS surface resulted in an increase in surface concentration of quaternary ammonium groups, accompanied by substantially enhanced antibacterial and anticorrosion capabilities against Desulfovibrio desulfuricans in anaerobic seawater, as revealed by antibacterial assay and electrochemical studies. With the inherent advantages of high corrosion resistance of SS, and the good antibacterial and anticorrosion capabilities of the viologen-quaternized P(DMAEMA) brushes, the functionalized SS is potentially useful in harsh seawater environments and for desalination plants. Copyright 2009 Wiley Periodicals, Inc.

Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization

Directory of Open Access Journals (Sweden)

Atsushi Narumi

2018-06-01

Full Text Available Macrocyclic polymers present an important class of macromolecules, displaying the reduced radius of gyration or impossibility to entangle. A rare approach for their synthesis is the ring expansion-controlled radical “vinyl” polymerization, starting from a cyclic alkoxyamine. We here describe ring-expansion radical crossover reactions of cyclic alkoxyamines which run in parallel to chain-propagation reactions in the polymerization system. The radical crossover reactions extensively occurred at 105–125 °C, eventually producing high molecular weight polymers with multiple inherent dynamic covalent bonds (NOC bonds. A subsequent ring-contraction radical crossover reaction and the second ring-expansion radical crossover reaction are also described. The major products for the respective three stages were shown to possess cyclic morphologies by the molecular weight profiles and the residual ratios for the NOC bonds (φ in %. In particular, the high φ values ranging from ca. 80% to 98% were achieved for this cyclic alkoxyamine system. This result verifies the high availability of this system as a tool demonstrating the ring-expansion “vinyl” polymerization that allows them to produce macrocyclic polymers via a one-step vinyl polymerization.

Zwitterionic sulfobetaine-grafted poly(vinylidene fluoride) membrane surface with stably anti-protein-fouling performance via a two-step surface polymerization

Energy Technology Data Exchange (ETDEWEB)

Li Qian; Bi Qiuyan; Zhou Bo [Membrane Technology and Engineering Research Center, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China); Wang Xiaolin, E-mail: xl-wang@tsinghua.edu.cn [Membrane Technology and Engineering Research Center, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

2012-03-01

A zwitterionic polymer, poly(3-(methacryloylamino) propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide) (poly(MPDSAH)) was successfully grafted in high density from the surface of poly(vinylidene fluoride) (PVDF) hollow fiber membrane via a two-step polymerization. Poly(2-hydroxyethyl methacrylate) (poly(HEMA)) chains were firstly grafted from outside surface of PVDF membrane through atom transfer radical polymerization (ATRP) to provide the initiation sites for subsequent cerium (Ce (IV))-induced graft copolymerization of polyMPDSAH in the presence of N,N Prime -ethylene bisacrylamide (EBAA) as a cross-linking agent. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) confirmed that the EBAA could stimulate zwitterionic polymers grafting onto the membrane surface. The dense poly(MPDSAH) layers on the PVDF membrane surface were revealed by the scanning electron microscope (SEM). The mechanical property of PVDF membrane was improved by the zwitterionic surface layers. The gravimetry results indicated the grafting amount increased to 520 {mu}g/cm{sup 2} for a copolymerization time of more than 3 h. Static and dynamic water contact angle measurements showed that the surface hydrophilicity of the PVDF membranes was significantly enhanced. As the grafting amount reached 513 {mu}g cm{sup -2}, the value of contact angle dropped to 22.1 Degree-Sign and the amount of protein adsorption decreased to zero. The cyclic experiments for BSA solution filtration demonstrated that the extent of protein fouling was significantly reduced and most of the fouling was reversible. The grafted polymer layer on the PVDF membrane showed a good stability during the membrane cleaning process. The experimental results concluded a good prospect in obtaining the sulfobetaine-modified PVDF membranes with high mechanical strength, good anti-protein-fouling performance, and long-term stability via the two-step polymerization.

Zwitterionic sulfobetaine-grafted poly(vinylidene fluoride) membrane surface with stably anti-protein-fouling performance via a two-step surface polymerization

International Nuclear Information System (INIS)

Li Qian; Bi Qiuyan; Zhou Bo; Wang Xiaolin

2012-01-01

A zwitterionic polymer, poly(3-(methacryloylamino) propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide) (poly(MPDSAH)) was successfully grafted in high density from the surface of poly(vinylidene fluoride) (PVDF) hollow fiber membrane via a two-step polymerization. Poly(2-hydroxyethyl methacrylate) (poly(HEMA)) chains were firstly grafted from outside surface of PVDF membrane through atom transfer radical polymerization (ATRP) to provide the initiation sites for subsequent cerium (Ce (IV))-induced graft copolymerization of polyMPDSAH in the presence of N,N′-ethylene bisacrylamide (EBAA) as a cross-linking agent. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) confirmed that the EBAA could stimulate zwitterionic polymers grafting onto the membrane surface. The dense poly(MPDSAH) layers on the PVDF membrane surface were revealed by the scanning electron microscope (SEM). The mechanical property of PVDF membrane was improved by the zwitterionic surface layers. The gravimetry results indicated the grafting amount increased to 520 μg/cm 2 for a copolymerization time of more than 3 h. Static and dynamic water contact angle measurements showed that the surface hydrophilicity of the PVDF membranes was significantly enhanced. As the grafting amount reached 513 μg cm -2 , the value of contact angle dropped to 22.1° and the amount of protein adsorption decreased to zero. The cyclic experiments for BSA solution filtration demonstrated that the extent of protein fouling was significantly reduced and most of the fouling was reversible. The grafted polymer layer on the PVDF membrane showed a good stability during the membrane cleaning process. The experimental results concluded a good prospect in obtaining the sulfobetaine-modified PVDF membranes with high mechanical strength, good anti-protein-fouling performance, and long-term stability via the two-step polymerization.

A novel process for ultrasound-induced radical polymerization in CO2-expanded fluids

NARCIS (Netherlands)

Kemmere, M.F.; Kuijpers, M.W.A.; Prickaerts, R.M.H.; Keurentjes, J.T.F.

2005-01-01

A strong viscosity increase upon polymerization hinders cavitation and subsequent radical formation during an ultrasound-induced bulk polymerization. In this work, ultrasound-induced radical polymerizations of methyl methacrylate (MMA) have been performed in CO2-expanded MMA in order to reduce the

Atom transfer radical polymerization of styrene under pulsed microwave irradiation

International Nuclear Information System (INIS)

Cheng Zhenping; Zhu Xiulin; Zhou Nianchen; Zhu Jian; Zhang Zhengbiao

2005-01-01

A homogeneous solution atom transfer radical polymerization (ATRP) and reverse atom transfer radical polymerization (RATRP) of styrene (St) in N,N-dimethylformamide (DMF) were successfully carried out under pulsed microwave irradiation (PMI), using 1-bromo-1-phenylethane (1-PEBr)/CuCl/N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA) as an initiating system at 85 deg. C and 2,2'-azo-bis-isobutyrontrile (AIBN)/CuCl 2 /PMDETA as an initiating system at 95 deg. C, respectively. The polymerization rates under PMI were greatly increased in comparison with those under identical conventional heating (CH)

A peroxidase mimic with atom transfer radical polymerization activity constructed through the grafting of heme onto metal-organic frameworks.

Science.gov (United States)

Jiang, Wei; Pan, Yue; Yang, Jiebing; Liu, Yong; Yang, Yan; Tang, Jun; Li, Quanshun

2018-07-01

Atom transfer radical polymerization (ATRP) has been considered to be an efficient strategy for constructing functional macromolecules owing to its simple operation and versatile monomers, and thus it is of great significance to develop ideal catalysts with higher activity and perfect reusability. We constructed a peroxidase mimic through the grafting of heme onto metal-organic frameworks UiO-66-NH 2 (ZrMOF), namely Heme-ZrMOF. After the systematic characterization of structure, the composite Heme-ZrMOF was demonstrated to possess high peroxidase activity using 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulphonate) and 3,3',5,5'-tetramethylbenzidine as substrates. The enzyme mimic was then used as catalysts in the ATRP reactions of different monomers, in which favorable monomer conversion (44.6-98.0%) and product molecular weight (8600-25,600 g/mol) could be obtained. Compared to free heme, Heme-ZrMOF could efficiently achieve the easy separation of heme from the catalytic system and facilitate the ATRP reaction in an aqueous environment to avoid the utilization of organic solvents. In conclusion, the enzyme mimic Heme-ZrMOF could be potentially used as an effective catalyst for preparing well-defined polymers with biomedical applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Radiation-induced polymerization and radiation effect on polymers

International Nuclear Information System (INIS)

Seguchi, Tadao

1977-12-01

The processes of radiation-induced polymerization of monomers and also radiation effects on polymers have been studied by instrumental analyses of electron spin resonance (ESR), nuclear magnetic resonance (NMR) and electron microscopy. In radiation-induced polymerization, graft-copolymerization and absorbed state polymerization were taken up. For graft-copolymerization, monomers such as methylmethacrylate and butadiene were made to react with irradiated polyethylene, and behaviors of the initiating radicals and propagating radicals were followed under the reaction by ESR. For absorbed state polymerization, acrylonitrile/zeolite and methylmethacrylate/zeolite were chosen. Absorbed monomers were irradiated at 77 0 K and polymerized at room temperature. Active species and the concentrations were measured by ESR and the yields of polymer were observed by NMR. In radiation effect on polymers, polyvinylfluoride, polyvinylidenfluoride and polytetrafluoroethylene were taken up. Active species trapped in the polymer matrixes were identified and decay and reactivity of the species were also studied. On the basis of information from the electron microscopy and x-ray analysis, radiation effects on these polymers are described. In polytetrafluoroethylene produced by radiation polymerization, the relation between morphology and polymerization conditions and also the process of crystallization during polymerization were studied. (auth.)

Effect of solubility parameter of monomers on electron beam induced graft-polymerization onto polyethylene films

International Nuclear Information System (INIS)

Mori, Koji; Koshiishi, Kenji; Masuhara, Ken-ichi

1991-01-01

Electron beam induced graft-polymerization by the mutual irradiation technique of monomers with different solubility parameters δ onto low density polyethylene films (LDPE) and high density polyethylene films (HDPE) were investigated at high dose rates (25 Mrad per second). Graft-polymerization mechanisms were discussed on the basis of grafting rates, surface tensions, atomic ratios of surface by XPS, and SEM images of the grafted films. Grafting rates decreased with increasing δ of monomers, and grafting rates onto LDPE were larger than those onto HDPE. Graft chain contents on surface, which were evaluated in terms of surface tensions and atomic ratios of the surface, increased with increasing δ of monomers, and graft chain contents on surface of HDPE were higher than those of LDPE. It is assumed that mutual solubility of PE and monomers, i.e., infiltration of monomers into PE during graft-polymerization influence grafting rates and graft sites in films. In case of high mutual solubility, grafting rates were large and graft sites spread from the surface into bulk. On the other hand, in case of low mutual solubility, grafting rates were small and graft sites localized on the surface of films. (author)

Living atom transfer radical polymerization of 4-acetoxystyrene

DEFF Research Database (Denmark)

Gao, Bo; Chen, Xianyi; Ivan, Bela

1997-01-01

Living atom transfer radical polymerization (ATRP) of 4-acetoxystyrene (1), a protected 4-vinylphenol, leading to poly(4-acetoxystyrene) with well-defined molecular weight and narrow molecular weight distribution was carried out in bulk with a,a'-dibromoxylene(2)/CuBr/2,2-bipyridine(bpy) as initi......Living atom transfer radical polymerization (ATRP) of 4-acetoxystyrene (1), a protected 4-vinylphenol, leading to poly(4-acetoxystyrene) with well-defined molecular weight and narrow molecular weight distribution was carried out in bulk with a,a'-dibromoxylene(2)/CuBr/2,2-bipyridine......(bpy) as initiating system. A linear (M) over bar(n), versus monomer conversion plot was found in good accordance with the theoretical line, indicating 100% initiating efficiency. The polymerization is first order in respect to monomer up to about 70% monomer conversion. Deviations from linearity at higher conversion...

Effect of solubility parameter of solvents on electron beam induced graft-polymerization onto polyethylene films

International Nuclear Information System (INIS)

Mori, Koji; Koshiishi, Kenji; Masuhara, Ken-ichi

1992-01-01

Electron beam induced graft-polymerization by the mutual irradiation technique of methyl methacrylate (MMA) and methacrylic acid (MAAc) blended with solvents, which have different solubility parameters δ, onto high density polyethylene films (PE) were investigated at high dose rates (25 Mrad per second). Graft-polymerization mechanisms were discussed on the basis of grafting rates, surface tensions, atomic rations on the surface by XPS, and SEM images of the grafted films. Grafting rates decreased with increasing δ of solvents, and grafting rates for MMA were larger than those for MAAc. Graft chain contents on the surface, which were evaluated in terms of surface tensions and atomic ratios on the surface, increased with increasing δ of solvents, and graft chain contents on the surface of MAAc grafted PE were higher than those of MMA grafted PE. It is assumed that mutual solubility of PE and solvents (monomer solutions), i.e., infiltration of monomer solutions into PE during graft-polymerization, influenced grafting rates and graft sites in films. In case of high mutual solubility, grafting rates were large and graft sites spread from the surface into bulk. On the other hand, in case of low mutual solubility, grafting rates were small and graft sites localized on the surface of films. (author)

Synthesis of Graft Copolymers Based on Poly(2‐Methoxyethyl Acrylate) and Investigation of the Associated Water Structure

DEFF Research Database (Denmark)

Javakhishvili, Irakli; Tanaka, Masaru; Ogura, Keiko

2012-01-01

Graft copolymers composed of poly(2‐methoxyethyl acrylate) are prepared employing controlled radical polymerization techniques. Linear backbones bearing atom transfer radical polymerization (ATRP) initiating sites are obtained by reversible addition–fragmentation chain transfer copolymerization...... polydispersity indices (1.17–1.38) are attained. Thermal investigations of the graft copolymers indicate the presence of the freezing bound water, and imply that the materials may exhibit blood compatibility....

Graft polymerization of vinyl acetate onto starch. Saponification to starch-g-poly(vinyl alcohol)

International Nuclear Information System (INIS)

Fanta, G.F.; Burr, R.C.; Doane, W.M.; Russell, C.R.

1979-01-01

Graft polymerizations of vinyl acetate onto granular cornstarch were initiated by cobalt-60 irradiation of starch-monomer-water mixtures, and ungrafted poly(vinyl acetate) was separated from the graft copolymer by benzene extraction. Conversions of monomer to polymer were quantitative at a radiation dose of 1.0 Mrad. Over half of the polymer was present as ungrafted poly(vinyl acetate) (grafting efficiency less than 50%), and the graft copolymer contained only 34% grafted synthetic polymer (34% add-on). Lower irradiation doses produced lower conversions of monomer to polymer and gave graft copolymers with lower % add-on. Addition of minor amounts of acrylamide, methyl acrylate, and methacrylic acid as comonomers produced only small increases in % add-on and grafting efficency. Grafting efficiency was increased to 70% when a monomer mixture containing about 10% methyl methacrylate was used. Grafting efficiency could be increased to over 90% if the graft polymerization of vinyl acetate--methyl methacrylate was carried out near 0 0 C; although conversion of monomers to polymer was low and grafted polymer contained 40 to 50% poly(methyl methacrylate). Selected graft copolymers were treated with methanolic sodium hydroxide to convert starch-g-poly(vinyl acetate) to starch-g-poly(vinyl alcohol). The molecular weight of the poly(vinyl alcohol) moiety was about 30,000. The solubility of starch-g-poly(vinyl alcohol) in hot water was less than 50; however, solubility could be increased by substituting either acid-modified or hypochlorite-oxidized for unmodified starch in the graft polymerization reaction. Vinyl acetate was also graft polymerized onto acid-modified starch which had been dispersed and partially solubilized by heating in water. A total irradiation dose of either 1.0 or 0.5 Mrad gave starch-g-poly

Graft polymerization of styrene onto starch by simultaneous cobalt-60 irradiation

International Nuclear Information System (INIS)

Fanta, G.F.; Burr, R.C.; Doane, W.M.; Russell, C.R.

1977-01-01

Starch-g-polystyrene copolymers have been prepared by the simultaneous 60 Co irradiation of starch--styrene mixtures, and copolymers have been characterized with respect to weight per cent polystyrene (% add-on) and also the molecular weight and molecular weight distribution of polystyrene grafts. In a typical polymerization, 4g each of starch and styrene were blended with 1 ml water and 1.5 ml of an organic solvent; the resulting semisolid paste was irradiated to a total dose of 1 Mrad. With ethylene glycol, acetonitrile, ethanol, methanol, acetone, and dimethylformamide as the organic solvent, values for % add-on ranged from 24% to 29%. The highest % add-on (43%) and the highest conversion of styrene to grafted polymer (76%) were obtained when the organic solvent was omitted, and water alone was used. When water was also omitted, polymerization of styrene was negligible; however, graft copolymer was formed in the absence of water when either ethylene glycol or ethanol was added. Attempts were unsuccessful to achieve a % add-on greater than 43% by doubling the amount of styrene in the polymerization recipe. Mixtures of equal weights of starch and styrene are relatively nonviscous, but these mixtures thicken when either water or ethylene glycol is blended in. Reasons for this thickening action and the possible influence of thickening on the graft polymerization reaction were explored

Plasma-grafting polymerization on carbon fibers and its effect on their composite properties

Energy Technology Data Exchange (ETDEWEB)

Zhang, Huanxia, E-mail: zhanghuanxia818@163.com [College of Materials and Textile Engineering, Jiaxing University, Jiaxing 314001, Zhejiang (China); Li, Wei [College of Textile Engineering, Donghua University, Shanghai 201620 (China); Key Laboratory of Textile Science and Technology, Ministry of Education, Shanghai 201620 (China)

2015-11-30

Graphical abstract: - Highlights: • A simple method to improve surface properties is applied to carbon fibers. • The maleic anhydride was grafted onto the carbon fiber with the FTIR spectra. • The plasma treatment time and polymerization condition affected on the grafting rate. • The carbon fibers exhibited excellent surface hydrophilicity and IFSS properties. - Abstract: Interfacial adhesion between matrix and fibers plays a crucial role in controlling the performance of composites. Carbon fibers have the major constraint of chemical interness and hence have limited adhesion with the matrix. Surface treatment of fibers is the best solution to this problem. In this work, carbon fibers were activated by plasma and grafting polymerization. The grafting ratio of polymerization was obtained by acid–base titration. The chemical and physical changes induced by the treatments on carbon fiber surface was examined using contact angle measurements, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR–ATR) technique. The interfacial adhesion of CF/EP (carbon fiber/epoxy) composites were analyzed by a single fiber composite (SFC) for filament fragmentation test. Experimental results show that the grafting rate was not only the function of the plasma-treat time but also the concentration of the grafting polymerization. The oxygen-containing groups (such as C−O, C=O, and O−C=O) and the interfacial shear strength (IFSS) of the plasma-grafting carbon fiber increased more significantly than the carbon fiber without plasma treatment grafted with MAH. This demonstrates that the surfaces of the carbon fiber samples are more active, hydrophilic, and rough after plasma-grafting treatments using a DBD operating in ambient argon mixture with oxygen. With DBD (dielectric barrier discharges) operating in ambient argon mixture with oxygen, the more active, hydrophilic, and rough surface was obtained by the

Plasma-grafting polymerization on carbon fibers and its effect on their composite properties

International Nuclear Information System (INIS)

Zhang, Huanxia; Li, Wei

2015-01-01

Graphical abstract: - Highlights: • A simple method to improve surface properties is applied to carbon fibers. • The maleic anhydride was grafted onto the carbon fiber with the FTIR spectra. • The plasma treatment time and polymerization condition affected on the grafting rate. • The carbon fibers exhibited excellent surface hydrophilicity and IFSS properties. - Abstract: Interfacial adhesion between matrix and fibers plays a crucial role in controlling the performance of composites. Carbon fibers have the major constraint of chemical interness and hence have limited adhesion with the matrix. Surface treatment of fibers is the best solution to this problem. In this work, carbon fibers were activated by plasma and grafting polymerization. The grafting ratio of polymerization was obtained by acid–base titration. The chemical and physical changes induced by the treatments on carbon fiber surface was examined using contact angle measurements, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR–ATR) technique. The interfacial adhesion of CF/EP (carbon fiber/epoxy) composites were analyzed by a single fiber composite (SFC) for filament fragmentation test. Experimental results show that the grafting rate was not only the function of the plasma-treat time but also the concentration of the grafting polymerization. The oxygen-containing groups (such as C−O, C=O, and O−C=O) and the interfacial shear strength (IFSS) of the plasma-grafting carbon fiber increased more significantly than the carbon fiber without plasma treatment grafted with MAH. This demonstrates that the surfaces of the carbon fiber samples are more active, hydrophilic, and rough after plasma-grafting treatments using a DBD operating in ambient argon mixture with oxygen. With DBD (dielectric barrier discharges) operating in ambient argon mixture with oxygen, the more active, hydrophilic, and rough surface was obtained by the

Laccase catalyzed grafting of-N-OH type mediators to lignin via radical-radical coupling

DEFF Research Database (Denmark)

Munk, Line; Punt, A. M.; Kabel, M. A.

2017-01-01

Lignin is an underexploited resource in biomass refining. Laccases (EC 1.10.3.2) catalyze oxidation of phenolic hydroxyls using O2 as electron acceptor and may facilitate lignin modification in the presence of mediators. This study assessed the reactivity of four different synthetic mediators...... better than HBT (1-hydroxybenzotriazole). Three different mechanisms are suggested to explain the grafting of HPI and HBT, all involving radical-radical coupling to produce covalent bonding to lignin. Lignin from exhaustive cellulase treatment of wheat straw was more susceptible to grafting than beech...... organosolv lignin with the relative abundance of grafting being 35% vs. 11% for HPI and 5% vs. 1% for HBT on these lignin substrates. The data imply that lignin can be functionalized via laccase catalysis with-N-OH type mediators....

A grafting from approach to graft polystyrene chains at the surface of graphene nanolayers by RAFT polymerization: Various graft densities from hydroxyl groups

Energy Technology Data Exchange (ETDEWEB)

Roghani-Mamaqani, Hossein, E-mail: r.mamaghani@sut.ac.ir [Department of Polymer Engineering, Sahand University of Technology, PO Box 51335-1996, Tabriz (Iran, Islamic Republic of); Khezri, Khezrollah [School of Chemistry, University College of Science, University of Tehran, PO Box 14155-6455, Tehran (Iran, Islamic Republic of)

2016-01-01

Graphical abstract: (3-Aminopropyl) triethoxysilane was grafted at the surface of GO in low and high different graft densities to yield GOHAL and GOHAH, respectively. Subsequently, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (RA) was attached at the surface of GOHAL and GOHAH by an amidation reaction to yield GOHRL and GOHRH, respectively. Then, GOHRL and GOHRH were used in grafting from RAFT polymerization of styrene. - Highlights: • A RAFT agent grafted GO was used in grafting from RAFT polymerization of styrene. • The efficiency of RAFT agent attachment at the surface of GO is 41.12% for high density sample. • Polystyrene molecular weight is decreased by the addition of graphene content and also graft density of RAFT agent. - Abstract: (3-Aminopropyl) triethoxysilane was grafted at the surface of GO in low and high different graft densities to yield GOHAL and GOHAH, respectively. Subsequently, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (RA) was attached at the surface of GOHAL and GOHAH by an amidation reaction to yield GOHRL and GOHRH, respectively. Then, GOHRL and GOHRH were used in grafting from RAFT polymerization of styrene. Grafting of APTES and RA was approved by Fourier transform infrared spectroscopy, X-ray photo electron spectroscopy, and Raman spectroscopy. Expansion of graphene interlayer by oxidation and functionalization processes was evaluated by X-ray diffraction. Conversion values of styrene were calculated using gas chromatography. Molecular weight and PDI values of attached polystyrene (PS) chains were studied by size exclusion chromatography. Thermogravimetric analysis was also used to investigate the degradation temperatures, char contents, and graft contents of modifiers and PS chains. GOHRH and GOHRL reach to char content of 55.3 and 45.2% at 600 °C, which shows that weight ratio of modifier (APTES and RA moieties) is 15.3 and 5.2%, respectively. Scanning and transmission electron microscopies show that

Surface-Initiated Atom Transfer Radical Polymerization and Electrografting Technique as a Means For Attaining Tailor-Made Polymer Coatings

DEFF Research Database (Denmark)

Chernyy, Sergey

2012-01-01

strategies for initiator grafting, physicochemical properties of polymer brushes and basic principles of quartz crystal microbalance technique (QCM) are discussed. In Chapter 2 various ATRP conditions are probed. The effects of solvent polarity, monomer concentration, initiator surface density, ligand nature......Atom transfer radical polymerization initiated from a surface of various substrates (SI-ATRP) has become a progressively popular technique for obtaining thin polymer films with predetermined properties. The present work addresses the main features of SI-ATRP with respect to the controllability...... and temperature on the kinetics of methyl methacrylate polymerization are elucidated. The strategy was based on the observation of dry polymer thickness versus time evolution by means of ellipsometry, profilometry and IR spectroscopy. An alternative approach, constituting Chapter 3, was based on optimization...

Graft-copolymerization of styrene on polypropylene in the solid phase

NARCIS (Netherlands)

Beenen, W.; VanderWal, D.; Janssen, L.P.B.M.; Buijtenhuijs, A.; Hogt, A.H.; Wal, Douwe J. v.d.

The graft-copolymerization of styrene on PP in the solid phase has been studied under various reaction conditions using a radical initiator. Polymerization kinetics were investigated by DSC experiments and reactions in glass ampoules. The conversion rate and grafting efficiency of styrene appeared

Research work of radiation induced graft polymerization for synthesis and modification of polymer materials in CRICI

Energy Technology Data Exchange (ETDEWEB)

Hu Fumin; Ma Xueming [Chenguan Research Institute of Chemical Industry, Chengdu (China)

2000-03-01

The direct and post radiation induced graft polymerization had been studied in CRICI (Chenguan Research Institute of Chemical Industry). The method consists of irradiation of various polymer substrates in the presence (or absence) of monomers in a liquid, saturated vapour or gaseous and non-saturated vapour. 1. Grafting of functional monomers. --- It is possible to divide the grafting into two main approaches for synthesis of functional polymer materials. The first is grafting of monomers attached required functional group such as unsaturated carboxylic acid (acrylic and methacrylic acid), unsaturated nitrogen containing (alkali) base (vinylpyridine), monomers with hydrophilic unionized and polar groups (acrylamide, N-vinylpyrrolidone glycidylmethacrylate) and so on. The second is grafting of monomers capable of continuing chemical modification after graft polymerization. This approach essentially expands synthetic possibility of RGP for preparing functional polymers. 2. The effect of some salts on aqueous solution graft polymerization. The grafting of AA or AAm onto PE by direct or post radiation method in the presence of Mohr's salt or cupric nitrate was studied in detail. 3. Radiation induced graft polymerization by gaseous phase of monomers. This method consists of irradiation or preirradiation of various polymer substrates in the presence (or absence for preirradiation) of monomer in a gaseous of nonsaturated vapour state. (J.P.N.)

Research work of radiation induced graft polymerization for synthesis and modification of polymer materials in CRICI

International Nuclear Information System (INIS)

Hu Fumin; Ma Xueming

2000-01-01

The direct and post radiation induced graft polymerization had been studied in CRICI (Chenguan Research Institute of Chemical Industry). The method consists of irradiation of various polymer substrates in the presence (or absence) of monomers in a liquid, saturated vapour or gaseous and non-saturated vapour. 1. Grafting of functional monomers. --- It is possible to divide the grafting into two main approaches for synthesis of functional polymer materials. The first is grafting of monomers attached required functional group such as unsaturated carboxylic acid (acrylic and methacrylic acid), unsaturated nitrogen containing (alkali) base (vinylpyridine), monomers with hydrophilic unionized and polar groups (acrylamide, N-vinylpyrrolidone glycidylmethacrylate) and so on. The second is grafting of monomers capable of continuing chemical modification after graft polymerization. This approach essentially expands synthetic possibility of RGP for preparing functional polymers. 2. The effect of some salts on aqueous solution graft polymerization. The grafting of AA or AAm onto PE by direct or post radiation method in the presence of Mohr's salt or cupric nitrate was studied in detail. 3. Radiation induced graft polymerization by gaseous phase of monomers. This method consists of irradiation or preirradiation of various polymer substrates in the presence (or absence for preirradiation) of monomer in a gaseous of nonsaturated vapour state. (J.P.N.)

Monomode microwave-assisted atom transfer radical polymerization

NARCIS (Netherlands)

Zhang, H.; Schubert, U.S.

2004-01-01

The first monomode microwave-assisted atom transfer radical polymerization (ATRP) is reported. The ATRP of methyl methacrylate was successfully performed with microwave heating, which was well controlled and provided almost the same results as experiments with conventional heating, demonstrating the

Surface modification of silica nanoparticles by UV-induced graft polymerization of methyl methacrylate.

Science.gov (United States)

Kim, Sooyeon; Kim, Eunhye; Kim, Sungsoo; Kim, Woosik

2005-12-01

In this study we modified the surface of silica nanoparticles with methyl methacrylate by UV-induced graft polymerization. It is a surface-initiated polymerization reaction induced by ultraviolet irradiation. The resulting organic-inorganic nanocomposites were near-monodisperse and fabricated without homopolymerization of the monomer. Substantial increase in mean particle size was observed by SEM image analysis after UV-induced grafting of methyl methacrylate onto pure silica particles. FT-Raman spectroscopy and X-ray photoelectron spectroscopy studies of these materials revealed the successful grafting of methyl methacrylate onto the silica surface. The formation of a covalent bond between the grafted PMMA chains and silica surface was indicated by FT-Raman spectra. Thermogravimetric analysis of the PMMA-grafted silica particles indicated the polymer contents in good agreement with SEM photographs.

Protein adsorption resistance of PVP-modified polyurethane film prepared by surface-initiated atom transfer radical polymerization

International Nuclear Information System (INIS)

Yuan, Huihui; Qian, Bin; Zhang, Wei; Lan, Minbo

2016-01-01

Highlights: • Antifouling PVP brushes were successfully grafted on PU films by SI-ATRP. • The effect of polymerization time on surface property and topography was studied. • Hydrophilicity and protein fouling resistance of PVP–PU films were greatly promoted. • Competitive adsorption of three proteins on PVP–PU films was evaluated. - Abstract: An anti-fouling surface of polyurethane (PU) film grafted with Poly(N-vinylpyrrolidone) (PVP) was prepared through surface-initiated atom transfer radical polymerization (SI-ATRP). And the polymerization time was investigated to obtain PU films with PVP brushes of different lengths. The surface properties and protein adsorption of modified PU films were evaluated. The results showed that the hydrophilicity of PU–PVP films were improved with the increase of polymerization time, which was not positive correlation with the surface roughness due to the brush structure. Additionally, the protein resistance performance was promoted when prolonging the polymerization time. The best antifouling PU–PVP (6.0 h) film reduced the adsoption level of bovine serum albumin (BSA), lysozyme (LYS), and brovin serum fibrinogen (BFG) by 93.4%, 68.3%, 85.6%, respectively, compared to the unmodified PU film. The competitive adsorption of three proteins indicated that LYS preferentially adsorbed on the modified PU film, while BFG had the lowest adsorption selectivity. And the amount of BFG on PU–PVP (6.0 h) film reduced greatly to 0.08 μg/cm"2, which was almost one-tenth of its adsorption from the single-protein system. Presented results suggested that both hydrophilicity and surface roughness might be the important factors in all cases of protein adsorption, and the competitive or selective adsorption might be related to the size of the proteins, especially on the non-charged films.

Protein adsorption resistance of PVP-modified polyurethane film prepared by surface-initiated atom transfer radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Yuan, Huihui; Qian, Bin; Zhang, Wei [Shanghai Key Laboratory of Functional Materials Chemistry and Research Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237 (China); Lan, Minbo, E-mail: minbolan@ecust.edu.cn [Shanghai Key Laboratory of Functional Materials Chemistry and Research Center of Analysis and Test, East China University of Science and Technology, Shanghai 200237 (China); State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237 (China)

2016-02-15

Highlights: • Antifouling PVP brushes were successfully grafted on PU films by SI-ATRP. • The effect of polymerization time on surface property and topography was studied. • Hydrophilicity and protein fouling resistance of PVP–PU films were greatly promoted. • Competitive adsorption of three proteins on PVP–PU films was evaluated. - Abstract: An anti-fouling surface of polyurethane (PU) film grafted with Poly(N-vinylpyrrolidone) (PVP) was prepared through surface-initiated atom transfer radical polymerization (SI-ATRP). And the polymerization time was investigated to obtain PU films with PVP brushes of different lengths. The surface properties and protein adsorption of modified PU films were evaluated. The results showed that the hydrophilicity of PU–PVP films were improved with the increase of polymerization time, which was not positive correlation with the surface roughness due to the brush structure. Additionally, the protein resistance performance was promoted when prolonging the polymerization time. The best antifouling PU–PVP (6.0 h) film reduced the adsoption level of bovine serum albumin (BSA), lysozyme (LYS), and brovin serum fibrinogen (BFG) by 93.4%, 68.3%, 85.6%, respectively, compared to the unmodified PU film. The competitive adsorption of three proteins indicated that LYS preferentially adsorbed on the modified PU film, while BFG had the lowest adsorption selectivity. And the amount of BFG on PU–PVP (6.0 h) film reduced greatly to 0.08 μg/cm{sup 2}, which was almost one-tenth of its adsorption from the single-protein system. Presented results suggested that both hydrophilicity and surface roughness might be the important factors in all cases of protein adsorption, and the competitive or selective adsorption might be related to the size of the proteins, especially on the non-charged films.

Plasma-grafting polymerization on carbon fibers and its effect on their composite properties

Science.gov (United States)

Zhang, Huanxia; Li, Wei

2015-11-01

Interfacial adhesion between matrix and fibers plays a crucial role in controlling the performance of composites. Carbon fibers have the major constraint of chemical interness and hence have limited adhesion with the matrix. Surface treatment of fibers is the best solution to this problem. In this work, carbon fibers were activated by plasma and grafting polymerization. The grafting ratio of polymerization was obtained by acid-base titration. The chemical and physical changes induced by the treatments on carbon fiber surface was examined using contact angle measurements, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) technique. The interfacial adhesion of CF/EP (carbon fiber/epoxy) composites were analyzed by a single fiber composite (SFC) for filament fragmentation test. Experimental results show that the grafting rate was not only the function of the plasma-treat time but also the concentration of the grafting polymerization. The oxygen-containing groups (such as Csbnd O, Cdbnd O, and Osbnd Cdbnd O) and the interfacial shear strength (IFSS) of the plasma-grafting carbon fiber increased more significantly than the carbon fiber without plasma treatment grafted with MAH. This demonstrates that the surfaces of the carbon fiber samples are more active, hydrophilic, and rough after plasma-grafting treatments using a DBD operating in ambient argon mixture with oxygen. With DBD (dielectric barrier discharges) operating in ambient argon mixture with oxygen, the more active, hydrophilic, and rough surface was obtained by the plasma-grafting treatments.

Electron beam induced graft-polymerization of methyl methacrylate onto polyethylene films at high dose rates

International Nuclear Information System (INIS)

Mori, Koji; Koshiishi, Kenji; Masuhara, Ken-ichi

1991-01-01

Electron beam induced graft-polymerization by the mutual irradiation technique of methyl methacrylate on the surface of low density polyethylene films (LD) and high density polyethylene films (HD) was investigated at high dose rates over 10 Mrad per second. Graft-polymerization mechanisms were discussed on the basis of O 2 permeability, tensile strength, elongation at break, and surface tension of the grafted films. As the degree of grafting increased, the O 2 permeability of LD decreased, while that of HD little changed at the grafting up to 4 ∼ 5 %. This indicates that the grafting occurred in the amorphous regions for LD and occurred in the amorphous regions in the neighborhood of crystalline regions for HD. For HD, when the degree of the grafting surpassed 4 ∼ 5 %, the O 2 permeability, tensile strength, elongation at break, and surface tension decreased with an increase in the degree of grafting. It was assumed that rapid grafting in the amorphous regions in the neighborhood of crystalline regions caused the increase in local temperature by the heat of polymerization, and the viscosity of polyethylene in the amorphous regions decreased with an increase in temperature. As a result, the graft chains, which formed micro domain structure, condensed in the amorphous regions and the domain increased in size. (author)

Poly(glycidyl methacrylate) grafted CdSe quantum dots by surface-initiated atom transfer radical polymerization: Novel synthesis, characterization, properties, and cytotoxicity studies

Energy Technology Data Exchange (ETDEWEB)

Bach, Long Giang; Islam, Md. Rafiqul [Department of Imaging System Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Lee, Doh Chang [Department of Chemical and Biomolecular Engineering, KAIST Institute for the Nanocentury (KINC), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Lim, Kwon Taek, E-mail: ktlim@pknu.ac.kr [Department of Imaging System Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2013-10-15

A novel approach for the synthesis of poly(glycidyl methacrylate) grafted CdSe quantum dot (QDs) (PGMA-g-CdSe) was developed. The PGMA-g-CdSe nanohybrids were synthesized by the surface-initiated atom transfer radical polymerization of glycidyl methacrylate from the surface of the strategic initiator, CdSe-BrIB QDs prepared by the interaction of 2-bromoisobutyryl bromide (BrIB) and CdSe-OH QDs. The structure, morphology, and optical property of the PGMA-g-CdSe nanohybrids were analyzed by FT-IR, XPS, TGA, XRD, TEM, and PL. The as-synthesized PGMA-g-CdSe nanohybrids having multi-epoxide groups were employed for the direct coupling of biotin via ring-opening reaction of the epoxide groups to afford the Biotin-f-PGMA-g-CdSe nanobioconjugate. The covalent immobilization of biotin onto PGMA-g-CdSe was confirmed by FT-IR, XPS, and EDX. Biocompatibility and imaging properties of the Biotin-f-PGMA-g-CdSe were investigated by MTT bioassay and PL analysis, respectively. The cell viability study suggested that the biocompatibility was significantly enhanced by the functionalization of CdSe QDs by biotin and PGMA.

Poly(glycidyl methacrylate) grafted CdSe quantum dots by surface-initiated atom transfer radical polymerization: Novel synthesis, characterization, properties, and cytotoxicity studies

International Nuclear Information System (INIS)

Bach, Long Giang; Islam, Md. Rafiqul; Lee, Doh Chang; Lim, Kwon Taek

2013-01-01

A novel approach for the synthesis of poly(glycidyl methacrylate) grafted CdSe quantum dot (QDs) (PGMA-g-CdSe) was developed. The PGMA-g-CdSe nanohybrids were synthesized by the surface-initiated atom transfer radical polymerization of glycidyl methacrylate from the surface of the strategic initiator, CdSe-BrIB QDs prepared by the interaction of 2-bromoisobutyryl bromide (BrIB) and CdSe-OH QDs. The structure, morphology, and optical property of the PGMA-g-CdSe nanohybrids were analyzed by FT-IR, XPS, TGA, XRD, TEM, and PL. The as-synthesized PGMA-g-CdSe nanohybrids having multi-epoxide groups were employed for the direct coupling of biotin via ring-opening reaction of the epoxide groups to afford the Biotin-f-PGMA-g-CdSe nanobioconjugate. The covalent immobilization of biotin onto PGMA-g-CdSe was confirmed by FT-IR, XPS, and EDX. Biocompatibility and imaging properties of the Biotin-f-PGMA-g-CdSe were investigated by MTT bioassay and PL analysis, respectively. The cell viability study suggested that the biocompatibility was significantly enhanced by the functionalization of CdSe QDs by biotin and PGMA.

Grafting of molecularly imprinted polymer to porous polyethylene filtration membranes by plasma polymerization.

Science.gov (United States)

Cowieson, D; Piletska, E; Moczko, E; Piletsky, S

2013-08-01

An application of plasma-induced grafting of polyethylene membranes with a thin layer of molecularly imprinted polymer (MIP) was presented. High-density polyethylene (HDPE) membranes, "Vyon," were used as a substrate for plasma grafting modification. The herbicide atrazine, one of the most popular targets of the molecular imprinting, was chosen as a template. The parameters of the plasma treatment were optimized in order to achieve a good balance between polymerization and ablation processes. Modified HDPE membranes were characterized, and the presence of the grafted polymeric layer was confirmed based on the observed weight gain, pore size measurements, and infrared spectrometry. Since there was no significant change in the porosity of the modified membranes, it was assumed that only a thin layer of the polymer was introduced on the surface. The experiments on the re-binding of the template atrazine to the membranes modified with MIP and blank polymers were performed. HDPE membranes which were grafted with polymer using continuous plasma polymerization demonstrated the best result which was expressed in an imprinted factor equal to 3, suggesting that molecular imprinting was successfully achieved.

Peptide block copolymers by N-carboxyanhydride ring-opening polymerization and atom transfer radical polymerization: The effect of amide macroinitiators

NARCIS (Netherlands)

Habraken, G.J.M.; Koning, C.E.; Heise, A.

2009-01-01

The synthesis of polypeptide-containing block copolymers combining N-carboxyanhydride (NCA) ring-opening polymerization and atom transfer radical polymerization (ATRP) was investigated. An amide initiator comprising an amine function for the NCA polymerization and an activated bromide for ATRP was

A short review of radiation-induced raft-mediated graft copolymerization: A powerful combination for modifying the surface properties of polymers in a controlled manner

Science.gov (United States)

Barsbay, Murat; Güven, Olgun

2009-12-01

Surface grafting of polymeric materials is attracting increasing attention as it enables the preparation of new materials from known and commercially available polymers having desirable bulk properties such as thermal stability, elasticity, permeability, etc., in conjunction with advantageous newly tailored surface properties such as biocompatibility, biomimicry, adhesion, etc. Ionizing radiation, particularly γ radiation is one of the most powerful tools for preparing graft copolymers as it generates radicals on most substrates. With the advent of living free-radical polymerization techniques, application of γ radiation has been extended to a new era of grafting; grafting in a controlled manner to achieve surfaces with tailored and well-defined properties. This report presents the current use of γ radiation in living free-radical polymerization and highlights the use of both techniques together as a combination to present an advance in the ability to prepare surfaces with desired, tunable and well-defined properties.

A short review of radiation-induced raft-mediated graft copolymerization: A powerful combination for modifying the surface properties of polymers in a controlled manner

International Nuclear Information System (INIS)

Barsbay, Murat; Gueven, Olgun

2009-01-01

Surface grafting of polymeric materials is attracting increasing attention as it enables the preparation of new materials from known and commercially available polymers having desirable bulk properties such as thermal stability, elasticity, permeability, etc., in conjunction with advantageous newly tailored surface properties such as biocompatibility, biomimicry, adhesion, etc. Ionizing radiation, particularly γ radiation is one of the most powerful tools for preparing graft copolymers as it generates radicals on most substrates. With the advent of living free-radical polymerization techniques, application of γ radiation has been extended to a new era of grafting; grafting in a controlled manner to achieve surfaces with tailored and well-defined properties. This report presents the current use of γ radiation in living free-radical polymerization and highlights the use of both techniques together as a combination to present an advance in the ability to prepare surfaces with desired, tunable and well-defined properties.

A short review of radiation-induced raft-mediated graft copolymerization: A powerful combination for modifying the surface properties of polymers in a controlled manner

Energy Technology Data Exchange (ETDEWEB)

Barsbay, Murat [Department of Chemistry, Hacettepe University, 06800 Beytepe, Ankara (Turkey)], E-mail: mbarsbay@hacettepe.edu.tr; Gueven, Olgun [Department of Chemistry, Hacettepe University, 06800 Beytepe, Ankara (Turkey)], E-mail: guven@hacettepe.edu.tr

2009-12-15

Surface grafting of polymeric materials is attracting increasing attention as it enables the preparation of new materials from known and commercially available polymers having desirable bulk properties such as thermal stability, elasticity, permeability, etc., in conjunction with advantageous newly tailored surface properties such as biocompatibility, biomimicry, adhesion, etc. Ionizing radiation, particularly {gamma} radiation is one of the most powerful tools for preparing graft copolymers as it generates radicals on most substrates. With the advent of living free-radical polymerization techniques, application of {gamma} radiation has been extended to a new era of grafting; grafting in a controlled manner to achieve surfaces with tailored and well-defined properties. This report presents the current use of {gamma} radiation in living free-radical polymerization and highlights the use of both techniques together as a combination to present an advance in the ability to prepare surfaces with desired, tunable and well-defined properties.

Sulfonated hydrocarbon graft architectures for cation exchange membranes

DEFF Research Database (Denmark)

Nielsen, Mads Møller; Jankova Atanasova, Katja; Hvilsted, Søren

2013-01-01

A synthetic strategy to hydrocarbon graft architectures prepared from a commercial polysulfone and aimed as ion exchange membrane material is proposed. Polystyrene is grafted from a polysulfone macroinitiator by atom transfer radical polymerization, and subsequently sulfonated with acetyl sulfate...... to various degrees. Series of grafting densities and graft lengths are prepared, and membranes are solvent cast from DMSO. The membrane properties in aqueous environments are evaluated from their water swelling behavior, and their thermal properties and stability are investigated by thermogravimetric...

Graft polymerization using radiation-induced peroxides and application to textile dyeing

Energy Technology Data Exchange (ETDEWEB)

Enomoto, Ichiro, E-mail: enomoto.ichiro@iri-tokyo.j [Tokyo Metropolitan Industrial Technology Research Institute, KFC Bldg., 12F, 1-6-1, Yokoami, Sumida-ku, Tokyo 130-0015 (Japan); School of Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Katsumura, Yosuke [School of Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai-mura, Ibaraki 319-1195 (Japan); Kudo, Hisaaki [School of Engineering, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Soeda, Shin [Tokyo Metropolitan Industrial Technology Research Institute, KFC Bldg., 12F, 1-6-1, Yokoami, Sumida-ku, Tokyo 130-0015 (Japan)

2011-02-15

To improve the dyeing affinity of ultra high molecular weight polyethylene (UHMWPE) fiber, surface treatment by radiation-induced graft polymerization was performed. Methyl methacrylate (MMA), acrylic acid (AA) and styrene (St) were used as the monomers. The grafting yields as a function of storage time after irradiation were examined. Although the grafting yield of St after the sulfonation processing was quite low compared with those of MMA and AA, it was successfully dyed to a dark color with a cationic dye. Some acid dyes can dye the grafted fiber with AA. The acid dye is distributed to the amorphous domains of the AA grafted fiber. The dyeing concentration depended on the grafting yield, and the higher the grafting yield the darker the dye color.

Graft polymerization using radiation-induced peroxides and application to textile dyeing

International Nuclear Information System (INIS)

Enomoto, Ichiro; Katsumura, Yosuke; Kudo, Hisaaki; Soeda, Shin

2011-01-01

To improve the dyeing affinity of ultra high molecular weight polyethylene (UHMWPE) fiber, surface treatment by radiation-induced graft polymerization was performed. Methyl methacrylate (MMA), acrylic acid (AA) and styrene (St) were used as the monomers. The grafting yields as a function of storage time after irradiation were examined. Although the grafting yield of St after the sulfonation processing was quite low compared with those of MMA and AA, it was successfully dyed to a dark color with a cationic dye. Some acid dyes can dye the grafted fiber with AA. The acid dye is distributed to the amorphous domains of the AA grafted fiber. The dyeing concentration depended on the grafting yield, and the higher the grafting yield the darker the dye color.

Polysulfone Functionalized With Phosphonated Poly(pentafluorostyrene) Grafts for Potential Fuel Cell Applications

DEFF Research Database (Denmark)

Dimitrov, Ivaylo; Takamuku, Shogo; Jankova Atanasova, Katja

2012-01-01

A multi‐step synthetic strategy to polysulfone (PSU) grafted with phosphonated poly(pentafluorostyrene) (PFS) is developed. It involves controlled radical polymerization resulting in alkyne‐end functional PFS. The next step is the modification of PSU with a number of azide side groups. The grafting...

Influence of temperature on radiation-induced graft polymerization of styrene onto poly(ethylene terephthalate) nuclear membranes and films

International Nuclear Information System (INIS)

Zhitaryuk, N.I.; Shtan'ko, N.I.

1989-01-01

Temperature effect on kinetics of radiation-induced graft polymerization of styrene onto poly(ethylene terephthalate) (PETP) nuclear membranes with various parameters (pore diameter, the average distance between the pores) as well as onto PETP films with different thickness has been studied. Graft polymerization has been carried out by the methods of preirradiation in air and in vacuum. The overall activation energy of grafting as well as the activation energy of swelling of PETP in toluene has been obtained. It was found that in the method of preirradiation in vacuum the initial grafting rate in Arrhenius plot has two linear ranges. Activation energy in low temperature range correlates with activation energy of PETP swelling. Activation energy in high temperature range is determined by kinetics of graft polymerization in the method of preirradiation in air. Arrhenius plot of the initial grafting rate gives the activation energy that approximately corresponds to the initiation of grafting with oxyradicals. Dependence of PETP matrix critical thickness on temperature has also been obtained. The form of this dependence is identical to the one of the rate of graft polymerization. 33 refs.; 6 figs.; 2 tabs

Estimation of degree of polymerization of poly-acrylonitrile-grafted carbon nanotubes using Guinier plot of small angle x-ray scattering.

Science.gov (United States)

Cho, Hyunjung; Jin, Kyeong Sik; Lee, Jaegeun; Lee, Kun-Hong

2018-07-06

Small angle x-ray scattering (SAXS) was used to estimate the degree of polymerization of polymer-grafted carbon nanotubes (CNTs) synthesized using a 'grafting from' method. This analysis characterizes the grafted polymer chains without cleaving them from CNTs, and provides reliable data that can complement conventional methods such as thermogravimetric analysis or transmittance electron microscopy. Acrylonitrile was polymerized from the surface of the CNTs by using redox initiation to produce poly-acrylonitrile-grafted CNTs (PAN-CNTs). Polymerization time and the initiation rate were varied to control the degree of polymerization. Radius of gyration (R g ) of PAN-CNTs was determined using the Guinier plot obtained from SAXS solution analysis. The results showed consistent values according to the polymerization condition, up to a maximum R g  = 125.70 Å whereas that of pristine CNTs was 99.23 Å. The dispersibility of PAN-CNTs in N,N-dimethylformamide was tested using ultraviolet-visible-near infrared spectroscopy and was confirmed to increase as the degree of polymerization increased. This analysis will be helpful to estimate the degree of polymerization of any polymer-grafted CNTs synthesized using the 'grafting from' method and to fabricate polymer/CNT composite materials.

Macromolecular Architectures Designed by Living Radical Polymerization with Organic Catalysts

Directory of Open Access Journals (Sweden)

Miho Tanishima

2014-01-01

Full Text Available Well-defined diblock and triblock copolymers, star polymers, and concentrated polymer brushes on solid surfaces were prepared using living radical polymerization with organic catalysts. Polymerizations of methyl methacrylate, butyl acrylate, and selected functional methacrylates were performed with a monofunctional initiator, a difunctional initiator, a trifunctional initiator, and a surface-immobilized initiator.

INITIATION EFFICIENCY f OF METHYL METHACRYLATE BULK RADICAL POLYMERIZATION

Institute of Scientific and Technical Information of China (English)

沈家骢; 田元; 王国斌; 杨梅林

1990-01-01

The values of the initiation efficiency f at various conversions in the bulk polymerization of MMA initiated by AIBME have first been determined according to a strict unsteady-state formula and based on the data of radical concentration and the termination rate constant determined using ESR method. A model of diffusion control initiation is proposed. The theory is well in agreement with the experiments during the whole process of polymerization.

Atom transfer radical polymerization of n-butyl acrylate catalyzed by atom transfer radical polymerization of n-butyl acrylate catalyzed by

NARCIS (Netherlands)

Zhang, H.; Linde, van der R.

2002-01-01

The homogeneous atom transfer radical polymerization (ATRP) of n-butyl acrylate with CuBr/N-(n-hexyl)-2-pyridylmethanimine as a catalyst and ethyl 2-bromoisobutyrate as an initiator was investigated. The kinetic plots of ln([M]0/[M]) versus the reaction time for the ATRP systems in different

Functionalization of Polymer Surfaces by Radiation-Induced Grafting for Separation of Heavy Metal Ions

Energy Technology Data Exchange (ETDEWEB)

Przybytniak, G; Kornacka, E M; Fuks, L; Walo, M; Lyczko, K; Mirkowski, K [Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw (Poland)

2012-09-15

The reported investigations were focused on the elucidation of the most important factors influencing radiation-induced grafting; particularly (1) the effect of radical population generated in polymeric matrix on degree of grafting, (2) parameters determined grafting and its procedure, (3) correlation between layer structure formed via copolymerization and content of monomers in the initial solution. Sorption capacity of the adsorbants was evaluated using {sup 152}Eu{sup 3+} as a marker monitoring depletion of the radioisotope from the initial solution by gamma radiometer. Electron spin resonance spectroscopy (EPR) and gas chromatography (GC) studies confirmed that yield of radiation-induced radicals increases in the following order polystyrene (PS) < polypropylene (PP) < polyethylene (PE). The same relationship was found for efficiency of radiation grafting. It was concluded that under comparable conditions the content of radicals in polymeric matrices determines grafting degree. It was found that application of the simultaneous method of grafting introduces to the grafted layers crosslinking or/and branching as well as degradation of functional groups. All these phenomena reduce access of Eu{sup 3+} to the studied sorbent therefore sorption capacity of the polyamide functionalized via pre-irradiation (indirect) method is higher than that determined for the sorbent prepared by simultaneous method of grafting. When two monomers, acrylic acid (AAc) and acrylamide (AAm) , contributed in the formation of grafted layer, their input into copolymerization was not proportional to the concentrations in the feed solution. It was confirmed that grafting of the monomers shows synergetic effect as the yield of copolymerization exceeds degree of grafting achieved for individual components. (author)

Surface modification of poly(styrene-b-(ethylene-co-butylene)-b-styrene) elastomer via photo-initiated graft polymerization of poly(ethylene glycol)

Energy Technology Data Exchange (ETDEWEB)

Li Xiaomeng [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Luan Shifang, E-mail: sfluan@ciac.jl.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Yang Huawei; Shi Hengchong; Zhao Jie; Jin Jing [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Yin Jinghua, E-mail: yinjh@ciac.jl.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Stagnaro, Paola [Istituto per Io Studio delle Macromolecole, Consiglio Nazionale delle Ricerche, Via de Marini 6, 16149 Genova (Italy)

2012-01-15

Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) copolymer biomedical elastomer was covalently grafted with poly(ethylene glycol) methyl ether methacrylate (PEGMA) via a photo-initiated graft polymerization technique. The surface graft polymerization of SEBS with PEGMA was verified by ATR-FTIR and XPS. Effect of graft polymerization parameters, i.e., monomer concentration, UV irradiation time and initiator concentration on the grafting density was investigated. Comparing with the virgin SEBS film, the PEGMA-modified SEBS film presented an enhanced wettability and a larger surface energy. Besides, the surface grafting of PEGMA imparted excellent anti-platelet adhesion and anti-protein adsorption to the SEBS surface.

Analysis of Gel Permeation Chromatography From Irradiation Copolymer Grafting of Methylmethacrylate on to Natural Rubber

International Nuclear Information System (INIS)

Hendrana, Sunit; Purwanto, Indratmoko Hari; Karyaningsih, Ipit; Utama, MargaHerwinarni

2004-01-01

Grafting of methyl methacrylate (MMA) onto natural rubber was carried out by γ-irradiation using 60 Co source at dose rate 1 KGy/h and total dose of 5 KGy. Gel permeation chromatography (GPC) was used to analyse the grafting. The GPC's chromatogram, molecular weight and molecular weight distribution data indicate that grafting of MMA onto natural rubber and homo polymerization of MMA are the reaction mostly occurs. Meanwhile, the presence of natural rubber radical with a chain end natural rubber radical affect the PMMA homopolymer occurred

Application of radiation-induced graft polymerization to preparation of functional materials

International Nuclear Information System (INIS)

Sugo, Takanobu

2010-01-01

Radiation-induced graft polymerization is a powerful method for appending various functionalities onto existing fabrics, nonwoven fabrics, fibers, membranes, and beads while maintaining the shape and mechanical strength. By using this method, the author has developed and commercialized functional polymeric materials over 45 years. The materials produced by the fruits of radiation chemistry contributed to the improvement of our lives and environments and the collection of rare metal resources. (author)

SYNTHESIS OF BLOCK COPOLYMER BY INTEGRATED LIVING ANIONIC POLYMERIZATION-ATOM TRANSFER RADICAL POLYMERIZATION (ATRP)

Institute of Scientific and Technical Information of China (English)

Bing Liu; Feng Liu; Ning Luo; Sheng-kang Ying; Qing Liu

2000-01-01

Alpha-trichloroacetoxy terminated polystyrene oligomer (PS-CH2CH2OCOCCl3) and poly-(styrene-b-butadiene)oligomer [P(S-b-B)-CH2CH2OCOCCl3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator.Then the PS-CH2CH2OCOCCl3 (PS-Cl3) or P(S-b-B)-CH2CH2O-COCCl3 (PSB-Cl3) was used as the macroinitiator in the polymerization of (meth)acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared by the integrated living anionic polymerization (LAP)-atom transfer radical polymerization (ATRP). The structures of the PSB-Cl3 and the P(S-b-MMA) were identified by FTIR and 1H-NMR spectrum, respectively. A new way to design block copolymers (the combination of LAP and ATRP) was developed.

Magnetic Levitation To Characterize the Kinetics of Free-Radical Polymerization.

Science.gov (United States)

Ge, Shencheng; Semenov, Sergey N; Nagarkar, Amit A; Milette, Jonathan; Christodouleas, Dionysios C; Yuan, Li; Whitesides, George M

2017-12-27

This work describes the development of magnetic levitation (MagLev) to characterize the kinetics of free-radical polymerization of water-insoluble, low-molecular-weight monomers that show a large change in density upon polymerization. Maglev measures density, and certain classes of monomers show a large change in density when monomers covalently join in polymer chains. MagLev characterized both the thermal polymerization of methacrylate-based monomers and the photopolymerization of methyl methacrylate and made it possible to determine the orders of reaction and the Arrhenius activation energy of polymerization. MagLev also made it possible to monitor polymerization in the presence of solids (aramid fibers, and carbon fibers, and glass fibers). MagLev offers a new analytical technique to materials and polymer scientists that complements other methods (even those based on density, such as dilatometry), and will be useful in investigating polymerizations, evaluating inhibition of polymerizations, and studying polymerization in the presence of included solid materials (e.g., for composite materials).

CONCERNING CHAIN GROWTH SPECIFIC REACTION RATE AS A PART OF THE PROCESS OF METHYL METHACRYLATE MASS RADICAL POLYMERIZATION

Directory of Open Access Journals (Sweden)

A. A. Sultanova

2017-02-01

Full Text Available It is the chain growth specific reaction rate that was determined for the process of methyl methacrylate mass radical polymerization within the temperature range of 40–900 С in quasi-steady approximation by means of Monte Carlo method. The theoretical model of radical polymerization was developed taking the gel effect into account. Computer software was developed that enables to imitate radical polymerization process taking gel effect into account within the minimum run time. The programme was tested on asymptotic examples as well as was applied for methyl methacrylate mass radical polymerization. The programme makes it possible to calculate monomer conversion, molecular mass variation, molecular-mass distribution, etc.

The use of radiation-induced graft polymerization for modification of polymer track membranes

International Nuclear Information System (INIS)

Shtanko, N.I.; Kabanov, V.Ya.; Apel, P.Yu.; Yoshida, M.

1999-01-01

Track membranes (TM) made of poly(ethylene terephtalate) (PET) and polypropylene (PP) films have a number of peculiarities as compared with other ones. They have high mechanical strength at a low thickness, narrow pore size distribution, low content of extractables. However, TM have some disadvantages such as low chemical resistance in alkaline media (PET TM), the low water flow rate due to the hydrophobic nature of their surface. The use of radiation-induced graft polymerization makes it possible to improve the basic characteristics of TM. In this communication our results on the modification of PET and PP TM are presented. The modified membranes were prepared by radiation-induced graft polymerization from the liquid phase. Three methods of grafting were used: (a) the direct method in argon atmosphere; (b) the pre-irradiation of TM in air followed by grafting in argon atmosphere; (c) pre-irradiation in vacuum followed by grafting in vacuum without contacting oxygen. The aim of the work was to investigate some properties of TM modified by grafted poly(methylvinyl pyridine) (PMVP) and poly(N-isopropylacrylamide) (PNIPAAM). It was shown that the modification of TM with hydrophilic polymer results in the growth of the water flow rate. In the past few years many works have been devoted to the synthesis of new polymers - the so-called 'intelligent' materials - such as PNIPAAM. However, it is very difficult to make thin membranes of this polymer. Recently, it has been proposed to manufacture composite membranes by grafting stimulus-responsive polymers onto TM. Following this principle, we prepared thermosensitive membranes by the radiation-induced graft polymerization of N-isopropylacrylamide (NIPAAM) onto PET TM. PET TM with the pore size of about 1 μm and pore density of 10 6 cm -2 were first inserted into a solution of NIPAAM containing inhibitor of homopolymerization (CuCl 2 ) and then exposed to the γ-rays from a 60 Co source. The transport properties of the

The use of radiation-induced graft polymerization for modification of polymer track membranes

Science.gov (United States)

Shtanko, N. I.; Kabanov, V. Ya.; Apel, P. Yu.; Yoshida, M.

1999-05-01

Track membranes (TM) made of poly(ethylene terephtalate) (PET) and polypropylene (PP) films have a number of peculiarities as compared with other ones. They have high mechanical strength at a low thickness, narrow pore size distribution, low content of extractables. However, TM have some disadvantages such as low chemical resistance in alkaline media (PET TM), the low water flow rate due to the hydrophobic nature of their surface. The use of radiation-induced graft polymerization makes it possible to improve the basic characteristics of TM. In this communication our results on the modification of PET and PP TM are presented. The modified membranes were prepared by radiation-induced graft polymerization from the liquid phase. Three methods of grafting were used: (a) the direct method in argon atmosphere; (b) the pre-irradiation of TM in air followed by grafting in argon atmosphere; (c) pre-irradiation in vacuum followed by grafting in vacuum without contacting oxygen. The aim of the work was to investigate some properties of TM modified by grafted poly(methylvinyl pyridine) (PMVP) and poly(N-isopropylacrylamide) (PNIPAAM). It was shown that the modification of TM with hydrophilic polymer results in the growth of the water flow rate. In the past few years many works have been devoted to the synthesis of new polymers - the so-called "intelligent" materials - such as PNIPAAM. However, it is very difficult to make thin membranes of this polymer. Recently, it has been proposed to manufacture composite membranes by grafting stimulus-responsive polymers onto TM. Following this principle, we prepared thermosensitive membranes by the radiation-induced graft polymerization of N-isopropylacrylamide (NIPAAM) onto PET TM. PET TM with the pore size of about 1 μm and pore density of 10 6 cm -2 were first inserted into a solution of NIPAAM containing inhibitor of homopolymerization (CuCl 2) and then exposed to the γ-rays from a 60Co source. The transport properties of the grafted

Electrospun regenerated cellulose nanofibrous membranes surface-grafted with polymer chains/brushes via the atom transfer radical polymerization method for catalase immobilization.

Science.gov (United States)

Feng, Quan; Hou, Dayin; Zhao, Yong; Xu, Tao; Menkhaus, Todd J; Fong, Hao

2014-12-10

In this study, an electrospun regenerated cellulose (RC) nanofibrous membrane with fiber diameters of ∼200-400 nm was prepared first; subsequently, 2-hydroxyethyl methacrylate (HEMA), 2-dimethylaminoethyl methacrylate (DMAEMA), and acrylic acid (AA) were selected as the monomers for surface grafting of polymer chains/brushes via the atom transfer radical polymerization (ATRP) method. Thereafter, four nanofibrous membranes (i.e., RC, RC-poly(HEMA), RC-poly(DMAEMA), and RC-poly(AA)) were explored as innovative supports for immobilization of an enzyme of bovine liver catalase (CAT). The amount/capacity, activity, stability, and reusability of immobilized catalase were evaluated, and the kinetic parameters (Vmax and Km) for immobilized and free catalase were determined. The results indicated that the respective amounts/capacities of immobilized catalase on RC-poly(HEMA) and RC-poly(DMAEMA) nanofibrous membranes reached 78 ± 3.5 and 67 ± 2.7 mg g(-1), which were considerably higher than the previously reported values. Meanwhile, compared to that of free CAT (i.e., 18 days), the half-life periods of RC-CAT, RC-poly(HEMA)-CAT, RC-poly(DMAEMA)-CAT, and RC-poly(AA)-CAT were 49, 58, 56, and 60 days, respectively, indicating that the storage stability of immobilized catalase was also significantly improved. Furthermore, the immobilized catalase exhibited substantially higher resistance to temperature variation (tested from 5 to 70 °C) and lower degree of sensitivity to pH value (tested from 4.0 and 10.0) than the free catalase. In particular, according to the kinetic parameters of Vmax and Km, the nanofibrous membranes of RC-poly(HEMA) (i.e., 5102 μmol mg(-1) min(-1) and 44.89 mM) and RC-poly(DMAEMA) (i.e., 4651 μmol mg(-1) min(-1) and 46.98 mM) had the most satisfactory biocompatibility with immobilized catalase. It was therefore concluded that the electrospun RC nanofibrous membranes surface-grafted with 3-dimensional nanolayers of polymer chains/brushes would be

N-Chlorosuccinimide (NCS): A Novel Initiator for Atom Transfer Radical Polymerization of Methyl Methacrylate

Institute of Scientific and Technical Information of China (English)

WANG,Xia-Yan; CHANG,Li-Qun; ZHOU,Hong; ZHANG,Ke-Da

2006-01-01

Atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was achieved, using N-chlorosuccinimide (NCS) as an initiator together with catalytic system CuCl/PMDETA (N,N,N',N',N"-pentamethyldiethyl-enetriamine), CuCl/MA5-DETA (N,N,N',N',N"-penta(methylacrylate)diethylenetriamine), and CuCl/bipy (bipy=2,2'-bipyridyl) respectively. The results indicated that the polymerization possessed typical controlled/living radical polymerization characteristics. The analysis for terminal group of obtained polymer by 1H NMR proved that NCS is an initiator for ATRP. In comparison with NBS, the polymerization rate was slower and the resulted polymer had narrower molecular weight distribution (MWD) when NCS was employed as the initiator.

Simultaneous FT-NIR and ESR analysis to study of the kinetics of photo induced polymerization of vinyl radical polymers

International Nuclear Information System (INIS)

Le, T.T.; Hill, D.J.T.; Pomery, P.J.

2000-01-01

Full text:The rate parameters for free vinyl radical polymerizations are difficult to determine accurately over the whole range of conversion. For systems which polymerize rapidly and for networks, this is a particular problem, because small differences in polymerization conditions, e.g., temperature, initiator concentration, photon flux, etc., can cause a large change in the time evolution of the concentration of carbon double bonds and radicals if these are monitored in separate experiments. The IUPAC Working Party on the Modeling of kinetics and processes of polymerization has the role of recommending the 'best' values for the kinetic parameters, using pulsed-laser polymerization (PLP) in conjunction with molar mass distribution (MMD) to determine k p as a function of temperature (T deg C) for bulk free-radical polymerization of methyl methacrylate at low conversions and ambient temperature. The vinyl radical polymers used in this study were methyl methacrylate and ethylene glycol dimethacrylate. In the past kinetic studies of vinyl photo-polymerization required the time dependence of the monomer and radical concentrations to be monitored separately by using FT-NIR spectroscopy and ESR spectroscopy, respectively. For the systems which polymerize rapidly, small differences in the conditions for two measurements, e.g. temperature and light intensity, can introduce significant errors. Hyphenated experiments involving in-situ ESR and FT-NIR spectroscopies using fibre optic, can overcome these problems. In this paper, the radical and monomer concentrations were measured under the same experimental conditions using the above techniques. The results obtained were used to evaluate the kinetic parameters for free radical vinyl polymerizations

Polymeric Coatings for Combating Biocorrosion

Science.gov (United States)

Guo, Jing; Yuan, Shaojun; Jiang, Wei; Lv, Li; Liang, Bin; Pehkonen, Simo O.

2018-03-01

Biocorrosion has been considered as big trouble in many industries and marine environments due to causing great economic loss. The main disadvantages of present approaches to prevent corrosion include being limited by environmental factors, being expensive, inapplicable to field, and sometimes inefficient. Studies show that polymer coatings with anti-corrosion and anti-microbial properties have been widely accepted as a novel and effective approach to preventbiocorrosion. The main purpose of this review is to summarize up the progressive status of polymer coatings used for combating microbially-induced corrosion. Polymers used to synthesize protective coatings are generally divided into three categories: i) traditional polymers incorporated with biocides, ii) antibacterial polymers containing quaternary ammonium compounds, and iii) conductive polymers. The strategies to synthesize polymer coatings resort mainly to grafting anti-bacterial polymers from the metal substrate surface using novel surface-functionalization approaches, such as free radical polymerization, chemically oxidative polymerization and surface-initiated atom transfer radical polymerization, as opposed to the traditional approaches of dip coating or spin coating.

Radiation graft polymerization of 4- vinylpyridine on polyvinylchloride-films. [Gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Kudryavtsev, V.N.; Shapiro, A.; Endrikhovska-Bonamur, A.M.

1984-01-01

Radiation graft liquid phase polymerization of 4-vinylpyridine on PVC-films by the method of direct radiation is investigated. The samples are irradiated by Co/sup 60/ ..gamma..-source at 20 deg C and the dose rate of 39 Gy/s for 4-vinylpyridine solutions in methonol, as well as at-78 deg C and dose rate of 1.3 kGy/s for monomer solutions in hexane. Modified polyvinylchloride films with grafted poly-4-vinylpyridine chains are prepared. Being introduced in grafted polyvinylpyridine chains of ion-exchange groups, materials are characterized by good swelling in water and are good to prepare anion-exchange membranes.

In-Situ Immobilization of Ni Complex on Amine-Grafted SiO₂ for Ethylene Polymerization.

Science.gov (United States)

Lee, Sang Yun; Ko, Young Soo

2018-02-01

The results on the In-Situ synthesis of Ni complex on amine-grafted SiO2 and its ethylene polymerization were explained. SiO2/2NS/(DME)NiBr2 and SiO2/3NS/(DME)NiBr2(Ni(II) bromide ethylene glycol dimethyl ether) catalysts were active for ethylene polymerization. The highest activity was shown at the polymerization temperature of 25 °C, and SiO2/2NS/(DME)NiBr2 exhibited higher activity than SiO2/3NS/(DME)NiBr2. The PDI values of SiO2/2NS/(DME)NiBr2 were in the range of 8~18. The aminosilane compounds and Ni were evenly grafted and distributed in the silica. It was proposed that DME ligand was mostly removed during the supporting process, and only NiBr2 was complexed with the amine group of 2NS based on the results of FT-IR and ethylene polymerization.

Synthesis of perm-selective membranes by grafting acrylic acid into air-irradiated Teflon-FEP films

Science.gov (United States)

Bozzi, Annick; Chapiro, Adolphe

Grafting acrylic acid into air-irradiated Teflon-FEP films was investigated. Pre-irradiation doses ranged from 0.5 to 10 kGy. Grafting occurred at 45 or 60°C. Homopolymerization inhibitors, ferrous ions or methylene blue, were added to the system. It was found that after completion of the reaction, within 40-100 min, membranes were obtained with very low electric resistivities. The influence of added inhibitors, pre-irradiation dose and grafting temperature was studied. From the results it is concluded that the initiating centers in air-irradiated Teflon-FEP are, on the one hand, peroxides of structure POOP', in which P is a polymeric radical and Pprime; a small fragment, and on the other trapped PO .2 radicals. The latter only react after losing their oxygen. In the presence of polymerization inhibitors, initiation involves a redox process which reduces the overall activation energy.

Synthesis of perm-selective membranes by grafting acrylic acid into air-irradiated Teflon-FEP films

International Nuclear Information System (INIS)

Bozzi, Annick; Chapiro, Adolphe

1988-01-01

Grafting acrylic acid into air-irradiated Teflon-FEP films was investigated. Pre-irradiation doses ranged from 0.5 to 10 kGy. Grafting occurred at 45 or 60 0 C. Homopolymerization inhibitors, ferrous ions or methylene blue, were added to the system. It was found that after completion of the reaction, within 40-100 min, membranes were obtained with very low electric resistivities. The influence of added inhibitors, pre-irradiation dose and grafting temperature was studied. From the results it is concluded that the initiating centers in air-irradiated Teflon-FEP are, on the one hand, peroxides of structure POOP', in which P is a polymeric radical and P' a small fragment, and on the other hand trapped PO 2 sup(·) radicals. The latter only react after losing their oxygen. In the presence of polymerization inhibitors, initiation involves a redox process which reduces the overall activation energy. (author)

Graft copolymers of polyurethane with various vinyl monomers via radiation-induced miniemulsion polymerization: Influential factors to grafting efficiency and particle morphology

Energy Technology Data Exchange (ETDEWEB)

Wang Hua [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China); Wang Mozhen [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China)], E-mail: pstwmz@ustc.edu.cn; Ge Xuewu [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China)], E-mail: xwge@ustc.edu.cn

2009-02-15

Graft copolymers of polyurethane (PU) with various vinyl monomers were synthesized through a one-pot but two-step miniemulsion polymerization process. Firstly, the polycondensation of isophorone diisocyanate (IPDI) with hydroxyl-terminated polybutadiene (HTPB) had been performed in aqueous miniemulsion at 40 deg. C in order to obtain PU dispersions. Consecutively, an in-situ graft copolymerization of the vinyl monomers with the synthesized PU was initiated by {gamma}-ray radiation at room temperature. The grafting efficiency of PU with vinyl monomer (G{sub PU/monomer}) was calculated from {sup 1}H NMR spectra and the particle morphology of the final hybrid latex was observed by transmission electron microscopy (TEM). As there was no monomer transferring in miniemulsion system, homogenous hybrid particles would be synthesized provided that the monomer was miscible with PU, such as styrene. With the increase of the polarity of the monomer, the compatibility of PU with monomer decreased. G{sub PU/monomer} varied as G{sub PU/styrene}(37%)>G{sub PU/butyl} {sub acrylate} {sub (BA)}(21%)>G{sub PU/methyl} {sub methacrylate} {sub (MMA)}(12%). The proportion of homogeneous nucleation would increase as the hydrophilicity of the monomer increased. High temperature would destabilize the miniemulsion so as to result in a less grafting efficiency. Compared to the phase separation during the seeded emulsion polymerization, the miniemulsion polymerization method facilitated the preparation of homogeneous materials owing to its monomer droplet nucleation mechanism.

Complex Macromolecular Architectures by Living Cationic Polymerization

KAUST Repository

Alghamdi, Reem D.

2015-05-01

Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or “grafting

Stable Protein-Repellent Zwitterionic Polymer Brushes Grafted from Silicon Nitride

NARCIS (Netherlands)

Nguyen, A.T.; Baggerman, J.; Paulusse, J.M.J.; Rijn, van C.J.M.; Zuilhof, H.

2011-01-01

Zwitterionic poly(sulfobetaine acrylamide) (SBMAA) brushes were grafted from silicon-rich silicon nitride (SixN4, x > 3) surfaces by atom transfer radical polymerization (ATRP) and studied in protein adsorption experiments. To this aim ATRP initiators were immobilized onto SixN4 through stable

Microwave-assisted grafting polymerization modification of nylon 6 capillary-channeled polymer fibers for enhanced weak cation exchange protein separations

Energy Technology Data Exchange (ETDEWEB)

Jiang, Liuwei; Marcus, R. Kenneth, E-mail: marcusr@clemson.edu

2017-02-15

A weak cation exchange liquid chromatography stationary phase (nylon-COOH) was prepared by grafting polyacrylic acid on to native nylon 6 capillary-channeled polymer (C-CP) fibers via a microwave-assisted radical polymerization. To the best of our knowledge, this is the first study of applying microwave-assisted grafting polymerization to affect nylon material for protein separation. The C-CP fiber surfaces were characterized by attenuated total reflection (ATR) infrared spectroscopy and scanning electron microscope (SEM). The anticipated carbonyl peak at 1722.9 cm{sup −1} was found on the nylon-COOH fibers, but was not found on the native fiber, indicating the presence of the polyacrylic acid on nylon fibers after grafting. The nylon-COOH phase showed a ∼12× increase in lysozyme dynamic binding capacity (∼12 mg mL{sup −1}) when compared to the native fiber phase (∼1 mg mL{sup −1}). The loading capacity of the nylon-COOH phase is nearly independent of the lysozyme loading concentration (0.05–1 mg mL{sup −1}) and the mobile phase linear velocity (7.3–73 mm s{sup −1}). The reproducibility of the lysozyme recovery from the nylon-COOH (RSD = 0.3%, n = 10) and the batch-to-batch variability in the functionalization (RSD = 3%, n = 5) were also investigated, revealing very high levels of consistency. Fast baseline separations of myoglobin, α-chymotrypsinogen A, cytochrome c and lysozyme were achieved using the nylon-COOH column. It was found that a 5× increase in the mobile phase linear velocity (7.3-to-36.5 mm s{sup −1}) had little effect on the separation resolution. The microwave-assisted grafting polymerization has great potential as a generalized surface modification methodology across the applications of C-CP fibers. - Highlights: • A microwave-assisted grafting method to attach acrylic acid is described for the first time for chromatographic phases. • A high-density, weak cation exchange surface is created on a nylon

Production and installation of equipments for radiation-induced graft polymerization in liquid phase and dipping techniques

International Nuclear Information System (INIS)

Seko, Noriaki; Kasai, Noboru; Tamada, Masao; Hasegawa, Shin; Katakai, Akio; Sugo, Takanobu

2005-01-01

Fibrous adsorbent which is synthesized by radiation induced graft polymerization on the trunk polymers such as polymer nonwoven fabrics and woven cloths exhibits an excellent selective adsorption against heavy metal ions and toxic gases at extremely low concentrations. Two equipments were installed to synthesize the metal-ion and gas adsorbents by means of the radiation-induced graft polymerization in the liquid phase and the dipping, respectively. In the reation chamber of the liquid phase reactor, the oxygen decreased to 100 ppm. The inside temperature was elevated at 80C. These characteristics satisfied the specification. The fabric transport can regulate the rate in the range from 1 to 10 m/min. The reactor for the dip grafting could reduce the inside oxygen to 100ppm and inside temperature could reach to 80C, also. The transport system is stable during the dip grafting reaction. The grafting of glycidyl methacrylate was carried out as a characteristic test. The degree of grafting was controlled in the range of 40-70%. The both equipments can graft the trunk polymer, 2000mm in maximum width and 1m in maximum diameter. This size is enough for confirmation practical scale synthesis. (author)

Stable Protein-Repellent Zwitterionic Polymer Brushes Grafted from Silicon Nitride

NARCIS (Netherlands)

Nguyen, Ai T.; Baggerman, Jacob; Paulusse, Jos Marie Johannes; van Rijn, Cees J.M.; Zuilhof, Han

2011-01-01

Zwitterionic poly(sulfobetaine acrylamide) (SBMAA) brushes were grafted from silicon-rich silicon nitride (SixN4, x > 3) surfaces by atom transfer radical polymerization (ATRP) and studied in protein adsorption experiments. To this aim ATRP initiators were immobilized onto SixN4 through stable Si−C

Ferroferric oxide/polystyrene (Fe3O4/PS superparamagnetic nanocomposite via facile in situ bulk radical polymerization

Directory of Open Access Journals (Sweden)

2010-03-01

Full Text Available Organo-modified ferroferric oxide superparamagnetic nanoparticles, synthesized by the coprecipitation of superparamagnetic nanoparticles in presence of oleic acid (OA, were incorporated in polystyrene (PS by the facile in situ bulk radical polymerization by using 2,2-azobisisobutyronitrile (AIBN as initiator. The transmission electron microscopy (TEM analysis of the resultant uniform ferroferric oxide/polystyrene superparamagnetic nanocomposite (Fe3O4/PS showed that the superparamagnetic nanoparticles had been dispersed homogeneously in the polymer matrix due to the surface grafted polystyrene, confirmed by Fourier transform infrared (FT-IR spectroscopy and thermogravimetric analysis (TGA. The superparamagnetic property of the Fe3O4/PS nanocomposite was testified by the vibrating sample magnetometer (VSM analysis. The strategy developed is expected to be applied for the large-scale industrial manufacturing of the superparamagnetic polymer nanocomposite.

Studies on surface graft polymerization of acrylic acid onto PTFE film by remote argon plasma initiation

International Nuclear Information System (INIS)

Wang Chen; Chen Jierong

2007-01-01

The graft polymerization of acrylic acid (AAc) was carried out onto poly(tetrafluoroethylene) (PTFE) films that had been pretreated with remote argon plasma and subsequently exposed to oxygen to create peroxides. Peroxides are known to be the species responsible for initiating the graft polymerization when PTFE reacts with AAc. We chose different parameters of remote plasma treatment to get the optimum condition for introducing maximum peroxides (2.87 x 10 -11 mol/cm 2 ) on the surface. The influence of grafted reaction conditions on the grafting degree was investigated. The maximum grafting degree was 25.2 μg/cm 2 . The surface microstructures and compositions of the AAc grafted PTFE film were characterized with the water contact angle meter, Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Contact angle measurements revealed that the water contact angle decreased from 108 o to 41 o and the surface free energy increased from 22.1 x 10 -5 to 62.1 x 10 -5 N cm -1 by the grafting of the AAc chains. The hydrophilicity of the PTFE film surface was greatly enhanced. The time-dependent activity of the grafted surface was better than that of the plasma treated film

Copolymers containing phosphorescent iridium(III) complexes obtained by free and controlled radical polymerization techniques

NARCIS (Netherlands)

Ulbricht, C.; Becer, C.R.; Winter, A.; Veldman, D.; Schubert, U.S.

2008-01-01

A methacrylate-functionalized phosphorescent Ir(III)-complex has been synthesized, characterized, and applied as a monomer in radical copolymerizations. Together with methyl methacrylate, the complex has been copolymerized under free radical polymerization conditions. Aiming for host-guest-systems,

The nature of the initiating centres for grafting in air-irradiated perfluoro polymers

International Nuclear Information System (INIS)

Bozzi, A.; Chapiro, A.

1987-01-01

Grafting of acrylic acid on polytetrafluoroethylene has been performed using films of the polymer gamma-irradiated in air and then treated with aqueous acrylic acid. It is concluded that the initiating centres are peroxides POOP', where P' is a small perfluorinated fragment, and also trapped peroxy radicals PO 2 radical which undergo deoxygenation. Homopolymerization is suppressed by polymerization inhibitors. (author)

PETMA-g-PETMA-b-PS 'palm tree' graft copolymer: A new polymeric architecture obtained via RAFT and ROP process

International Nuclear Information System (INIS)

Soares, Paula P.; Silva, Eduardo de O. da; Petzhold, Cesar L.

2009-01-01

Block copolymer with pendant thiirane moiety PETMA-b-PS is the base for a new class of 'palm tree' graft copolymers, which can show interesting properties. ETMA can be polymerized through ring opening polymerization with Lewis bases as initiator, e.g., Br- and tertiary amines. We used this reaction as a way to graft a copolymer PETMA-b-PS possessing 5% of ETMA unities, with chains having poly(propylene sulfide), obtained by graft from method. Produced materials were characterized through H1 NMR, SEC and DSC. (author)

SIMULTANEOUS MEASUREMENT OF FREE RADICAL DECAY IN POLYMERIZATION OF MMA INITIATED BY AIBN USING ESR AND ITS KINETIC MODEL

Institute of Scientific and Technical Information of China (English)

Ping Xia; Qing-song Hu; Xiao-lan Qian; Xul-in Jiang; De-yue Yan

2001-01-01

The kinetics of free radical decay in the polymerization of MMA initiated by AIBN was studied by means of ESR spectroscopy. It was found that the curves of radical decay are strongly associated with the reaction temperature, the initiator concentration and the solvent. In the case of the radical polymerization carried out at high temperature or in solution, the radical concentration first reached a maximum, then declined monotonously with reaction time. It was also found that the greater the amount of initiator or the higher the temperature, the more rapidly the radicals decay. When the bulk polymerization was implemented at a relatively low temperature, the curves of radical decay became more complicated, i.e.,the radical concentration rapidly rose to a maximum, then dropped to a minimum, finally increased again with reaction time.Taking into account the diffusion effect, a semi-empirical equation is suggested to describe the kinetics of propagating radical decay.

Improved biotribological properties of PEEK by photo-induced graft polymerization of acrylic acid

Energy Technology Data Exchange (ETDEWEB)

Zhao, Xiaoduo; Xiong, Dangsheng, E-mail: xiongds@163.com; Wang, Kun; Wang, Nan

2017-06-01

The keys of biomaterials application in artificial joints are good hydrophilicity and wear resistance. One kind of the potential bio-implant materials is polyetheretherketone (PEEK), which has some excellent properties such as non-toxic and good biocompatibility. However, its bioinert surface and inherent chemical inertness hinder its application. In this study, we reported an efficient method for improving the surface wettability and wear resistance for PEEK, a layer of acrylic acid (AA) polymer brushes on PEEK surface was prepared by UV-initiated graft polymerization. The effects of different grafting parameters (UV-irradiation time/AA monomer solution concentration) on surface characteristics were clearly investigated, and the AA-g-PEEK specimens were examined by ATR-FTIR, static water contact angle measurements and friction tests. Our results reveal that AA can be successfully grafted onto the PEEK surface after UV irradiation, the water wettability and tribological properties of AA-g-PEEK are much better than untreated PEEK because that AA is a hydrophilic monomer, the AA layer on PEEK surface can improve its bearing capacity and reduce abrasion. This detailed understanding of the grafting parameters allows us to accurately control the experimental products, and this method of surface modification broadens the use of PEEK in orthopedic implants. - Highlights: • Acrylic acid was successful grafted onto PEEK substrate by UV-initiated graft polymerization. • AA-g-PEEK owned better hydrophilicity than untreated PEEK. • Wear resistance of AA-g-PEEK were significantly improved due to AA brushes could bear high contact stress.

Control of lipid oxidation by nonmigratory active packaging films prepared by photoinitiated graft polymerization.

Science.gov (United States)

Tian, Fang; Decker, Eric A; Goddard, Julie M

2012-08-08

Transition metal-promoted oxidation impacts the quality, shelf life, and nutrition of many packaged foods. Metal-chelating active packaging therefore offers a means to protect foods against oxidation. Herein, we report the development and characterization of nonmigratory metal-chelating active packaging. To prepare the films, carboxylic acids were grafted onto the surfaces of polypropylene films by photoinitiated graft polymerization of acrylic acid. Attenuated total reflectance/Fourier transform infrared spectroscopy, contact angle, scanning electron microscopy, and iron-chelating assay were used to characterize film properties. Graft polymerization yielded a carboxylic acid density of 68.67 ± 9.99 nmol per cm(2) film, with ferrous iron-chelating activity of 71.07 ± 12.95 nmol per cm(2). The functionalized films extended the lag phase of lipid oxidation in a soybean oil-in-water emulsion system from 2 to 9 days. The application of such nonmigratory active packaging films represents a promising approach to reduce additive use while maintaining food quality.

The effect of reducing monosaccharides on the atom transfer radical polymerization of butyl methacrylate

NARCIS (Netherlands)

Vries, de Andrew; Klumperman, B.; Wet-Roos, de D.; Sanderson, R.D.

2001-01-01

The effect of various reducing monosaccharides on the rate of atom transfer radical polymerization (ATRP) of butyl methacrylate is reported in this study. The addition of reducing sugars affects the rate of ATRP positively with a 100% increase in the rate of polymerization in some cases. In

Design and synthesis of structurally well-defined functional polypropylenes via transition metal-mediated olefin polymerization chemistry

Institute of Scientific and Technical Information of China (English)

Dong Jinyong

2006-01-01

Functionalization of polyolefins is an industrially important yet scientifically challenging research subject.This paper summarizes our recent effort to access structurally well-defined functional polypropylenes via transition metal-mediated olefin polymerization.In one approach,polypropylenes containing side chain functional groups of controlled concentrations were obtained by Ziegler-Natta-catalyzed copolymerization of propylene in combination with either living anionic or controlled radical polymerization of polar monomers.The copolymerization of propylene with 1,4-divinylbenzene using an isospecific MgC12-supported TIC14 catalyst yielded potypropylenes containing pendant styrene moieties.Both metalation reaction with n-butyllithium and hydrochlorination reaction with dry hydrogen chloride selectively and quantitatively occurred at the pendant reactive sites,generating polymeric benzyllithium and 1-chloroethylbenzene species.These species initiated living anionic polymerization of styrene(S)and atom transfer radical polymerization(in the presence of CuC1 and pentamethyldiethylenetriamine) of methyl methacrylate(MMA),respectively,resulting in functional polypropylene graft copolymers(PP-g-PS and PP-g-PMMA)with controllable graft lengths.In another approach,chain end-functionalized polypropylenes containing a terminal OH-group with controlled molecular weights were directly prepared by propylene polymerization with a metaUocene catalyst through a selective aluminum chain transfer reaction.Both approaches proved to be desirable polyolefin functionalization routes in terms of efficiency and polymer structure controllability.

Hydrolysis of 4-Acetoxystyrene Polymers Prepared by Atom Transfer Radical Polymerization

DEFF Research Database (Denmark)

Chen, Xianyi; Jankova, Katja; Kops, Jørgen

1999-01-01

Hydrolysis of 4-acetoxystyrene polymers prepared by atom transfer radical polymerization was carried out under various reaction conditions. It was found that hydrazinolysis of 4-acetoxystyrene homopolymers, random and block copolymers with styrene in 1,4-dioxane, afforded the corresponding narrow...

TERMINATION PROCESS AND THE TERMINATION PARAMETER k_t OF METHYL METHACRYLATE BULK RADICAL POLYMERIZATION

Institute of Scientific and Technical Information of China (English)

沈家骢; 田元; 王国斌; 杨梅林

1990-01-01

In this work the exact k_t data during the whole process of MMA bulk radical polymerization have been determined under unsteady state by using the post effect technique and ESR method. The effect of the micro-environment of radicals on the termination is discussed.

Critically evaluated rate coefficients for free-radical polymerization, 5. Propagation rate coefficient for butyl acrylate

NARCIS (Netherlands)

Asua, J.M.; Beuermann, S.; Buback, M.; Castignolles, P.; Charleux, B.; Gilbert, R.G.; Hutchinson, R.A.; Leiza, J.R.; Nikitin, A.N.; Vairon, J.P.; Herk, van A.M.

2004-01-01

Propagation rate coefficients, kp, for free-radical polymerization of butyl acrylate (BA) previously reported by several groups are critically evaluated. All data were determined by the combination of pulsed-laser polymerization (PLP) and subsequent polymer analysis by size exclusion (SEC)

Enhanced protein retention on poly(caprolactone) via surface initiated polymerization of acrylamide

International Nuclear Information System (INIS)

Ma, Yuhao; Cai, Mengtan; He, Liu; Luo, Xianglin

2016-01-01

Graphical abstract: - Highlights: • Dense package of poly(acrylamide) on poly(caprolactone) surface was achieved by surface-initiated atom transfer radical polymerization. • Poly(acrylamide) grafted surface exhibited high protein retention ability. • Loaded protein was resistant to detachment and maintained its structure without denaturation. - Abstract: To enhance the biocompatibility or extend the biomedical application of poly(caprolactone) (PCL), protein retention on PCL surface is often required. In this study, poly(acrylamide) (PAAm) brushes were grown from PCL surface via surface-initiated atom transfer radical polymerization (SI-ATRP) and served as a protein-capturing platform. Grafted PAAm was densely packed on surface and exhibited superior protein retention ability. Captured protein was found to be resistant to washing under detergent environment. Furthermore, protein structure after being captured was investigated by circular dichroism (CD) spectroscopy, and the CD spectra verified that secondary structure of captured proteins was maintained, indicating no denaturation of protein happened for retention process.

Novel fluorinated block copolymer architectures fuelled by atom transfer radical polymerization

DEFF Research Database (Denmark)

Jankova, Katja; Hvilsted, Søren

2005-01-01

Block copolymers based on poly(pentafluorostyrene), PFS, in various numbers and of different lengths, and polystyrene are prepared by atom transfer radical polymerization (ATRP). Di- and triblock copolymers with varying amounts of PFS were synthesized employing either I phenylethylbromide or 1,4-...

Atom-transfer radical polymerization of methyl methacrylate (MMA) using CuSCN as the catalyst

NARCIS (Netherlands)

Singha, N.K.; Klumperman, B.

2000-01-01

The effect of CuSCN as a catalyst in atom-transfer radical polymerization (ATRP) was investigated. CuSCN can successfully be used for the ATRP of MMA. Substituted bipyridines as well as imines can be used to stabilize the copper complex in solution. CuSCN induces faster polymerization compared to

Modeling of free radical polymerization up to high conversion. II. Development of a mathematical model.

NARCIS (Netherlands)

Tefera shibeshe, N.; Tefera, N.; Weickert, G.; Westerterp, K.R.

1997-01-01

In free radical polymerization diffusion-controlled processes take place simultaneously to the normal chemical reactions. Despite extensive efforts to model such processes a consistent model for the design of a polymerization reactor has not yet been established. In this article a semiempirical

On Surface-Initiated Atom Transfer Radical Polymerization Using Diazonium Chemistry To Introduce the Initiator Layer

DEFF Research Database (Denmark)

Iruthayaraj, Joseph; Chernyy, Sergey; Lillethorup, Mie

2011-01-01

This work features the controllability of surface-initiated atom transfer radical polymerization (SI-ATRP) of methyl methacrylate, initiated by a multilayered 2-bromoisobutyryl moiety formed via diazonium chemistry. The thickness as a function of polymerization time has been studied by varying di...

Monte Carlo simulation on kinetics of batch and semi-batch free radical polymerization

KAUST Repository

Shao, Jing

2015-10-27

Based on Monte Carlo simulation technology, we proposed a hybrid routine which combines reaction mechanism together with coarse-grained molecular simulation to study the kinetics of free radical polymerization. By comparing with previous experimental and simulation studies, we showed the capability of our Monte Carlo scheme on representing polymerization kinetics in batch and semi-batch processes. Various kinetics information, such as instant monomer conversion, molecular weight, and polydispersity etc. are readily calculated from Monte Carlo simulation. The kinetic constants such as polymerization rate k p is determined in the simulation without of “steady-state” hypothesis. We explored the mechanism for the variation of polymerization kinetics those observed in previous studies, as well as polymerization-induced phase separation. Our Monte Carlo simulation scheme is versatile on studying polymerization kinetics in batch and semi-batch processes.

Study of energy transfer to solvent in radiation graft polymerization of styrene onto polyethylene

International Nuclear Information System (INIS)

Rabie, A.; Odian, G.

1977-01-01

The radiation-initiated graft polymerization of styrene onto polyethylene was studied to determine whether energy transfer to diluent was responsible for the previously observed high orders of dependence of the grafting rate on monomer concentration. n-Octane was used as the diluent instead of benzene. If energy transfer from excited polyethylene to benzene were present, it should not be with n-octane. The percent swelling of polyethylene by various n-octane--styrene mixtures was determined. The compositions of various n-octane--styrene mixtures absorbed inside polyethylene were determined by ultraviolet and refractive index measurements and found to be richer in styrene than the corresponding mixtures in which the polyethylene had been placed. The graft polymerization rates were determined at 0.000761, 0.0371, and 0.213 Mrad/hr and plotted against the inside styrene concentrations on a log-log scale to yield the kinetic orders of dependence of rate on monomer as 2, 3, and 3, respectively. It was concluded that energy transfer to diluent was not responsible for the high-order dependence observed

Potassium fulvate as co-interpenetrating agent during graft polymerization of acrylic acid from cellulose.

Science.gov (United States)

Ghazy, Mohamed B M; El-Hai, Farag Abd; Mohamed, Magdy F; Essawy, Hisham A

2016-10-01

Grafting polymerization of acrylic acid onto cellulose in presence of potassium fulvate (KF) as a co-interpenetrating agent results enhanced water sorption compared to materials prepared similarly in its absence. The insertion of potassium fulvate (KF) did not affect the grafting process and is thought to proceed in parallel to the graft polymerization via intensive polycondensation reactions of its function groups (-COOH and OH) with COOH of the monomer and OH groups of cellulose. The combination of graft copolymerization and polycondensation reactions is assumed to produce interpenetrating network structure. Fourier transform infrared (FTIR) confirmed successful incorporation within the network structure which is an evidence for formation of interpenetrating network. The obtained structures showed homogeneous uniform surface as revealed by scanning electron microscopy (SEM). The obtained superabsorbent possessed high water absorbency 422 and 48.8g/g in distilled water and saline (0.9wt.% NaCl solution), respectively, and enhanced water retention even at elevated temperatures as revealed by thermogravimetric analysis (TGA). This could be explained by the high content of hydrophilic groups. The new superabsorbents proved to be efficient devices for controlled release of fertilizers which expands their use in agricultural applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Radical polymerization in holographic grating formation in PQ-PMMA photopolymer part II: Consecutive exposure and dark decay

Science.gov (United States)

Yu, Dan; Liu, Hongpeng; Geng, Yaohui; Wang, Weibo; Zhao, Yuanyuan

2014-11-01

Photochemical radical polymerization in phenathrenequinone doped poly(methyl methacrylate) photopolymer are investigated theoretically and experimentally under consecutive exposure. The detailed photochemical mechanisms are analyzed. Based on the rate equations of photochemical reactions, the diffusion models with nonlocal response are proposed to describe the kinetic process of radical polymerization and the significance of photochemical processes for the grating formation. In experiments, the temporal evolution of diffraction efficiency in grating formation is measured under consecutive exposure and after exposure. The percentages of these radical polymerizations, namely the polymerization of PQ with matrix, the bimolecular combination of MMA molecules, and the disproportionation of MMA molecules, are extracted quantitatively by comparing theory with experiments. It is indicated that the polymerization of PQ with matrix is primary photochemical process which dominated the grating formation under consecutive exposure. In this period, the contribution of chain polymerization of MMA radicals is weak for the grating formation. After reaching the peak values of grating strength, the influence of the free MMA molecules and photoproduct macromolecules on the grating decay is discussed in a long-term period. The diffusion coefficients of MMA and photoproduct are extracted by fitting the curves using double exponential function. MMA’s diffusion contributed to the fast decay process of grating after exposure and photoproduct’s diffusion contributed to the slow and long decay of grating. The results break previous understanding about the diffusion of single photoproduct macromolecules lead to the dark decay of grating. This investigation can provide a significant foundation for improving modulation depth and long-term stability by photochemical mechanism.

Modification of dispersibility of nanodiamond by grafting of polyoxyethylene and by the introduction of ionic groups onto the surface via radical trapping

International Nuclear Information System (INIS)

Cha, I.; Hashimoto, K.; Fujiki, K.; Yamauchi, T.; Tsubokawa, N.

2014-01-01

To improve the dispersibility of polycrystalline nanodiamond (ND) in solvents, the grafting of polymers and introduction of ionic groups onto ND surface via radical trapping by ND surface were investigated. The grafting of polyoxyethylene (POE) onto ND surface by trapping of POE radicals formed by the thermal decomposition of POE macro azo-initiator (Azo-POE) was examined. The polymer radicals formed by the thermal decomposition of Azo-POE were successfully trapped by ND surface to give POE-grafted ND. The effect of temperature on the grafting of POE onto ND was discussed. In addition, the introduction of cationic protonated amidine groups onto ND was achieved by the trapping of radicals bearing protonated amidine groups formed by thermal decomposition of 2,2′-azobis(2-methylpropionamidine)dihydrochloride (AMPA). The anionic carboxylate groups was introduced onto ND surface by the trapping of the radicals bearing carboxyl groups formed by thermal decomposition of 4,4′-azobis(4-cyonovaleric acid) (ACVA) followed by the treatment with NaOH aqueous solution. The dispersibility of ND in water was remarkably improved by the grafting of POE, based on the steric hindrance of polymer chains and by the introduction of ionic groups, based on the ionic repulsion, onto ND surface. - Highlights: • Grafting of PEG onto nanodiamond was achieved by radical trapping. • Introduction of ionic groups onto nanodiamond was achieved by radical trapping. • Nanodiamond was dispersed by PEG grafting based on steric hindrance of PEG chains. • Nanodiamond was dispersed by introduction of ionic groups based on ionic repulsion

Modification of dispersibility of nanodiamond by grafting of polyoxyethylene and by the introduction of ionic groups onto the surface via radical trapping

Energy Technology Data Exchange (ETDEWEB)

Cha, I. [Graduate School of Science and Technology, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-2181 (Japan); Hashimoto, K. [Department of Material Science and Technology, Faculty of Engineering, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-218 (Japan); Fujiki, K. [Department of Environmental Science, Niigata Institute of Technology, 1719, Fujihashi, Kashiwazaki, Niigata 945-1195 (Japan); Yamauchi, T. [Graduate School of Science and Technology, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-2181 (Japan); Department of Material Science and Technology, Faculty of Engineering, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-218 (Japan); Tsubokawa, N., E-mail: ntsuboka@eng.niigata-u.ac.jp [Graduate School of Science and Technology, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-2181 (Japan); Department of Material Science and Technology, Faculty of Engineering, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-218 (Japan)

2014-02-14

To improve the dispersibility of polycrystalline nanodiamond (ND) in solvents, the grafting of polymers and introduction of ionic groups onto ND surface via radical trapping by ND surface were investigated. The grafting of polyoxyethylene (POE) onto ND surface by trapping of POE radicals formed by the thermal decomposition of POE macro azo-initiator (Azo-POE) was examined. The polymer radicals formed by the thermal decomposition of Azo-POE were successfully trapped by ND surface to give POE-grafted ND. The effect of temperature on the grafting of POE onto ND was discussed. In addition, the introduction of cationic protonated amidine groups onto ND was achieved by the trapping of radicals bearing protonated amidine groups formed by thermal decomposition of 2,2′-azobis(2-methylpropionamidine)dihydrochloride (AMPA). The anionic carboxylate groups was introduced onto ND surface by the trapping of the radicals bearing carboxyl groups formed by thermal decomposition of 4,4′-azobis(4-cyonovaleric acid) (ACVA) followed by the treatment with NaOH aqueous solution. The dispersibility of ND in water was remarkably improved by the grafting of POE, based on the steric hindrance of polymer chains and by the introduction of ionic groups, based on the ionic repulsion, onto ND surface. - Highlights: • Grafting of PEG onto nanodiamond was achieved by radical trapping. • Introduction of ionic groups onto nanodiamond was achieved by radical trapping. • Nanodiamond was dispersed by PEG grafting based on steric hindrance of PEG chains. • Nanodiamond was dispersed by introduction of ionic groups based on ionic repulsion.

Process for the graft polymerization of polyvinyl chloride. [electron beams

Energy Technology Data Exchange (ETDEWEB)

Kageyama, E; Kusama, Y; Udagawa, A; Hashimoto, S

1970-08-14

The graft polymerization of acrylonitrile on polyvinyl chloride is effected by simultaneous irradiation with ionizing radiations in a reaction bath consisting of 30% acrylonitrile and 70% n-hexane. The acrylonitrile-hydrocarbon reaction bath increases the graft efficiency markedly when the content of acrylonitrile is 30%. In this case, the formation rate of acrylonitrile homopolymer decreases with a decrease in the content of acrylonitrile. The immersion time may be from a few minutes to a few hours, depending on the type, property and desired graft efficiency of the polyvinyl chloride resin. The polyvinyl chloride may be any available on the market. The acrylonitrile may contain a small quantity of copolymerizable monomer if it does not influence the thermal property of the polyvinyl chloride graft polymer. The ionizing radiations must have enough energy to form an ion pair by removing one electron from one atom of a gas. In examples, 10 g of polyvinyl chloride in powder form were immersed in 100 cc of a mixed solution consisting of 70% to 90% of n-hexane and 10% to 30% of acrylonitrile. The polyvinyl chloride in the solution was exposed to electron beams of 2 Mrad at a dose rate of 7.2 x 10/sup 7/ rad/hr. under a reduced pressure. The graft efficiency was 50% to 80% and the yield of acrylonitrile homopolymer was 0.42 g to 1.26 g.

Bifunctional groups grafted polyethersulfone magnetic beads for selective sequestration of plutonium

International Nuclear Information System (INIS)

Paul, Sumana; Aggarwal, S.K.; Pandey, A.K.

2014-01-01

The present study involves synthesis of polyethersulfone (PES) beads grafted with two different monomers viz. 2-hydroxyethylmethacrylate phosphoric acid ester (HEMP) and 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS) by photo-induced free radical polymerization method. The selection of bifunctional polymer was based on our previous studies, which indicated its efficacy for selective preconcentration of Pu from 3-4 mol L -1 HNO 3 . The HEMP-co-AMPS grafted PES beads were used for selective extraction of plutonium from dissolver solution

The LEGO toolbox: Supramolecular building blocks by nitroxide-mediated controlled radical polymerization

NARCIS (Netherlands)

Lohmeijer, B.G.G.; Schubert, U.S.

2005-01-01

A terpyridine-functionalized alkoxyamine unimolecular initiator was used for the nitroxide-mediated controlled living radical polymerization of n-butylacrylate, N,N-dimethylacrylamide, 4-vinylpyridine, 2-vinylpyridine, and isoprene. For the former three monomers, the kinetics were studied. All

Poly(lauryl acrylate) and poly(stearyl acrylate) grafted multiwalled carbon nanotubes for polypropylene composites

DEFF Research Database (Denmark)

Daugaard, Anders Egede; Jankova Atanasova, Katja; Hvilsted, Søren

2014-01-01

Two new polymer grafts on an industrial grade multiwalled carbon nanotube (MWCNT) were prepared through a non-oxidative pathway employing controlled free radical polymerization for surface initiated polymer grafting. After photochemical introduction of an ATRP initiator onto the MWCNT......, polymerizations of lauryl or stearyl acrylate were performed, resulting in two novel polymer modifications on the MWCNT (poly(lauryl acrylate) or poly(stearyl acrylate)). The method was found to give time dependent loading of polymers as a function of time (up to 38 wt% for both acrylates), and showed a plateau...... in loading after 12 h of polymerization. The modified nanomaterials were melt mixed into polypropylene composites with very low filler loading (0.3 wt%), whereafter both the thermal and electrical properties were investigated by DSC and dielectric resonance spectroscopy. The electrical properties were found...

Homogeneous synthesis of cellulose acrylate-g-poly (n-alkyl acrylate) solid-solid phase change materials via free radical polymerization.

Science.gov (United States)

Qian, Yong-Qiang; Han, Na; Bo, Yi-Wen; Tan, Lin-Li; Zhang, Long-Fei; Zhang, Xing-Xiang

2018-08-01

A novel solid-solid phase change materials, namely, cellulose acrylate-g-poly (n-alkyl acrylate) (CA-g-PAn) (n = 14, 16 and 18) were successfully synthesized by free radical polymerization in N, N-dimethylacetamide (DMAc). The successful grafting was confirmed by fourier transform infrared spectra (FT-IR) and nuclear magnetic resonance (NMR). The properties of the CA-g-PAn copolymers were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA). The phase change temperatures and the melting enthalpies of CA-g-PAn copolymers are in the range of 10.1-53.2 °C and 15-95 J/g, respectively. It can be adjusted by the contents of poly (n-alkyl acrylate) and the length of alkyl side-chain. The thermal resistant temperatures of CA-g-PA14, 16 and 18 copolymers are 308 °C, 292 °C and 273 °C, respectively. It show that all of grafting materials exhibit good thermal stability and shape stability. Therefore, it is expected to be applied in the cellulose-based thermos-regulating field. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of Inhibitors on Atom Transfer Radical Polymerization of MMA

Institute of Scientific and Technical Information of China (English)

张鸿; 徐冬梅; 张可达

2005-01-01

Effect of a series of inhibitors as additives on atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) with FeCl2/PPh3 as catalyst system was studied, including 2,4,6-trinitrophenol (TNP), 4-methoxyphenol (4-MP), hydroquinone (HQ) and nitrobenzene (NB). It was found that TNP was the only. efficient additive for ATRP among these inhibitors. In the presence of small amounts of TNP, the polymerization proceeded rapidly after induction period to yield the polymers with controlled molecular weights and narrow molecular weight distributions (MWD). The initiating efficiency of the modified catalyst system with TNP was increased. The mechanism was proposed and confirmed by the end group analysis of the polymer.

Mechanistic investigations of novel photoinitiators for radical polymerization

International Nuclear Information System (INIS)

Griesser, M.

2012-01-01

Nowadays, there is a wide variety of photoinitiators (PIs) available for radical polymerizations. A common example are two-component (Type II) systems such as benzophenone and tertiary amines. However these systems also suffer from problems due to bimolecularity. These include the possible back electron transfer (BET) leading to deactivation, as well as the solvent cage effect, occurring in highly viscous media. The aim of this thesis was to investigate the reaction mechanism of several photoinitiating systems, which show superior performance. Moreover, they exhibit additional benefits such as circumvention of oxygen inhibition by decarboxylation. Thereby this work helps to understand the molecular basis of the performance of different PI systems. In vestigated PIs included benzaldoxime esters, covalently linked benzophenone and N-phenylglycine as well as derivatives of both systems. Furthermore a PI based on benzophenone extended by ethynyl moeities is discussed. The main tool in this investigation was photo-CIDNP (chemically induced dynamic nuclear polarization), an NMR based technique for studying radical reactions. A complementary view was obtained with TR-EPR (time-resolved electron paramagnetic resonance), which provides direct information about the active radical species. The results were further compared with quantum mechanical calculations (DFT) of the magnetic properties of the radicals. The theoretical approach was further applied to other paramagnetic species such as donor-acceptor systems. (author) [de

Study of Radiation Induced Radicals in HAP and β-TCP Based Bone Graft Materials by ERP Spectroscopy

International Nuclear Information System (INIS)

Maltar-Strmecki, N.; Matkovic, I.

2013-01-01

Calcium phosphates such as beta-tricalcium phosphate (β-TCP) and hydroxyapatite (HAP) are frequently used as dental implants due to proven excellent biocompatibility. Because of their resorption in the body and direct contact with tissues, in order to inactivate bacteria, fungal spores and viruses, they are usually sterilized by γ-irradiation. However, literature provides little information about effects of γ-irradiation on the formation and stability of the free radicals in the bone graft materials during and after sterilization procedure. In this study EPR (electron paramagnetic resonance) spectroscopy was used to investigate HAP and β-TCP based dental implants present on the market. Eight dental graft materials present on the market were investigated: Bioresorb R Macropore, Poresorb R -TCP, Easy-Graft T M and Cerasorb R synthetic β-tricalcium phosphates, Easy-Graft T M crystal and Ossceram R two phase synthetic CaP consisting of 60 % HAP and 40 % β-TCP, and Dexabone R and Bio-Oss R bone graft material of bovine origin. EPR study shows that this is the only technique for characterization of free radicals that can simultaneously determine not only the presence and content, but also the position and the structure of free radicals formed by γ-sterilization in the investigated materials, as well as the paramagnetic substitutions incorporated in the materials during the synthesis (such as Mn 2+ , Fe 3+ or Cr 2+ ). Additionally, EPR provides information on stability of irradiation-induced radicals (CO 2 - , trapped H-atoms, NO 3 2 etc.) and processes for reducing them. Results show that EPR should be considered as a valuable technique in improving the quality of bone graft materials, which must be sterile, and to offer the high quality, efficacy and reliable materials to the patients.(author)

Studies on atom transfer radical polymerization of acrylates and styrenes with controlled polymeric block structures

OpenAIRE

Ibrahim, Khalid

2006-01-01

Atom transfer radical polymerization (ATRP) was applied to homo and block copolymerization of vinyl monomers methacrylates, acrylates, and styrene with iron (FeCl2.4H2O) as the transition metal in most cases. As complexing ligand either a commercially available ligand (triphenyl phosphine) (PPh3) or synthetic aliphatic amines were used. As initiators, methyl 2-bromopropionate, ethyl 2-bromoisobutyrate, α,α-dichloroacetophenone, and poly(ethylene oxide) macroinitiator were employed. Block ...

Grafting of Polystyrene Chains at the Edge of Graphene Nanolayers by "Grafting Through" Approach Using Reversible Addition-Fragmentation Chain Transfer Polymerization

Directory of Open Access Journals (Sweden)

Hossein Roghani-Mamaqani

2017-09-01

Full Text Available Edge-functionalized graphene nanolayers with polystyrene chains were prepared by a “grafting through” reversible addition-fragmentation chain transfer (RAFT polymerization. For this purpose, double-bond containing modifier (MD was prepared. After edge-functionalization of graphene oxide (GO by two different amounts of MD and preparation of modified graphenes (LFG and HFG, RAFT polymerization of styrene was applied for preparation of functionalized GO with different densities of polystyrene chains. Fourier transform infrared spectroscopy showed that MD and polystyrene chains were grafted at the edge of GO. Gas chromatography showed that conversion decreased by the addition of modified GO content and also grafting density of MD. Number-average molecular weight and polydispersity index of polystyrene chains were derived from gel permeation chromatography. Increase of modified graphene content results in a decrease in molecular weight of attached polystyrene chains and also an increase in their PDI value. Increase of grafting density of MD results in decrease of molecular weight of polystyrene chains with no considerable variation in PDI value. Thermogravimetric analysis results showed that char residue is about 45.1 and 46.8% for LFG and HFG, respectively. The content of degradation ascribed to polystyrene increased with increase of grafting density of MD and decreased with increase of modified graphene content. X-ray diffraction results were used for evaluation of interlayer spacing of graphene layers after functionalization process and also study of nanocomposites structure. The results of scanning electron microscopy and transmission electron microscopy show that graphene layers with high clarity turned to opaque layers with lots of creases by oxidation and attachment of polystyrene chains.

Surface modification of carbon nanotubes via combination of mussel inspired chemistry and chain transfer free radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Wan, Qing; Tian, Jianwen; Liu, Meiying; Zeng, Guangjian; Huang, Qiang [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031 (China); Wang, Ke; Zhang, Qingsong [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing, 100084 (China); Deng, Fengjie, E-mail: fengjiedeng@aliyun.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing, 100084 (China)

2015-08-15

Graphical abstract: A novel strategy combination of mussel inspired chemistry and chain transfer free radical polymerization has been developed for surface modification of carbon nanotubes with polymers for the first time. - Highlights: • Surface modification of CNTs via mussel inspired chemistry. • Preparation of aminated polymers through free radical polymerization. • Functionalized CNTs with aminated polymers via Michael addition reaction. • Highly dispersed CNTs in organic and aqueous solution. - Abstract: In this work, a novel strategy for surface modification of carbon nanotubes (CNTs) was developed via combination of mussel inspired chemistry and chain transfer free radical polymerization. First, pristine CNTs were functionalized with polydopamine (PDA), which is formed via self-polymerization of dopamine in alkaline conditions. These PDA functionalized CNTs can be further reacted with amino-terminated polymers (named as PDMC), which was synthesized through chain transfer free radical polymerization using cysteamine hydrochloride as chain transfer agent and methacryloxyethyltrimethyl ammonium chloride as the monomer. PDMC perfectly conjugated with CNT-PDA was ascertained by a series of characterization techniques including transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The dispersibility of obtained CNT nanocomposites (named as CNT-PDA-PDMC) was further examined. Results showed that the dispersibility of CNT-PDA-PDMC in aqueous and organic solutions was obviously enhanced. Apart from PDMC, many other amino-terminated polymers can also be used to functionalization of CNTs via similar strategy. Therefore, the method described in this work should be a general strategy for fabrication various polymer nanocomposites.

A New Initiator Cholesteryl Chloroformate for Cupper-Based Atom Transfer Radical Polymerization of Methyl Methacrylate

Institute of Scientific and Technical Information of China (English)

曹健; 楚娟; 张可达

2004-01-01

The polymerization of metyl methacrylate (MMA) was studied in detail by use of CuCl/L as a catalyst and cholesteryl chloroformate (CC) as an initiator. It was found that the atom transfer radical polymerization of MMA could proceed when L equals to a multidentate aliphatic amine ligand, N,N,N',N",N"-penta(methyl acrylate)diethylenetriamine (MA5-DETA), and no polymerization was occurred while L=2,2'-bipyridine and 1,10-phenanthroline. The linear proportionality of the molecular weights to the conversions and straight lines observed in ln[M]0/[M] versus time plots indicated that the present polymerization system had the typical controlled polymerization characteristics.

Controlled radical polymerization of acrylates by {gamma}-irradiation in the presence of 1,1-diphenylethene

Energy Technology Data Exchange (ETDEWEB)

Wu Zongtao [Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang Zhicheng [Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026 (China)]. E-mail: zczhang@ustc.edu.cn

2005-12-15

Poly (butyl acrylate) and poly (methyl acrylate) were successfully prepared in the presence of 1,1-diphenylethene (DPE) by {gamma}-irradiation-induced polymerization in both bulk and solution. The influences of polymerization time, amounts of DPE in system on conversion, molecular weight (MW) and its distribution (M{sub w}/M{sub n}) were studied. The results indicate that the polymerization initiated by {gamma}-irradiation in the presence of DPE shows the character of living radical reaction.

ATOM TRANSFER RADICAL POLYMERIZATION OF N-BUTYL METHACRYLATE IN AQUEOUS DISPERSED SYSTEMS: A MINIEMULSION APPROACH. (R826735)

Science.gov (United States)

Ultrasonication was applied in combination with a hydrophobe for the copper-mediated atom transfer radical polymerization of n-butyl methacrylate in an aqueous dispersed system. A controlled polymerization was successfully achieved, as demonstrated by a linear correlation between...

Study and Optimization on graft polymerization under normal pressure and air atmospheric conditions, and its application to metal adsorbent

International Nuclear Information System (INIS)

Ueki, Yuji; Chandra Dafader, Nirmal; Hoshina, Hiroyuki; Seko, Noriaki; Tamada, Masao

2012-01-01

Radiation-induced graft polymerization of glycidyl methacrylate (GMA) onto non-woven polyethylene (NWPE) fabric was achieved under normal pressure and air atmospheric conditions, without using unique apparatus such as glass ampoules or vacuum lines. To attain graft polymerization under normal pressure and air atmospheric conditions, the effects of the pre-irradiation dose, pre-irradiation atmosphere, pre-irradiation temperature, de-aeration of GMA-emulsion, grafting atmosphere in a reactor, and dissolved oxygen (DO) concentration in GMA-emulsion on the degree of grafting (Dg) were investigated in detail. It was found that the DO concentration had the strongest influence, the pre-irradiation dose, de-aeration of emulsion and grafting atmosphere had a relatively strong impact, and the pre-irradiation atmosphere and pre-irradiation temperature had the least effect on Dg. The optimum DO concentration before grafting was 2.0 mg/L or less. When a polyethylene bottle was used as a reactor instead of a glass ampoule, graft polymerization under normal pressure and air atmospheric conditions could be achieved under the following conditions; the pre-irradiation dose was more than 50 kGy, the volume ratio of GMA-emulsion to air was 50:1 or less, and the DO concentration in GMA-emulsion during grafting was below 2.0 mg/L. Under these grafting conditions, Dg was controlled within a range of up to 362%. The prepared GMA–grafted NWPE (GMA–g-NWPE) fabric was modified with a phosphoric acid to obtain an adsorbent for heavy metal ions. In the column-mode adsorption tests of Pb(II), the adsorption performance of the produced phosphorylated GMA–g-NWPE fabric (fibrous metal adsorbent) was not essentially dependent on the flow rate of the feed. The breakthrough points of 200, 500, and 1000 h −1 in space velocity were 483, 477 and 462 bed volumes, and the breakthrough capacities of the three flow rates were 1.16, 1.15 and 1.16 mmol-Pb(II)/g-adsorbent.

Study and Optimization on graft polymerization under normal pressure and air atmospheric conditions, and its application to metal adsorbent

Science.gov (United States)

Ueki, Yuji; Chandra Dafader, Nirmal; Hoshina, Hiroyuki; Seko, Noriaki; Tamada, Masao

2012-07-01

Radiation-induced graft polymerization of glycidyl methacrylate (GMA) onto non-woven polyethylene (NWPE) fabric was achieved under normal pressure and air atmospheric conditions, without using unique apparatus such as glass ampoules or vacuum lines. To attain graft polymerization under normal pressure and air atmospheric conditions, the effects of the pre-irradiation dose, pre-irradiation atmosphere, pre-irradiation temperature, de-aeration of GMA-emulsion, grafting atmosphere in a reactor, and dissolved oxygen (DO) concentration in GMA-emulsion on the degree of grafting (Dg) were investigated in detail. It was found that the DO concentration had the strongest influence, the pre-irradiation dose, de-aeration of emulsion and grafting atmosphere had a relatively strong impact, and the pre-irradiation atmosphere and pre-irradiation temperature had the least effect on Dg. The optimum DO concentration before grafting was 2.0 mg/L or less. When a polyethylene bottle was used as a reactor instead of a glass ampoule, graft polymerization under normal pressure and air atmospheric conditions could be achieved under the following conditions; the pre-irradiation dose was more than 50 kGy, the volume ratio of GMA-emulsion to air was 50:1 or less, and the DO concentration in GMA-emulsion during grafting was below 2.0 mg/L. Under these grafting conditions, Dg was controlled within a range of up to 362%. The prepared GMA-grafted NWPE (GMA-g-NWPE) fabric was modified with a phosphoric acid to obtain an adsorbent for heavy metal ions. In the column-mode adsorption tests of Pb(II), the adsorption performance of the produced phosphorylated GMA-g-NWPE fabric (fibrous metal adsorbent) was not essentially dependent on the flow rate of the feed. The breakthrough points of 200, 500, and 1000 h-1 in space velocity were 483, 477 and 462 bed volumes, and the breakthrough capacities of the three flow rates were 1.16, 1.15 and 1.16 mmol-Pb(II)/g-adsorbent.

Surface grafting via photo-induced copper-mediated radical polymerization at extremely low catalyst concentrations

Czech Academy of Sciences Publication Activity Database

Laun, J.; Vorobii, Mariia; de los Santos Pereira, Andres; Pop-Georgievski, Ognen; Trouillet, V.; Welle, A.; Barner-Kowollik, C.; Rodriguez-Emmenegger, Cesar; Junkers, T.

2015-01-01

Roč. 36, č. 18 (2015), s. 1681-1686 ISSN 1022-1336 R&D Projects: GA ČR(CZ) GJ15-09368Y; GA MŠk(CZ) ED1.1.00/02.0109 Grant - others:OPPK(XE) CZ.2.16/3.1.00/21545 Program:OPPK Institutional support: RVO:61389013 Keywords : copper-mediated polymerization * photo-induced polymerization * polymer brushes Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.638, year: 2015

In Vitro Antioxidant-Activity Evaluation of Gallic-Acid-Grafted Chitosan Conjugate Synthesized by Free-Radical-Induced Grafting Method.

Science.gov (United States)

Hu, Qiaobin; Wang, Taoran; Zhou, Mingyong; Xue, Jingyi; Luo, Yangchao

2016-07-27

The major objective of this work was to develop a green and facile process to prepare gallic acid-chitosan conjugate and comprehensively evaluate the physicochemical properties and biological activities of an as-prepared water-soluble chitosan derivative. A free-radical-induced grafting approach using an ascorbic acid-hydrogen peroxide redox pair was adopted. The obtained conjugate was characterized by Fourier transform infrared spectroscopy, UV-vis, X-ray diffraction, and pKa analysis. The antioxidant activities were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6)-sulphonic acid (ABTS), reducing power, and oxygen-radical antioxidant-capacity assays. The results showed that the mass ratio of gallic acid to chitosan played a vital role in determining the grafting degree and ζ potential of the conjugates, with the ratio of 0.5:1 being the optimal ratio that resulted in the highest grafting degree. The antioxidant assays demonstrated that conjugation significantly improved the antioxidant activities, being dramatically higher than that of free chitosan. It was notable that the DPPH- and ABTS-scavenging activities of conjugate at 0.4 mg/mL reached the same level as the free gallic acid at the equivalent concentration. Our study demonstrated a green and facile synthesis approach to preparing a novel water-soluble chitosan derivative that may have promising potentials in the food industry.

Syntheses of amine-type adsorbents with emulsion graft polymerization of glycidyl methacrylate

International Nuclear Information System (INIS)

Seko, N.; Bang, L.T.; Tamada, M.

2007-01-01

Glycidyl methacrylate (GMA) which was precursor monomer for the synthesis of metal ion adsorbent was emulsified by surfactant of Tween 20 (Tw-20). The emulsion of 5% GMA in the water was stable for 48 h at Tw-20 concentration of 0.5%. Graft polymerization of GMA on polyethylene fiber was carried out in the emulsion state at various pre-irradiation doses. Degree of grafting (Dg) reached 103%, 301% and 348% for 1 h grafting at 40 deg. C with pre-irradiation of 10, 30 and 40 kGy, respectively. But the Dg was depressed when the pre-irradiation dose was over 50 kGy since cross-linking occurred simultaneously in the trunk polymer. Dg decreased with increment of Tw-20 concentration in emulsion of 5% GMA at pre-irradiation of 40 kGy. The three kinds of amine-type adsorbents were synthesized by reacting diethylenetriamine (DETA), triethylenetetramine (TETA) and ethylenediamine (EDA) with GMA-grafted polyethylene fiber. The synthesized EDA-type adsorbent had the highest selectivity against U ion and the distribution coefficient was 2.0 x 10 6

ESR investigations of radiation grafting of methyl methacrylate in aqueous emulsion onto chrome-tanned pig skin

International Nuclear Information System (INIS)

Pietrucha, K.; Pekala, W.; Plonka, A.

1980-01-01

Upon γ-irradiation at 77 K of the aqueous emulsions of methyl methacrylate embedded into chrome-tanned pig skins there are formed only the radicals of collagen and of 2-el-2-methylopropionic acid methyl ester. The presence of water in the system increases markedly the radiation yield of collagen radicals. During gradual heating up the polymerization reactions start and the macro-radical of growing polymer is observed. Chromium does not participate in the processes of initiation and grafting. (author)

Synthesis of poly(2-ethyl-2-oxazoline)-b-poly(styrene) copolymers via a dual initiator route combining cationic ring-opening polymerization and atom transfer radical polymerization

NARCIS (Netherlands)

Becer, C.R.; Paulus, R.M.; ppener, S.; Hoogenboom, R.; Fustin, C.A.; Gohy, J.M.W.; Schubert, U.S.

2008-01-01

Block copolymers of 2-ethyl-2-oxazoline (EtOx) and styrene were synthesized by a combination of cationic ring-opening polymerization (CROP) and atom transfer radical polymerization (ATRP). Initially, a detailed kinetic investigation for the ?-bromoisobutyrylbromide (BrEBBr) initiated CROP of EtOx

Antioxidant multi-walled carbon nanotubes by free radical grafting of gallic acid: new materials for biomedical applications.

Science.gov (United States)

Cirillo, Giuseppe; Hampel, Silke; Klingeler, Rüdiger; Puoci, Francesco; Iemma, Francesca; Curcio, Manuela; Parisi, Ortensia Ilaria; Spizzirri, Umile Gianfranco; Picci, Nevio; Leonhardt, Albrecht; Ritschel, Manfred; Büchner, Bernd

2011-02-01

To prove the possibility of covalently functionalizing multi-walled carbon nanotubes (CNTs) by free radical grafting of gallic acid on their surface with the subsequent synthesis of materials with improved biological properties evaluated by specific in-vitro assays. Antioxidant CNTs were synthesized by radical grafting of gallic acid onto pristine CNTs. The synthesis of carbon nanotubes was carried out in a fixed-bed reactor and, after the removal of the amorphous carbon, the grafting process was performed. The obtained materials were characterized by fluorescence and Fourier transform infrared spectroscopy (FT-IR) analyses. After assessment of the biocompatibility and determination of the disposable phenolic group content, the antioxidant properties were evaluated in terms of total antioxidant activity and scavenger ability against 2,2'-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl and peroxyl radicals. Finally the inhibition activity on acetylcholinesterase was evaluated.   The covalent functionalization of CNTs with gallic acid was confirmed and the amount of gallic acid bound per g of CNTs was found to be 2.1±0.2 mg. Good antioxidant and scavenging properties were recorded in the functionalized CNTs, which were found to be able to inhibit the acetylcholinesterase with potential improved activity for biomedical and pharmaceutical applications. For the first time, a free radical grafting procedure was proposed as a synthetic approach for the covalent functionalization of CNTs with an antioxidant polyphenol. © 2010 The Authors. JPP © 2010 Royal Pharmaceutical Society.

Cellulose-based graft copolymers with controlled architecture prepared in a homogeneous phase

Czech Academy of Sciences Publication Activity Database

Raus, Vladimír; Štěpánek, M.; Uchman, M.; Šlouf, Miroslav; Látalová, Petra; Čadová, Eva; Netopilík, Miloš; Kříž, Jaroslav; Dybal, Jiří; Vlček, Petr

2011-01-01

Roč. 49, č. 20 (2011), s. 4353-4367 ISSN 0887-624X R&D Projects: GA ČR GA106/09/1348; GA ČR GAP208/10/0353 Institutional research plan: CEZ:AV0Z40500505 Keywords : atom transfer radical polymerization (ATRP) * cellulose * graft copolymers Subject RIV: JI - Composite Materials Impact factor: 3.919, year: 2011

Super water absorbent by radiation graft polymerization of acrylic monomers onto cassava starch

International Nuclear Information System (INIS)

Doan Binh

2008-01-01

Water superabsorbent gel has been applying in personal care, agriculture, medical supplies and water purification. In agricultural application, the gel will help to control soil erosion, limit loss of nutrients and slit for plants, decrease irrigation frequency, improve infiltration, and increase water retention in prolonged arid soil and droughts. The gel absorbs many times its weight in available water. The gel from poly(acrylamide) was developed in the 60's to grow plants in the deserts. The other gel from poly(acrylic acid) was used to absorb rapidly in baby diapers, sanitary napkins. These polymers are commonly produced from natural gas, which have recently been introduced as a soil conditioner with great success. Prior to these polymers, peat moss, agro-waste (sugar-cane waste, coffee-shell, etc.), activated kaolin were the alternative soil additives to hold water (20 times its weight), but poly(acrylamide) absorbs 400 times its weight and polyacrylate is capable of absorbing greater amounts of liquid than poly(acrylamide). In addition, starch and cellulose are biodegradable naturally occurring polymers, which are not capable of holding a great amount of water, but their modification by graft polymerization or crosslinking through radiation or chemical initiation techniques, they become the potential superabsorbent polymers. Radiation initiation of chemical reactions has been widely known for making novel materials because the degree of polymerization, grafting and crosslinking process can easily be controlled. Recently, it was shown that the starch and cellulose derivatives such as carboxymethyl starch, carboxymethyl starch can be synthesized by radiation-induced crosslinking at high concentrations. Their utilization in agriculture seems to be appropriately evaluated. In this article, the graft polymerization and crosslinking of acrylic acid onto cassava starch and field trial of its product (GAM-Sorb S) are reported. (author)

Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization (ATRP) from Poly(vinyl chloride)- co -chlorinated Poly(vinyl chloride) (PVC- co -CPVC) Fiber

Energy Technology Data Exchange (ETDEWEB)

Brown, Suree; Yue, Yanfeng; Kuo, Li-Jung; Mehio, Nada; Li, Meijun; Gill, Gary; Tsouris, Costas; Mayes, Richard T.; Saito, Tomonori; Dai, Sheng

2016-04-20

The need to secure future supplies of energy attracts researchers in several countries to a vast resource of nuclear energy fuel: uranium in seawater (estimated at 4.5 billion tons in seawater). In this study, we developed effective adsorbent fibers for the recovery of uranium from seawater via atom-transfer radical polymerization (ATRP) from a poly- (vinyl chloride)-co-chlorinated poly(vinyl chloride) (PVC-co-CPVC) fiber. ATRP was employed in the surface graft polymerization of acrylonitrile (AN) and tert-butyl acrylate (tBA), precursors for uranium-interacting functional groups, from PVC-co-CPVC fiber. The [tBA]/[AN] was systematically varied to identify the optimal ratio between hydrophilic groups (from tBA) and uranyl-binding ligands (from AN). The best performing adsorbent fiber, the one with the optimal [tBA]/[AN] ratio and a high degree of grafting (1390%), demonstrated uranium adsorption capacities that are significantly greater than those of the Japan Atomic Energy Agency (JAEA) reference fiber in natural seawater tests (2.42-3.24 g/kg in 42 days of seawater exposure and 5.22 g/kg in 49 days of seawater exposure, versus 1.66 g/kg in 42 days of seawater exposure and 1.71 g/kg in 49 days of seawater exposure for JAEA). Adsorption of other metal ions from seawater and their corresponding kinetics were also studied. The grafting of alternative monomers for the recovery of uranium from seawater is now under development by this versatile technique of ATRP.

Effect of organoelemental compounds of group 3 elements on radical polymerization of vinyl monomers

International Nuclear Information System (INIS)

Grishin, D.F.; Mojkin, A.A.

1996-01-01

When alkyl, alkyl alkoxy, and alkyl halide derivatives of boron and aluminium are introduced into the system in amounts that are comparable to the concentration of initiator, they coordinate to the growing macroradicals, thus changing their reactivity, and exert regulating effect on the rate of polymerization of vinyl monomers and the molecular mass of the resulting polymers. The said organoelemental compounds accelerate the polymerization of butyl acrylate, methyl methacrylate, acrylonitrile, vinyl acetate, and vinylidene chloride, reduce the molecular mass of acrylic polymers, and virtually do not affect the polymerization of styrene. The specific features of vinyl polymerization are associated with participation of organoelemental additives at the stages of chain growth and chain termination and can be explained within the framework of the mechanism of radical-coordination polymerization. 32 refs., 3 tabs

Synthesis of graft copolymers onto starch and its semiconducting properties

Directory of Open Access Journals (Sweden)

Nevin Çankaya

Full Text Available Literature review has revealed that, although there are studies about grafting on natural polymers, especially on starch, few of them are about electrical properties of graft polymers. Starch methacrylate (St.met was obtained by esterification of OH groups on natural starch polymer for this purpose. Grafting of synthesized N-cyclohexyl acrylamide (NCA and commercial methyl methacrylate (MMA monomers with St.met was done by free radical polymerization method. The graft copolymers were characterized with FT-IR spectra, thermal and elemental analysis. Thermal stabilities of the graft copolymers were determined by TGA (thermo gravimetric analysis method and thermal stability of the copolymers is decreased via grafting. The electrical conductivity of the polymers was measured as a function of temperature and it has been observed that electrical conductivity increases with increasing temperature. The absorbance and transmittance versus wavelength of the polymers have been measured. Keywords: Starch, Graft copolymer, Semiconducting, Thermal stability, Starch methacrylate

Synthesis, Characterization and Bulk Properties of Amphiphilic Copolymers Containing Fluorinated Methacrylates from Sequential Copper-Mediated Radical Polymerization

DEFF Research Database (Denmark)

Hansen, Natanya Majbritt Louie; Gerstenberg, Michael; Haddleton, David M.

2008-01-01

acrylate (MEA), and poly(ethylene glycol) methyl ether methacrylate (PEGMA) by Atom Transfer Radical Polymerization. A kinetic study of the 3FM homopolymerization initiated with ethyl bromoisobutyrate and Cu(I)Br/N-(n-propyl)-2-pyridylmethanimine reveals a living/ controlled polymerization in the range 80...

3D scaffolds from vertically aligned carbon nanotubes/poly(methyl methacrylate) composites via atom transfer radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Tebikachew, Behabtu; Magina, Sandra [CICECO, Department of Chemistry, University of Aveiro (Portugal); Mata, Diogo; Oliveira, Filipe J.; Silva, Rui F. [CICECO, Department of Materials and Ceramic Engineering, University of Aveiro (Portugal); Barros-Timmons, Ana, E-mail: anabarros@ua.pt [CICECO, Department of Chemistry, University of Aveiro (Portugal)

2015-01-15

Vertically aligned carbon nanotubes (VACNTs) synthesized by Thermal Chemical Vapour Deposition (TCVD) were modified using an Ar:O{sub 2} (97:3) plasma to generate oxygen-containing functional groups on the surface for subsequent modification. X-ray photo-emission spectroscopy (XPS) and micro-Raman analyses confirmed the grafting of those functional groups onto the surface of the nanotubes as well as the removal of amorphous carbon produced and deposited on the VACNT forests during the CVD process. The plasma treated VACNT forests were further modified with 2-bromo-2-methylpropionyl bromide, an atom transfer radical polymerization (ATRP) initiator, to grow poly(methyl methacrylate) (PMMA) chains from the forests via ATRP. Scanning transmission electron microscopy (STEM) of the ensuing VACNT/PMMA composites confirmed the coating of the nanotube forests with the PMMA polymer. 3D scaffolds of polymeric composites with honeycomb like structure were then obtained. Compressive tests have shown that the VACNT/PMMA composite has higher compressive strength than the pristine forest. - Highlights: • Vertically aligned carbon nanotubes (VACNTs) were synthesized and plasma modified. • X-ray photo-emission and Raman spectroscopies confirmed the VACNTs modification. • Poly(methyl methacrylate) chains were grown via ATRP from the VACNTs. • STEM of the VACNT/PMMA composites confirmed that PMMA surrounds the nanotubes. • VACNT/PMMA composite has higher compressive strength compared to the pristine forest.

3D scaffolds from vertically aligned carbon nanotubes/poly(methyl methacrylate) composites via atom transfer radical polymerization

International Nuclear Information System (INIS)

Tebikachew, Behabtu; Magina, Sandra; Mata, Diogo; Oliveira, Filipe J.; Silva, Rui F.; Barros-Timmons, Ana

2015-01-01

Vertically aligned carbon nanotubes (VACNTs) synthesized by Thermal Chemical Vapour Deposition (TCVD) were modified using an Ar:O 2 (97:3) plasma to generate oxygen-containing functional groups on the surface for subsequent modification. X-ray photo-emission spectroscopy (XPS) and micro-Raman analyses confirmed the grafting of those functional groups onto the surface of the nanotubes as well as the removal of amorphous carbon produced and deposited on the VACNT forests during the CVD process. The plasma treated VACNT forests were further modified with 2-bromo-2-methylpropionyl bromide, an atom transfer radical polymerization (ATRP) initiator, to grow poly(methyl methacrylate) (PMMA) chains from the forests via ATRP. Scanning transmission electron microscopy (STEM) of the ensuing VACNT/PMMA composites confirmed the coating of the nanotube forests with the PMMA polymer. 3D scaffolds of polymeric composites with honeycomb like structure were then obtained. Compressive tests have shown that the VACNT/PMMA composite has higher compressive strength than the pristine forest. - Highlights: • Vertically aligned carbon nanotubes (VACNTs) were synthesized and plasma modified. • X-ray photo-emission and Raman spectroscopies confirmed the VACNTs modification. • Poly(methyl methacrylate) chains were grown via ATRP from the VACNTs. • STEM of the VACNT/PMMA composites confirmed that PMMA surrounds the nanotubes. • VACNT/PMMA composite has higher compressive strength compared to the pristine forest

Preparation of Bottlebrush Polymers via a One-Pot Ring-Opening Polymerization (ROP) and Ring-Opening Metathesis Polymerization (ROMP) Grafting-Through Strategy.

Science.gov (United States)

Radzinski, Scott C; Foster, Jeffrey C; Matson, John B

2016-04-01

Bottlebrush polymers are synthesized using a tandem ring-opening polymerization (ROP) and ring-opening metathesis polymerization (ROMP) strategy. For the first time, ROP and ROMP are conducted sequentially in the same pot to yield well-defined bottlebrush polymers with molecular weights in excess of 10(6) Da. The first step of this process involves the synthesis of a polylactide macromonomer (MM) via ROP of d,l-lactide initiated by an alcohol-functionalized norbornene. ROMP grafting-through is then carried out in the same pot to produce the bottlebrush polymer. The applicability of this methodology is evaluated for different MM molecular weights and bottlebrush backbone degrees of polymerization. Size-exclusion chromatographic and (1)H NMR spectroscopic analyses confirm excellent control over both polymerization steps. In addition, bottlebrush polymers are imaged using atomic force microscopy and stain-free transmission electron microscopy on graphene oxide. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

BenzoDODA grafted polymeric resin—Plutonium selective solid sorbent

Energy Technology Data Exchange (ETDEWEB)

Ruhela, R., E-mail: riteshr@barc.gov.in [Materials Processing Division, Materials Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Panja, S., E-mail: surajit@barc.gov.in [Fuel Reprocessing Division, Nuclear Fuels Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Singh, A.K. [Materials Processing Division, Materials Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Dhami, P.S.; Gandhi, P.M. [Fuel Reprocessing Division, Nuclear Fuels Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2016-11-15

Highlights: • BenzoDODA grafted polymeric resin was synthesized and evaluated for sorption of Pu(IV). • Fast sorption kinetics for ‘Pu(IV)’. • Ease of back extraction of ‘Pu’ form loaded resin. • Ease of recyclability and fair stability in HNO{sub 3} medium. - Abstract: A new ligand grafted polymeric resin (BenzoDODA SDVB) was synthesized by covalently attaching plutonium selective ligand (BenzoDODA) on to styrene divinyl benzene (SDVB) polymer matrix. BenzoDODA SDVB resin was evaluated for separation and recovery of plutonium(IV) from nitric acid medium. Sorption of Pu(IV) was found to decrease with the increase in nitric acid concentration, with very small sorption above 7.0 M HNO{sub 3}. Sorption kinetics was fast enough to achieve the equilibrium within 60 min of contact where the kinetic data fitted well to pseudo-second-order model. Sorption isotherm data fitted well to Langmuir model suggesting chemical interaction between the BenzoDODA moiety and plutonium(IV) ions. Sorption studies with some of representative radionuclides of high level waste showed that BenzoDODA SDVB is selective and therefore could be a promising solid sorbent for separation and recovery of plutonium. Further, the theoretical calculations done on BenzoDODA SDVB resin suggested Pu(NO{sub 3}){sub 4}·BenzoDODA (1:1) sorbed complex conformed to generally observed square antiprism geometry of the plutonium complexes, with contributions from oxygen atoms of four nitrate ions as well as from four oxygen atoms present in BenzoDODA (two phenolic ether oxygen atoms and two carbonyl oxygen atoms of amidic moiety).

In situ development of self-reinforced cellulose nanocrystals based thermoplastic elastomers by atom transfer radical polymerization.

Science.gov (United States)

Yu, Juan; Wang, Chunpeng; Wang, Jifu; Chu, Fuxiang

2016-05-05

Recently, the utilization of cellulose nanocrystals (CNCs) as a reinforcing material has received a great attention due to its high elastic modulus. In this article, a novel strategy for the synthesis of self-reinforced CNCs based thermoplastic elastomers (CTPEs) is presented. CNCs were first surface functionalized with an initiator for surface-initiated atom transfer radical polymerization (SI-ATRP). Subsequently, SI-ATRP of methyl methacrylate (MMA) and butyl acrylate (BA) was carried out in the presence of sacrificial initiator to form CTPEs in situ. The CTPEs together with the simple blends of CNCs and linear poly(MMA-co-BA) copolymer (P(MMA-co-BA)) were characterized for comparative study. The results indicated that P(MMA-co-BA) was successfully grafted onto the surface of CNCs and the compatibility between CNCs and the polymer matrix in CTPEs was greatly enhanced. Specially, the CTPEs containing 2.15wt% CNCs increased Tg by 19.2°C and tensile strength by 100% as compared to the linear P(MMA-co-BA). Copyright © 2016 Elsevier Ltd. All rights reserved.

Functionalized polymer film surfaces via surface-initiated atom transfer radical polymerization

International Nuclear Information System (INIS)

Hu, Y.; Li, J.S.; Yang, W.T.; Xu, F.J.

2013-01-01

The ability to manipulate and control the surface properties of polymer films, without altering the substrate properties, is crucial to their wide-spread applications. In this work, a simple one-step method for the direct immobilization of benzyl chloride groups (as the effective atom transfer radical polymerization (ATRP) initiators) on the polymer films was developed via benzophenone-induced coupling of 4-vinylbenzyl chloride (VBC). Polyethylene (PE) and nylon films were selected as examples of polymer films to illustrate the functionalization of film surfaces via surface-initiated ATRP. Functional polymer brushes of (2-dimethylamino)ethyl methacrylate, sodium 4-styrenesulfonate, 2-hydroxyethyl methacrylate and glycidyl methacrylate, as well as their block copolymer brushes, have been prepared via surface-initiated ATRP from the VBC-coupled PE or nylon film surfaces. With the development of a simple approach to the covalent immobilization of ATRP initiators on polymer film surfaces and the inherent versatility of surface-initiated ATRP, the surface functionality of polymer films can be precisely tailored. - Highlights: ► Atom transfer radical polymerization initiators were simply immobilized. ► Different functional polymer brushes were readily prepared. ► Their block copolymer brushes were also readily prepared

Olefin copolymerization via controlled radical polymerization : copolymerization of methyl methacrylate and 1-octene

NARCIS (Netherlands)

Venkatesh, R.; Klumperman, B.

2004-01-01

The atom transfer radical (co)polymerization (ATRP) of methyl methacrylate (MMA) with 1-octene was investigated. Well controlled homopolymer of MMA was obtained with 2,2,2-trichoroethanol (TCE) and p-toluenesulfonyl chloride (pTsCl), although, uncontrolled copolymerization occurred when pTsCl was

Synthesis of triblock and random copolymers of 4- acetoxystyrene and styrene by living atom transfer radical polymerization

DEFF Research Database (Denmark)

Gao, Bo; Chen, Xianyi; Ivan, Bela

1997-01-01

Triblock copolymers containing polystyrene (PSt) and poly(4-acetoxystyrene) (PAcOSt) segments have been prepared by atom transfer radical polymerization (ATRP). In the first step one of the two monomers was polymerized in bulk using the initiating system alpha,alpha'-dibromo-p-xylene/CuBr/2,2'-bi...

Preparation of poly(vinyl alcohol)-grafted graphene oxide/poly(vinyl alcohol) nanocomposites via in-situ low-temperature emulsion polymerization and their thermal and mechanical characterization

Energy Technology Data Exchange (ETDEWEB)

Zhang, Shengchang; Liu, Pengqing, E-mail: liupq@scu.edu.cn; Zhao, Xiangsen; Xu, Jianjun, E-mail: xujj@scu.edu.cn

2017-02-28

Highlights: • In-situ emulsion polymerization and alcoholysis reaction is a good method to prepare GO/PVA nanocomposites. • Surface chemical grafting modification of GO with PVA chains was also carried out during the in-situ emulsion polymerization and alcoholysis reaction. • The surface chemical grafting modification of GO by in-situ polymerization and alcoholysis reaction could not only improve the dispersion of fillers in matrix, but also the interfacial interactions between fillers and matrix. • The thermal and mechanical properties of PVA-g-GO/PVA nanocompistes were also studied. - Abstract: An in-situ polymerization combined with chemical grafting modification method for preparing Poly(vinyl alcohol)-grafted graphene oxide/Poly(vinyl alcohol) (PVA-g-GO/PVA) nanocomposites was reported. Firstly, Poly(vinyl acetate)-grafted graphene oxide/Poly(vinyl acetate) nanocomposites were prepared, and then the PVA-g-GO/PVA nanocomposites could be obtained through alcoholysis reaction. X-ray photoelectron spectrometer and fourier-transform infrared spectrometer confirmed that the PVAc or PVA chains were successfully grafted to GO sheets during in-situ polymerization and alcoholysis. And the results from transmission electron microscopy, scanning electron microscopy and X-ray diffraction showed that the well compatibility and homogenous dispersion of PVA-g-GO in PVA matrix could be achieved. Differential scanning calorimetric, thermogravimetry analysis and tensile test were employed to study the thermal and mechanical properties of the PVA-g-GO/PVA nanocomposites. The results indicated that a 53% improvement of tensile strength and a 36% improvement of Young’s modulus were achieved by addition of 0.5 wt% of GO sheets. And the glass transition temperature of PVA-g-GO/PVA nanocomposites was increased, and their thermal stability and crystallization degree were both decreased. Due to well dispersion of fillers and strong interfacial interactions at the filler

Preparation of poly(vinyl alcohol)-grafted graphene oxide/poly(vinyl alcohol) nanocomposites via in-situ low-temperature emulsion polymerization and their thermal and mechanical characterization

International Nuclear Information System (INIS)

Zhang, Shengchang; Liu, Pengqing; Zhao, Xiangsen; Xu, Jianjun

2017-01-01

Highlights: • In-situ emulsion polymerization and alcoholysis reaction is a good method to prepare GO/PVA nanocomposites. • Surface chemical grafting modification of GO with PVA chains was also carried out during the in-situ emulsion polymerization and alcoholysis reaction. • The surface chemical grafting modification of GO by in-situ polymerization and alcoholysis reaction could not only improve the dispersion of fillers in matrix, but also the interfacial interactions between fillers and matrix. • The thermal and mechanical properties of PVA-g-GO/PVA nanocompistes were also studied. - Abstract: An in-situ polymerization combined with chemical grafting modification method for preparing Poly(vinyl alcohol)-grafted graphene oxide/Poly(vinyl alcohol) (PVA-g-GO/PVA) nanocomposites was reported. Firstly, Poly(vinyl acetate)-grafted graphene oxide/Poly(vinyl acetate) nanocomposites were prepared, and then the PVA-g-GO/PVA nanocomposites could be obtained through alcoholysis reaction. X-ray photoelectron spectrometer and fourier-transform infrared spectrometer confirmed that the PVAc or PVA chains were successfully grafted to GO sheets during in-situ polymerization and alcoholysis. And the results from transmission electron microscopy, scanning electron microscopy and X-ray diffraction showed that the well compatibility and homogenous dispersion of PVA-g-GO in PVA matrix could be achieved. Differential scanning calorimetric, thermogravimetry analysis and tensile test were employed to study the thermal and mechanical properties of the PVA-g-GO/PVA nanocomposites. The results indicated that a 53% improvement of tensile strength and a 36% improvement of Young’s modulus were achieved by addition of 0.5 wt% of GO sheets. And the glass transition temperature of PVA-g-GO/PVA nanocomposites was increased, and their thermal stability and crystallization degree were both decreased. Due to well dispersion of fillers and strong interfacial interactions at the filler

Radical polymerization by a supramolecular catalyst: cyclodextrin with a RAFT reagent

Directory of Open Access Journals (Sweden)

Kohei Koyanagi

2016-11-01

Full Text Available Supramolecular catalysts have received a great deal of attention because they improve the selectivity and efficiency of reactions. Catalysts with host molecules exhibit specific reaction properties and recognize substrates via host–guest interactions. Here, we examined radical polymerization reactions with a chain transfer agent (CTA that has α-cyclodextrin (α-CD as a host molecule (α-CD-CTA. Prior to the polymerization of N,N-dimethylacrylamide (DMA, we investigated the complex formation of α-CD with DMA. Single X-ray analysis demonstrated that α-CD includes DMA inside its cavity. When DMA was polymerized in the presence of α-CD-CTA using 2,2'-azobis[2-(2-imidazolin-2-ylpropane dihydrochloride (VA-044 as an initiator in an aqueous solution, poly(DMA was obtained in good yield and with narrow molecular weight distribution. In contrast, the polymerization of DMA without α-CD-CTA produced more widely distributed polymers. In the presence of 1,6-hexanediol (C6 diol which works as a competitive molecule by being included in the α-CD cavity, the reaction yield was lower than that without C6 diol.

Studies in reactive extrusion processing of biodegradable polymeric materials

Science.gov (United States)

Balakrishnan, Sunder

Various reaction chemistries such as Polymerization, Polymer cross-linking and Reactive grafting were investigated in twin-screw extruders. Poly (1,4-dioxan-2-one) (PPDX) was manufactured in melt by the continuous polymerization of 1,4-dioxan-2-one (PDX) monomer in a twin-screw extruder using Aluminum tri-sec butoxide (ATSB) initiator. Good and accurate control over molecular weight was obtained by controlling the ratio of monomer to initiator. A screw configuration consisting of only conveying elements was used for the polymerization. The polymerization reaction was characterized by a monomer-polymer dynamic equilibrium, above the melting temperature of the polymer, limiting the equilibrium conversion to 78-percent. Near complete (˜100-percent) conversion was obtained on co-polymerizing PDX monomer with a few mol-percent (around 8-percent) Caprolactone (CL) monomer in a twin-screw extruder using ATSB initiator. The co-polymers exhibited improved thermal stability with reduction in glass transition temperature. The extruder was modeled as an Axial Dispersed Plug Flow Reactor for the polymerization of CL monomer using Residence Time Distribution (RTD) Analysis. The model provided a good fit to the experimental RTD and conversion data. Aliphatic and aliphatic-aromatic co-polyesters, namely Polycaprolactone (PCL) and Poly butylenes (adipate-co-terephthalate) (Ecoflex) were cross-linked in a twin-screw extruder using radical initiator to form micro-gel reinforced biodegradable polyesters. Cross-linked Ecoflex was further extrusion blended with talc to form blends suitable to be blown into films. A screw configuration consisting of conveying and kneading elements was found to be effective in dispersion of the talc particles (5--10 microns) in the polyester matrix. While the rates of crystallization increased for the talc filled polyester blends, overall crystallinity reduced. Mechanical, tear and puncture properties of films made using the talc filled polyester blends

STUDIES ON RADICAL POLYMERIZATION OF METHYL METHACRYLATE INITIATED WITH ORGANIC PEROXIDE-AMINE SYSTEMS

Institute of Scientific and Technical Information of China (English)

QIU Kunyuan; SHUI Li; FENG Xinde

1984-01-01

Radical polymerization of methyl methacrylate (MMA) initiated with various diacyl peroxideamine systems was studied. Benzoyl peroxide (BPO) and lauroyl peroxide (LPO) were used as diacyl peroxide component, N,N-dimethyl aniline (DMA) and its para substituted derivatives, i.e., N,N-dimethyl-p-toluidine (DMT), p-hydroxymethyl-N,N-dimethyl aniline (HDMA), p-nitro-N,N-dimethyl aniline (NDMA) and p-dimethylamino benzaldehyde (DMAB) were used as amine components. It was found that the peroxide-DMT systems give higher rates of bulk polymerization Rp of MMA than the organic hydroperoxide-DMT systems with the following descending order BPO-DMT＞LPO-DMT＞CHP (cumene hydroperoxide)-DMT＞TBH (tert-butyl hydroperoxide)-DMT.The aromatic tertiary amines possess obvious structural effect on the Rp values in the diacyl peroxideamine system. The overall activation energy of MMA polymerization was determined and the kinetics of polymerization of MMA initiated with BPO-DMT system was investigated.

Heparin molecularly imprinted polymer thin flm on gold electrode by plasma-induced graft polymerization for label-free biosensor.

Science.gov (United States)

Orihara, Kouhei; Hikichi, Atsushi; Arita, Tomohiko; Muguruma, Hitoshi; Yoshimi, Yasuo

2018-03-20

Heparin, a highly sulfated glycosaminoglycan, is an important biomaterial having biological and therapeutic functionalities such as anticoagulation, regeneration, and protein stabilization. This study addresses a label-free quartz crystal microbalance (QCM) biosensor for heparin detection based on a macromolecularly imprinted polymer (MIP) as an artificial recognition element. We demonstrate the novel strategy for MIP in the form of thin film on a gold (Au) electrode with the plasma-induced graft polymerization (PIP) technique. The procedure of PIP is as follows: (i) Hexamethyldisiloxane plasma-polymerized thin film (PPF) as a pre-coating scaffold of active species for PIP (post-polymerization) is deposited on an Au electrode. (ii) The PPF/Au electrode is soaked in an water solution containing heparin (template), (2-(methacryloxy)-ethyl)trimethylammonium chloride acrylamide (functional monomer), acrylamide, and N,N-methylenebisacrylamide (crosslinker). Double bonds of monomer and crosslinker attacked by residually active species in pre-coating PPF cause radical chain reaction. Consequently, a growing polymer network of 20 nm thickness of PIP-MIP thin film is formed and grafted on the PPF/Au surface. (iii) The PIP-MIP/PPF/Au is washed by sodium chloride solution so as to remove the template. Non-imprinted polymer (NIP) is carried out like the same procedure without a template. The AFM, XPS, and QCM measurements show that the PIP process facilitates macromolecularly surface imprinting of template heparin where the template is easily removed and is rapidly rebound to PIP-MIP without a diffusional barrier. The heparin-PIP-MIP specifically binds to heparin compared with heparin analog chondroitin sulfate C (selective factor: 4.0) and a detectable range of heparin in the presence of CS (0.1 wt%) was 0.001-0.1 wt%. The PIP-NIP does not show selectivity between them. The evaluated binding kinetics are association (k a  = 350 ± 100 M -1  s -1

Mussel inspired polymerized P(TA-TETA) for facile functionalization of carbon nanotube

Science.gov (United States)

Si, Shuxian; Gao, Tingting; Wang, Junhao; Liu, Qinze; Zhou, Guowei

2018-03-01

This article describes a novel and effective approach for non-covalent modification of carbon nanotube (CNT) via the mussel inspired polymerization of tannic acid (TA) and triethylenetetramine (TETA) and subsequent surface initiated atom transfer radical polymerization (SI-ATRP). Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and photograph were used to study the successful preparation of polymer brush grafted CNT (CNT-P(TA-TETA)-PDMAEMA) composite as well as the pH-responsive behavior of the composite. Furthermore, by amine protonation and in situ reduction, gold nanoparticles were successfully uploaded and the catalytic property of CNT-P(TA-TETA)-PDMAEMA/Au was investigated. We believe that the surface functionalization strategy can be extended to graphene and other substrates, and the surface properties can be regulated by grafting polymer brushes with different functionalities.

Preparation of high-capacity, weak anion-exchange membranes by surface-initiated atom transfer radical polymerization of poly(glycidyl methacrylate) and subsequent derivatization with diethylamine

International Nuclear Information System (INIS)

Qian, Xiaolei; Fan, Hua; Wang, Chaozhan; Wei, Yinmao

2013-01-01

Ion-exchange membrane is of importance for the development of membrane chromatography. In this work, a high-capacity anion-exchange membrane was prepared by grafting of glycidyl methacrylate (GMA) onto the surface of regenerated cellulose (RC) membranes via surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequent derivatization with diethylamine. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to characterize changes in the chemical functionality, surface topography and pore morphology of the modified membranes. The static capacity of the prepared anion-exchange membrane was evaluated with bovine serum albumin (BSA) as a model protein. The results indicated that the anion-exchange membrane which could reach a maximum capacity of 96 mg/mL for static adsorption possesses a higher adsorption capacity, and the adsorption capacity increases with the polymerization time. The effect of pH and salt concentration confirmed that the adsorption of BSA followed ion-exchange mechanism. The established method would have potential application in the preparation of anion-exchange membrane.

Radiation crosslinking of poly(butyl acrylate) during polymerization and grafted copolymerization with Cr(III) crosslinked collagen

International Nuclear Information System (INIS)

Pietrucha, K.; Kroh, J.

1984-01-01

Enhanced crosslinking of synthetic polymer simultaneous with grafting and homopolymerization processes have been observed in irradiated leather tanned with Cr(III) and embedded with aqueous emulsions of butyl acrylate. Extent of poly(butyl acrylate) crosslinking during copolymerization was found to be approximately one order higher than in the case of radiation polymerization of butyl acrylate in emulsion. New method for isolation of grafted copolymer based on degradation of collagen has been developed. The extent of crosslinking was calculated from the swelling data. (author)

Stability of radicals in electron-irradiated fluoropolymer film for the preparation of graft copolymer fuel cell electrolyte membranes

DEFF Research Database (Denmark)

Larsen, Mikkel Juul; Ma, Yue; Qian, Huan

This presentation concerns the stability of radicals generated in poly(ethylene-alt-tetra­fluoro­ethylene) (ETFE) film by electron irradiation prior to grafting of styrene onto this base material. It has been demonstrated that the grafting yield decreases as the storage time of the irradiated fil...

A Review on Grafting of Biofibers for Biocomposites.

Science.gov (United States)

Wei, Liqing; McDonald, Armando G

2016-04-22

A recent increase in the use of biofibers as low-cost and renewable reinforcement for the polymer biocomposites has been seen globally. Biofibers are classified into: lignocellulosic fibers ( i.e. , cellulose, wood and natural fibers), nanocellulose ( i.e. , cellulose nanocrystals and cellulose nanofibrils), and bacterial cellulose, while polymer matrix materials can be petroleum based or bio-based. Green biocomposites can be produced using both biobased fibers and polymers. Incompatibility between the hydrophilic biofibers and hydrophobic polymer matrix can cause performance failure of resulting biocomposites. Diverse efforts have focused on the modification of biofibers in order to improve the performances of biocomposites. "Grafting" copolymerization strategy can render the advantages of biofiber and impart polymer properties onto it and the performance of biocomposites can be tuned through changing grafting parameters. This review presents a short overview of various "grafting" methods which can be directly or potentially employed to enhance the interaction between biofibers and a polymer matrix for biocomposites. Major grafting techniques, including ring opening polymerization, grafting via coupling agent and free radical induced grafting, have been discussed. Improved properties such as mechanical, thermal, and water resistance have provided grafted biocomposites with new opportunities for applications in specific industries.

PNIPAAm-grafted thermoresponsive microcarriers: Surface-initiated ATRP synthesis and characterization

Energy Technology Data Exchange (ETDEWEB)

Çakmak, Soner [Nanotechnology and Nanomedicine Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey); Çakmak, Anıl S. [Bioengineering Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey); Gümüşderelioğlu, Menemşe, E-mail: menemse@hacettepe.edu.tr [Nanotechnology and Nanomedicine Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey); Bioengineering Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey); Chemical Engineering Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey)

2013-07-01

In this study, we developed novel thermoresponsive microcarriers as a powerful tool for cell culture and tissue engineering applications. For this purpose, two types of commercially available spherical microparticles (approximately 100 μm in diameter), dextran-based Sephadex® and vinyl acetate-based VA-OH (Biosynth®), were used and themoresponsive poly(N-isopropylacrylamide) (PNIPAAm) was grafted to the beads' surfaces by surface-initiated atom transfer radical polymerization (SI-ATRP). Initially, hydroxyl groups of microbeads were reacted with 2-bromopropionyl bromide to form ATRP macroinitiator. Then, NIPAAm was successfully polymerized from the initiator attached microbeads by ATRP with CuBr/2,2′-dipyridyl, catalyst complex. Furthermore, grafted and ungrafted microbeads were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscope (SEM), atomic force microscopy (AFM) and electron spectroscopy for chemical analysis (ESCA). The results of characterization studies confirmed that PNIPAAm was successfully grafted onto both dextran and vinyl acetate-based beads by means of ATRP reaction and thus, grafted microbeads gained thermoresponsive characteristics which will be evaluated for cell harvesting in further studies. Highlights: • PNIPAAm was grafted to the hydroxyl group carrying polymer beads by SI-ATRP. • Dex-g-PNIPAAm and VA-OH-g-PNIPAAm beads exhibited thermoresponsive characteristics. • They are appropriate candidates for microcarrier-facilitated cell cultures.

PNIPAAm-grafted thermoresponsive microcarriers: Surface-initiated ATRP synthesis and characterization

International Nuclear Information System (INIS)

Çakmak, Soner; Çakmak, Anıl S.; Gümüşderelioğlu, Menemşe

2013-01-01

In this study, we developed novel thermoresponsive microcarriers as a powerful tool for cell culture and tissue engineering applications. For this purpose, two types of commercially available spherical microparticles (approximately 100 μm in diameter), dextran-based Sephadex® and vinyl acetate-based VA-OH (Biosynth®), were used and themoresponsive poly(N-isopropylacrylamide) (PNIPAAm) was grafted to the beads' surfaces by surface-initiated atom transfer radical polymerization (SI-ATRP). Initially, hydroxyl groups of microbeads were reacted with 2-bromopropionyl bromide to form ATRP macroinitiator. Then, NIPAAm was successfully polymerized from the initiator attached microbeads by ATRP with CuBr/2,2′-dipyridyl, catalyst complex. Furthermore, grafted and ungrafted microbeads were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscope (SEM), atomic force microscopy (AFM) and electron spectroscopy for chemical analysis (ESCA). The results of characterization studies confirmed that PNIPAAm was successfully grafted onto both dextran and vinyl acetate-based beads by means of ATRP reaction and thus, grafted microbeads gained thermoresponsive characteristics which will be evaluated for cell harvesting in further studies. Highlights: • PNIPAAm was grafted to the hydroxyl group carrying polymer beads by SI-ATRP. • Dex-g-PNIPAAm and VA-OH-g-PNIPAAm beads exhibited thermoresponsive characteristics. • They are appropriate candidates for microcarrier-facilitated cell cultures

Nitroxide-Mediated Radical Polymerization of Styrene Initiated from the Surface of Titanium Oxide Nanoparticles

Directory of Open Access Journals (Sweden)

M. Abbasian

2016-01-01

Full Text Available Titanium dioxide (TiO2 nanoparticles, with an average size of about 45 nm, were encapsulated by polystyrene using in situ nitroxide mediated radical polymerization   in the presence of 3-aminopropyl triethoxy silane (APTES as a coupling agent and 2, 2, 6, 6-tetramethylpiperidinyl-1-oxy  as a initiator. First, the initiator for NMRP was covalently bonded onto the surface of Titanium dioxide nanoparticles through our novel method. For this purpose, the surface of TiO2 nanoparticle was treated with 3-aminopropyl triethoxy silane, a silane coupling agent, and then these functionalized nanoparticles was reacted with ±-chloro phenyl acetyl chloride. The chlorine groups were converted to nitroxide mediated groups by coupling with 1-hydroxy-2, 2, 6, 6-tetramethyl piperidine. These modified TiO2 nanoparticles were then dispersed in styrene (St monomers to carry out the in situ free radical polymerization.

Fabrication of Robust and Antifouling Superhydrophobic Surfaces via Surface-Initiated Atom Transfer Radical Polymerization.

Science.gov (United States)

Xue, Chao-Hua; Guo, Xiao-Jing; Ma, Jian-Zhong; Jia, Shun-Tian

2015-04-22

Superhydrophobic surfaces were fabricated via surface-initiated atom transfer radical polymerization of fluorinated methacrylates on poly(ethylene terephthalate) (PET) fabrics. The hydrophobicity of the PET fabric was systematically tunable by controlling the polymerization time. The obtained superhydrophobic fabrics showed excellent chemical robustness even after exposure to different chemicals, such as acid, base, salt, acetone, and toluene. Importantly, the fabrics maintained superhydrophobicity after 2500 abrasion cycles, 100 laundering cycles, and long time exposure to UV irradiation. Also, the surface of the superhydrophobic fabrics showed excellent antifouling properties.

In situ AFM investigation of electrochemically induced surface-initiated atom-transfer radical polymerization.

Science.gov (United States)

Li, Bin; Yu, Bo; Zhou, Feng

2013-02-12

Electrochemically induced surface-initiated atom-transfer radical polymerization is traced by in situ AFM technology for the first time, which allows visualization of the polymer growth process. It affords a fundamental insight into the surface morphology and growth mechanism simultaneously. Using this technique, the polymerization kinetics of two model monomers were studied, namely the anionic 3-sulfopropyl methacrylate potassium salt (SPMA) and the cationic 2-(metharyloyloxy)ethyltrimethylammonium chloride (METAC). The growth of METAC is significantly improved by screening the ammonium cations by the addition of ionic liquid electrolyte in aqueous solution. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel block, graft and random copolymers for biomedical applications

DEFF Research Database (Denmark)

Javakhishvili, Irakli; Jankova Atanasova, Katja; Tanaka, Masaru

Despite the simple structure, poly(2-methoxyethyl acrylate) (PMEA) shows excellent blood compatibility [1]. Both the freezing-bound water (intermediate water: preventing the biocomponents from directly contacting the polymer surface) and non-freezing water on the polymer surface play important...... copolymers with MMA [4] utilizing ATRP. Here we present other block, graft and random copolymers of MEA intended for biomedical applications. These macromolecular architectures have been constructed by employing controlled radical polymerization methods such as RAFT and ATRP....

Functionalized and graft copolymers of chitosan and its pharmaceutical applications.

Science.gov (United States)

Bhavsar, Chintan; Momin, Munira; Gharat, Sankalp; Omri, Abdelwahab

2017-10-01

Chitosan is the second most abundant natural polysaccharide. It belongs a family of polycationic polymers comprised of repetitive units of glucosamine and N-acetylglucosamine. Its biodegradability, nontoxicity, non-immunogenicity and biocompatibility along with properties like mucoadhesion, fungistatic and bacteriogenic have made chitosan an appreciated polymer with numerous applications in the pharmaceutical, comestics and food industry. However, the limited solubility of chitosan at alkaline and neutral pH limits its widespread commercial use. This can be circumvented by fabrication of chitosan by graft copolymerization with acyl, alkyl, monomeric and polymeric moieties. Areas covered: Modifications like quarterization, thiolation, acylation and grafting result in copolymers with higher mucoadhesion strength, increased hydrophobic interactions (advantageous in hydrophobic drug entrapment), and increased solubility in alkaline pH, the ability for adsorption of metal ions, protein and peptide delivery and nutrient delivery. Insights on methods of polymerization, including atomic transfer radical polymerization and click chemistry are discussed. Applications of such modified chitosan copolymers in medical and surgical, and drug delivery, including nasal, oral and buccal delivery have also been covered. Expert opinion: Despite a number of successful investigations, commercialization of chitosan copolymers still remains a challenge. Further advancements in polymerization techniques may address the unmet needs of the healthcare industry.

Radiation crosslinking of poly(butyl acrylate) during polymerization and grafted copolymerization with Cr(III) crosslinked collagen

International Nuclear Information System (INIS)

Pietrucha, K.; Kroh, J.

1986-01-01

Enhanced crosslinking of synthetic polymer simultaneously with grafting and homopolymerization processes has been observed in irradiated leather tanned with Cr(III) and embedded with aqueous emulsions of butyl acrylate. The extent of poly(butyl acrylate) crosslinking during copolymerization was found to be approximately one order higher than in the case of radiation polymerization of butyl acrylate in emulsion. A new method for isolation of grafted copolymer based on degradation of collagen has been developed. The extent of crosslinking was calculated from the swelling data. (author)

Controlled radical polymerization of an acrylamide containing L-alanine moiety via ATRP.

Science.gov (United States)

Rafiee, Zahra

2016-02-01

Homopolymerization of an optically active acrylamide having an amino acid moiety in the side chain, N-acryloyl-L-alanine (AAla) was carried out via atom transfer radical polymerization (ATRP) at room temperature using 2-hydroxyethyl-2'-methyl-2'-bromopropionate (HMB) or sodium-4-(bromomethyl)benzoate (SBB) as initiator in pure water, methanol/water mixture and pure methanol solvents. The polymerization reaction resulted in the optically active biocompatible amino acid-based homopolymer in good yield with narrow molecular weight distribution. The number average molecular weight increased with conversion and polydispersity was low. The structure and molecular weight of synthesized polymer were characterized by (1)H NMR, FT-IR spectroscopic techniques and size-exclusion chromatography.

Synthesis of Well-defined Amphiphilic Block Copolymers by Organotellurium-Mediated Living Radical Polymerization (TERP).

Science.gov (United States)

Kumar, Santosh; Changez, Mohammad; Murthy, C N; Yamago, Shigeru; Lee, Jae-Suk

2011-10-04

Low-molecular weight amphiphilic diblock copolymers, polystyrene-block-poly (2-vinylpyridine) (PS-b-P2VP), and (P2VP-b-PS) with different block ratios were synthesized for the first time via organotellurium-mediated living radical polymerization (TERP). For both the homo- and block copolymerizations, good agreement between the theoretical, and experimental molecular weights was found with nearly 100% yield in every case. The molecular weight distribution for all the samples ranged between 1.10 and 1.24, which is well below the theoretical lower limit of 1.50 for a conventional free radical polymerization. Furthermore, a very simple approach to producing highly dense arrays of titania nanoparticles (TiO2 ) is presented using a site-selective reaction of titanium tetraisopropoxide within the P2VP domains of micellar film of P2VP-b-PS in toluene through the sol-gel method. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Application of living radical polymerization to the synthesis of resist polymers for radiation lithography

International Nuclear Information System (INIS)

Shimizu, Takashi; Ichikawa, Tsuneki

2005-01-01

Poly(styrene) and poly(methyl acrylate) with benzyl ester of carboxylic acid at the center of the polymer skeletons were synthesized by living radical polymerization for developing a new type of radiation resist with high resistivity to plasma etching and high sensitivity and spatial resolution to ionizing radiations. The initiators were benzyl esters with two functional groups for living radical polymerization on the benzyl and the carboxylic sides. Introduction of benzyl ester to the polymer skeletons changed the polymers from cross-link type to scission type upon γ-irradiation. Irradiation of the polymers resulted in the binary change of the molecular weight, due to dissociative capture of secondary electrons by the benzyl ester, as M n R 1 COOCH(C 6 H 5 )R 2 M n +e - ->M n R 1 COO - + · CH(C 6 H 5 )R 2 M n . The generated polymer fragments were not decomposed by further irradiation, which suggests that the synthesized polymers have high resistivity to plasma etching

Graft polymerization of acrylic acid and methacrylic acid onto poly(vinylidene fluoride) powder in presence of metallic salt and sulfuric acid

Science.gov (United States)

Deng, Bo; Yu, Yang; Zhang, Bowu; Yang, Xuanxuan; Li, Linfan; Yu, Ming; Li, Jingye

2011-02-01

Poly(vinylidene fluoride) (PVDF) powder was grafted with acrylic acid (AAc) or methacrylic acid (MAA) by the pre-irradiation induced graft polymerization technique. The presence of graft chains was proven by FT-IR spectroscopy. The degree of grafting (DG) was calculated by the acid-base back titration method. The synergistic effect of acid and Mohr's salt on the grafting kinetics was examined. The results indicated that adding sulfuric acid and Mohr's salt simultaneously in AAc or MAA solutions led to a strong enhancement in the degree of grafting. The grafted PVDF powder was cast into microfiltration (MF) membranes using the phase inversion method and some properties of the obtained MF membranes were characterized.

Graft polymerization of acrylic acid and methacrylic acid onto poly(vinylidene fluoride) powder in presence of metallic salt and sulfuric acid

Energy Technology Data Exchange (ETDEWEB)

Deng Bo [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, No. 2019, Jialuo Road, Jiading Dist., 201800 Shanghai (China); Yu Yang; Zhang Bowu; Yang Xuanxuan [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, No. 2019, Jialuo Road, Jiading Dist., 201800 Shanghai (China); Graduate University of Chinese Academy of Sciences, No. 19, Yuquan Road, Shijingshan Dist., 100049 Beijing (China); Li Linfan; Yu Ming [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, No. 2019, Jialuo Road, Jiading Dist., 201800 Shanghai (China); Li Jingye, E-mail: jingyeli@sinap.ac.c [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, No. 2019, Jialuo Road, Jiading Dist., 201800 Shanghai (China)

2011-02-15

Poly(vinylidene fluoride) (PVDF) powder was grafted with acrylic acid (AAc) or methacrylic acid (MAA) by the pre-irradiation induced graft polymerization technique. The presence of graft chains was proven by FT-IR spectroscopy. The degree of grafting (DG) was calculated by the acid-base back titration method. The synergistic effect of acid and Mohr's salt on the grafting kinetics was examined. The results indicated that adding sulfuric acid and Mohr's salt simultaneously in AAc or MAA solutions led to a strong enhancement in the degree of grafting. The grafted PVDF powder was cast into microfiltration (MF) membranes using the phase inversion method and some properties of the obtained MF membranes were characterized.

Graft polymerization of acrylic acid and methacrylic acid onto poly(vinylidene fluoride) powder in presence of metallic salt and sulfuric acid

International Nuclear Information System (INIS)

Deng Bo; Yu Yang; Zhang Bowu; Yang Xuanxuan; Li Linfan; Yu Ming; Li Jingye

2011-01-01

Poly(vinylidene fluoride) (PVDF) powder was grafted with acrylic acid (AAc) or methacrylic acid (MAA) by the pre-irradiation induced graft polymerization technique. The presence of graft chains was proven by FT-IR spectroscopy. The degree of grafting (DG) was calculated by the acid-base back titration method. The synergistic effect of acid and Mohr's salt on the grafting kinetics was examined. The results indicated that adding sulfuric acid and Mohr's salt simultaneously in AAc or MAA solutions led to a strong enhancement in the degree of grafting. The grafted PVDF powder was cast into microfiltration (MF) membranes using the phase inversion method and some properties of the obtained MF membranes were characterized.

Quantitative investigation of free radicals in bio-oil and their potential role in condensed-phase polymerization.

Science.gov (United States)

Kim, Kwang Ho; Bai, Xianglan; Cady, Sarah; Gable, Preston; Brown, Robert C

2015-03-01

We report on the quantitative analysis of free radicals in bio-oils produced from pyrolysis of cellulose, organosolv lignin, and corn stover by EPR spectroscopy. Also, we investigated their potential role in condensed-phase polymerization. Bio-oils produced from lignin and cellulose show clear evidence of homolytic cleavage reactions during pyrolysis that produce free radicals. The concentration of free radicals in lignin bio-oil was 7.5×10(20)  spin g(-1), which was 375 and 138 times higher than free-radical concentrations in bio-oil from cellulose and corn stover. Pyrolytic lignin had the highest concentration in free radicals, which could be a combination of carbon-centered (benzyl radicals) and oxygen-centered (phenoxy radicals) organic species because they are delocalized in a π system. Free-radical concentrations did not change during accelerated aging tests despite increases in molecular weight of bio-oils, suggesting that free radicals in condensed bio-oils are stable. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protein repellent hydrophilic grafts prepared by surface-initiated atom transfer radical polymerization from polypropylene

DEFF Research Database (Denmark)

Fristrup, Charlotte Juel; Jankova Atanasova, Katja; Eskimergen, Rüya

2012-01-01

with Attenuated Total Reflectance (ATR) Fourier Transform Infrared (FTIR) spectroscopy and Water Contact Angle (WCA) measurements. Confocal fluorescence microscopy of modified and unmodified substrates immersed in labelled insulin aspart showed superior repulsion of this protein for the poly(PEGMA) grafts, due...

Single-electron transfer living radical copolymerization of SWCNT-g-PMMA via graft from approach

Czech Academy of Sciences Publication Activity Database

Jaisankar, S. N.; Haridharan, N.; Murali, A.; Ponyrko, Sergii; Špírková, Milena; Mandal, A. B.; Matějka, Libor

2014-01-01

Roč. 55, č. 13 (2014), s. 2959-2966 ISSN 0032-3861 R&D Projects: GA ČR GAP108/12/1459 Institutional support: RVO:61389013 Keywords : single electron transfer * single-walled carbon nanotubes * controlled radical polymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.562, year: 2014

Organic thin film transistors with polymer brush gate dielectrics synthesized by atom transfer radical polymerization

DEFF Research Database (Denmark)

Pinto, J.C.; Whiting, G.L.; Khodabakhsh, S.

2008-01-01

, synthesized by atom transfer radical polymerization (ATRP), were used to fabricate low voltage OFETs with both evaporated pentacene and solution deposited poly(3-hexylthiophene). The semiconductor-dielectric interfaces in these systems were studied with a variety of methods including scanning force microscopy...

Ability of nitrones of various structures to control the radical polymerization of styrene mediated by in situ formed nitroxides.

NARCIS (Netherlands)

Sciannamea, V.; Guerrero-Sanchez, C.A.; Schubert, U.S.; Catala, J.-M.; Jerome, R.; Detrembleur, C.

2005-01-01

The ability of several nitrones to control the radical polymerization of styrene at 110 °C has been investigated by high-throughput experimentation. The nitrone/free radical initiator pair dictates the structure of the nitroxide and the alkoxyamine formed in situ, which determines the position of

SYNTHESIS AND POLYMERIZATION OF α-METHACRYLYOXYL-ETHYLOXYCARBONYLMETHYL- ω-(N,N-DIETHYLDITHIOCARBAMYL) POLYSTYRENE MACROMONOMERS

Institute of Scientific and Technical Information of China (English)

Shu-hui Qin; Kun-yuan Qiu

2000-01-01

Polystyrene macromonomers with different molecular weight were prepared by radical polymerization of styrene (St) in benzene using β-methacryloxylethyl 2-N,N-diethyldithiocarbamylacetate (MAEDCA) as a monomer-iniferter.Characterization of the macromonomer by 1H-NMR showed that the end groups were α-methacrylyoxylethyloxycarbonyl-methyl and ω-(N,N-diethyldithiocarbamyl). The macromonomer was difficult to homopolymerize, but it was easily copolymerized with methyl methacrylate (MMA) initiated by AIBN to form graft copolymers (PMMA-g-PSt) with PSt branches randomly distributed along the PMMA backbone. Copolymerization reaction and the structure of the graft copolymers were strongly affected by Mn and concentration of the macromonomer. The composition and Mn of the purified graft copolymer were determined by 1H-NMR and GPC analysis.

Improved biotribological properties of PEEK by photo-induced graft polymerization of acrylic acid.

Science.gov (United States)

Zhao, Xiaoduo; Xiong, Dangsheng; Wang, Kun; Wang, Nan

2017-06-01

The keys of biomaterials application in artificial joints are good hydrophilicity and wear resistance. One kind of the potential bio-implant materials is polyetheretherketone (PEEK), which has some excellent properties such as non-toxic and good biocompatibility. However, its bioinert surface and inherent chemical inertness hinder its application. In this study, we reported an efficient method for improving the surface wettability and wear resistance for PEEK, a layer of acrylic acid (AA) polymer brushes on PEEK surface was prepared by UV-initiated graft polymerization. The effects of different grafting parameters (UV-irradiation time/AA monomer solution concentration) on surface characteristics were clearly investigated, and the AA-g-PEEK specimens were examined by ATR-FTIR, static water contact angle measurements and friction tests. Our results reveal that AA can be successfully grafted onto the PEEK surface after UV irradiation, the water wettability and tribological properties of AA-g-PEEK are much better than untreated PEEK because that AA is a hydrophilic monomer, the AA layer on PEEK surface can improve its bearing capacity and reduce abrasion. This detailed understanding of the grafting parameters allows us to accurately control the experimental products, and this method of surface modification broadens the use of PEEK in orthopedic implants. Copyright © 2017 Elsevier B.V. All rights reserved.

Polymer coating comprising 2-methoxyethyl acrylate units synthesized by surface-initiated atom transfer radical polymerization

DEFF Research Database (Denmark)

2011-01-01

Source: US2012184029A The present invention relates to preparation of a polymer coating comprising or consisting of polymer chains comprising or consisting of units of 2-methoxyethyl acrylate synthesized by Surface-Initiated Atom Transfer Radical Polymerization (SI ATRP) such as ARGET SI ATRP...

Surface nanostructuring of thin film composite membranes via grafting polymerization and incorporation of ZnO nanoparticles

Science.gov (United States)

Isawi, Heba; El-Sayed, Magdi H.; Feng, Xianshe; Shawky, Hosam; Abdel Mottaleb, Mohamed S.

2016-11-01

A new approach for modification of polyamid thin film composite membrane PA(TFC) using synthesized ZnO nanoparticles (ZnO NPs) was shown to enhance the membrane performances for reverse osmosis water desalination. First, active layer of synthesis PA(TFC) membrane was activated with an aqueous solution of free radical graft polymerization of hydrophilic methacrylic acid (MAA) monomer onto the surface of the PA(TFC) membrane resulting PMAA-g-PA(TFC). Second, the PA(TFC) membrane has been developed by incorporation of ZnO NPs into the MAA grafting solution resulting the ZnO NPs modified PMAA-g-PA(TFC) membrane. The surface properties of the synthesized nanoparticles and prepared membranes were investigated using the FTIR, XRD and SEM. Morphology studies demonstrated that ZnO NPs have been successfully incorporated into the active grafting layer over PA(TFC) composite membranes. The zinc leaching from the ZnO NPs modified PMAA-g-PA(TFC) was minimal, as shown by batch tests that indicated stabilization of the ZnO NPs on the membrane surfaces. Compared with the a pure PA(TFC) and PMAA-g-PA(TFC) membranes, the ZnO NPs modified PMAA-g-PA(TFC) was more hydrophilic, with an improved water contact angle (∼50 ± 3°) over the PMAA-g-PA(TFC) (63 ± 2.5°). The ZnO NPs modified PMAA-g-PA(TFC) membrane showed salt rejection of 97% (of the total groundwater salinity), 99% of dissolved bivalent ions (Ca2+, SO42-and Mg2+), and 98% of mono valent ions constituents (Cl- and Na+). In addition, antifouling performance of the membranes was determined using E. coli as a potential foulant. This demonstrates that the ZnO NPs modified PMAA-g-PA(TFC) membrane can significantly improve the membrane performances and was favorable to enhance the selectivity, permeability, water flux, mechanical properties and the bio-antifouling properties of the membranes for water desalination.

Graft-copolymerization onto carbon black

International Nuclear Information System (INIS)

Nakase, Yoshiaki; Nishii, Masanobu; Kijima, Toshiyuki; Kato, Hiroshi.

1988-07-01

Radiation-induced graft copolymerization of vinyl monomer onto carbon black was performed. During the γ-ray- and electron beam-induced polymerization (In-source), or the electron beam post-polymerization, the graft-copolymerization behavior was affected by the kinds of both carbon blacks and monomers, i.e. the smaller the size of carbon black particles, the higher the apparent grafted fraction. Homopolymer in the grafted carbon black samples was washed out by the solvent of the polymer, and the extracted polymer seemed to be dimer or trimer of the used monomer. In the case of the post-polymerization with the pre-irradiation doses of 50 Mrad, homopolymer was hardly observed. The polymer sheets of plastics or rubbers with grafted carbon black had an electrical conductivity unalterable considerably by the heating cycles. The particles of grafted carbon black in the sheet might be kept much more at the surface layer within 100 nm depth than at the inner layer. (author)

Facile Synthesis of Well-Defined MDMO-PPV Containing (TriBlock—Copolymers via Controlled Radical Polymerization and CuAAC Conjugation

Directory of Open Access Journals (Sweden)

Neomy Zaquen

2015-02-01

Full Text Available A systematic investigation into the chain transfer polymerization of the so-called radical precursor polymerization of poly(p-phenylene vinylene (PPV materials is presented. Polymerizations are characterized by systematic variation of chain transfer agent (CTA concentration and reaction temperature. For the chain transfer constant, a negative activation energy of −12.8 kJ·mol−1 was deduced. Good control over molecular weight is achieved for both the sulfinyl and the dithiocarbamate route (DTC. PPVs with molecular weights ranging from thousands to ten thousands g·mol−1 were obtained. To allow for a meaningful analysis of the CTA influence, Mark–Houwink–Kuhn–Sakurada (MHKS parameters were determined for conjugated MDMO-PPV ([2-methoxy-5-(3',7'-dimethyloctyloxy]-1,4-phenylenevinylene to α = 0.809 and k = 0.00002 mL·g−1. Further, high-endgroup fidelity of the CBr4-derived PPVs was proven via chain extension experiments. MDMO-PPV-Br was successfully used as macroinitiator in atom transfer radical polymerization (ATRP with acrylates and styrene. A more polar PPV counterpart was chain extended by an acrylate in single-electron transfer living radical polymerization (SET-LRP. In a last step, copper-catalyzed azide alkyne cycloaddition (CuAAC was used to synthesize block copolymer structures. Direct azidation followed by macromolecular conjugation showed only partial success, while the successive chain extension via ATRP followed by CuAAC afforded triblock copolymers of the poly(p-phenylene vinylene-block-poly(tert-butyl acrylate-block-poly(ethylene glycol (PPV-b-PtBuA-b-PEG.

Modification of Jute Fibers with Polystyrene via Atom Transfer Radical Polymerization

DEFF Research Database (Denmark)

Plackett, David; Jankova, Katja Atanassova; Egsgaard, Helge

2005-01-01

Atom transfer radical polymerization (ATRP) was investigated as a method of covalently bonding polystyrene to jute (Corchorus capsularis) and as a possible approach to fiber composites with enhanced properties. Jute fibers were modified with a brominated initiator and subsequently ATRP modified...... to attach polystyrene and then examined using SEM, DSC, TGA, FTIR, XPS, elemental analysis, and Py-GC-MS. These techniques confirmed that polystyrene had been covalently bound to the fibers and consequently ATRP-modified jute fiber mats were used to prepare hot-pressed polystyrene composites. Composite...

Enhancement of mechanical properties of poly(vinyl chloride with polymethyl methacrylate-grafted halloysite nanotube

Directory of Open Access Journals (Sweden)

2011-07-01

Full Text Available Halloysite nanotubes(HNTs grafted with Polymethyl methacrylate(PMMA were synthesized via radical polymerization. The properties of PMMA-grafted HNTs were characterized by transmission electron microscopy (TEM, fourier transform infrared spectroscopy (FTIR, thermogravimetric analysis (TGA and X-ray photoelectron spectroscopy (XPS. The results showed that PMMA grafted to the surfaces of HNTs successfully. Then, PVC/PMMA-grafted HNTs nanocomposites were prepared by melt compounding. The morphology, mechanical properties and thermal properties of the nanocomposites were investigated. PMMA-grafted HNTs can effectively improve the toughness, strength and modulus of PVC. The glass transition and thermal decomposition temperatures of PVC phase in PVC/PMMA-grafted HNTs nanocomposites are shifted toward slightly higher temperatures. The grafted HNTs were uniformly dispersed in PVC matrix as revealed by TEM photos. The fracture surfaces of the nanocomposites exhibited plastic deformation feature indicating ductile fracture behaviors. The improvement of toughness of PVC by PMMA-grafted HNTs was attributed to the improved interfacial bonding by grafting and the toughening mechanism was explained according to the cavitation mechanism.

Radiation Synthesis of Poly(N-Vinyl Pyrrolidone) Nanogels and Nanoscale Grafting of Poly(Acrylic Acid) from Cellulose

Energy Technology Data Exchange (ETDEWEB)

Guven, Olgun; Isik, Semiha Duygu; Barsbay, Murat [Hacettepe University, Department of Chemistry, 06800 Ankara (Turkey)

2010-07-01

Ionizing radiation has long been known to be a very useful tool for the preparation of nanogels. Although preparation is straightforward, the control of the sizes of nanogels has been a challenging issue. This report shows the results of our work on using radiation for the synthesis of PVP nanogels in the range of 40-200nm by making use of the principles of solution thermodynamics of aqueous polymer solutions. Nanoscale grafting of responsive polymers however has been of scientific and industrial importance due to fine control of the molecular weight and molecular weight distribution of grafted polymers. The second part of this report deals with the grafting of poly(acrylic acid) onto the surface of cellulose, thus imparting pH response to the substrate. The use of radiation as a constant source of radical generation and Reversible-Addition-Fragmentation-Chain transfer agents for the control of free radical polymerization provided a full control over the molecular weight and distribution of poly(acrylic acid) grafts on cellulose. (author)

Radiation Synthesis of Poly(N-Vinyl Pyrrolidone) Nanogels and Nanoscale Grafting of Poly(Acrylic Acid) from Cellulose

International Nuclear Information System (INIS)

Guven, Olgun; Isik, Semiha Duygu; Barsbay, Murat

2010-01-01

Ionizing radiation has long been known to be a very useful tool for the preparation of nanogels. Although preparation is straightforward, the control of the sizes of nanogels has been a challenging issue. This report shows the results of our work on using radiation for the synthesis of PVP nanogels in the range of 40-200nm by making use of the principles of solution thermodynamics of aqueous polymer solutions. Nanoscale grafting of responsive polymers however has been of scientific and industrial importance due to fine control of the molecular weight and molecular weight distribution of grafted polymers. The second part of this report deals with the grafting of poly(acrylic acid) onto the surface of cellulose, thus imparting pH response to the substrate. The use of radiation as a constant source of radical generation and Reversible-Addition-Fragmentation-Chain transfer agents for the control of free radical polymerization provided a full control over the molecular weight and distribution of poly(acrylic acid) grafts on cellulose. (author)

Application of living radical polymerization to the synthesis of resist polymers for radiation lithography

Energy Technology Data Exchange (ETDEWEB)

Shimizu, Takashi [Nitto Denko Co. LTD., Shimohozumi 1-1-2, Ibaraki, Osaka 567-8680 (Japan); Ichikawa, Tsuneki [Division of Materials Chemistry, Graduate school of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)]. E-mail: ichikawa@eng.hokudai.ac.jp

2005-07-01

Poly(styrene) and poly(methyl acrylate) with benzyl ester of carboxylic acid at the center of the polymer skeletons were synthesized by living radical polymerization for developing a new type of radiation resist with high resistivity to plasma etching and high sensitivity and spatial resolution to ionizing radiations. The initiators were benzyl esters with two functional groups for living radical polymerization on the benzyl and the carboxylic sides. Introduction of benzyl ester to the polymer skeletons changed the polymers from cross-link type to scission type upon {gamma}-irradiation. Irradiation of the polymers resulted in the binary change of the molecular weight, due to dissociative capture of secondary electrons by the benzyl ester, as M{sub n}R{sub 1}COOCH(C{sub 6}H{sub 5})R{sub 2}M{sub n}+e{sup -}->M{sub n}R{sub 1}COO{sup -}+{sup {center_dot}}CH(C{sub 6}H{sub 5})R{sub 2}M{sub n}. The generated polymer fragments were not decomposed by further irradiation, which suggests that the synthesized polymers have high resistivity to plasma etching.

Free radical induced grafting of acrylonitrile on pre-treated rice straw for enhancing its durability and flame retardancy

Directory of Open Access Journals (Sweden)

Aparna Mukherjee

2017-01-01

Full Text Available The present investigation highlights the feasibility of a polymer grafting process to enhance the durability and flame retardancy of rice straw towards application as a low cost roofing material. The success of this grafting methodology was perceived to depend upon a bi-step pre-treatment process encompassing delignification and inorganic salts dispersion. Subsequently free radical polymer grafting of acrylonitrile onto rice straw was implemented by immersion mechanism initiated by oxalic acid-potassium permanganate initiator. The percentage of grafting, limiting oxygen index (LOI, biodegradability of the grafted rice straw and grafting yield percentage was estimated to be 57%, 27%, 0.02% and 136.67%, respectively. The weight loss of polymer grafted rice straw implied its less biodegradability over raw straw. Thus, the process of grafting contrived in the present analysis can be a promising and reliable technique for the efficient utilization of rice straw as an inexpensive roofing element through the augmentation of its durability and flame retardancy.

Radioactive cesium removal from seawater using adsorptive fibers prepared by radiation-induced graft polymerization

International Nuclear Information System (INIS)

Goto, Shota; Kawai-Noma, Shigeko; Umeno, Daisuke; Saito, Kyoichi; Fujiwara, Kunio; Sugo, Takanobu; Kikuchi, Takahiro; Morimoto, Yasutomi

2015-01-01

The meltdown of three reactors of the TEPCO Fukushima Daiichi nuclear power station (NPS) caused by the Great East Japan Earthquake on March 11th 2011 resulted in the emission of radionuclides such as cesium-137 and strontium-90 to the environment. For example, radioactive cesium exceeding the legal discharge limit (90 Bq/L, 2×10 -13 M) was detected in the seawater of the seawater-intake area of the NPS at the end of September 2014. Adsorbents with a high selectivity for cesium ions over other alkali metal ions such as sodium and potassium ions are required for cesium removal from seawater because sodium and potassium ions dissolve respectively at much higher concentrations of 5×10 -1 and 1×10 -2 M than cesium ions (2×10 -9 M). In addition, the simple operations of the immersion in seawater and the recovery of the adsorbents from seawater are desirable at decontamination sites. We prepared a cobalt-ferrocyanide-impregnated fiber capable of specifically capturing cesium ions in seawater by radiation-induced graft polymerization and chemical modifications. First, a commercially available 6-nylon fiber was irradiated with γ-rays. Second, an epoxy-group-containing vinyl monomer, glycidyl methacrylate, was graft-polymerized onto the γ-ray-irradiated nylon fiber. Third, the epoxy ring of the grafted polymer chain was reacted with triethylenediamine to obtain an anion-exchange fiber. Fourth, ferrocyanide ions, [Fe(CN) 6 ] 4 - , were bound to the anion-exchange group of the polymer chains. Finally, the ferrocyanide-ion-bound-fiber was placed in contact with cobalt chloride to precipitate insoluble cobalt ferrocyanide onto the polymer chains. Insoluble cobalt ferrocyanide was immobilized at the periphery of the fiber. However, the impregnation structure remains unclear. Here, we clarified the structure of insoluble cobalt ferrocyanide impregnated onto the polymer chain grafted onto the fiber to ensure the chemical and physical stability of the adsorptive fiber in

Acrylonitrile-Butadiene Rubber (NBR) Prepared via Living/Controlled Radical Polymerization (RAFT).

Science.gov (United States)

Kaiser, Andreas; Brandau, Sven; Klimpel, Michael; Barner-Kowollik, Christopher

2010-09-15

In the current work we present results on the controlled/living radical copolymerization of acrylonitrile (AN) and 1,3-butadiene (BD) via reversible addition fragmentation chain transfer (RAFT) polymerization techniques. For the first time, a solution polymerization process for the synthesis of nitrile butadiene rubber (NBR) via the use of dithioacetate and trithiocarbonate RAFT agents is described. It is demonstrated that the number average molar mass, $\\overline M _{\\rm n} $, of the NBR can be varied between a few thousand and 60 000 g · mol(-1) with polydispersities between 1.2 and 2.0 (depending on the monomer to polymer conversion). Excellent agreement between the experimentally observed and the theoretically expected molar masses is found. Detailed information on the structure of the synthesized polymers is obtained by variable analytical techniques such as infrared spectroscopy (IR), nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry, and electrospray ionization-mass spectrometry (ESI-MS). Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of poly(vinyl alcohol)-grafted graphene oxide/poly(vinyl alcohol) nanocomposites via in-situ low-temperature emulsion polymerization and their thermal and mechanical characterization

Science.gov (United States)

Zhang, Shengchang; Liu, Pengqing; Zhao, Xiangsen; Xu, Jianjun

2017-02-01

An in-situ polymerization combined with chemical grafting modification method for preparing Poly(vinyl alcohol)-grafted graphene oxide/Poly(vinyl alcohol) (PVA-g-GO/PVA) nanocomposites was reported. Firstly, Poly(vinyl acetate)-grafted graphene oxide/Poly(vinyl acetate) nanocomposites were prepared, and then the PVA-g-GO/PVA nanocomposites could be obtained through alcoholysis reaction. X-ray photoelectron spectrometer and fourier-transform infrared spectrometer confirmed that the PVAc or PVA chains were successfully grafted to GO sheets during in-situ polymerization and alcoholysis. And the results from transmission electron microscopy, scanning electron microscopy and X-ray diffraction showed that the well compatibility and homogenous dispersion of PVA-g-GO in PVA matrix could be achieved. Differential scanning calorimetric, thermogravimetry analysis and tensile test were employed to study the thermal and mechanical properties of the PVA-g-GO/PVA nanocomposites. The results indicated that a 53% improvement of tensile strength and a 36% improvement of Young's modulus were achieved by addition of 0.5 wt% of GO sheets. And the glass transition temperature of PVA-g-GO/PVA nanocomposites was increased, and their thermal stability and crystallization degree were both decreased. Due to well dispersion of fillers and strong interfacial interactions at the filler-matrix interface, in-situ polymerization combined with chemical grafting modification was a good choice to prepare graphene/PVA nanocomposite with excellent mechanical properties.

The graft polymers from different species of lignin and acrylic acid: synthesis and mechanism study.

Science.gov (United States)

Ye, De zhan; Jiang, Li; Ma, Chao; Zhang, Ming-hua; Zhang, Xi

2014-02-01

The influence of lignin species on the grafting mechanism of lignosulfonate (from eucalyptus and pine, recorded as HLS and SLS, respectively) with acrylic acid (AA) was investigated. The graft polymers were confirmed by the absorption of carbonyl groups in the FTIR spectra. The decreasing phenolic group's content (Ph-OH) is not only due to its participation as grafting site but also to the negative effect of initiator. In the initial period (0-60 min), HLS and SLS both accelerate the polymerization of AA. Additionally, Ph-OH group's content is proportional to product yield (Y%), monomer conversion (C%) and grafting efficiency (GE%), strongly indicating that it acts as active center. Nevertheless, compared with HLS, Y% and C% in SLS grafting system are lower though it has higher Ph-OH group's content, which is due to the quinonoid structure formed by the self-conjugated of phenoxy radical in Guaiacyl unit. Finally, the lignosulfonate grafting mechanism was proposed. Copyright © 2013 Elsevier B.V. All rights reserved.

Radiation chemistry of polymeric system

International Nuclear Information System (INIS)

Machi, Sueo; Ishigaki, Isao

1978-01-01

Among wide application of radiation in the field of polymer chemistry, practices of polymerization, graft polymerization, bridging, etc. are introduced hereinafter. As for the radiation sources of radiation polymerization, in addition to the 60 Co-γ ray with long permeation distance which has been usually applied, electron beam accelerators with high energy, large current and high reliability have come to be produced, and the liquid phase polymerization by electron beam has attracted attention industrially. Concerning polymerizing reactions, explanations were given to electron beam polymerization under high dose rate, the polymerization in supercooling state or under high pressure, and emulsifying polymerization. As for radiation bridging, radiation is applied for the bridging of hydrogel, acceleration of bridging and improvement of radiation resistance. It is also utilized for reforming membranes by graft polymerization, and synthesis of polymers for medical use. Application of fixed enzymes in the medical field has been investigated by fixing various enzymes by low temperature γ-ray polymerization with glassy monomers such as HEMA. (Kobatake, H.)

Stability of SG1 nitroxide towards unprotected sugar and lithium salts: a preamble to cellulose modification by nitroxide-mediated graft polymerization

Directory of Open Access Journals (Sweden)

Guillaume Moreira

2013-08-01

Full Text Available The range of applications of cellulose, a glucose-based polysaccharide, is limited by its inherently poor mechanical properties. The grafting of synthetic polymer chains by, for example, a “grafting from” process may provide the means to broaden the range of applications. The nitroxide-mediated polymerization (NMP method is a technique of choice to control the length, the composition and the architecture of the grafted copolymers. Nevertheless, cellulose is difficult to solubilize in organic media because of inter- and intramolecular hydrogen bonds. One possibility to circumvent this limitation is to solubilize cellulose in N,N-dimethylformamide (DMF or N,N-dimethylacetamide (DMA with 5 to 10 wt % of lithium salts (LiCl or LiBr, and carry out grafted polymerization in this medium. The stability of nitroxides such as SG1 has not been studied under these conditions yet, even though these parameters are of crucial importance to perform the graft modification of polysaccharide by NMP. The aim of this work is to offer a model study of the stability of the SG1 nitroxide in organic media in the presence of unprotected glucose or cellobiose (used as a model of cellulose and in the presence of lithium salts (LiBr or LiCl in DMF or DMA.Contrary to TEMPO, SG1 proved to be stable in the presence of unprotected sugar, even with an excess of 100 molar equivalents of glucose. On the other hand, lithium salts in DMF or DMA clearly degrade SG1 nitroxide as proven by electron-spin resonance measurements. The instability of SG1 in these lithium-containing solvents may be explained by the acidification of the medium by the hydrolysis of DMA in the presence of LiCl. This, in turn, enables the disproportionation of the SG1 nitroxide into an unstable hydroxylamine and an oxoammonium ion.Once the conditions to perform an SG1-based nitroxide-mediated graft polymerization from cellobiose have been established, the next stage of this work will be the modification of

The Nanoconfined Free Radical Polymerization: Reaction Kinetics and Thermodynamics

Science.gov (United States)

Zhao, Haoyu; Simon, Sindee

The reaction kinetics and thermodynamics of nanoconfined free radical polymerizations are investigated for methyl methacrylate (MMA) and ethyl methacrylate (EMA) monomers using differential scanning calorimetry. Controlled pore glass is used as the confinement medium with pore diameters as small as 7.5 nm; the influence of both hydrophobic (silanized such that trimethylsilyl groups cover the surface) and hydrophilic (native silanol) surfaces is investigated. Propagation rates increase when monomers are reacted in the hydrophilic pores presumably due to the specific interactions between the carbonyl and silanol groups; however, the more flexible EMA monomer shows weaker effects. On the other hand, initial rates of polymerization in hydrophobic pores are unchanged from the bulk. In both pores, the onset of autoacceleration occurs earlier due to the reduced diffusivity of confined chains, which may be compensated at high temperatures. In addition to changes in kinetics, the reaction thermodynamics can be affected under nanoconfinement. Specifically, the ceiling temperature (Tc) is shifted to lower temperatures in nanopores, with pore surface chemistry showing no significant effects; the equilibrium conversion is also reduced at high temperatures below Tc. These observations are attributed to a larger negative change in entropy on propagation for the confined system, with the MMA system again showing greater effects. Funding from ACS PRF is gratefully acknowledged.

In situ polymerization and characterization of grafted poly (3,4-ethylenedioxythiophene)/multiwalled carbon nanotubes composite with high electrochemical performances

International Nuclear Information System (INIS)

Bai, Xiaoxia; Hu, Xiujie; Zhou, Shuyun; Yan, Jun; Sun, Chenghua; Chen, Ping; Li, Laifeng

2013-01-01

Graphical abstract: The homogeneously grafted PEDOT/MWCNTs containing numerous whorl fingerprint-like open ends endows with excellent electrochemical performances. Highlights: ► A ternary phase system with the surfactant AOT is utilized to efficiently solve the problem of the aggregation of MWCNTs. ► The homogenously grafted PEDOT/MWCNTs composite is synthesized by in situ chemical polymerization in the ternary phase system. ► The core–shell nanotubes contain many whorl fingerprint-like open ends that are greatly favorable for the transportation of the electrons and ions. ► The energy density of grafted PEDOT/MWCNTs has been enhanced by a factor of four comparing to that of native MWCNTs. ► The grafted PEDOT/MWCNTs composite manifests better cycle durability than both the constituents. - Abstract: The homogenously grafted composite of poly (3,4-ethylenedioxythiophene)/multiwalled carbon nanotubes (PEDOT/MWCNTs) is synthesized by in situ chemical polymerization in a ternary phase system. When carbon nanotubes are dispersed in this system containing sodium bis(2-ethylhexyl) sulfosuccinate (AOT), the surfactant AOT can efficiently hinter the aggregation of MWCNTs by absorbing and arranging regularly on the MWCNT surface. It is greatly advantageous to the stabilization of MWCNTs, which leads to the equally grafted composite. Its morphology was observed by scanning and transmission electron microscopes. Especially, the core–shell nanotubes contain many whorl fingerprint-like open ends that are efficiently favorable for the transportation of the electrons and ions. Such grafted PEDOT/MWCNTs composite nanotubes manifest enhanced electrochemical performances. We investigate the application of PEDOT/MWCNTs as a high-property supercapacitor and test its capacitive performance by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The energy density of grafted composite, 11.3 Wh kg −1 , has been enhanced by a factor

UV-induced graft polymerization of acrylic acid in the sub-micronchannels of oxidized PET track-etched membrane

Science.gov (United States)

Korolkov, Ilya V.; Mashentseva, Anastassiya A.; Güven, Olgun; Taltenov, Abzal A.

2015-12-01

In this article, we report on functionalization of track-etched membrane based on poly(ethylene terephthalate) (PET TeMs) oxidized by advanced oxidation systems and by grafting of acrylic acid using photochemical initiation technique for the purpose of increasing functionality thus expanding its practical application. Among advanced oxidation processes (H2O2/UV) system had been chosen to introduce maximum concentration of carboxylic acid groups. Benzophenone (BP) photo-initiator was first immobilized on the surfaces of cylindrical pores which were later filled with aq. acrylic acid solution. UV-irradiation from both sides of PET TeMs has led to the formation of grafted poly(acrylic acid) (PAA) chains inside the membrane sub-micronchannels. Effect of oxygen-rich surface of PET TeMs on BP adsorption and subsequent process of photo-induced graft polymerization of acrylic acid (AA) were studied by ESR. The surface of oxidized and AA grafted PET TeMs was characterized by UV-vis, ATR-FTIR, XPS spectroscopies and by SEM.

Superabsorbent hydrogels via graft polymerization of acrylic acid from chitosan-cellulose hybrid and their potential in controlled release of soil nutrients.

Science.gov (United States)

Essawy, Hisham A; Ghazy, Mohamed B M; El-Hai, Farag Abd; Mohamed, Magdy F

2016-08-01

Superabsorbent polymers fabricated via grafting polymerization of acrylic acid from chitosan (CTS) yields materials that suffer from poor mechanical strength. Hybridization of chitosan with cellulose (Cell) via chemical bonding using thiourea formaldehyde resin increases the flexibility of the produced hybrid (CTS/Cell). The hybridization process and post graft polymerization of acrylic acid was followed using Fourier transform infrared (FTIR). Also, the obtained structures were homogeneous and exhibited uniform surface as could be shown from imaging with scanning electron microscopy (SEM). Thus, the polymers derived from the grafting of polyacrylic acid from (CTS/Cell) gave rise to much more mechanically robust structures ((CTS/Cell)-g-PAA) that bear wide range of pH response due to presence of chitosan and polyacrylic acid in one homogeneous entity. Additionally, the obtained structures possessed greater water absorbency 390, 39.5g/g in distilled water and saline (0.9wt.% NaCl solution), respectively, and enhanced retention potential even at elevated temperatures as revealed by thermogravimetric analysis (TGA). This could be explained by the high grafting efficiency (GE%), 86.4%, and grafting yield (GY%), 750%. The new superabsorbent polymers proved to be very efficient devices for controlled release of fertilizers into the soil which expands their use in agriculture and horticultural applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Surface grafting density analysis of high anti-clotting PU-Si-g-P(MPC) films

Energy Technology Data Exchange (ETDEWEB)

Lu Chunyan [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097 (China); Jiangsu Engineering Research Center for Biomedical Function Materials, Nanjing Normal University, Nanjing 210097 (China); Zhou Ninglin, E-mail: ninglinzhou@yahoo.com [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097 (China); Jiangsu Engineering Research Center for Biomedical Function Materials, Nanjing Normal University, Nanjing 210097 (China); Jiangsu Technological Research Center for Interfacial Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Xiao Yinghong; Tang Yida; Jin Suxing; Wu Yue [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097 (China); Jiangsu Engineering Research Center for Biomedical Function Materials, Nanjing Normal University, Nanjing 210097 (China); Zhang Jun; Shen Jian [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097 (China); Jiangsu Engineering Research Center for Biomedical Function Materials, Nanjing Normal University, Nanjing 210097 (China); Jiangsu Technological Research Center for Interfacial Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

2012-02-01

Well-defined zwitterionic polymer brushes with good blood compatibility were studied, grafted from polyurethane (PU) substrate (PU-Si-g-P(MPC)) by surface-initiated reverse atom transfer radical polymerization (SI-RATRP). We found that the structure of polymer brushes and hence their properties greatly depend on the grafting density. To solve the problems of the normal method for grafting density measurement, i.e., more requirements for qualified and proficient instrument operator, we established an effective and feasible way instead of the conventional method of spectroscopic ellipsometer combined with gel permeation chromatograph (ELM/GPC) to calculate the grafting density of PU-Si-g-P(MPC) films by using a software named ImageJ 1.44e in combination with scanning electronic microscope (SEM) or atomic microscope (AFM). X-ray photoelectron spectroscopy (XPS), SEM and AFM were employed to analyze the surface topography and changes of elements before and after graft modification of the synthetic PU-Si-g-P(MPC) biofilms.

Improving Hemocompatibility of Membranes for Extracorporeal Membrane Oxygenators by Grafting Nonthrombogenic Polymer Brushes.

Science.gov (United States)

Obstals, Fabian; Vorobii, Mariia; Riedel, Tomáš; de Los Santos Pereira, Andres; Bruns, Michael; Singh, Smriti; Rodriguez-Emmenegger, Cesar

2018-03-01

Nonthrombogenic modifications of membranes for extracorporeal membrane oxygenators (ECMOs) are of key interest. The absence of hemocompatibility of these membranes and the need of anticoagulation of patients result in severe and potentially life-threatening complications during ECMO treatment. To address the lack of hemocompatibility of the membrane, surface modifications are developed, which act as barriers to protein adsorption on the membrane and, in this way, prevent activation of the coagulation cascade. The modifications are based on nonionic and zwitterionic polymer brushes grafted directly from poly(4-methyl-1-pentene) (TPX) membranes via single electron transfer-living radical polymerization. Notably, this work introduces the first example of well-controlled surface-initiated radical polymerization of zwitterionic brushes. The antifouling layers markedly increase the recalcification time (a proxy of initiation of coagulation) compared to bare TPX membranes. Furthermore, platelet and leukocyte adhesion is drastically decreased, rendering the ECMO membranes hemocompatible. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stereocontrol during the radical polymerization of methyl methacrylates with combined Lewis acids:Aluminium trichloride（AlCl3） and iron dichloride tetrahydrate

Institute of Scientific and Technical Information of China (English)

无

2010-01-01

The radical polymerization of methyl methacrylate(MMA) was carried out in the presence of combined Lewis acids of the AlCl3-FeCl2 system.Compared with the polymerization produced in the presence of single Lewis acids,AlCl3 or FeCl2,the MMA polymerization in the presence of AlCl3-FeCl2 composite in CHCl3 or 1-butanol produced a polymer with a higher isotacticity and in toluene produced a polymer with a much higher isotacticity(mm=50%) .The molecular weight and polydispersity of PMMA in the presence of Lewis acids were similar with those in the absence of Lewis acids,although Lewis acids decelerate the polymerization of MMA.The effects of the Lewis acids were greater in a solvent with a lower polarity.A possible stereocontrol mechanism of the polymerization was proposed.The Lewis acid composite of AlCl3-FeCl2 readily formed a complex with growing species.These complexes possessed apparent bulkiness that changes the direction of monomer addition to the growing radical center.

Amine functionalization of cellulose surface grafted with glycidyl methacrylate by γ-initiated RAFT polymerization

International Nuclear Information System (INIS)

Barsbay, Murat; Güven, Olgun; Kodama, Yasko

2016-01-01

This study presents the functionalization of poly(glycidyl methacrylate) (PGMA) grafted cellulose filter paper by a model compound, ethylenediamine (EDA), through the epoxy groups of PGMA. Cellulose based copolymers were prepared via the radiation-induced and RAFT-mediated graft polymerization. The samples were characterized by ATR–FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), elemental analysis, contact angle measurements and scanning electron microscopy (SEM). An efficient modification density of around 1 mmol EDA/mg copolymer was attained within ca. 8 h, indicating that chemical composition of well-defined copolymers may further be tuned by appropriately selecting the reactive agents for use in many emerging fields. - Highlights: • Ethylenediamine (EDA) was immobilized to cellulose-g-PGMA copolymers. • FTIR, XPS, SEM, EA and CA measurements were used for characterization. • The useful qualities of the RAFT were combined with the versatility of PGMA.

A Review on Grafting of Biofibers for Biocomposites

Directory of Open Access Journals (Sweden)

Liqing Wei

2016-04-01

Full Text Available A recent increase in the use of biofibers as low-cost and renewable reinforcement for the polymer biocomposites has been seen globally. Biofibers are classified into: lignocellulosic fibers (i.e., cellulose, wood and natural fibers, nanocellulose (i.e., cellulose nanocrystals and cellulose nanofibrils, and bacterial cellulose, while polymer matrix materials can be petroleum based or bio-based. Green biocomposites can be produced using both biobased fibers and polymers. Incompatibility between the hydrophilic biofibers and hydrophobic polymer matrix can cause performance failure of resulting biocomposites. Diverse efforts have focused on the modification of biofibers in order to improve the performances of biocomposites. “Grafting” copolymerization strategy can render the advantages of biofiber and impart polymer properties onto it and the performance of biocomposites can be tuned through changing grafting parameters. This review presents a short overview of various “grafting” methods which can be directly or potentially employed to enhance the interaction between biofibers and a polymer matrix for biocomposites. Major grafting techniques, including ring opening polymerization, grafting via coupling agent and free radical induced grafting, have been discussed. Improved properties such as mechanical, thermal, and water resistance have provided grafted biocomposites with new opportunities for applications in specific industries.

A corrosion-protective coating based on a solution-processable polymer-grafted graphene oxide nanocomposite

International Nuclear Information System (INIS)

Qi, Kai; Sun, Yimin; Duan, Hongwei; Guo, Xingpeng

2015-01-01

Highlights: • Solution-processable polymer-grafted graphene nanocomposite is synthesized. • The nanocomposite exhibits synergistic properties of both building blocks. • The nanocomposite can be easily applied to form a protective coating on metals. • The coating can effectively prevent corrosion of copper substrate. - Abstract: A new type of solution-processable graphene coating has been synthesized by grafting polymethylmethacrylate (PMMA) brushes on graphene oxide (GO) via surface-initiated atom transfer radical polymerization (ATRP). One major finding is that the PMMA-grafted GO nanocomposite exhibits synergistic properties of both building blocks, i.e., permeation inhibition of GO and solubility of PMMA in a variety of solvents, which makes it compatible with commonly used coating methods to form uniform coatings with controlled thickness. Our results demonstrate that PMMA-grafted GO coating can effectively block charge transfer at the metal–electrolyte interface and prevent corrosion of the copper substrate under aggressive saline conditions

The effect of polymerization mode on monomer conversion, free radical entrapment, and interaction with hydroxyapatite of commercial self-adhesive cements.

Science.gov (United States)

D'Alpino, Paulo Henrique Perlatti; Silva, Marília Santos; Vismara, Marcus Vinícius Gonçalves; Di Hipólito, Vinicius; Miranda González, Alejandra Hortencia; de Oliveira Graeff, Carlos Frederico

2015-06-01

This study evaluated the degree of conversion, the free radical entrapment, and the chemical interaction of self-adhesive resin cements mixed with pure hydroxyapatite, as a function of the polymerization activation mode among a variety of commercial self-adhesive cements. Four cements (Embrace WetBond, MaxCem Elite, Bifix SE, and RelyX U200) were mixed, combined with hydroxyapatite, dispensed into molds, and distributed into three groups, according to polymerization protocols: IP (photoactivation for 40s); DP (delayed photoactivation, 10 min self-curing plus 40s light-activated); and CA (chemical activation, no light exposure). Infrared (IR) spectra were obtained and monomer conversion (%) was calculated by comparing the aliphatic-to-aromatic IR absorption peak ratio before and after polymerization (n=10). The free radical entrapment values of the resin cements were characterized using Electron Paramagnetic Resonance (EPR) and the concentration of spins (number of spins/mass) calculated (n=3). Values were compared using two-way ANOVA and Tukey's post-hoc test (α=5%). X-ray diffraction (XRD) characterized the crystallinity of hydroxyapatite as a function of the chemical interactions with the resin cements. The tested parameters varied as a function of resin cement and polymerization protocol. Embrace WetBond and RelyX U200 demonstrated dependence on photoactivation (immediate or delayed), whereas MaxCem Elite exhibited dependence on the chemical activation mode. Bifix SE presented the best balance based on the parameters analyzed, irrespective of the activation protocol. Choice of polymerization protocol affects the degree of conversion, free radical entrapment, and the chemical interaction between hydroxyapatite and self-adhesive resin cement mixtures. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fluorinated polyimides grafted with poly(ethylene glycol) side chains by the RAFT-mediated process and their membranes

International Nuclear Information System (INIS)

Chen Yiwang; Chen Lie; Nie Huarong; Kang, E.T.; Vora, R.H.

2005-01-01

Graft polymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA) from fluorinated polyimide (FPI) was carried out by the reversible addition-fragmentation chain transfer (RAFT)-mediated process. The peroxides generated by the ozone treatment on FPI facilitated the thermally-initiated graft copolymerization from FPI backbone. The 'living' character of the graft chain growing was ascertained in the subsequent chain extension of PEGMA. Nuclear magnetic resonance (NMR) and molecular weight measurements were used to characterize the chemical composition and structure of the copolymers. Microfiltration (MF) membranes were fabricated from the FPI-g-PEGMA comb copolymers by phase inversion in aqueous media. Surface composition analysis of the membranes scanned by X-ray photoelectron spectroscopy (XPS) revealed a substantial surface enrichment of the hydrophilic components. The pore size distribution of the resulting membranes was found to be much more uniform than that of the corresponding membranes cast from FPI-g-PEGMA prepared by the conventional radical polymerization process in the absence of the chain transfer agent. The morphology of the membranes was characterized by scanning electron microscopy (SEM)

Diffusion-controlled reaction. V. Effect of concentration-dependent diffusion coefficient on reaction rate in graft polymerization

International Nuclear Information System (INIS)

Imre, K.; Odian, G.

1979-01-01

The effect of diffusion on radiation-initiated graft polymerization has been studied with emphasis on the single- and two-penetrant cases. When the physical properties of the penetrants are similar, the two-penetrant problems can be reduced to the single-penetrant problem by redefining the characteristic parameters of the system. The diffusion-free graft polymerization rate is assumed to be proportional to the upsilon power of the monomer concentration respectively, and, in which the proportionality constant a = k/sub p/R/sub i//sup w//k/sub t//sup z/, where k/sub p/ and k/sub t/ are the propagation and termination rate constants, respectively, and R/sub i/ is the initiation rate. The values of upsilon, w, and z depend on the particular reaction system. The results of earlier work were generalized by allowing a non-Fickian diffusion rate which predicts an essentially exponential dependence on the monomer concentration of the diffusion coefficient, D = D 0 [exp(deltaC/M)], where M is the saturation concentration. A reaction system is characterized by the three dimensionless parameters, upsilon, delta, and A = (L/2)[aM/sup (upsilon--1)//D 0 ]/sup 1/2/, where L is the polymer film thickness. Graft polymerization tends to become diffusion controlled as A increases. Larger values of delta and ν cause a reaction system to behave closer to the diffusion-free regime. Transition from diffusion-free to diffusion-controlled reaction involves changes in the dependence of the reaction rate on film thickness, initiation rate, and monomer concentration. Although the diffusion-free rate is w order in initiation rate, upsilon order in monomer, and independent of film thickness, the diffusion-controlled rate is w/2 order in initiator rate and inverse first-order in film thickness. Dependence of the diffusion-controlled rate on monomer is dependent in a complex manner on the diffusional characteristics of the reaction system. 11 figures, 4 tables

Synthesis of defined polyhedral oligosilsesquioxane-containing diblock and triblock methacrylate copolymers by atom transfer radical polymerization

Czech Academy of Sciences Publication Activity Database

Janata, Miroslav; Sikora, Antonín; Látalová, Petra; Čadová, Eva; Raus, Vladimír; Matějka, Libor; Vlček, Petr

2013-01-01

Roč. 128, č. 6 (2013), s. 4294-4301 ISSN 0021-8995 R&D Projects: GA ČR GAP106/12/0844; GA ČR GAP108/12/1459 Institutional support: RVO:61389013 Keywords : copolymers * nanostructured polymers * radical polymerization Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.640, year: 2013

Kinetics of Waterborne Alkyd/Acrylic Hybrid Resin Free Radical Polymerization by Two Systems of Redox and Thermal Initiators

OpenAIRE

shirin Madadi; ali akbar Yousefi; elham Keshmirizadeh

2012-01-01

Kinetics of radical polymerizations of waterborne alkyd/acrylic hybrid resin via batch mini-emulsion technique was studied using redox initiators (TBHP/Fe2+/EDTA/AsAc  and  TBHP/Fe2+/EDTA/SFS) at relatively low temperatures and thermal initiators (BPO, KPS and AIBN) at higher temperatures to seek the most suitable initiator system. At the end of all reactions the unreacted monomer content was reduced using post-polymerization technique; consequently, leading to increased monomer conversion an...

Preliminary studies on 1-vinyl-2-pyrrolidone grafting onto cellulose by pre-irradiation method

Energy Technology Data Exchange (ETDEWEB)

Severich, Patrick; Dutra, Rodrigo da Costa; Kodama, Yasko, E-mail: ykodama@ipen.br, E-mail: patrick.severich@ipen.br, E-mail: rodrigo.dutra@ipen.br [Instituto de Pesquisas Energética s e Nucleares (IPEN-CNEN/SP), São Paulo, SP (Brazil)

2017-07-01

Cellulose is considered a renewable biopolymer most abundant in nature. Better functional surfaces can be Obtained by modifying cellulose. On the other hand, poly vinyl pyrrolidone, PVP, is a synthetic nontoxic, water-soluble polymer frequently used in an extensive variety of applications including several pharmaceutical applications. Grafting 1-vinyl-2-pyrrolidone, NVP, onto polymeric cellulose can be obtained by ionizing radiation. Ionizing radiation grafting can be affected by several factors as environment, solvent, monomer concentration, temperature of graft reaction. Grafting by ionizing radiation can be performed by three methods, pre-irradiation, oxidation by peroxide and simultaneous irradiation. In this study, it was used pre-irradiation method of cellulose. Paper filter without ash, NVP without purification was used in this study. Paper samples were exposed to electron beam from Dynamitron Accelerator with radiation absorbed dose of 25 kGy. Influence of NVP concentration, temperature of reaction after irradiation on degree of grafting (DG) was studied. Also, cellulose radicals of grafted paper samples was studied by electron paramagnetic resonance using a Bruker X-band ESR at room temperature just after heating reaction. Small decrease of cellulose radicals was observed with increasing reaction temperature. It was observed DG small increase with increasing concentration of monomer in solution of water ethanol 50-50 v:v and rising temperature of reaction. Further tests using simultaneous method of grafting of NVP in cellulose paper, in water:ethanol 75:25 v:v solution, induced by gamma irradiation were performed. It was observed homopolymerization forming PVP with increasing monomer concentration. (author)

Preliminary studies on 1-vinyl-2-pyrrolidone grafting onto cellulose by pre-irradiation method

International Nuclear Information System (INIS)

Severich, Patrick; Dutra, Rodrigo da Costa; Kodama, Yasko

2017-01-01

Cellulose is considered a renewable biopolymer most abundant in nature. Better functional surfaces can be Obtained by modifying cellulose. On the other hand, poly vinyl pyrrolidone, PVP, is a synthetic nontoxic, water-soluble polymer frequently used in an extensive variety of applications including several pharmaceutical applications. Grafting 1-vinyl-2-pyrrolidone, NVP, onto polymeric cellulose can be obtained by ionizing radiation. Ionizing radiation grafting can be affected by several factors as environment, solvent, monomer concentration, temperature of graft reaction. Grafting by ionizing radiation can be performed by three methods, pre-irradiation, oxidation by peroxide and simultaneous irradiation. In this study, it was used pre-irradiation method of cellulose. Paper filter without ash, NVP without purification was used in this study. Paper samples were exposed to electron beam from Dynamitron Accelerator with radiation absorbed dose of 25 kGy. Influence of NVP concentration, temperature of reaction after irradiation on degree of grafting (DG) was studied. Also, cellulose radicals of grafted paper samples was studied by electron paramagnetic resonance using a Bruker X-band ESR at room temperature just after heating reaction. Small decrease of cellulose radicals was observed with increasing reaction temperature. It was observed DG small increase with increasing concentration of monomer in solution of water ethanol 50-50 v:v and rising temperature of reaction. Further tests using simultaneous method of grafting of NVP in cellulose paper, in water:ethanol 75:25 v:v solution, induced by gamma irradiation were performed. It was observed homopolymerization forming PVP with increasing monomer concentration. (author)

Gamma radiation grafting process for preparing separator membranes for electrochemical cells

International Nuclear Information System (INIS)

Agostino, V.F. D'; Lee, J.Y.

1982-01-01

An irradiation grafting process for preparing separator membranes for use in electrochemical cells, comprises contacting a polymeric base film with an aqueous solution of a hydrophilic monomer and a polymerization retardant; and irradiating said contacted film to form a graft membrane having low electrical resistivity and having monomer molecules uniformly grafted thereon. In the examples (meth) acrylic acid is grafted on to polyethylene, polypropylene and polytetrafluoroethylene in the presence of ferrous sulphate or cupric sulphate as polymerization retardants. (author)

Development of novel ion-exchange membranes for electrodialysis of seawater by electron-beam-induced graft polymerization (4). Polymeric structures of cation-exchange membranes based on nylon-6 film

International Nuclear Information System (INIS)

Miyazawa, Tadashi; Asari, Yuki; Miyoshi, Kazuyoshi; Umeno, Daisuke; Saito, Kyoichi; Nagatani, Takeshi; Yoshikawa, Naohito; Motokawa, Ryuhei; Koizumi, Satoshi

2010-01-01

Cation-exchange membranes containing a sulfonic acid group were prepared by electron-beam-induced graft polymerization of sodium styrene sulfonate (SSS) onto a nylon-6 film with a thickness of 25 μm. The lamella sizes and lamella-to-lamella intervals of the resultant cation-exchange membranes (SSS membranes) were evaluated by X-ray diffraction (XRD) analysis and small-angle neutron scattering (SANS), respectively. With increasing degrees of grafting, the lamella size decreased, whereas the lamella-to-lamella interval increased. This can be explained by that the poly-SSS chain grafted to the periphery of the lamella of nylon 6 partially destroys the lamella and invades the amorphous domain among the lamella. The SSS membrane with a degree of grafting of 150% exhibited a similar performance in the electrodialysis of 0.5 M sodium chloride as a current cation-exchange membrane and possessed the lamella sizes and lamella-to-lamella intervals of 7.6 and 13 nm, respectively. (author)

Radiation induced emulsion graft polymerization of 4-vinylpyridine onto PE/PP nonwoven fabric for As(V) adsorption

Science.gov (United States)

Akkaş Kavaklı, Pınar; Kavaklı, Cengiz; Seko, Noriaki; Tamada, Masao; Güven, Olgun

2016-10-01

A novel nonwoven fabric adsorbent having 4-vinylpyridine functional groups was prepared by using radiation-induced emulsion graft polymerization method and grafting 4-vinylpyridine monomer onto a polyethylene-coated polypropylene nonwoven fabric (NWF) in aqueous emulsion solution. The grafting conditions of the 4-vinylpyridine monomer onto the NWF were optimised and 150% Dg VP-g-NWF was prepared using 30 kGy pre-irradiation dose, 5% VP monomer concentration and 0.5% (w/w) Tween 20 in aqueous emulsion. Grafted 4-vinylpyridine chains on the NWF were then quaternized for the preparation of QVP-g-NWF adsorbent. All fabric structures were characterized by using Fourier-transform infrared spectrometer, x-ray photoelectron spectrometer and scanning electron microscope. QVP-g-NWF adsorbent was used in batch adsorption experiments for As(V) ions by studying the pH, contact time, and initial As(V) ion concentration parameters. Results showed that QVP-g-NWF adsorbent has significant As(V) adsorption and experimental As(V) adsorption capacity was 98.04 mg As(V)/g polymer from 500 mg/L initial As(V) concentration at pH 7.00.

Kinetics of Free Radical Polymerization of N-Substituted Amides and Their Structural Implications

Directory of Open Access Journals (Sweden)

Anca Aldea

2016-01-01

Full Text Available Two N-substituted amides (N-acryloyl morpholine and N-methyl-N-vinylacetamide were polymerized in different solvents using radical initiator. The tacticity of obtained polymers was determined by 400 MHz 1H-NMR and 13C-NMR. At a given temperature, the syndiotacticity increased with increasing the solvent polarity. This solvent effect may be related to the hydrogen bonding interaction among solvent, monomer, and/or growing species. A peculiar aspect regards the steric hindrance at the nitrogen atom.

Synthesis of Well-Defined Three-Arm Star-Branched Polystyrene through Arm-First Coupling Approach by Atom Transfer Radical Polymerization

OpenAIRE

Shahabuddin, Syed; Hamime Ismail, Fatem; Mohamad, Sharifah; Muhamad Sarih, Norazilawati

2015-01-01

Here we describe a simple route to synthesize three-arm star-branched polystyrene. Atom transfer radical polymerization technique has been utilized to yield branched polystyrene involving Williamson coupling strategy. Initially a linear polymeric chain of predetermined molecular weight has been synthesized which is further end-functionalized into a primary alkyl bromide moiety, a prime requisition for Williamson reaction. The end-functionalized polymer is then coupled using 1,1,1-tris(4-hydro...

NMR, ESI/MS, and MALDI-TOF/MS analysis of pear juice polymeric proanthocyanidins with potent free radical scavenging activity.

Science.gov (United States)

Es-Safi, Nour-Eddine; Guyot, Sylvain; Ducrot, Paul-Henri

2006-09-20

The structure of a polymeric proanthocyanidin fraction isolated from pear juice was characterized by NMR, ESI/MS, and MALDI-TOF/MS analyses, and its antioxidant activity was investigated using the DPPH free radical scavenging method. The results obtained from 13C NMR analysis showed the predominance of signals representative of procyanidins. Typical signals in the chemical shift region between 70 and 90 ppm demonstrated the exclusive presence of epicatechin units. The results obtained through negative ESI/MS analysis showed singly and doubly charged ions corresponding to the molecular mass of procyanidins with a degree of polymerization up to 22. The spectra obtained through MALDI-TOF/MS analysis revealed the presence of two series of tannin oligomers. Supporting the observations from NMR spectroscopy, the first series consists of well-resolved tannin identified as procyanidin polymers units with chain lengths of up to 25. A second series of monogalloyl flavan-3-ols polymers with polymerization degree up to 25 were also detected. This is the first mass spectrometric evidence confirming the existence of galloylated procyanidin oligomers in pear fruits. Within each of these oligomers, various signals exist suggesting the presence of several oligomeric tannins. The antioxidant properties of the polymeric fraction were investigated through reduction of the DPPH free radical, and the results obtained showed that the polymeric fraction exhibited a higher antioxidant power compared to those of (+)-catechin and B3 procyanidin dimer.

Radiation graft copolymerization of styrene with m/e and styrene with acrylic acid at highthyl methacryl dose rate

International Nuclear Information System (INIS)

Aliev, R.Eh.; Kabanov, B.Ya.

1984-01-01

Comparative investigation of radiation graft copolymerization of styrene with methyl methacrylate (MMA) and styrene with acrylic acid (AA) is carried out at considerably differing radiation dose rates. The monomer mixture was grafted to PE low density films at dose rates of 0.16, 0.25 Gy/s (1 MeV electron acceleration). The value of graft was 3-6 and 5-10%, respectively, for the styrene-MMA and styrene-AA systems. An essential difference in the dependences of the formed copolymer composition on initial monomer mixture composition is noticed. Difference in composition of graft polymers prepared at different dose rates is less for the systems with AA, than for systems with MMA. It is shown that at high dose rates in difference with low ones not only radical graft copolymerization of the styrene mixture with AA takes place, but a contribution of the graft styrene polymerization according to cation mechanism as well

Methyleneation of peptides by N,N,N,N-tetramethylethylenediamine (TEMED) under conditions used for free radical polymerization: a mechanistic study.

Science.gov (United States)

Shirangi, Mehrnoosh; Sastre Toraño, Javier; Sellergren, Börje; Hennink, Wim E; Somsen, Govert W; van Nostrum, Cornelus F

2015-01-21

Free radical polymerization is often used to prepare protein and peptide-loaded hydrogels for the design of controlled release systems and molecular imprinting materials. Peroxodisulfates (ammonium peroxodisulfates (APS) or potassium peroxodisulfates (KPS)) with N,N,N,N-tetramethylethylenediamine (TEMED) are frequently used as initiator and catalyst. However, exposure to these free radical polymerization reagents may lead to modification of the protein and peptide. In this work, we show the modification of lysine residues by ammonium peroxodisulfate (APS)/TEMED of the immunostimulant thymopentin (TP5). Parallel studies on a decapeptide and a library of 15 dipeptides were performed to reveal the mechanism of modification. LC-MS of APS/TEMED-exposed TP5 revealed a major reaction product with an increased mass (+12 Da) with respect to TP5. LC-MS(2) and LC-MS(3) were performed to obtain structural information on the modified peptide and localize the actual modification site. Interpretation of the obtained data demonstrates the formation of a methylene bridge between the lysine and arginine residue in the presence of TEMED, while replacing TEMED with a sodium bisulfite catalyst did not show this modification. Studies with the other peptides showed that the TEMED radical can induce methyleneation on peptides when lysine is next to arginine, proline, cysteine, aspargine, glutamine, histidine, tyrosine, tryptophan, and aspartic acid residues. Stability of peptides and protein needs to be considered when using APS/TEMED in in situ polymerization systems. The use of an alternative catalyst such as sodium bisulfite may preserve the chemical integrity of peptides during in situ polymerization.

Polymerization by radiation. Application

International Nuclear Information System (INIS)

Romero, M.; Fernandez Miranda, J.

1997-01-01

Achieved results of the research work done in the field of radiation polymerization are summarized. Developing new chromatographic matrices, the radiation grafting of Glycidyl methacrylate on the surface of Low Density Polyethylene beads was studied. The dependence of both, the grafted degree and width of the grafted layer, with the radiation dose applied, is presented

Ion conducting solid polymer electrolytes based on polypentafluorostyrene-b-polyether-b-polypentafluorostyrene prepared by atom transfer radical polymerization

DEFF Research Database (Denmark)

Jankova, Katja; Jannasch, P.; Hvilsted, Søren

2004-01-01

Novel triblock copolymers based on central poly( ethylene glycol) ( PEG) or poly( ethylene glycol-co-propylene glycol) (PEGPG) blocks with poly( pentafluorostyrene) (PFS) outer blocks were prepared by Atom Transfer Radical Polymerization (ATRP) with polydispersities on the order of 1.2 - 1...

Improvement of the polymer stability by radiation grafting

International Nuclear Information System (INIS)

Ranogajec, F.; Mlinac-Misak, M.

2004-01-01

Losses of the stabilizer due to extractability or volatility immediately affect the ultimate performance of polymer products. A new approach to increase the persistence of the stabilizer in the final product is to chemically bind it to the polymer backbone. Radiation grafting or crosslinking could be an efficient method for this, when the stabilizer is polymerizable. By a mutual gamma irradiation method photoprotector 2-hydroxy-4-(3-methacryloxy-2-hydroxy-propoxy) benzophenone has been readily grafted to low-density polyethylene in benzene, tetrahydrofuran and methanol solution, respectively. Surface grafting occurs in a methanol solution of stabilizer, while in benzene and tetrahydrofuran solutions of the stabilizer, grafting proceeds more or less in the inner parts of the polymeric film as well. UV stability tests and changes in the mechanical properties of artificially and naturally aged films indicate pronounced protective effect achieved by the grafted stabilizer. Surface grafting is an efficient photostabilization method since the grafted stabilizer is chemically bound to a polymeric surface and in this way the problem of evaporation of blended stabilizers during the prolonged use of polymeric materials is eliminated

Analysis of polymer grafted inside the porous hydrogel using confocal laser scanning microscopy

Directory of Open Access Journals (Sweden)

2007-04-01

Full Text Available Graft polymerization of glycidyl methacrylate onto the pore surface of polyacrylamide macroporous gel was implemented in DMSO-aqueous solution using diperiodatocuprate(III complexes as an initiator. The grafting densities up to 410% were achieved. The graft polymerization was confirmed by gravimetrical methods and FTIR. The graft polymerization of polymer inside the pores of the macroporous gel resulted in increased flow resistance through the gel matrix. The distribution of grafted polymer on the gel pore surface material was studied by scanning electron microscopy (SEM and confocal laser scanning microscopy (CLSM. CLSM is an alternative method for studying morphology of gel surface with grafted polymer having the advantages over the SEM allowing to investigate the distribution of grafted polymer inside the hydrogel in a native hydrated state. The microscopic techniques demonstrated uneven distribution of the grafted polymer inside the gel pores as a result of initiating the graft polymerization by insoluble initiator deposited on the pore surface.

Storage Stability Improvement of Copolymer Grafted Polypropylene-AcrylicAcid (PP-AA), by means of Various After Treatment Processes

International Nuclear Information System (INIS)

Gitopadmojo, Isminingsih

2000-01-01

Polypropylene yams that have been subjected to irradiation induced graftco-polymerization with acrylic acid, have gained its moisture regain and dyeability, that fulfilled the requirement as textile material for garment.However, the copolymer grafted PP-AA has suffered from degradation in thestorage, which was indicated in the previous study that the strengthretention has dropped tremendously by photo-oxidation or photo-degradation.After treatments of PP-AA yams with chemical compound that was able toprevent further photo-oxidation, will be expected to improve the stability ofPP-AA in storage. In this research activity, the polypropylene (PP) yams weresubjected to irradiation induced graft co-polymerization by means ofγ-Ray Co-60 as irradiation source with acrylic acid (AA) as monomer.Various after treatments were subjected to the grafted PP-AA yams such asalkalisation process; dyeing (anionic dyes, cationic dyes and nonionic dyes);as well as processing with optical brightening agent and UV stabilizer,separately. The PP-AA yams (before and after treatment) were subjected tostorage from 1 month up to 42 months, and then being tested for theirmoisture regain, strength retention and elongation at breaks. The samplesbeing stored for 12 months were subjected to radical analysis. It isconcluded from the experiment that after treatment of grafted PP-AA by meansof those various processes were able to improve the stability of copolymergrafted PP-AA in storage. The presence of peroxide radical in the ESR(electron spin resonance) spectrum on PP-AA yams before treatment and theones after treated with alkaline and being stored for 12 months haveindicated the presence of photo oxidation or photo degradation, while thepresence of poly enyl radical in the ESR spectrum of after treated PP-AA withdyes having azo and azine compound as chromophore, as well as with UVstabilizer with carbonyl as chromophore and being stored for 12 months haveproved that its presence have protected such

Surface modification of nanodiamond through metal free atom transfer radical polymerization

Science.gov (United States)

Zeng, Guangjian; Liu, Meiying; Shi, Kexin; Heng, Chunning; Mao, Liucheng; Wan, Qing; Huang, Hongye; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

2016-12-01

Surface modification of nanodiamond (ND) with poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] has been achieved by using metal free surface initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiator was first immobilized on the surface of ND through direct esterification reaction between hydroxyl group of ND and 2-bromoisobutyryl bromide. The initiator could be employed to obtain ND-poly(MPC) nanocomposites through SI-ATRP using an organic catalyst. The final functional materials were characterized by 1H nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis in detailed. All of these characterization results demonstrated that ND-poly(MPC) have been successfully obtained via metal free photo-initiated SI-ATRP. The ND-poly(MPC) nanocomposites shown enhanced dispersibility in various solvents as well as excellent biocompatibility. As compared with traditional ATRP, the metal free ATRP is rather simple and effective. More importantly, this preparation method avoided the negative influence of metal catalysts. Therefore, the method described in this work should be a promising strategy for fabrication of polymeric nanocomposites with great potential for different applications especially in biomedical fields.

Twin screw extruders as polymerization reactors for a free radical homo polymerization

NARCIS (Netherlands)

Ganzeveld, K.J.; Janssen, L.P.B.M.

The bulk polymerization of n-butylmethacrylate was investigated in a counter-rotating twin screw extruder. It appeared that the gel effect, occurring with bulk polymerizations, affected the polymerization progress very strongly. Due to this effect the conversion of the reaction is independent of the

Tribological and mechanical investigation of acrylic-based nanocomposite coatings reinforced with PMMA-grafted-MWCNT

Energy Technology Data Exchange (ETDEWEB)

Al-Kawaz, A. [UPR22/CNRS, Institut Charles Sadron, Université de Strasbourg, 23 Rue du Loess, BP 84047, F-67034 Strasbourg Cedex 2 (France); Rubin, A., E-mail: anne.rubin@ics-cnrs.unistra.fr [UPR22/CNRS, Institut Charles Sadron, Université de Strasbourg, 23 Rue du Loess, BP 84047, F-67034 Strasbourg Cedex 2 (France); Badi, N.; Blanck, C.; Jacomine, L. [UPR22/CNRS, Institut Charles Sadron, Université de Strasbourg, 23 Rue du Loess, BP 84047, F-67034 Strasbourg Cedex 2 (France); Janowska, I.; Pham-Huu, C. [Institute of Chemistry and Processes for Energy, Environment and Health (UMR 7515) CNRS - University of Strasbourg, 25 Rue Becquerel Strasbourg, 67087 Cedex 08 (France); Gauthier, C. [UPR22/CNRS, Institut Charles Sadron, Université de Strasbourg, 23 Rue du Loess, BP 84047, F-67034 Strasbourg Cedex 2 (France)

2016-06-01

The chemical functionalization of carbon nanotubes (CNTs) could improve their chemical compatibility. Poly(methyl methacrylate) (PMMA)-functionalized multi-walled carbon nanotubes (MWCNTs) are prepared by in situ atom transfer radical polymerization (ATRP) using a “grafting from” approach. It allows the control of the thickness of the polymer layer grafted on MWCNTs from two parameters: the feed ratio of MMA to MWCNT, the volume fraction of solvent to MMA. This work compared the effect of several PMMA-grafted-MWNCT fillers embedded into a PMMA matrix, PMMA-grafted-MWCNT/PMMA, and obtained by solution mixing technique. We studied the tribological performances of 20 μm coatings of these nanocomposites deposited on neat PMMA. The percentage of embedded fillers is kept low to maintain the transparency of the PMMA. The coefficient of friction was found to relatively decrease with the increase of the weight fraction of polymer grafted to the surface of MWCNT. Moreover the elastic modulus also increased with increasing the weight fraction of PMMA coated MWCNT. - Highlights: • Synthesis of MWCNT-PMMA nanoparticles by ATRP “grafting from” approach. • PMMA-grafted-MWCNT/PMMA coatings with good mechanical properties. • High tribological performance of PMMA-grafted-MWCNT/PMMA coatings.

Radiation induced emulsion graft polymerization of 4-vinylpyridine onto PE/PP nonwoven fabric for As(V) adsorption

International Nuclear Information System (INIS)

Akkaş Kavaklı, Pınar; Kavaklı, Cengiz; Seko, Noriaki; Tamada, Masao; Güven, Olgun

2016-01-01

A novel nonwoven fabric adsorbent having 4-vinylpyridine functional groups was prepared by using radiation-induced emulsion graft polymerization method and grafting 4-vinylpyridine monomer onto a polyethylene-coated polypropylene nonwoven fabric (NWF) in aqueous emulsion solution. The grafting conditions of the 4-vinylpyridine monomer onto the NWF were optimised and 150% D g VP-g-NWF was prepared using 30 kGy pre-irradiation dose, 5% VP monomer concentration and 0.5% (w/w) Tween 20 in aqueous emulsion. Grafted 4-vinylpyridine chains on the NWF were then quaternized for the preparation of QVP-g-NWF adsorbent. All fabric structures were characterized by using Fourier-transform infrared spectrometer, x-ray photoelectron spectrometer and scanning electron microscope. QVP-g-NWF adsorbent was used in batch adsorption experiments for As(V) ions by studying the pH, contact time, and initial As(V) ion concentration parameters. Results showed that QVP-g-NWF adsorbent has significant As(V) adsorption and experimental As(V) adsorption capacity was 98.04 mg As(V)/g polymer from 500 mg/L initial As(V) concentration at pH 7.00. - Highlights: • Radiation induced grafting of 4-vinylpyridine onto PE/PP nonwoven fabric in emulsion. • 4-vinylpyridine grafting was characterized by FTIR, SEM and XPS. • As(V) adsorption was studied by QVP-g- NWF. • As(V) adsorption capacity was found to be 98.04 mg As(V)/g polymer.

Iron halide mediated atom transfer radical polymerization of methyl methacrylate with N-Alkyl-2-pyridylmethanimine as the ligand

NARCIS (Netherlands)

Zhang, H.; Schubert, U.S.

2004-01-01

The controlled atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) catalyzed by iron halide/N-(n-hexyl)-2-pyridylmethanimine (NHPMI) is described. The ethyl 2-bromoisobutyrate (EBIB)-initiated ATRP with [MMA]0/[EBIB]0/[iron halide]0/[NHPMI]0 = 150/1/1/2 was better controlled in

Synthesis of polystyrene with high melting temperature through BDE/CuCl catalyzed polymerization

Institute of Scientific and Technical Information of China (English)

WAN; Xiaolong

2001-01-01

［1］Ewen, J. A., Novel method for plastic production, Science (in Chinese), 1997, 9: 34.［2］Brintzinger, H. H., Fischer, D., Waymouth, R. M. et al., Stereospecific olefin polymerization with chiral metallocene catalysts, Angewandte Chemie International Edition in English, 1995, 34(11): 1143.［3］Matyjaszewski, K., Atom transfer radical polymerization, role of various components and reaction conditions, Polym. Prep., 1997, 38(2): 736.［4］Wang, J. S., Matyjaszewski, K., Controlled/"living" radical polymerization, atom transfer radical polymerization in the presence of transition-metal complex, J. Am. Soc., 1995, 117: 5614.［5］Wang, J. S., Matyjaszewski, K., Controlled/"living" radical polymerization, halogen atom transfer radical polymerization promoted by a Cu(I)/Cu(II) redox process, Macromolecules, 1995, 28: 7901.［6］Koto, M., Kamigaito, M., Sawamoto, M. et al., Polymerization of methyl methacrylate with the carbon tetrachloride/dichloro-tris(triphenyphosphine) ruthenium(II)/methylaluminum bis(2,6-di-tert-butylphenoxide) initiating system: possible of living radical polymerization, Macromolecules, 1995, 28: 1721.［7］Ando, T., Kato, M., Living radical polymerization of methyl methacrylate with Ruthenium complex: formation of polymers with controlled molecular weights and very narrow distributions, Macromolecules, 1996, 29: 1070.［8］Granel, C., Dubios, P., Jerome, R. et al., Controlled radical polymerization of methacrylic monomers in the presence of a bis(ortho-chelated) arylnickel(II) complex and different activated alkyl halides, Macromolecules, 1996, 29: 8576.［9］Granel, C., Moineau, G., Lecome, P. et al., (Meth)acrylates pseudo-living radical polymerization in the presence of transition metal complexes: the kharasch reaction revisited, Polym. Prep., 1997, 38(1): 450.［10］Ando, T., Kamigaito, M., Sawamoto, M., Iron(II) chloride complex for living radical polymerization of methyl methacrylate, Macromolecules, 1997, 30: 4507.［11�

Synthesis of Well-Defined Three-Arm Star-Branched Polystyrene through Arm-First Coupling Approach by Atom Transfer Radical Polymerization

Directory of Open Access Journals (Sweden)

Syed Shahabuddin

2015-01-01

Full Text Available Here we describe a simple route to synthesize three-arm star-branched polystyrene. Atom transfer radical polymerization technique has been utilized to yield branched polystyrene involving Williamson coupling strategy. Initially a linear polymeric chain of predetermined molecular weight has been synthesized which is further end-functionalized into a primary alkyl bromide moiety, a prime requisition for Williamson reaction. The end-functionalized polymer is then coupled using 1,1,1-tris(4-hydroxyphenylethane, a trifunctional core molecule, to give well-defined triple-arm star-branched polystyrene.

Conditional Monte Carlo sampling to find branching architectures of polymers from radical polymerizations with transfer to polymer and recombination termination

NARCIS (Netherlands)

Iedema, P.D.; Wulkow, M.; Hoefsloot, H.C.J.

2007-01-01

A model is developed that predicts branching architectures of polymers from radical polymerization with transfer to polymer and termination by disproportionation and recombination, in a continuously stirred tank reactor (CSTR). It is a so-called conditional Monte Carlo (MC) method generating

Thermo-responsive wound dressings by grafting chitosan and poly(N-isopropylacrylamide) to plasma-induced graft polymerization modified non-woven fabrics

International Nuclear Information System (INIS)

Chen, Jyh-Ping; Kuo, Chang-Yi; Lee, Wen-Li

2012-01-01

Highlights: ► Poly(N-isopropylacrylamide) and chitosan were grafted to polypropylene non-wovens. ► An easily stripped off thermo-responsive wound dressing was developed. ► The wound dressing is biocompatible, has antibacterial and wound healing abilities. ► The bigraft non-woven will be a potential wound dressing for biomedical use. - Abstract: To obtain a chitosan wound dressings with temperature-responsive characteristics, polypropylene (PP) non-woven fabric (NWF) was modified by direct current pulsed oxygen plasma-induced grafting polymerization of acrylic acid (AAc) to improve hydrophilicity and to introduce carboxylic acid groups. Conjugation of chitosan and poly(N-isopropylacrylamide) (PNIPAAm) followed by using water-soluble carbodiimide as a coupling agent to form a novel bigraft PP-g-chitosan-g-PNIPAAm wound dressing. The amount of chitosan and PNIPAAm grafted to PP-g-chitosan-g-PNIPAAm were 83.0 ± 4.6 μg/cm 2 and 189.5 ± 8.2 μg/cm 2 , respectively. The surface chemical composition and microstructure of the NWF were studied by electron spectroscopy for chemical analysis (ESCA) and scanning electron microscopy (SEM). The linkages between AAc, chitosan, and PNIPAAm were confirmed with the formation of amide bonds. Physical properties of the NWF were characterized and potentials of these NWFs as wound dressings were evaluated using SD rat as the animal model. NWFs contained PNIPAAm were better than those contained only chitosan in wound healing rates and the wound areas covered by PP-g-chitosan-g-PNIPAAm wound dressings healed completely in 17 days.

Improvement of polymer stability by radiation grafting

International Nuclear Information System (INIS)

Ranogajec, F.; Mlinac-Misak, M.

1999-01-01

Losses of the stabilizer due to extractability or volatility immediately affect ultimate performance of polymer product. A new approach to increase the persistence of the stabilizer in the final product is to chemically bind it to the polymer backbone. Radiation grafting or crosslinking could be an efficient method for this, when the stabilizer is polymerizable. By a mutual gamma irradiation method, photoprotector 2-hydroxy-4-(3-methacryloxy-2- hydroxy-propoxy) benzophenone (HMB) has been readily grafted to low density polyethylene (LDPE) in benzene, tetrahydrofuran and methanol solution, respectively. Surface grafting occurs in a methanol solution of stabilizer, while in benzene and tetrahydrofuran solutions of stabilizer, grafting proceeds more or less in the inner parts of the polymeric film as well. The grafted LDPE film in methanol and tetrahydrofuran (containing 1 w/w % of grafted HMB), 1 w/w % blended HMB with LDPE and nongrafted LDPE film, were all exposed to accelerated aging and natural weathering and their spectral changes, expressed by the carbonyl index, were then compared. The change of elongation at break and tensile strength were measured in the course of aging. UV stability tests on aged films and change in mechanical properties indicate a pronounced protective effect achieved by grafted stabilizer. Grafting in methanol solution appears to be an efficient photostabilization treatment and the most economical with respect to the consumption of monomer, the grafting yield being less than 0.5%. Surface grafting is an efficient photostabilization method since grafted stabilizer is chemically bound to a polymeric surface and in this way the problem of evaporation of blended stabilizers during the prolonged use of polymeric materials is eliminated. (author)

Near-Infrared Free-Radical and Free-Radical-Promoted Cationic Photopolymerizations by In-Source Lighting Using Upconverting Glass.

Science.gov (United States)

Kocaarslan, Azra; Tabanli, Sevcan; Eryurek, Gonul; Yagci, Yusuf

2017-11-13

A method is presented for the initiation of free-radical and free-radical-promoted cationic photopolymerizations by in-source lighting in the near-infrared (NIR) region using upconverting glass (UCG). This approach utilizes laser irradiation of UCG at 975 nm in the presence of fluorescein (FL) and pentamethyldiethylene triamine (PMDETA). FL excited by light emitted from the UCG undergoes electron-transfer reactions with PMDETA to form free radicals capable of initiating polymerization of methyl methacrylate. To execute the corresponding free-radical-promoted cationic polymerization of cyclohexene oxide, isobutyl vinyl ether, and N-vinyl carbazole, it was necessary to use FL, dimethyl aniline (DMA), and diphenyliodonium hexafluorophosphate as sensitizer, coinitiator, and oxidant, respectively. Iodonium ions promptly oxidize DMA radicals formed to the corresponding cations. Thus, cationic polymerization with efficiency comparable to the conventional irradiation source was achieved. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radiation induced, raft mediated grafting of styrene onto poly(ethylene-alt-tetrafluoroethylene) (ETFE)

International Nuclear Information System (INIS)

Celik, G.; Barsbay, M.; Gueven, O.

2011-01-01

Complete text of publication follows. The development of cost-effective proton exchange membranes to replace the state-of-the-art and expensive perfluorinated membranes such as Nafion, Flemion, and Aciplex is one of the main challenges for commercialization of polymer electrolyte fuel cell technology. Recently, partially fluorinated poly(ethlyene-alt-tetrafluoroethylene) (ETFE) has been identified as a promising alternative base polymer film to prepare low-cost polymer electrolyte membranes because of its advantageous characters like superior mechanical properties and high resistance to radiation-induced damage. The radiation-induced grafting technique, based on the utilization of a polymer material such as ETFE in combination with further chemical modification steps (sulfonation) allows the functionalization of the base material and the introduction of the desired property (proton conductivity) for preparing a fuel cell membrane. However this simple conventional method suffers from one simple flaw: The molecular weight and the polydispersity of the grafted chains cannot be controlled. Predetermined molecular weights and low dispersities as well as homogeneous composition and desired architecture can be achieved by grafting of monomer onto base polymer under living/controlled free radical polymerization (CRP) conditions. Among the CRP methods, Reversible Addition Fragmentation-Chain Transfer (RAFT) is of particular interest as a very wide range of functional monomers can be polymerized in a controlled manner under non-demanding reaction conditions (e.g., tolerance to oxygen and low temperatures). The present study deals with the RAFT mediated radiation-induced (0.032 kGyh -1 , 60 Co) grafting of styrene on ETFE films followed by the sulfonation of the polystyrene grafts. The effect of monomer concentration, absorbed dose and RAFT agent concentration on the grafting were investigated. The synthesized films were characterized by ATR-FTIR, XPS, DSC and TGA methods

Inorganic-organic hybrid coatings on stainless steel by layer-by-layer deposition and surface-initiated atom-transfer-radical polymerization for combating biocorrosion.

Science.gov (United States)

Yuan, S J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T

2009-03-01

To improve the biocorrosion resistance of stainless steel (SS) and to confer the bactericidal function on its surface for inhibiting bacterial adhesion and biofilm formation, well-defined inorganic-organic hybrid coatings, consisting of the inner compact titanium oxide multilayers and outer dense poly(vinyl-N-hexylpyridinium) brushes, were successfully developed. Nanostructured titanium oxide multilayer coatings were first built up on the SS substrates via the layer-by-layer sol-gel deposition process. The trichlorosilane coupling agent, containing the alkyl halide atom-transfer-radical polymerization (ATRP) initiator, was subsequently immobilized on the titanium oxide coatings for surface-initiated ATRP of 4-vinylpyridine (4VP). The pyridium nitrogen moieties of the covalently immobilized 4VP polymer, or P(4VP), brushes were quaternized with hexyl bromide to produce a high concentration of quaternary ammonium salt on the SS surfaces. The excellent antibacterial efficiency of the grafted polycations, poly(vinyl-N-pyridinium bromide), was revealed by viable cell counts and atomic force microscopy images of the surface. The effectiveness of the hybrid coatings in corrosion protection was verified by the Tafel plot and electrochemical impedance spectroscopy measurements.

UV-Induced [2+2] Grafting-To Reactions for Polymer Modification of Cellulose.

Science.gov (United States)

Conradi, Matthias; Ramakers, Gijs; Junkers, Thomas

2016-01-01

Benzaldehyde-functional cellulose paper sheets have been synthesized via tosylation of cellulose (Whatman No 5) followed by addition of p-hydroxy benzaldehyde. Via UV-induced Paterno-Büchi [2+2] cycloaddition reactions, these aldehyde functional surfaces are grafted with triallylcyanurate, trimethylolpropane allyl ether, and vinyl chloroacetate. In the following, allyl-functional polymers (poly(butyl acrylate), pBA, Mn = 6990 g mol(-1) , Đ = 1.12 and poly(N-isopropyl acrylamide), pNIPAAm, Mn = 9500 g mol(-1) , Đ = 1.16) synthesized via reversible addition fragmentation chain transfer polymerization are conjugated to the celloluse surface in a UV-induced grafting-to approach. With pBA, hydrophobic cellulose sheets are obtained (water contact angle 116°), while grafting of pNIPAAm allows for generation of "smart" surfaces, which are hydrophilic at room temperature, but that become hydrophobic when heated above the characteristic lower critical solution temperature (93° contact angle). The Paterno-Büchi reaction has been shown to be a versatile synthetic tool that also performs well in grafting-to approaches whereby its overall performance seems to be close to that of radical thiol-ene reactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface PEGylation of mesoporous silica materials via surface-initiated chain transfer free radical polymerization: Characterization and controlled drug release.

Science.gov (United States)

Huang, Long; Liu, Meiying; Mao, Liucheng; Huang, Qiang; Huang, Hongye; Wan, Qing; Tian, Jianwen; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

2017-12-01

As a new type of mesoporous silica materials with large pore diameter (pore size between 2 and 50nm) and high specific surface areas, SBA-15 has been widely explored for different applications especially in the biomedical fields. The surface modification of SBA-15 with functional polymers has demonstrated to be an effective way for improving its properties and performance. In this work, we reported the preparation of PEGylated SBA-15 polymer composites through surface-initiated chain transfer free radical polymerization for the first time. The thiol group was first introduced on SBA-15 via co-condensation with γ-mercaptopropyltrimethoxysilane (MPTS), that were utilized to initiate the chain transfer free radical polymerization using poly(ethylene glycol) methyl ether methacrylate (PEGMA) and itaconic acid (IA) as the monomers. The successful modification of SBA-15 with poly(PEGMA-co-IA) copolymers was evidenced by a series of characterization techniques, including 1 H NMR, FT-IR, TGA and XPS. The final SBA-15-SH- poly(PEGMA-co-IA) composites display well water dispersity and high loading capability towards cisplatin (CDDP) owing to the introduction of hydrophilic PEGMA and carboxyl groups. Furthermore, the CDDP could be released from SBA-15-SH-poly(PEGMA-co-IA)-CDDP complexes in a pH dependent behavior, suggesting the potential controlled drug delivery of SBA-15-SH-poly(PEGMA-co-IA). More importantly, the strategy should be also useful for fabrication of many other functional materials for biomedical applications owing to the advantages of SBA-15 and well monomer adoptability of chain transfer free radical polymerization. Copyright © 2017 Elsevier B.V. All rights reserved.

Silica-Polystyrene Nanocomposite Particles Synthesized by Nitroxide-Mediated Polymerization and Their Encapsulation through Miniemulsion Polymerization

Directory of Open Access Journals (Sweden)

Bérangère Bailly

2006-01-01

Full Text Available Polystyrene (PS chains with molecular weights comprised between 8000 and 64000 g⋅mol-1 and narrow polydispersities were grown from the surface of silica nanoparticles (Aerosil A200 fumed silica and Stöber silica, resp. through nitroxide-mediated polymerization (NMP. Alkoxyamine initiators based on N-tert-butyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide (DEPN and carrying a terminal functional group have been synthesized in situ and grafted to the silica surface. The resulting grafted alkoxyamines have been employed to initiate the growth of polystyrene chains from the inorganic surface. The maximum grafting density of the surface-tethered PS chains was estimated and seemed to be limited by initiator confinement at the interface. Then, the PS-grafted Stöber silica nanoparticles were entrapped inside latex particles via miniemulsion polymerization. Transmission electron microscopy indicated the successful formation of silica-polystyrene core-shell particles.

Study on the role of active radicals on plasma sterilization inside small diameter flexible polymeric tubes

Science.gov (United States)

Mstsuura, Hiroto; Fujiyama, Takatomo; Okuno, Yasuki; Furuta, Masakazu; Okuda, Shuichi; Takemura, Yuichiro

2015-09-01

Recently, atmospheric pressure discharge plasma has gathered attention in various fields. Among them, plasma sterilization with many types of plasma source has studied for decades and its mechanism is still an open question. If active radicals produced in plasma has main contribution of killing bacterias, direct contact of the so-called plasma flame might not be necessary. To confirm this, sterilization inside small diameter flexible polymeric tubes is studied in present work. DBD type plasma jet is produce by flowing helium gas in a glass tube. A long polymeric tube is connected and plasma jet is introduced into it. Plasma flame length depends on helium gas flow rate, but limited to about 10 cm in our experimental condition. E.colis set at the exit plasma source is easily killed during 10 min irradiation. At the tube end (about 20 cm away from plasma source exit), sterilization is possible with 30 min operation. This result shows that active radical is produced with helium plasma and mist contained in sample, and it can be transferred more than 20 cm during it life time. More plasma diagnostic data will also be shown at the conference. This work was partially supported by the ''ZE Research Program, IAE(ZE27B-4).

Precision design of ethylene- and polar-monomer-based copolymers by organometallic-mediated radical polymerization

Science.gov (United States)

Kermagoret, Anthony; Debuigne, Antoine; Jérôme, Christine; Detrembleur, Christophe

2014-03-01

The copolymerization of ethylene with polar monomers is a major challenge when it comes to the manufacture of materials with potential for a wide range of commercial applications. In the chemical industry, free-radical polymerization is used to make a large proportion of such copolymers, but the forcing conditions result in a lack of fine control over the architecture of the products. Herein we introduce a synthetic tool, effective under mild experimental conditions, for the precision design of unprecedented ethylene- and polar-monomer-based copolymers. We demonstrate how an organocobalt species can control the growth of the copolymer chains, their composition and the monomer distribution throughout the chain. By fine tuning the ethylene pressure during polymerization and by exploiting a unique reactive mode of the end of the organometallic chain, novel block-like copolymer structures can be prepared. This highly versatile synthetic platform provides access to a diverse range of polymer materials.

Poly(n-isopropylacrylamide)-based hydrogel coatings on magnetite nanoparticles via atom transfer radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Frimpong, Reynolds A; Hilt, J Zach [Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506 (United States)], E-mail: hilt@engr.uky.edu

2008-04-30

Core magnetite (Fe{sub 3}O{sub 4}) nanoparticles have been functionalized with a model intelligent hydrogel system based on the temperature responsive polymer poly(n-isopropyl acrylamide) (PNIPAAm) to obtain magnetically responsive core-shell nanocomposites. Fe{sub 3}O{sub 4} nanoparticles were obtained from a one-pot co-precipitation method which provided either oleic acid (hydrophobic) or citric acid (hydrophilic) coated nanoparticles. Subsequent ligand exchange of these coatings with various bromine alkyl halides and a bromo silane provided initiating sites for functionalization with NIPAAm using atom transfer radical polymerization (ATRP). The bromine alkyl halides that were used were 2-bromo-2-methyl propionic acid (BMPA) and 2-bromopropionyl bromide (BPB). The bromo silane that was used was 3-bromopropyl trimethoxysilane (BPTS). The intelligent polymeric shell consists of NIPAAm crosslinked with poly(ethylene glycol) 400 dimethacrylate (PEG400DMA). Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) were used to confirm the presence of the polymeric shell. Dynamic light scattering (DLS) was used to characterize the nanocomposites for particle size changes with temperature. Their magnetic and temperature responsiveness show great promise for further biomedical applications. This platform for functionalizing magnetic nanoparticles with intelligent hydrogels promises to impact a wide range of medical and biological applications of magnetic nanoparticles.

Poly(n-isopropylacrylamide)-based hydrogel coatings on magnetite nanoparticles via atom transfer radical polymerization

International Nuclear Information System (INIS)

Frimpong, Reynolds A; Hilt, J Zach

2008-01-01

Core magnetite (Fe 3 O 4 ) nanoparticles have been functionalized with a model intelligent hydrogel system based on the temperature responsive polymer poly(n-isopropyl acrylamide) (PNIPAAm) to obtain magnetically responsive core-shell nanocomposites. Fe 3 O 4 nanoparticles were obtained from a one-pot co-precipitation method which provided either oleic acid (hydrophobic) or citric acid (hydrophilic) coated nanoparticles. Subsequent ligand exchange of these coatings with various bromine alkyl halides and a bromo silane provided initiating sites for functionalization with NIPAAm using atom transfer radical polymerization (ATRP). The bromine alkyl halides that were used were 2-bromo-2-methyl propionic acid (BMPA) and 2-bromopropionyl bromide (BPB). The bromo silane that was used was 3-bromopropyl trimethoxysilane (BPTS). The intelligent polymeric shell consists of NIPAAm crosslinked with poly(ethylene glycol) 400 dimethacrylate (PEG400DMA). Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM) were used to confirm the presence of the polymeric shell. Dynamic light scattering (DLS) was used to characterize the nanocomposites for particle size changes with temperature. Their magnetic and temperature responsiveness show great promise for further biomedical applications. This platform for functionalizing magnetic nanoparticles with intelligent hydrogels promises to impact a wide range of medical and biological applications of magnetic nanoparticles

Synthesis of HNTs@PEDOT composites via in situ chemical oxidative polymerization and their application in electrode materials

Science.gov (United States)

Wang, Fang; Zhang, Xianhong; Ma, Yuhong; Yang, Wantai

2018-01-01

The hybrid composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and halloysite nanotubes (HNTs) was synthesized by a two-step process. First, poly(sodium styrene sulfonate) (PSSNa) was grafted onto HNTs via surface initiated atom transfer radical polymerization. Then with the HNTs-g-PSS as a template and the grafted PSS chains as the counterion dopant, PEDOT was precipitated onto the template via in situ oxidization polymerization of EDOT to form HNTs@PEDOT hybrid composites. The conductivity of HNTs@PEDOT can reach up to 9.35 S/cm with the content of 40% HNTs-g-PSS, which increased almost 78 times than that of pure PEDOT (about 0.12 S/cm) prepared at the similar condition. Further treated with p-toluenesulfonic acid (TsOH) as external dopant, the conductivity of HNTs@PEDOT increased to 24.3 S/cm. The electrochemical properties of the composites were investigated with cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy with three-electrode cell configuration. The results showed that the capacitance of HNTs@PEDOT composite increased 55% than that of pure PEDOT.

Tunable, Quantitative Fenton-RAFT Polymerization via Metered Reagent Addition.

Science.gov (United States)

Nothling, Mitchell D; McKenzie, Thomas G; Reyhani, Amin; Qiao, Greg G

2018-05-10

A continuous supply of radical species is a key requirement for activating chain growth and accessing quantitative monomer conversions in reversible addition-fragmentation chain transfer (RAFT) polymerization. In Fenton-RAFT, activation is provided by hydroxyl radicals, whose indiscriminate reactivity and short-lived nature poses a challenge to accessing extended polymerization times and quantitative monomer conversions. Here, an alternative Fenton-RAFT procedure is presented, whereby radical generation can be finely controlled via metered dosing of a component of the Fenton redox reaction (H 2 O 2 ) using an external pumping system. By limiting the instantaneous flux of radicals and ensuring sustained radical generation over tunable time periods, metered reagent addition reduces unwanted radical "wasting" reactions and provides access to consistent quantitative monomer conversions with high chain-end fidelity. Fine tuning of radical concentration during polymerization is achieved simply via adjustment of reagent dose rate, offering significant potential for automation. This modular strategy holds promise for extending traditional RAFT initiation toward more tightly regulated radical concentration profiles and affords excellent prospects for the automation of Fenton-RAFT polymerization. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radiation induced emulsion polymerization

International Nuclear Information System (INIS)

Stannett, V.T.; Stahel, E.P.

1990-01-01

High energy radiation is particularly favored for the initiation of emulsion polymerization. The yield of free radicals, for example, from the radiolysis of the aqueous phase, is high; G(radical) values of 5-7. In addition, the rather special kinetics associated with emulsion polymerization lead, in general, to very large kinetic chain lengths, even with 'non-ideal' monomers such as vinyl acetate. Together, high polymerization rates at low doses become possible. There are some important advantages of radiation polymerization compared with chemical initiators, such as potassium persulfate. Perhaps the most important among them is the temperature independence of the initiation step. This makes low temperature polymerization very accessible. With monomers such as vinyl acetate, where chain termination to monomer is predominant, low temperatures lead to often highly desirable higher molecular weights. With styrene, the classical ideally behaved monomer, there are the advantages such as, for example, the feasibility of using cationic monomers. These and some attendant disadvantages are discussed in detail, including pilot plant studies

Functionalization of graphene and grafting of temperature-responsive surfaces from graphene by ATRP 'on water'

Energy Technology Data Exchange (ETDEWEB)

Ren Lulu; Huang Shu; Zhang Chao; Wang Ruiyu [Fudan University, State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science (China); Tjiu, Weng Weei [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR) (Singapore); Liu Tianxi, E-mail: txliu@fudan.edu.cn [Fudan University, State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science (China)

2012-06-15

Water-dispersible graphene with temperature-responsive surfaces has successfully been synthesized by grafting poly(N-isopropylacrylamide) (PNIPAM) from graphene via surface-initiated atom transfer radical polymerization (ATRP). First, graphene surfaces are functionalized with aminophenol groups by diazonium reaction on water. Subsequently, bromoisobutyrate groups are covalently attached to the phenol-functionalized graphene (G-OH) surface by esterification of 2-bromoisobutyrate with the hydroxyl groups, forming bromoisobutyrate-functionalized graphene (G-Br). Finally, PNIPAM is then grafted from G-Br via ATRP. Data from Raman spectroscopy, {sup 1}H NMR, and transmission electron microscopy (TEM) confirm that PNIPAM chains grow from graphene by ATRP. Thermogravimetric analysis shows that the amount of PNIPAM grown from the graphene increases with the increase of monomer ratios. TEM images also show that functionalized polymer structures (PNIPAM cluster or agglutination) on graphene sheets can be well tuned by controlled polymerization. The obtained graphene-PNIPAM (G-PNIPAM) composite has PNIPAM surface which is highly sensitive to the temperature change. This temperature-responsive and water-dispersible G-PNIPAM composite may find potential applications in environmental devices as well as controlled release drug delivery.

Development of a water purifier for radioactive cesium removal from contaminated natural water by radiation-induced graft polymerization

Science.gov (United States)

Seko, Noriaki; Hoshina, Hiroyuki; Kasai, Noboru; Shibata, Takuya; Saiki, Seiichi; Ueki, Yuji

2018-02-01

Six years after the Fukushima-nuclear accident, the dissolved radioactive cesium (Cs) is now hardly detected in environmental natural waters. These natural waters are directly used as source of drinking and domestic waters in disaster-stricken areas in Fukushima. However, the possibility that some radioactive Cs adsorbed on soil or leaves will contaminate these natural waters during heavy rains or typhoon is always present. In order for the returning residents to live with peace of mind, it is important to demonstrate the safety of the domestic waters that they will use for their daily life. For this purpose, we have synthesized a material for selective removal of radioactive Cs by introducing ammonium 12-molybdophosphate (AMP) onto polyethylene nonwoven fabric through radiation-induced emulsion graft polymerization technique. Water purifiers filled with the grafted Cs adsorbent were installed in selected houses in Fukushima. The capability of the grafted adsorbent to remove Cs from domestic waters was evaluated for a whole year. The results showed that the tap water filtered through the developed water purifier contained no radioactive Cs, signifying the very effective adsorption performance of the developed grafted adsorbent. From several demonstrations, we have commercialized the water purifier named "KranCsair®". Furthermore, we have also developed a method for the mass production of the grafted nonwoven fabric. Using a 30 L grafting reactor, it was possible to produce the grafted nonwoven fabric with a suitable range of degree of grafting. When an irradiated roll of nonwoven trunk fabric with a length of 10 m and a width of 30 cm was set in the reactor filled with glycidyl methacrylate (GMA), AMP, Tween 80 monomer emulsion solution at 40 °C for 1 h, the difference of Dgs in the length and the width on roll of fabrics was negligible.

SYNTHESIS AND CHARACTERISTICS OF GRAFT COPOLYMERS OF POLY (BUTYL ACRYLATE AND CELLULOSE WITH ULTRASONIC PROCESSING AS A MATERIAL FOR OIL ABSORPTION

Directory of Open Access Journals (Sweden)

Ping Qu

2011-11-01

Full Text Available A series of materials used for oil absorption based on cellulose fiber grafted with butyl acrylate (BuAc have been prepared by radical polymerization under ultrasonic waves processing. Effects of ultrasonic dose for the maximum graft yield were considered. The dependency of optimum conditions for oil absorption rate on parameters such as ultrasonic processing time and ultrasonic power were also determined. Fourier infrared (FT-IR analysis was used to confirm the chemical reaction taking place between cellulose and butyl acrylate. The thermogravimetric behavior of the graft copolymer was characterized by thermogravimetric analysis (TGA. Scanning electron microscope (SEM analysis was used to determine the surface structure of the grafted material. With the increase of the ultrasonic treatment dose, the surface of the ultrasonic processed material became more regular, and the material was transformed into a homogeneous network polymer having a good structure and good adsorbing ability.

Polymerization of N-(fluoro phenyl) maleimides

International Nuclear Information System (INIS)

Barrales-Rienda, J.M.; Ramos, J.G.; Chaves, M.S.

1979-01-01

Poly(N-aryl maleimide)s of characteristic structures have been synthesized and some of their physical properties studied. The polymerization of N-(fluoro phenyl) maleimides by free-radical initiation in bulk or in solution and by anionic catalyst have been studied to compare the characteristics of polymerization by γ-ray irradiation with that by free-radical initiation. The polymers were characterized by elemental analysis, intrinsic viscosity, spectroscopy (IR and NMR), programmed thermogravimetric analysis, and x-ray diffraction. Spectra of polymers prepared by radiation and anionic polymerization were nearly identical with those of polymers prepared by free-radical polymerization initiated by azobisisobutyronitrile in bulk or in solution and by the self-initiated thermal polymerization. A variety of reaction conditions were tried, but all attempts to change the molecular structure of the polymers were unsuccessful. Rates of thermal degradation for poly[N-(fluoro phenyl) maleimide]s have been analyzed by using a multiple-heating-rate procedure. Overall activation energy, order of reaction, and frequency factor have been evaluated. 6 figures, 8 tables

Poly(vinyl acetate-Based Block Copolymer/Clay Nanocomposites Prepared by In Situ Atom Transfer Radical Polymerization

Directory of Open Access Journals (Sweden)

M.A. Semsarzadeh

2009-12-01

Full Text Available Atom transfer radical polymerization of styrene (St and methyl methacrylate (MMA was performed at 90oC in the absence and presence of nanoclay (Cloisite 30B. Trichloromethyl-terminated poly(vinyl acetate telomerand CuCl/ PMDETA were used as a macroinitiator and catalyst system, respectively. The experimental results showed that the atom transfer radical polymerization of St and MMA in the absence or presence of nanoclay proceeds via a controlled/living mode. It was observed that nanoclay significantly enhances the homopolymerization rate of MMA, which was attributed to the activated conjugated C=C bond of MMA monomer via interaction between the carbonyl group of MMA monomer and the hydroxyl moiety (Al-O-H of nanoclay as well as the effect of nanoclay on the dynamic equilibrium between the active (macro radicals and dormant species.Homopolymerization rate of St (a non-coordinative monomer with nanoclay decreased slightly in the presence of nanoclay. This could be explained by insertion of a portion of macroinitiator into the clay galleries, where no sufficient St monomer exists due to the low compatibility or interaction of St monomer with nanoclay to react with the macroinitiator. The results obtained from XRD, TEM and TGA analyses were fully in agreement with the kinetic data. Structure of the poly(vinyl acetate-bpolystyrene nanocomposite was found to be a combination of stacking layers and exfoliated structures while poly(vinyl acetate-b-poly(methyl methacryale nanocomposite had an exfoliated structure. This difference in the structure of nanocomposites was attributed to the different capability of the monomers (styrene and methyl methacrylate to react with the hydroxyl moiety (Al-O-H of nanoclay.

Grafting

Energy Technology Data Exchange (ETDEWEB)

Garnett, J L [New South Wales Univ., Kensington (Australia). School of Chemistry

1979-01-01

The unique value of ionizing radiation for the initiation of grafting to backbone polymers is discussed. The principles of the technique are briefly reviewed. The conditions under which free radicals and ions participate in these reactions are examined. Examples of representative grafting processes are considered to illustrate where the technique can be of potential commercial value to a wide range of industries. The general principles of these grafting reactions are shown to be applicable to radiation induced rapid cure technology such as is provided by electron beam processing facilities. Grafting reactions initiated by UV are also treated and shown to be of importance because of the many similarities in properties of the ionizing radiation and UV systems, also the rapid industrial exploitation of EB and sensitized UV processing technology. Possible future trends in radiation grafting are outlined.

An Engineering Scale Study on Radiation Grafting of Polymeric Adsorbents for Recovery of Heavy Metal Ions from Seawater

International Nuclear Information System (INIS)

Prasad, Tl; Saxena, Ak; Tewari, Pk; Sathiyamoorthy, D

2009-01-01

The ocean contains around eighty elements of the periodic table and uranium is also one among them, with a uniform concentration of 3.3 ppb and a relative abundance factor of 23. With a large coastline, India has a large stake in exploiting the 4 billion tonnes of uranium locked in seawater. The development of radiation grafting techniques, which are useful in incorporating the required functional groups, has led to more efficient adsorbent preparations in various geometrical configurations. Separation based on a polymeric adsorbent is becoming an increasingly popular technique for the extraction of trace heavy metals from seawater. Radiation grafting has provided definite advantages over chemical grafting. Studies related to thermally bonded non woven porous polypropylene fiber sheet substrate characterization and parameters to incorporate specific groups such as acrylonitrile (AN) into polymer back bones have been investigated. The grafted polyacrylonitrile chains were chemically modified to convert acrylonitrile group into an amidoxime group, a chelating group responsible for heavy metal uptake from seawater/brine. The present work has been undertaken to concentrate heavy metal ions from lean solutions from constant potential sources only. A scheme was designed and developed for investigation of the recovery of heavy metal ions such as uranium and vanadium from seawater

Environmental application of radiation grafting

International Nuclear Information System (INIS)

Tamada, Masao

2007-01-01

Adsorbent having high selectivity against a certain metal ion was synthesized by means of radiation-induced graft polymerization for the purpose of environmental application. The resulting adsorbents were utilized for the removal of toxic metal from scallop waste and the collection of uranium from seawater. As a novel application of grafting, the biodegradability of poly-hydroxybutylate was controlled by grafting. The biodegradability could be depressed by the graft chain and then recovered by external stimuli such as thermal and chemical treatments. (author)

Grafting of GMA and some comonomers onto chitosan for controlled release of diclofenac sodium.

Science.gov (United States)

Sharma, Rajeev Kr; Lalita; Singh, Anirudh P; Chauhan, Ghanshyam S

2014-03-01

In order to develop pH sensitive hydrogels for controlled drug release we have graft copolymerized glycidyl methacrylate (GMA) with comonomers acrylic acid, acrylamide and acrylonitrile, onto chitosan (Ch) by using potassium persulphate (KPS) as free radical initiator in aqueous solution. The optimum percent grafting for GMA was recorded for 1g chitosan at [KPS]=25.00 × 10(-3)mol/L, [GMA]=0.756 × 10(-3)mol/L, reaction temperature=60 °C and reaction time=1h in 20 mL H2O. Binary monomers were grafted for five different concentrations at optimum grafting conditions evaluated for GMA alone onto chitosan. The graft copolymers were characterized by FTIR, XRD, TGA and SEM. The swelling properties of chitosan and graft copolymers were investigated at different pH to define their end uses in sustained release of an anti-inflammatory drug, diclofenac sodium. Percent drug release w.r.t. drug loaded in polymeric sample was studied as function of time in buffer solutions of pH 2.0 and 7.4. In vitro release data was analyzed using Fick's Law. Chitosan grafted with binary monomers, GMA-co-AAm and GMA-co-AN showed very good results for sustained release of drug at 7.4 pH. Copyright © 2014 Elsevier B.V. All rights reserved.

Atom Transfer Radical Polymerization of Styrene in Presence of Mesoporous Silica Nanoparticles: Application of Reverse, Simultaneous Reverse and Normal Initiation Techniques

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Khezrollah Khezri

2014-04-01

Full Text Available Atom transfer radical polymerization (ATRP of styrene in presence of mesoporous silica nanoparticles was carried out at 110 °C. Reverse atom transfer radical polymerization (RATRP and simultaneous reverse and normal initiation for atom transfer radical polymerization (SR&NI ATRP techniques were used as two appropriate introduced techniques for circumventing oxidation problems. Usage of metal catalyst in its higher oxidation state was the main feature of these initiation techniques in which deficiencies of normal ATRP were circumvented. Structure, surface area and pore diameter of synthesized mesoporous silica nanoparticles were evaluated using X–ray diffraction and nitrogen adsorption/desorption isotherm analysis. Average particle size was estimated around 600 nm by electron microscopy images. In addition, according to these images, nanoparticles revealed an appropriate size distribution. Particles size and their distribution were examined using scanning. Final monomer conversion was determined by using gas chromatography. The number and weight average molecular weights (Mn and Mw and polydispersity indexes (PDI were also evaluated by gel permeation chromatography. According to the results obtained, addition of mesoporous silica nanoparticles in both RATRP and SR&NI ATRP systems revealed similar effects: decrement of conversion and Mn and also increment of PDI values observed by increasing of mesoporous silica nanoparticles content. Improvement in thermal stability of the nanocomposites in comparison with neat polystyrene was demonstrated by thermogravimetric analysis (TGA. Moreover, in case of nanocomposites, thermal stability was obtained by higher loading of nanoparticles. A decrease in glass transition temperature by higher content of mesoporous silica nanoparticles has been demonstrated by differential scanning calorimetry analysis.

Diazonium salts as grafting agents and efficient radical-hydrosilylation initiators for freestanding photoluminescent silicon nanocrystals.

Science.gov (United States)

Höhlein, Ignaz M D; Kehrle, Julian; Helbich, Tobias; Yang, Zhenyu; Veinot, Jonathan G C; Rieger, Bernhard

2014-04-07

The reactivity of diazonium salts towards freestanding, photoluminescent silicon nanocrystals (SiNCs) is reported. It was found that SiNCs can be functionalized with aryl groups by direct reductive grafting of the diazonium salts. Furthermore, diazonium salts are efficient radical initiators for SiNC hydrosilylation. For this purpose, novel electron-deficient diazonium salts, highly soluble in nonpolar solvents were synthesized. The SiNCs were functionalized with a variety of alkenes and alkynes at room temperature with short reaction times. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antifouling coatings via plasma polymerization and atom transfer radical polymerization on thin film composite membranes for reverse osmosis

Science.gov (United States)

Hirsch, Ulrike; Ruehl, Marco; Teuscher, Nico; Heilmann, Andreas

2018-04-01

A major drawback to otherwise highly efficient membrane-based desalination techniques like reverse osmosis (RO) is the susceptibility of the membranes to biofouling. In this work, a combination of plasma activation, plasma bromination and surface-initiated atom transfer radical polymerization (si-ATRP) of hydrophilic and zwitterionic monomers, namely hydroxyethyl methacrylate (HEMA), 2-methacryloyloxyethyl phosphorylcholine (MPC) and [2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA), was applied to generate non-specific, anti-adhesive coatings on thin film composite (TFC) membranes. The antifouling effect of the coatings was shown by short-time batch as well as long-time steady state cultivation experiments with the microorganism Pseudomonas fluorescens. It could be shown that plasma functionalization and polymerization is possible on delicate thin film composite membranes without restricting their filtration performance. All modified membranes showed an increased resistance towards the adhesion of Pseudomonas fluorescens. On average, the biofilm coverage was reduced by 51.4-12.6% (for HEMA, SBMA, and MPC), the highest reduction was monitored for MPC with a biofilm reduction by 85.4%. The hydrophilic coatings applied did not only suppress the adhesion of Pseudomonas fluorescens, but also significantly increase the permeate flux of the membranes relative to uncoated membranes. The stability of the coatings was however not ideal and will have to be improved for future commercial use.

The oxidation of PET track-etched membranes by hydrogen peroxide as an effective method to increase efficiency of UV-induced graft polymerization

Directory of Open Access Journals (Sweden)

Il'ya Korolkov

2015-12-01

Full Text Available In this article, we report on functionalization of track-etched membrane based on poly(ethylene terephthalate (PET TeMs oxidized by advanced oxidation systems and by grafting of acrylic acid using photochemical initiation technique for the purpose of increasing functionality thus expanding its practical application. Among advanced oxidation processes (H2O2/UV system had been chosen to introduce maximum concentration of carboxylic acid groups. Benzophenone (BP photo-initiator was first immobilized on the surfaces of cylindrical pores which were later filled with aq. acrylic acid solution. UV-irradiation from both sides of PET TeMs has led to the formation of grafted poly(acrylic acid (PAA chains inside the membrane nanochannels. Effect of oxygen-rich surface of PET TeMs on BP adsorption and subsequent process of photo-induced graft polymerization of acrylic acid (AA were studied by ESR. The surface of oxidized and AA grafted PET TeMs was characterized by UV-vis, ATR-FTIR, XPS spectroscopies and by SEM.

Industrial application of electron beams for grafting and vulcanization

Energy Technology Data Exchange (ETDEWEB)

Makuuchi, Keizo [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

1994-12-31

The topics discussed are radiation graft polymerization; industrial application of radiation grafting - ion exchange membrane for a battery separator, ammonia adsorbent, non-flammable PE (polyethylene) foam; R and D on radiation grafting, radiation vulcanization of natural rubber.

Industrial application of electron beams for grafting and vulcanization

International Nuclear Information System (INIS)

Keizo Makuuchi

1994-01-01

The topics discussed are radiation graft polymerization; industrial application of radiation grafting - ion exchange membrane for a battery separator, ammonia adsorbent, non-flammable PE (polyethylene) foam; R and D on radiation grafting, radiation vulcanization of natural rubber

Ultrasound-induced radical polymerization

NARCIS (Netherlands)

Kuijpers, M.W.A.; Kemmere, M.F.; Keurentjes, J.T.F.

2004-01-01

Sonochemistry comprises all chemical effects that are induced by ultrasound. Most of these effects are caused by cavitations, ie, the collapse of microscopic bubbles in a liquid. The chemical effects of ultrasound include the formation of radicals and the enhancement of reaction rates at ambient

Obtention of injectable platelets rich-fibrin (i-PRF) and its polymerization with bone graft: technical note.

Science.gov (United States)

Mourão, Carlos Fernando de Almeida Barros; Valiense, Helder; Melo, Elias Rodrigues; Mourão, Natália Belmock Mascarenhas Freitas; Maia, Mônica Diuana-Calasans

2015-01-01

The use of autologous platelet concentrates, represent a promising and innovator tools in the medicine and dentistry today. The goal is to accelerate hard and soft tissue healing. Among them, the platelet-rich plasma (PRP) is the main alternative for use in liquid form (injectable). These injectable form of platelet concentrates are often used in regenerative procedures and demonstrate good results. The aim of this study is to present an alternative to these platelet concentrates using the platelet-rich fibrin in liquid form (injectable) and its use with particulated bone graft materials in the polymerized form.

Obtention of injectable platelets rich-fibrin (i-PRF and its polymerization with bone graft: technical note

Directory of Open Access Journals (Sweden)

Carlos Fernando de Almeida Barros Mourão

Full Text Available The use of autologous platelet concentrates, represent a promising and innovator tools in the medicine and dentistry today. The goal is to accelerate hard and soft tissue healing. Among them, the platelet-rich plasma (PRP is the main alternative for use in liquid form (injectable. These injectable form ofplatelet concentrates are often used in regenerative procedures and demonstrate good results. The aim of this study is to present an alternative to these platelet concentrates using the platelet-rich fibrin in liquid form (injectable and its use with particulated bone graft materials in the polymerized form.

Nitroxide radicals formed in situ as polymer chain growth regulators

International Nuclear Information System (INIS)

Kolyakina, Elena V; Grishin, Dmitry F

2009-01-01

Published data on controlled synthesis of macromolecules using nitroxide radicals, formed in situ during polymerization, as polymer chain growth regulators are systematized and generalized. The attention is focused on the mechanism of polymer chain growth control during reversibly inhibited radical homopolymerization and the effect of structure of precursors and regulating additives on the polymerization kinetics of monomers of different nature and the molecular-mass characteristics of the polymers thus formed. The key methods for generation of nitroxide radicals directly during polymerization are considered. The prospects for development and practical use of these approaches for the synthesis of new polymeric materials are evaluated.

Preparation and characterization of poly(glycidyl methacrylate) grafted from magnesium hydroxide particles via SI-ATRP

International Nuclear Information System (INIS)

Liu Jianhui; Feng Na; Chang Suqin; Kang Hongliang

2012-01-01

In order to improve the compatibility of magnesium hydroxide particles [Mg(OH) 2 ] and polymer matrix, poly(glycidyl methacrylate) (PGMA) grafted from magnesium hydroxide particles were synthesized via surface-initiated atom transfer radical polymerization (SI-ATRP). In this work, two approaches for the immobilization of ATRP initiator on the magnesium hydroxide particles surface were compared and selected. The density of initiator was significantly increased by the method of introducing more hydroxyl groups via ATRP of 2-hydroxyethyl methacrylate (HEMA) on the surface. The percentage of bromine atom for the initiator-functionalized magnesium hydroxide particles [Mg(OH) 2 -g-PHEMA-Br] reached to 1.75%, compared to 0.48% for Mg(OH) 2 -Br determined by XPS analysis. The surface-initiated ATRP of glycidyl methacrylate (GMA) can be conducted in a controlled manner, as revealed by the linear kinetic plot, linear increase of number average molecular weight (M n ) with monomer conversions, and the relatively narrow molecular weight distributions (M w /M n ∼ 1.4) of PGMA chains. The percentage of grafting PG (%) and the thickness of the grafted polymer layer increased with the increasing of polymerization time and reached to 116.6% and 197.6 nm after 300 min respectively. As for the polymerization with different initial monomer concentration, the number average molecular weights (M n ) and weight average molecular weights (M w ) of PGMA increased with the increasing of initial monomer concentration. TGA indicated that the initial decomposition temperature of Mg(OH) 2 -g-PHEMA-PGMA composite particles (253 °C) was much lower than that of unmodified magnesium hydroxide particles (337 °C).

Preparation and characterization of poly(glycidyl methacrylate) grafted from magnesium hydroxide particles via SI-ATRP

Energy Technology Data Exchange (ETDEWEB)

Liu Jianhui [School of Textile and Materials Engineering, Dalian Polytechnic University, Dalian 116034 (China); Feng Na, E-mail: fengna12@163.com [School of Textile and Materials Engineering, Dalian Polytechnic University, Dalian 116034 (China); Chang Suqin [China Leather and Footwear Industry Research Institute, Beijing 100015 (China); Kang Hongliang [State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Material, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)

2012-06-01

In order to improve the compatibility of magnesium hydroxide particles [Mg(OH){sub 2}] and polymer matrix, poly(glycidyl methacrylate) (PGMA) grafted from magnesium hydroxide particles were synthesized via surface-initiated atom transfer radical polymerization (SI-ATRP). In this work, two approaches for the immobilization of ATRP initiator on the magnesium hydroxide particles surface were compared and selected. The density of initiator was significantly increased by the method of introducing more hydroxyl groups via ATRP of 2-hydroxyethyl methacrylate (HEMA) on the surface. The percentage of bromine atom for the initiator-functionalized magnesium hydroxide particles [Mg(OH){sub 2}-g-PHEMA-Br] reached to 1.75%, compared to 0.48% for Mg(OH){sub 2}-Br determined by XPS analysis. The surface-initiated ATRP of glycidyl methacrylate (GMA) can be conducted in a controlled manner, as revealed by the linear kinetic plot, linear increase of number average molecular weight (M{sub n}) with monomer conversions, and the relatively narrow molecular weight distributions (M{sub w}/M{sub n} {approx} 1.4) of PGMA chains. The percentage of grafting PG (%) and the thickness of the grafted polymer layer increased with the increasing of polymerization time and reached to 116.6% and 197.6 nm after 300 min respectively. As for the polymerization with different initial monomer concentration, the number average molecular weights (M{sub n}) and weight average molecular weights (M{sub w}) of PGMA increased with the increasing of initial monomer concentration. TGA indicated that the initial decomposition temperature of Mg(OH){sub 2}-g-PHEMA-PGMA composite particles (253 Degree-Sign C) was much lower than that of unmodified magnesium hydroxide particles (337 Degree-Sign C).

Preparation of polymethacrylic acid-grafted HEMA/PVP microspheres and preliminary study on basic protein adsorption.

Science.gov (United States)

Gao, Baojiao; Hu, Hongyan; Guo, Jianfeng; Li, Yanbin

2010-06-01

The crosslinked copolymeric microspheres (HEMA/NVP) of N-vinylpyrrolidone (NVP) and 2-hydroxyethyl methacrylate (HEMA) were prepared using inverse suspension polymerization method. Subsequently, the reaction of methacryloyl chloride with the hydroxyl groups on the surfaces of HEMA/NVP microspheres was performed, leading to the introduction of polymerisable double bonds onto the surfaces of microspheres HEMA/NVP. Afterward, methacrylic acid was allowed to be graft-polymerized on microspheres HEMA/NVP in the manner of "grafting from", resulting in the grafted microspheres PMAA-HEMA/NVP. The grafted microspheres PMAA-HEMA/NVP were fully characterized with several means. The graft-polymerization of MAA on microspheres HEMA/NVP was studied in detail, and the optimal reaction conditions were determined. Thereafter, the adsorption property of the grafted microspheres PMAA-HEMA/NVP for lysozyme as a basic protein model was preliminarily examined to explore the feasibility of removing deleterious basic protein such as density lipoprotein from blood. The experimental results indicate that the PMAA grafting degree on microspheres HEMA/NVP is limited because an enwinding polymer layer as a kinetic barrier on the surfaces of HEMA/NVP microspheres will be formed during the graft-polymerization, and block the graft-polymerization. In order to enhance PMAA grafting degree, reaction temperature, monomer concentration and the used amount of initiator should be effectively controlled. The experimental results also reveal that the grafted microspheres PMAA-HEMA/NVP possess very strong adsorption ability for lysozyme by right of strong electrostatic interaction. Copyright 2010 Elsevier B.V. All rights reserved.

Kinetics of Waterborne Alkyd/Acrylic Hybrid Resin Free Radical Polymerization by Two Systems of Redox and Thermal Initiators

Directory of Open Access Journals (Sweden)

shirin Madadi

2012-12-01

Full Text Available Kinetics of radical polymerizations of waterborne alkyd/acrylic hybrid resin via batch mini-emulsion technique was studied using redox initiators (TBHP/Fe2+/EDTA/AsAc  and  TBHP/Fe2+/EDTA/SFS at relatively low temperatures and thermal initiators (BPO, KPS and AIBN at higher temperatures to seek the most suitable initiator system. At the end of all reactions the unreacted monomer content was reduced using post-polymerization technique; consequently, leading to increased monomer conversion and flm formation with improved properties. The kinetics of mini-emulsion polymerization showed that in all redox initiator systems (Fe2+ catalyst + EDTA chelating agent, the radials are produced at relatively low temperature with more effcient control of the reactor temperature. It was found that at 45°C TBHP/Fe2+/EDTA/SFS redox initiator system leads to 98% monomer conversion, a much higher rate than that of systems involved thermal initiators.

3D-Printed Biodegradable Polymeric Vascular Grafts.

Science.gov (United States)

Melchiorri, A J; Hibino, N; Best, C A; Yi, T; Lee, Y U; Kraynak, C A; Kimerer, L K; Krieger, A; Kim, P; Breuer, C K; Fisher, J P

2016-02-04

Congenital heart defect interventions may benefit from the fabrication of patient-specific vascular grafts because of the wide array of anatomies present in children with cardiovascular defects. 3D printing is used to establish a platform for the production of custom vascular grafts, which are biodegradable, mechanically compatible with vascular tissues, and support neotissue formation and growth. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radiation-Induced Graft Polymerization of Vinyl Monomers with Anion Groups onto MWNT Supports and Their Application as Electrogenerated Chemiluminescence (ECL Biosensors

Directory of Open Access Journals (Sweden)

Ji-Hye Park

2014-01-01

Full Text Available Vinyl polymer-grafted multiwalled carbon nanotube (MWNT supports with anion groups were prepared for use as biosensor supports by radiation-induced graft polymerization (RIGP of the vinyl monomers acryloyl diphosphoric acid (ADPA, acrylic acid (AA, sodium styrenesulfonate (NaSS, and methacrylic acid (MA onto the surface of MWNTs. The electrogenerated chemiluminescence sensors based on a glass carbon electrode (ECL-GCE and a screen printed electrode (ECL-SPE were fabricated by immobilization of Ru(bpy3 2+ complex after coating of vinyl polymer-grafted MWNT inks on the surface of the GCE and SPE without any polymer binders in order to obtain high electrogenerated chemiluminescence intensity. For detection of alcohol concentration, alcohol dehydrogenase (ADH was immobilized onto an ECL-GCE sensor prepared by poly(NaSS-g-MWNT supports. The prepared biosensor based on ADH is suitable for the detection of ethanol concentration in commercial drinks.

Surface modification of nanodiamond through metal free atom transfer radical polymerization

Energy Technology Data Exchange (ETDEWEB)

Zeng, Guangjian; Liu, Meiying; Shi, Kexin; Heng, Chunning; Mao, Liucheng; Wan, Qing; Huang, Hongye [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Deng, Fengjie, E-mail: fengjiedeng@aliyun.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing, 100084 (China)

2016-12-30

Highlights: • Surface modification of ND with water soluble and biocompatible polymers. • Functionalized ND through metal free surface initiated ATRP. • The metal free surface initiated ATRP is rather simple and effective. • The ND-poly(MPC) showed high dispersibility and desirable biocompatibility. - Abstract: Surface modification of nanodiamond (ND) with poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] has been achieved by using metal free surface initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiator was first immobilized on the surface of ND through direct esterification reaction between hydroxyl group of ND and 2-bromoisobutyryl bromide. The initiator could be employed to obtain ND-poly(MPC) nanocomposites through SI-ATRP using an organic catalyst. The final functional materials were characterized by {sup 1}H nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis in detailed. All of these characterization results demonstrated that ND-poly(MPC) have been successfully obtained via metal free photo-initiated SI-ATRP. The ND-poly(MPC) nanocomposites shown enhanced dispersibility in various solvents as well as excellent biocompatibility. As compared with traditional ATRP, the metal free ATRP is rather simple and effective. More importantly, this preparation method avoided the negative influence of metal catalysts. Therefore, the method described in this work should be a promising strategy for fabrication of polymeric nanocomposites with great potential for different applications especially in biomedical fields.

Surface modification of nanodiamond through metal free atom transfer radical polymerization

International Nuclear Information System (INIS)

Zeng, Guangjian; Liu, Meiying; Shi, Kexin; Heng, Chunning; Mao, Liucheng; Wan, Qing; Huang, Hongye; Deng, Fengjie; Zhang, Xiaoyong; Wei, Yen

2016-01-01

Highlights: • Surface modification of ND with water soluble and biocompatible polymers. • Functionalized ND through metal free surface initiated ATRP. • The metal free surface initiated ATRP is rather simple and effective. • The ND-poly(MPC) showed high dispersibility and desirable biocompatibility. - Abstract: Surface modification of nanodiamond (ND) with poly(2-methacryloyloxyethyl phosphorylcholine) [poly(MPC)] has been achieved by using metal free surface initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiator was first immobilized on the surface of ND through direct esterification reaction between hydroxyl group of ND and 2-bromoisobutyryl bromide. The initiator could be employed to obtain ND-poly(MPC) nanocomposites through SI-ATRP using an organic catalyst. The final functional materials were characterized by 1 H nuclear magnetic resonance, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermo gravimetric analysis in detailed. All of these characterization results demonstrated that ND-poly(MPC) have been successfully obtained via metal free photo-initiated SI-ATRP. The ND-poly(MPC) nanocomposites shown enhanced dispersibility in various solvents as well as excellent biocompatibility. As compared with traditional ATRP, the metal free ATRP is rather simple and effective. More importantly, this preparation method avoided the negative influence of metal catalysts. Therefore, the method described in this work should be a promising strategy for fabrication of polymeric nanocomposites with great potential for different applications especially in biomedical fields.

Influence of CO2 on ultrasound-induced polymerizations in high-pressure fluids

NARCIS (Netherlands)

Kuijpers, M.W.A.; Jacobs, L.J.M.; Kemmere, M.F.; Keurentjes, J.T.F.

2005-01-01

A strong viscosity increase upon polymerization hinders cavitation and subsequent radical formation during an ultrasound-induced bulk polymerization. Ultrasound-induced radical polymerizations of methyl methacrylate (MMA) have been performed in CO2-expanded MMA, as well as in bulk MMA. For this

Biocompatibility of polypropylene non-woven fabric membrane via UV-induced graft polymerization of 2-acrylamido-2-methylpropane sulfonic acid

Energy Technology Data Exchange (ETDEWEB)

Song Lingjie [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao Jie; Yang Huawei; Jin Jing; Li Xiaomeng [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Stagnaro, Paola [Istituto per Io Studio delle Macromolecole, Consiglio Nazionale delle Ricerche, Via de Marini 6, 16149 Genova (Italy); Yin Jinghua, E-mail: yinjh@ciac.jl.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

2011-10-15

This work described the graft polymerization of a sulfonic acid terminated monomer, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), onto the surface of polypropylene non-woven (NWF PP) membrane by O{sub 2} plasma pretreatment and UV-induced photografting method. The chemical structure and composition of the modified surfaces were analyzed by FTIR-ATR and XPS, respectively. The wettability was investigated by water contact angle and equilibrium water adsorption. And the biocompatibility of the modified NWF PP membranes was evaluated by protein adsorption and platelet adhesion. It was found that the graft density increased with prolonging UV irradiation time and increasing AMPS concentration; the water contact angles of the membranes decreased from 124{sup o} to 26{sup o} with the increasing grafting density of poly(AMPS) from 0 to 884.2 {mu}g cm{sup -2}, while the equilibrium water adsorption raised from 5 wt% to 75 wt%; the protein absorption was effectively suppressed with the introduction of poly(AMPS) even at the low grafting density (132.4 {mu}g cm{sup -2}); the number of platelets adhering to the modified membrane was dramatically reduced when compared with that on its virgin surface. These results indicated that surface modification of NWF PP membrane with AMPS was a facile approach to construct biocompatible surface.

PETMA-g-PETMA-b-PS 'palm tree' graft copolymer: A new polymeric architecture obtained via RAFT and ROP process;Copolimero PETMA-PS-G-P(PSMA) do tipo 'palma': nova arquitetura polimerica obtida via processo RAFT e ROP

Energy Technology Data Exchange (ETDEWEB)

Soares, Paula P.; Silva, Eduardo de O. da; Petzhold, Cesar L., E-mail: poli_pps@yahoo.com.b [Universidade Federal do Rio Grande do Sul (IQ/UFRS), Porto Alegre, RS (Brazil). Dept. de Quimica Organica. Lab. de Sintese e Polimeros

2009-07-01

Block copolymer with pendant thiirane moiety PETMA-b-PS is the base for a new class of 'palm tree' graft copolymers, which can show interesting properties. ETMA can be polymerized through ring opening polymerization with Lewis bases as initiator, e.g., Br- and tertiary amines. We used this reaction as a way to graft a copolymer PETMA-b-PS possessing 5% of ETMA unities, with chains having poly(propylene sulfide), obtained by graft from method. Produced materials were characterized through H1 NMR, SEC and DSC. (author)

PREPARATION AND PROPERTIES OF MMA/1-PROPYLMETHACRYLATE-POSS COPOLYMER WITH ATOM TRANSFER RADICAL POLYMERIZATION

Institute of Scientific and Technical Information of China (English)

He-xin Zhang; Ho-young Lee; Young-jun Shin; Dong-ho Lee; Seok Kyun Noh

2008-01-01

The methyl methacrylate(MMA)/1-propylmethacrylate-polyhedral oligomeric silsesquioxane(PM-POSS) copolymers were synthesized via atom transfer radical polymerization with CuBr as catalyst.The unreacted PM-POSS monomer could be removed completely by washing the copolymerization product with n-hexane.The copolymers were characterized with 1H-NMR,X-ray diffraction,difierential scanning calorimetry,thermogravimetric analysis and gel permeatlon chromatography.With increasing PM-POSS feed ratio.the total conversion increased while the glass transition temperatures of copolymer decreased.The thermogravimetric analysis demonstrated that the thermal stability of copolymer improved slightly with PM-POSS addition.The molecular weight of copolymers increased with incorporation of PM-POSS.

Surface grafting of a dense and rigid coordination polymer based on tri-para-carboxy-polychlorotriphenylmethyl radical and copper acetate

KAUST Repository

Mugnaini, Veró nica; Paradinas, Markos; Shekhah, Osama; Roques, Nans; Ocal, Carmen; Wö ll, Christof H.; Veciana, Jaume

2013-01-01

The step-by-step method is here presented as suitable to anchor on appropriately functionalized gold surfaces a metal-organic coordination polymer based on a non-planar trigonal tri-para-carboxy-polychlorotriphenylmethyl radical derivative and copper acetate. The structural characteristics of the grafted coordination polymer are derived during the step-wise growth from the real time changes in refractive index and oscillation frequency. The film thickness, as measured by scanning force microscopy, combined with the mass uptake value from the quartz crystal microbalance, are used to estimate an average density of the grafted metal-organic coordination polymer that suggests the formation of a dense and rather rigid thin film. This journal is © 2013 The Royal Society of Chemistry.

Preparation and characterization of poly(acrylic acid)-hydroxyethyl cellulose graft copolymer.

Science.gov (United States)

Abdel-Halim, E S

2012-10-01

Poly(acrylic acid) hydroxyethyl cellulose [poly(AA)-HEC] graft copolymer was prepared by polymerizing acrylic acid (AA) with hydroxyethyl cellulose (HEC) using potassium bromate/thiourea dioxide (KBrO(3)/TUD) as redox initiation system. The polymerization reaction was carried out under a variety of conditions including concentrations of AA, KBrO(3) and TUD, material to liquor ratio and polymerization temperature. The polymerization reaction was monitored by withdrawing samples from the reaction medium and measuring the total conversion. The rheological properties of the poly(AA)-HEC graft copolymer were investigated. The total conversion and rheological properties of the graft copolymer depended on the ratio of KBrO(3) to TUD and on acrylic acid concentration as well as temperature and material to liquor ratio. Optimum conditions of the graft copolymer preparation were 30 mmol KBrO(3) and 30 mmol TUD/100g HEC, 100% AA (based on weight of HEC), duration 2h at temperature 50 °C using a material to liquor ratio of 1:10. Copyright © 2012. Published by Elsevier Ltd.

Free Radical Addition Polymerization Kinetics without Steady-State Approximations: A Numerical Analysis for the Polymer, Physical, or Advanced Organic Chemistry Course

Science.gov (United States)

Iler, H. Darrell; Brown, Amber; Landis, Amanda; Schimke, Greg; Peters, George

2014-01-01

A numerical analysis of the free radical addition polymerization system is described that provides those teaching polymer, physical, or advanced organic chemistry courses the opportunity to introduce students to numerical methods in the context of a simple but mathematically stiff chemical kinetic system. Numerical analysis can lead students to an…

Red fluorescent chitosan nanoparticles grafted with poly(2-methacryloyloxyethyl phosphorylcholine) for live cell imaging.

Science.gov (United States)

Wang, Ke; Fan, Xingliang; Zhang, Xiaoyong; Zhang, Xiqi; Chen, Yi; Wei, Yen

2016-08-01

Poly(2-methacryloyloxyethyl phosphorylcholine) conjugated red fluorescent chitosan nanoparticles (GCC-pMPC) were facilely fabricated by "grafting from" method via surface initiated atom transfer radical polymerization (ATRP). Firstly, glutaraldehyde crosslinked red fluorescent chitosan nanoparticles (GCC NPs) with many amino groups and hydroxyl groups on their surface were prepared, which were then reacted with 2-bromoisobutyryl bromide to form GCC-Br; subsequently, poly(MPC) (pMPC) brushes were grafted onto GCC NPs surface using GCC-Br as initiator via ATRP. Compared with PEGylated nanoparticles, zwitterionic polymers modified nanoparticles demonstrated better performance in their cellular uptake. Moreover, the obtained GCC-pMPC demonstrated excellent water-dispersibility, biocompatibility, and photostability, which made them highly potential for long-term tracing applications. Importantly, the successful live cell imaging of GCC-pMPC would remarkably advance the research of their further bioapplications. Copyright © 2016 Elsevier B.V. All rights reserved.

The potential of Cu(I)Cl/2,2'-bipyridine catalysis in a triblock copolymer preparation by atom transfer radical polymerization

Czech Academy of Sciences Publication Activity Database

Masař, Bohumil; Vlček, Petr; Kříž, Jaroslav

2001-01-01

Roč. 81, č. 14 (2001), s. 3514-3522 ISSN 0021-8995 R&D Projects: GA MŠk OC P1.10; GA AV ČR KSK2050602 Institutional research plan: CEZ:AV0Z4050913 Keywords : atom transfer radical polymerization * triblock copolymers * sequential synthesis Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.992, year: 2001

Nanoparticles from a controlled polymerization process

International Nuclear Information System (INIS)

Tirumala, V.R.; Caneba, G.T.; Dar, Y.; Wang, H.-H.; Mancini, D.C.

2003-01-01

Free-radical retrograde precipitation polymerization process in the past has shown excellent control characteristics over reaction rate, molecular weight, and in the entrapment of live radicals for the generation of block copolymers. The same principle has now been extended to study the reaction confinement to a nanoscale region. Nanosized polymer particles have been reported to form from block copolymers, conventional precipitation polymerization methods, or through emulsion polymerization approaches. In this work, we present a new method of generating nanosized polymer particles by polymerizing the monomer in an environment that precipitates the polymer above the lower critical solution temperature. The nanoparticles have been characterized by both tapping-mode atomic force microscopy observations and in situ synchrotron time-resolved small-angle X-ray scattering analysis. The results from both the techniques showed the formation of nanoparticles in the size range of 15-30 nm, directly from the polymerization process.

Biodegradability of poly(3-hydroxybutyrate) film grafted with vinyl acetate: Effect of grafting and saponification

Science.gov (United States)

Wada, Yuki; Seko, Noriaki; Nagasawa, Naotsugu; Tamada, Masao; Kasuya, Ken-ichi; Mitomo, Hiroshi

2007-06-01

Radiation-induced graft polymerization of vinyl acetate (VAc) onto poly(3-hydroxybutyrate) (PHB) film was carried out. At a degree of grafting higher than 5%, the grafted films (PHB-g-VAc) completely lost the enzymatic degradability that is characteristic of PHB due to the grafted VAc covering the surface of the PHB film. However, the biodegradability of the PHB-g-VAc films was recovered when the films were saponified in alkali solution under optimum conditions. Graft chains of the PHB-g-VAc film reacted selectively to become biodegradable polyvinyl alcohol (PVA). The biodegradability of the saponified PHB-g-VAc film increased rapidly with time.

Biodegradability of poly(3-hydroxybutyrate) film grafted with vinyl acetate: Effect of grafting and saponification

International Nuclear Information System (INIS)

Wada, Yuki; Seko, Noriaki; Nagasawa, Naotsugu; Tamada, Masao; Kasuya, Ken-ichi; Mitomo, Hiroshi

2007-01-01

Radiation-induced graft polymerization of vinyl acetate (VAc) onto poly(3-hydroxybutyrate) (PHB) film was carried out. At a degree of grafting higher than 5%, the grafted films (PHB-g-VAc) completely lost the enzymatic degradability that is characteristic of PHB due to the grafted VAc covering the surface of the PHB film. However, the biodegradability of the PHB-g-VAc films was recovered when the films were saponified in alkali solution under optimum conditions. Graft chains of the PHB-g-VAc film reacted selectively to become biodegradable polyvinyl alcohol (PVA). The biodegradability of the saponified PHB-g-VAc film increased rapidly with time

ESR spectroscopic investigations of the radiation-grafting of fluoropolymers

Energy Technology Data Exchange (ETDEWEB)

Huebner, G; Roduner, E [University of Stuttgart (Germany); Brack, H P; Scherer, G G [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1999-08-01

ESR spectroscopic investigations have clarified the influence of several preparative parameters on the reaction rates and yields obtained in the radiation-grafting method used at PSI to prepare proton-conducting polymer membranes. At a given irradiation dose, a higher concentration of reactive radical sites was detected in ETFE films than in FEP films. This higher concentration explains the higher grafting levels and rates of the ETFE films found in our previous grafting experiments. Taken together, the in-situ ESR experiments and grafting experiments show that the rates of disappearance of radical species and grafting rates and final grafting levels depend strongly on the reaction temperature and the oxygen content of the system. Average grafted chain lengths were calculated to contain about 1,000 monomer units. (author) 2 figs., 4 refs.

Zwitterionic phosphorylcholine grafted chitosan nanofiber: Preparation, characterization and in-vitro cell adhesion behavior

Energy Technology Data Exchange (ETDEWEB)

Oktay, Burcu; Kayaman-Apohan, Nilhan, E-mail: napohan@marmara.edu.tr; Süleymanoğlu, Mediha; Erdem-Kuruca, Serap

2017-04-01

In this study, zwitterionic phosphorylcholine grafted electrospun chitosan fiber was accomplished in three steps: (1) Azide groups on the chitosan were regioselectively replaced with hydroxyl side group and then the product was electrospun. (2) Chitosan based macroinitiator was prepared using an azide-alkyne click reaction from azide-functionalized electrospun chitosan fiber. (3) Poly(2-methacryloyloxyethyl phosphorylcholine) (MPC) was grafted onto the electrospun chitosan fiber by atom transfer radical polymerization (ATRP) in order to enhance cellular viability and proliferation of 3T3, ECV and Saos. The structure of surface modified chitosan was characterized by Fourier transform infrared spectrometer (FT-IR) and {sup 1}H nuclear magnetic resonance ({sup 1}H NMR). The surface morphology of the nanofibers was investigated by scanning electron microscope (SEM). In-vitro cellular attachment and spreading experiments of 3T3, ECV304 and Saos were performed on electrospun chitosan fibers in the presence and the absence of MPC grafting. Poly(MPC) grafted electrospun fiber showed an excellent performance due to phosphorylcholine groups mimicking the natural phospholipid. - Highlights: • Chitosan was functionalized in a controlled way. • Poly(MPC) grafted electrospun chitosan fiber was prepared by click and ATRP. • Controlled molecular architecture was achieved. • Cellular attachment and spreading efficiency of the nanofiber were investigated. • These nanofibers have potential applications in tissue engineering with tissue.

PREPARATION OF BLOCK COPOLYMERS OF POLY(STYRENE) AND POLY(T-BUTYL ACRYLATE) OF VARIOUS MOLECULAR WEIGHTS AND ARCHITECTURES BY ATOM TRANSFER RADICAL POLYMERIZATION. (R826735)

Science.gov (United States)

Block copolymers of polystyrene and poly(t-butyl acrylate) were prepared using atom transfer radical polymerization techniques. These polymers were synthesized with a CuBr/N,N,N,NPotassium diperiodatocuprate-mediated preparation of poly(methyl methacrylate/organo-montmorillonite composites via in situ grafting copolymerization

Directory of Open Access Journals (Sweden)

2008-09-01

Full Text Available In this study, potassium diperiodatocuprate (Cu3+ was selected as an initiator to prepare poly(methyl methacrylate/organo-montmorillonite composites (OMMT-g-PMMA by in situ graft copolymerization. Three synthetic parameters were systematically evaluated as a function of the temperature, the concentration of initiator, pH and the ratio of MMA to OMMT. It was found that Cu3+ was a highly efficient initiator for the preparation of OMMT-g-PMMA i.e., monomer conversion and grafting efficiency were as higher as 95%. The X-ray diffraction measurement showed the intercalation of PMMA chains into OMMT layers on base of an increasing basal spacing after polymerization. FTIR analysis also suggested that the PMMA chains were effectively grafted onto OMMT substrate. The enhanced thermal stabilities of OMMT-g-PMMA composites were confirmed by the thermal gravimetric analysis (TGA. Finally, a single-electron-transfer mechanism was proposed to illustrate the formation of radicals and the preparation process of OMMT-g-PMMA composites. Cu3+ can be used as an effective and practical initiator in preparing the organic/inorganic composite due to its high grafting efficiency and the milder reaction condition.

Recyclable crosslinked polymer networks with full property recovery made via one-step controlled radical polymerization

Science.gov (United States)

Jin, Kailong; Li, Lingqiao; Torkelson, John

Rubber tires illustrate well the issues ranging from economic loss to environmental problems and sustainability issues that arise with spent, covalently crosslinked polymers. A nitroxide-mediated polymerization (NMP) strategy has been developed that allows for one-step synthesis of recyclable crosslinked polymers from monomers or polymers that contain carbon-carbon double bonds amenable to radical polymerization. Resulting materials possess dynamic alkoxyamine crosslinks that undergo reversible decrosslinking as a function of temperature. Using polybutadiene as starting material, and styrene, an appropriate nitroxide molecule and bifunctional initiator for initial crosslinking, a model for tire rubber can be produced by reaction at temperatures comparable to those employed in tire molding. Upon cooling, the crosslinks are made permanent due to the extraordinarily strong temperature dependence of the reverisible nitroxide capping and uncapping reaction. Based on thermomechanical property characterization, when the original crosslinked model rubber is chopped into bits and remolded in the melt state, a well-consolidated material is obtained which exhibits full recovery of properties reflecting crosslink density after multiple recycling steps.

On the mechanism of activation of copper-catalyzed atom transfer radical polymerization

International Nuclear Information System (INIS)

Isse, Abdirisak Ahmed; Bortolamei, Nicola; De Paoli, Patrizia; Gennaro, Armando

2013-01-01

The mechanism of activation of atom transfer radical polymerization (ATRP) has been analyzed by investigating the kinetics of dissociative electron transfer (ET) to alkyl halides (RX) in acetonitrile. Using a series of alkyl halides, including both bromides and chlorides, the rate constants of ET (k ET ) to RX by electrogenerated aromatic radical anions (A· − ) acting as outer-sphere donors have been measured and analyzed according to the current theories of dissociative ET. This has shown that the kinetic data fit very well the “sticky” dissociative ET model with the formation of a weak adduct held together by electrostatic interactions. The rate constants of activation, k act , of some alkyl halides, namely chloroacetonitrile, methyl 2-bromopropionate and ethyl chloroacetate, by [Cu I L] + (L = tris(2-dimethylaminoethyl)amine, tris(2-pyridylmethyl)amine, 1,1,4,7,7-pentamethyldiethylenetriamine) have also been measured in the same experimental conditions. Comparisons of the measured k act values with those predicted assuming an outer-sphere ET for the complexes have shown that activation by Cu(I) is 7–10 orders of magnitude faster than required by outer-sphere ET. Therefore, the mechanism of RX activation by Cu(I) complexes used as catalysts in ATRP occurs by an inner-sphere ET or more appropriately by a halogen atom abstraction

New cobalt-mediated radical polymerization (CMRP of methyl methacrylate initiated by two single-component dinuclear β-diketone cobalt (II catalysts.

Directory of Open Access Journals (Sweden)

Feng Bao

Full Text Available Two dinuclear cobalt complexes based on bis-diketonate ligands (ligand 1: 3,3'-(1,3-phenylenebis(1-phenylpropane-1,3-dione; ligand 2: 3,3'-(1,4-phenylenebis(1-phenylpropane-1,3-dione were successfully synthesized. The two neutral catalysts all showed satisfactory activities in the cobalt-mediated radical polymerization (CMRP of methyl methacrylate (MMA with the common initiator of azodiisobutyronitrile (AIBN. The resulting polymerizations have all of the characteristics of a living polymerization and displayed linear semilogarithmic kinetic plots, a linear correlation between the number-average molecular weight and the monomer conversion, and low polydispersities. Mono- or dicomponent low polydispersity polymers could be obtained by using the two dinuclear catalysts under proper reaction conditions. All these improvements facilitate the implementation of the acrylate CMRP and open the door to the scale-up of the syntheses and applications of the multicomponent low polydispersity polymers.

A DFT Study of R-X Bond Dissociation Enthalpies of Relevance to the Initiation Process of Atom Transfer Radical Polymerization

DEFF Research Database (Denmark)

Gillies, Malcolm Bjørn; Matyjaszewski, Krzysztof; Norrby, Per-Ola

2003-01-01

DFT calculations at the B3P86/6-31G** level have been carried out to derive the bond dissociation energies (BDE) and free energies for a number of R-X systems (X ) Cl, Br, I, N3, and S2-CNMe2) that have been or can potentially be used as initiators for atom transfer radical polymerization (ATRP...

Smart polymeric materials in forms of fiber and film

International Nuclear Information System (INIS)

Sugo, Takanobu

1998-01-01

Chemical grafting: graft polymerization is a powerful technology to append novel functionality to base fibers, clothes, felts, films and others, while maintaining their original properties. As shown in Figure 1, while a gardener may use a pair of shears to cut the branch, to cut the molecular branch of a polymeric material, one can utilize the radiation energy. Effective utilization of the radiation energy can proceed to a novel reaction that is impossible for other conventional methods and develop a new material bearing outstanding functions. This technology is named radiation-induced graft polymerization (RIGP). In this article, the present research and development of novel functional polymeric materials by radiation-induced graft polymerization is described. The felt of intertwined fibers has been widely used as a filter to remove particles from air but not toxic gaseous compounds. However, by RIGP, one can transform the felt into a high functional filter that will absorb the toxic gaseous compounds while removing particles simultaneously. As a result, the RIGP technology, which is impossible by conventional technology, has enabled the development of a novel functional material that produce highly pure air. Commercialization of this filter for applications in a semiconductor manufacturing facility and as an air purifier is under process. Moreover, this filter can also be used to produce highly purified water by removing toxic heavy metals. Commercially available polyethylene films are also been transform into conductive separators by RIGP to increase the lifetime of a battery by more than five-fold. (J.P.N)

Radiation graft post-polymerization of sodium styrene sulfonate onto polyethylene

International Nuclear Information System (INIS)

Kitaeva, N.K.; Duflot, V.R.; Ilicheva, N.S.

2013-01-01

Post-irradiation grafting of sodium styrene sulfonate (SSS) in the presence of acrylic acid (AA) has been investigated on polyethylene (PE) pre-exposed to gamma radiation at room temperature in the air. Special attention was paid to the effect of low molecular weight salt additives on the kinetics of graft copolymerization of SSS and AA. The presence of SSS links in the grafted PE copolymers was detected by the methods of UV and FTIR spectroscopy. Based on the FTIR spectroscopy and element analysis data, a mechanism was proposed for graft copolymerization of SSS and AA onto PE. The mechanical properties of the graft copolymers were studied. It was established that PE copolymers grafted with sulfonic acid and carboxyl groups have higher strength characteristics (16.3 MPa) compared to the samples containing only carboxyl groups (11 MPa). (author)

Vinylimidazole-Based Asymmetric Ion Pair Comonomers: Synthesis, Polymerization Studies and Formation of Ionically Crosslinked PMMA

NARCIS (Netherlands)

Jana, S.; Vasantha, V.A.; Stubbs, L.P.; Parthiban, A.; Vancso, Gyula J.

2013-01-01

Vinylimidazole-based asymmetric ion pair comonomers (IPCs) which are free from nonpolymerizable counter ions have been synthesized, characterized and polymerized by free radical polymerization (FRP), atom transfer radical polymerization (ATRP), and reversible addition-fragmentation chain transfer

Chemical modification of polyaniline by N-grafting of polystyrenic chains synthesized via nitroxide-mediated polymerization

International Nuclear Information System (INIS)

Hatamzadeh, Maryam; Mahyar, Ali; Jaymand, Mehdi

2012-01-01

This study aims to explore an effective route for the preparation of conductive N-substituted polyaniline (PANI) by the incorporation of brominated poly(styrene-co-p-methylstyrene) onto the emeraldine form of polyaniline. For this purpose, at first, poly(styrene-co-p-methylstyrene) was synthesized via nitroxide-mediated polymerization (NMP), and then, N-bromosuccinimide was used as brominating agent to obtain a copolymer with bromine. Thereafter, deprotonated polyaniline was reacted with brominated poly(styrene-co-p-methylstyrene) to prepare the poly(styrene-co-p-methylstyrene)-graft-polyaniline [(PSt-co-PMSt)-g-PANI] terpolymer through N-grafting reaction. The terpolymer was characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Optical properties of (PSt-co-PMSt)-g-PANI in the undoped and doped states were obtained by ultraviolet-visible spectroscopy (UV-Vis), and electrical conductivity at room temperature was measured using samples in which the conductive materials was sandwiched between two Ni electrodes. Moreover, electroactivity of the synthesized terpolymer was verified under cyclic voltammetric conditions on the surface of the working glassy carbon electrode (GCE). The solubility of (PSt-co-PMSt)-g-PANI terpolymer was examined in common organic solvents, such as, tetrahydrofuran (THF), chloroform and xylene. (author)

Synthesis and polymerization of vinyl triazolium ionic liquids

Science.gov (United States)

Luebke, David; Nulwala, Hunaid; Matyjaszewski, Krzysztof; Adzima, Brian

2018-05-15

Herein, we describe polymerized ionic liquids, demonstrate the synthesis of polymerized ionic liquids, and demonstrate the polymerization of triazolium monomers. One embodiment shows the polymeriazation of the triazolium monomers with bis(trifluoromethanesulfonyl)imide anions. In another embodiment we show the feasibility of copolymerizing with commodity monomers such as styrene using free radical polymerization techniques.

Immobilization of urease on grafted starch by radiation method

International Nuclear Information System (INIS)

Nguyenanh Dung; Nguyendinh Huyen

1995-01-01

The acrylamide was grafted by radiation onto starch which is a kind of polymeric biomaterial. The urease was immobilized on the grafted starch. Some experiments to observe the quantitative relationships between the percent graft and the activity of immobilized enzyme were determined. The enzyme activity was maintained by more than seven batch enzyme reactions. (author)

Interfacial Polymerization of Polyaniline Nanofibers Grafted to Au Surfaces

National Research Council Canada - National Science Library

Sawall, D

2004-01-01

.... The in-situ polymerization technique of these PANI nanofibers in the presence of sulfonated polystyrene allowed for the growth of PANI 2-D nanostructures embedded in the polymerized sulfonated host...

Activators generated by electron transfer for atom transfer radical polymerization of styrene in the presence of mesoporous silica nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Khezri, Khezrollah, E-mail: kh.khezri@ut.ac.ir [School of Chemistry, University College of Science, University of Tehran, PO Box 14155-6455, Tehran (Iran, Islamic Republic of); Roghani-Mamaqani, Hossein [Department of Polymer Engineering, Sahand University of Technology, PO Box 51335-1996, Tabriz (Iran, Islamic Republic of)

2014-11-15

Graphical abstract: Effect of mesoporous silica nanoparticles (MCM-41) on the activator generated by electron transfer for atom transfer radical polymerization (AGET ATRP) is investigated. Decrement of conversion and number average molecular weight and also increment of polydispersity index (PDI) values are three main results of addition of MCM-41 nanoparticles. Incorporation of MCM-41 nanoparticles in the polystyrene matrix can clearly increase thermal stability and decrease glass transition temperature of the nanocomposites. - Highlights: • Spherical morphology, hexagonal structure, and high surface area with regular pore diameters of the synthesized MCM-41 nanoparticles are examined. • AGET ATRP of styrene in the presence of MCM-41 nanoparticles is performed. • Effect of MCM-41 nanoparticles addition on the polymerization rate, conversion and molecular weights of the products are discussed. • Improvement in thermal stability of the nanocomposites and decreasing T{sub g} values was also observed by incorporation of MCM-41 nanoparticles. - Abstract: Activator generated by electron transfer for atom transfer radical polymerization was employed to synthesize well-defined mesoporous silica nanoparticles/polystyrene composites. Inherent features of spherical mesoporous silica nanoparticles were evaluated by nitrogen adsorption/desorption isotherm, X-ray diffraction and scanning electron microscopy analysis techniques. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. By the addition of only 3 wt% mesoporous silica nanoparticles, conversion decreases from 81 to 58%. Similarly, number average molecular weight decreases from 17,116 to 12,798 g mol{sup −1}. However, polydispersity index (PDI) values increases from 1.24 to 1.58. A peak around 4.1–4.2 ppm at proton nuclear magnetic resonance spectroscopy results clearly confirms the living nature of the polymerization. Thermogravimetric

Radiation grafting of dimethylaminopropylacrylamide and dimethylaminopropylmethacrylamide onto polyethylene

Energy Technology Data Exchange (ETDEWEB)

Burillo, Guillermina; Oseguera, M.A. [UNAM, Inst. de Ciencias Nucleares, Mexico City (Mexico); Vazquez, Carmen; Castillo, L.P. del [UNAM, Inst. de Investigaciones en Materiales, Mexico City (Mexico)

1997-11-01

Radiation-induced grafting of dimethylaminopropylacrylamide and dimethylamino-propylmethacrylamide onto polyethylene films, by direct grafting of the vinyl monomers to a polymer by mutual irradiation, has been investigated. The kinetics of the reaction were studied at different irradiation temperatures, monomer concentration and dose rates of gamma rays, and the appropriate reaction conditions for graft polymerization were determined. The thermal and mechanical behavior of the grafted films by means of DMA, TMA, DSC and TGA were also investigated. (author).

Toward transparent nanocomposites based on polystyrene matrix and PMMA-grafted CeO2 nanoparticles.

Science.gov (United States)

Parlak, Onur; Demir, Mustafa M

2011-11-01

The association of transparent polymer and nanosized pigment particles offers attractive optical materials for various potential and existing applications. However, the particles embedded into polymers scatter light due to refractive index (RI) mismatch and reduce transparency of the resulting composite material. In this study, optical composites based on polystyrene (PS) matrix and poly(methyl methacrylate) (PMMA)-grafted CeO(2) hybrid particles were prepared. CeO(2) nanoparticles with an average diameter of 18 ± 8 nm were precipitated by treating Ce(NO(3))·6H(2)O with urea in the presence of a polymerizable surfactant, 3-methacyloxypropyltrimethoxy silane. PMMA chains were grafted on the surface of the nanoparticles upon free radical in situ solution polymerization. While blending of unmodified CeO(2) particles with PS resulted in opaque films, the transparency of the composite films was remarkably enhanced when prepared by PMMA-grafted CeO(2) hybrid particles, particularly those having a PMMA thickness of 9 nm. The improvement in transparency is presumably due to the reduction in RI mismatch between CeO(2) particles and the PS matrix when using PMMA chains at the interface.

Models for formation of macroheterogeneous structure in radiation-grafted polymers

International Nuclear Information System (INIS)

Babkin, I.Yu.; Burukhin, S.B.; Maksimov, A.F.

1994-01-01

Mathematical models, which describe the formation of grafted polymer layer with respect to variations in sorption and kinetic characteristics due to the changes in composition of the modified polymer and grafted polymer under variable boundary conditions were obtained. The influence of heat effect of polymerization reaction on concentration profiles was estimated. Taking into account the nonlinear diffusion kinetics, the conditions providing diffuse and step profiles of concentration of grafted polymer in polymer matrix were revealed. Step concentration profiles were shown to be associated with a nonlinear dependence of diffusion and kinetic parameters of polymerization on the composition of modified polymer. 22 refs.; 11 figs.; 2 tabs

In Situ Investigation of Electrochemically Mediated Surface-Initiated Atom Transfer Radical Polymerization by Electrochemical Surface Plasmon Resonance.

Science.gov (United States)

Chen, Daqun; Hu, Weihua

2017-04-18

Electrochemically mediated atom transfer radical polymerization (eATRP) initiates/controls the controlled/living ATRP chain propagation process by electrochemically generating (regenerating) the activator (lower-oxidation-state metal complex) from deactivator (higher-oxidation-state metal complex). Despite successful demonstrations in both of the homogeneous polymerization and heterogeneous systems (namely, surface-initiated ATRP, SI-ATRP), the eATRP process itself has never been in situ investigated, and important information regarding this process remains unrevealed. In this work, we report the first investigation of the electrochemically mediated SI-ATRP (eSI-ATRP) by rationally combining the electrochemical technique with real-time surface plasmon resonance (SPR). In the experiment, the potential of a SPR gold chip modified by the self-assembled monolayer of the ATRP initiator was controlled to electrochemically reduce the deactivator to activator to initiate the SI-ATRP, and the whole process was simultaneously monitored by SPR with a high time resolution of 0.1 s. It is found that it is feasible to electrochemically trigger/control the SI-ATRP and the polymerization rate is correlated to the potential applied to the gold chip. This work reveals important kinetic information for eSI-ATRP and offers a powerful platform for in situ investigation of such complicated processes.

PVDF multifilament yarns grafted with polystyrene induced by γ-irradiation: Influence of the grafting parameters on the mechanical properties

International Nuclear Information System (INIS)

Marmey, P.; Porte, M.C.; Baquey, Ch.

2003-01-01

The development of alternative prosthetic materials for cardiovascular applications has found growing interest due to the failure to date to be able to implement functional patent small diameter vascular grafts (diameter <5 mm). For instance, the successful implantation of small diameter polyester (PET) and expanded polytetrafluoroethylene (PTFEe) vascular grafts has not been achieved in humans. Our strategy is to work with a new multifilament yarns biomaterial, produced from polyvinylidene fluoride (PVDF), which shows suitable mechanical properties, such as a lower tensile modulus than PET and PTFEe. The required biological properties sought for (i.e. low thrombogenicity) could be achieved by 'heparin-like' surface modification treatments in order to modify the thrombogenicity levels of the polymeric materials [Ann. Biomed. Eng. 7 (1979) 429]. A four step method is necessary to achieve this 'heparin-like' surface transformation [J. Biomed. Mater. Res. 52 (2000) 119]. The first step consists in grafting polystyrene onto the PVDF surface by γ irradiation. The purpose of this study was to evaluate the influence of grafting parameters on the mechanical properties: (i) γ-ray irradiation time and (ii) grafting time of styrene monomers, which polymerize and form polystyrene bound to the PVDF surface

Thermoplastic elastomers via controlled radical graft polymerization

NARCIS (Netherlands)

Tuzcu, G.

2012-01-01

Rubbery behavior with a consistent modulus over a wide temperature range is a challenge in the search for ultimate structure-property relations of thermoplastic elastomers (TPEs). This feature is closely related to the phase separation behavior of the constitutional segments and the Tg of the

Polar-Nonpolar Radical Copolymerization under Li+ Catalysis

Science.gov (United States)

2008-09-21

bonds or aromatic rings. Thus, we propose that a transfer of a methyl radical from CB11Me12C to IB triggers a radical polymerization chain that yields ...b-PIB and the resulting CB11Me11 byproduct concurrently triggers a cationic polymerization chain that yields l-PIB terminated with a carborate anion...tetrahydrofuran and passed through a column of alumina about five times to remove the bulk of the catalyst. A Soxhlet apparatus was used to recover

13C Kinetic isotopic effect of polymerization on monomers with multiple bond

International Nuclear Information System (INIS)

Berman, E.L.; Polyakov, V.B.; Makovetskij, K.L.; Golenko, T.G.; Galimov, Eh.M.; AN SSSR, Moscow. Inst. Organicheskoj Khimii; AN SSSR, Moscow. Inst. Geokhimii i Analiticheskoj Khimii)

1988-01-01

13 C kinetic isotopic effect (KIE) of anionic and radical polymerization and metathesis reaction of monomers with multiple bonds are studied and correlation between the found KIE values of polymerization and the structure of transition state is established. 13 C KIE of polymerization reactions are investigated using monomers with natural content of the isotope. Polymerization was carried out using high-vacuum equipment: radical polymerization of methyl acrylate (MA) and vinyl acetate in benzene solution under the effect of benzoyl peroxide (60 deg C); anionic polymerization of MA, initiated by potassium butyl cellosolvolate, was realized in mass at 25 deg C; cyclopentene metathesis reaction was conducted in benzene under the effect of initiating system WCl 6 - (C 3 H 5 ) 2 Si(CH 3 ) 2 at -30 deg C; phenylacetylene polymers were prepared by polymerization in benzene solution at 20 deg C under the effect of WCl 6 . It is ascertained that 13 C KIE of radical and anionic polymerization of olefins and cycloolefin metathesis constitutes 2.0 -2.4%. Polymerization of compound with ternary bond is accompanied by a lower value of 13 C KIE (<1%), which is explained by double bond of reacting bond in transition state

Three Arm Star Homo- And Co-Polymers Via Atom Transfer Radical Polymerization

International Nuclear Information System (INIS)

Amin, A.; Sobh, R.A.; Ayoub, M.M.H.

2005-01-01

Star homo and co-polymers of some vinyl monomers such as methylmethacrylate, butylmethacrylate and styrene (MMA, BMA, St.) were prepared using N, N, N', N' tetramethylethylenediamine ligand/ CuBr catalytic system via atom transfer radical polymerization (ATRP). Three armed benzene based core was successfully used as initiator. Low polydispersities and regular molecular weight values were obtained in most cases especially at low conversions. MMA and BuMA showed comparable behavior where controlled and true ATRP was observed even at the high conversions. However, styrene monomer recorded irregular high polydispersities at high conversions in spite of the relatively low molecular weight values. 1HNMR confirmed the structures of the resulting polymers. Transmission Electron microscope (TEM) proved the nano-structure of the star polymers. The thermal behavior of the MMA star homo and copolymers was studied. The effect of the star shape on the thermal behavior was very clear with respect to the linear ones

Reversible-Deactivation Radical Polymerization of Methyl Methacrylate Induced by Photochemical Reduction of Various Copper Catalysts

Directory of Open Access Journals (Sweden)

Jaroslav Mosnáček

2014-11-01

Full Text Available Photochemically mediated reversible-deactivation radical polymerization of methyl methacrylate was successfully performed using 50–400 ppm of various copper compounds such as CuSO4·5H2O, copper acetate, copper triflate and copper acetylacetonate as catalysts. The copper catalysts were reduced in situ by irradiation at wavelengths of 366–546 nm, without using any additional reducing agent. Bromopropionitrile was used as an initiator. The effects of various solvents and the concentration and structure of ligands were investigated. Well-defined polymers were obtained when at least 100 or 200 ppm of any catalyst complexed with excess tris(2-pyridylmethylamine as a ligand was used in dimethyl sulfoxide as a solvent.

Synthesis of Amphiphilic Copolymwers by Atom Transfer Radical Polymerization

DEFF Research Database (Denmark)

Hansen, Natanya Majbritt Louie

2007-01-01

Fluorerede polymerer besidder en række enestående egenskaber såsom god biokom-patibilitet og lav overfladeenergi såvel som god kemisk og termisk stabilitet. Målsæt-ningen for denne afhandling var at fremstille fluorerede polymerer og copolymerer, der potentielt kunne finde anvendelse som...... egenskaber der genfindes i homopolymerer af den dominerende monomer i copolymeren. Som indikation af de nye materialers mulige vekselvirkning med omgivelserne udførtes omfattende studier af kontaktvinkler. Film fremstillet af de fluorerede copolymerer og polymerer udviste øget hydrofobicitet (vandafvisning...

Semi-interpenetrating network of acrylamide-grafted-sodium alginate microspheres for controlled release of diclofenac sodium, preparation and characterization.

Science.gov (United States)

Al-Kahtani, Ahmed A; Sherigara, B S

2014-03-01

The semi-interpenetrating networks (semi-IPNs) of acrylamide grafted sodium alginate (AAm-g-NaAlg) microspheres (MPs) were prepared by emulsion-crosslinking method using glutaraldehyde (GA) as a crosslinking agent. The grafting of acrylamide onto sodium alginate was prepared by free-radical graft polymerization using ceric ammonium nitrate (CAN) as initiator at three acrylamide concentrations with monomer to polymer ratio of 1:1, 2:1 and 3:1, respectively. The grafting efficiency was found to be 91%. The produced MPs are almost spherical in nature with smooth surfaces. Diclofenac sodium (DS), an anti-inflammatory drug was successfully encapsulated into the MPs. The encapsulation efficiency was found to vary between 83% and 95%. The MPs were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The diffusion coefficient (D) was dependent upon the amount of crosslinking agent (GA) and amount of grafting ratio in the matrix. The rate of release was found to be dependent on the amount of GA, AAm:NaAlg grafting ratio and % drug loading in the MPs. The release data have been fitted to an empirical equation to investigate the diffusional exponent (n), which indicated that the release mechanism from MPs follows the super Case II transport. Copyright © 2013 Elsevier B.V. All rights reserved.

Graft copolymers of ethyl methacrylate on waxy maize starch derivatives as novel excipients for matrix tablets: physicochemical and technological characterisation.

Science.gov (United States)

Marinich, J A; Ferrero, C; Jiménez-Castellanos, M R

2009-05-01

Nowadays, graft copolymers are being used as an interesting option when developing a direct compression excipient for controlled release matrix tablets. New graft copolymers of ethyl methacrylate (EMA) on waxy maize starch (MS) and hydroxypropylstarch (MHS) were synthesised by free radical polymerization and alternatively dried in a vacuum oven (OD) or freeze-dried (FD). This paper evaluates the performance of these new macromolecules and discusses the effect of the carbohydrate nature and drying process on their physicochemical and technological properties. Grafting of EMA on the carbohydrate backbone was confirmed by IR and NMR spectroscopy, and the grafting yields revealed that graft copolymers present mainly a hydrophobic character. The graft copolymerization also leads to more amorphous materials with larger particle size and lower apparent density and water content than carbohydrates (MS, MHS). All the products show a lack of flow, except MHSEMA derivatives. MSEMA copolymers underwent much plastic flow and less elastic recovery than MHSEMA copolymers. Concerning the effect of drying method, FD derivatives were characterised by higher plastic deformation and less elasticity than OD derivatives. Tablets obtained from graft copolymers showed higher crushing strength and disintegration time than tablets obtained from raw starches. This behaviour suggests that these copolymers could be used as excipients in matrix tablets obtained by direct compression and with a potential use in controlled release.

Engineering a horseradish peroxidase C stable to radical attacks by mutating multiple radical coupling sites.

Science.gov (United States)

Kim, Su Jin; Joo, Jeong Chan; Song, Bong Keun; Yoo, Young Je; Kim, Yong Hwan

2015-04-01

Peroxidases have great potential as industrial biocatalysts. In particular, the oxidative polymerization of phenolic compounds catalyzed by peroxidases has been extensively examined because of the advantage of this method over other conventional chemical methods. However, the industrial application of peroxidases is often limited because of their rapid inactivation by phenoxyl radicals during oxidative polymerization. In this work, we report a novel protein engineering approach to improve the radical stability of horseradish peroxidase isozyme C (HRPC). Phenylalanine residues that are vulnerable to modification by the phenoxyl radicals were identified using mass spectrometry analysis. UV-Vis and CD spectra showed that radical coupling did not change the secondary structure or the active site of HRPC. Four phenylalanine (Phe) residues (F68, F142, F143, and F179) were each mutated to alanine residues to generate single mutants to examine the role of these sites in radical coupling. Despite marginal improvement of radical stability, each single mutant still exhibited rapid radical inactivation. To further reduce inactivation by radical coupling, the four substitution mutations were combined in F68A/F142A/F143A/F179A. This mutant demonstrated dramatic enhancement of radical stability by retaining 41% of its initial activity compared to the wild-type, which was completely inactivated. Structure and sequence alignment revealed that radical-vulnerable Phe residues of HPRC are conserved in homologous peroxidases, which showed the same rapid inactivation tendency as HRPC. Based on our site-directed mutagenesis and biochemical characterization, we have shown that engineering radical-vulnerable residues to eliminate multiple radical coupling can be a good strategy to improve the stability of peroxidases against radical attack. © 2014 Wiley Periodicals, Inc.

Development of Highly Efficient Grafting Technique and Synthesis of Natural Polymer-Based Graft Adsorbent

Energy Technology Data Exchange (ETDEWEB)

Ueki, Y; Seko, N; Tamada, M [Japan Atomic Energy Agency, Quantum Beam Science Directorate, Takasaki (Japan)

2012-09-15

In the framework of the CRP, Japan has focused on the development of fibrous adsorbents for removal of toxic metal ions and recovery of significant metal ions from industrial wastewater and streaming water. Graft polymerization was carried out by using gamma irradiation facility and electron beam accelerator. Emulsion grafting is a novel topic for synthesis of metal ion adsorbents which are prepared from fibrous trunk polymers such as polyethylene fibre and biodegradable nonwoven fabrics. The emulsion grafting, where monomer micelles are dispersed in water in the presence of surfactant, is a highly efficient and economic grafting technique as compared to general organic solvent system. The resultant cotton-based adsorbent has high adsorption efficiency and high adsorption capacity for Hg, besides, it is biodegradable. Polylactic acid can also be used as a trunk material for the grafting. (author)

Surface-Initiated Atom Transfer Radical Polymerization of Magnetite Nanoparticles with Statistical Poly(tert-butyl acrylate-poly(poly(ethylene glycol methyl ether methacrylate Copolymers

Directory of Open Access Journals (Sweden)

Patcharin Kanhakeaw

2015-01-01

Full Text Available This work presented the surface modification of magnetite nanoparticle (MNP with poly[(t-butyl acrylate-stat-(poly(ethylene glycol methyl ether methacrylate] copolymers (P[(t-BA-stat-PEGMA] via a surface-initiated “grafting from” atom transfer radical polymerization (ATRP. Loading molar ratio of t-BA to PEGMA was systematically varied (100 : 0, 75 : 25, 50 : 50, and 25 : 75, resp. such that the degree of hydrophilicity of the copolymers, affecting the particle dispersibility in water, can be fine-tuned. The reaction progress in each step of the synthesis was monitored via Fourier transform infrared spectroscopy (FTIR. The studies in the reaction kinetics indicated that PEGMA had higher reactivity than that of t-BA in the copolymerizations. Gel permeation chromatography (GPC indicated that the molecular weights of the copolymers increased with the increase of the monomer conversion. Transmission electron microscopy (TEM revealed that the particles were spherical with averaged size of 8.1 nm in diameter. Dispersibility of the particles in water was apparently improved when the copolymers were coated as compared to P(t-BA homopolymer coating. The percentages of MNP and the copolymer in the composites were determined via thermogravimetric analysis (TGA and their magnetic properties were investigated via vibrating sample magnetometry (VSM.

Advances in radiation grafting

International Nuclear Information System (INIS)

Hegazy, El-Sayed A.; AbdEl-Rehim, H.A.; Kamal, H.; Kandeel, K.A.

2001-01-01

Graft copolymerization is an attractive means for modifying base polymers because grafting frequently results in the superposition of properties relating to the backbone and pendent chains. Among the various methods for initiating the grafting reaction, ionizing radiation is the cleanest and most versatile method of grafting available. Ion-exchange membranes play an important role in modern technology, especially in separation and purification of materials. The search for improved membrane composition has considered almost every available polymeric material because of its great practical importance. Grafting of polymers with a mixture of monomers is important since different types of chains containing different functional groups are included. A great deal is focused on the waste treatment of heavy and toxic metals from wastewater because of the severe problems of environmental pollution. Functionalized polymers suitable for metal adsorption with their reactive functional groups such as carboxylic and pyridine groups suitable for waste treatment were prepared by radiation grafting method. More reactive chelating groups were further introduced to the grafted copolymer through its functional groups by chemical treatments with suitable reagents. The advances of radiation grafting and possible uses are briefly discussed

Simple preparation of thiol-ene particles in glycerol and surface functionalization by thiol-ene chemistry (TEC) and surface chain transfer free radical polymerization (SCT-FRP)

DEFF Research Database (Denmark)

Hoffmann, Christian; Chiaula, Valeria; Yu, Liyun

2018-01-01

functionalization of excess thiol groups via photochemical thiol-ene chemistry (TEC) resulting in a functional monolayer. In addition, surface chain transfer free radical polymerization (SCT-FRP) was used for the first time to introduce a thicker polymer layer on the particle surface. The application potential...

Graft Copolymerization of Styrene from Poly(vinyl alcohol via RAFT Process

Directory of Open Access Journals (Sweden)

Gholam Ali Koohmareh

2011-01-01

Full Text Available Polystyrene, PS, was grafted from poly(vinyl alcohol, PVA, backbone by reversible addition-fragmentation chain transfer (RAFT polymerization. The hydroxyl groups of the PVA were converted into aromatic dithioester RAFT agent and polymerization began in the presence of this agent. The structure of compounds was confirmed by FT-IR and 1HNMR spectroscopy. The graft copolymer was characterized by thermogravimetric analysis (TGA, X-ray diffraction (XRD, and scanning electron microscopy (SEM. Grafted polystyrene chains were cleaved from the PVA backbone by acidic hydrolysis of the PVA-g-PS, and its polydispersity index, PDI, was determined by gel permeation chromatography (GPC showing narrow molecular weight distribution.

Obtention of graft copolymers by ionizing radiation, characterization and study of hemo-compatible properties

International Nuclear Information System (INIS)

Queiroz, A.A.A. de.

1993-01-01

The present work had as objectives the obtention and characterization of grafting copolymers by radiation induced polymerization and the study of its hemo compatible properties. The relationship between grafting conditions and anti-trombogenicity was examined for the purpose of clearing the necessity of controlling grafting conditions to enhance the copolymers blood compatibility. Two methods were chosen to accomplish the irradiation: mutual and pre-irradiation (peroxidation) of the films in 6O Co source and electron beam accelerator. Primarily grafting parameters were studied in the systems of the monomers N, N-dimethyl acrylamide (DMAA) and acrylic acid (AA) with the polymeric films: poly (tetrafluoroethylene) (PTFE), poly (ethylene-co-tetrafluoroethylene) (PETFE), low density polyethylene (LDPE) and poly (vinyl chloride) (PVC). The simultaneous irradiation was effective in the polymerization of all the substrates above mentioned, although the peroxidation method has given better results for PETFE-DMAA, LDPE-g-DMAA, LDPE-g-AA and PVC-g-AA. In the system AA/LDPE and AA/PVC the homo polymerization was controlled by the addition of the comonomer N, N-dimethyl acrylic acid (DMA). As for the grafting parameters, low dose rate and low irradiation dose, showed to be very effective for the graftability of DMAA and AA on the substrates. (author). 129 refs, 51 figs, 7 tabs

Synthesis of nanosized (polymerization in miniemulsion employing in situ surfactant formation.

Science.gov (United States)

Guo, Yi; Zetterlund, Per B

2011-10-18

A novel method for synthesis of ultrafine polymeric nanoparticles of diameters less than 20 nm has been developed. The method is based on miniemulsion polymerization exploiting combination of the in situ surfactant generation approach (whereby the surfactant is formed at the oil-water interface by reaction between an organic acid and a base) and ultrasonication. Conventional radical polymerization and nitroxide-mediated radical polymerization of styrene have been conducted in miniemulsion using oleic acid/potassium hydroxide, demonstrating that particles with diameters less than 20 nm can be obtained by this approach at surfactant contents much lower than traditionally required in microemulsion polymerizations. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and enhanced properties of polyaniline/grafted intercalated ZnAl-LDH nanocomposites

Science.gov (United States)

Hu, Jinlong; Gan, Mengyu; Ma, Li; Zhang, Jun; Xie, Shuang; Xu, Fenfang; Shen, JiYue Zheng Xiaoyu; Yin, Hui

2015-02-01

The polymeric nanocomposites (PANI/AD-LDH) were prepared by in situ polymerization based on polyaniline (PANI) and decavanadate-intercalated and γ-aminopropyltriethoxysilane (APTS)-grafted ZnAl-layered double hydroxide (AD-LDH). FTIR and XRD studies confirm the grafting of APTS with decavanadate-intercalated LDH (D-LDH). The extent of grafting (wt%) has also been estimated on the basis of the residue left in nitrogen atmosphere at 800 °C in TGA. SEM and XPS studies show the partial exfoliation of grafted LDH in the PANI matrix and the interfacial interaction between PANI and grafted LDH, respectively. The grafted intercalated layered double hydroxide in reinforcing the properties of the PANI nanocomposites has also been investigated by open circuit potential (OCP), tafel polarization curves (TAF), electrochemical impendence spectroscopy (EIS), salt spray test and TGA-DTA. The experimental results indicate that the PANI/AD-LDH has a higher thermal stability and anticorrosion properties relative to the PANI.

Acrylamide-b-N-isopropylacrylamide block copolymers : Synthesis by atomic transfer radical polymerization in water and the effect of the hydrophilic-hydrophobic ratio on the solution properties

NARCIS (Netherlands)

Wever, Diego Armando Z.; Ramalho, Graham; Picchioni, Francesco; Broekhuis, Antonius Augustinus

2014-01-01

A series of block copolymers of acrylamide and N-isopropylacrylamide (NIPAM) characterized by different ratios between the length of the two blocks have been prepared through atomic transfer radical polymerization in water at room temperature. The solution properties of the block copolymers were

Radiation-induced polymerization of water-saturated styrene in a wide range of dose rate

International Nuclear Information System (INIS)

Takezaki, J.; Okada, T.; Sakurada, I.

1978-01-01

Radiation-induced polymerization of water-saturated styrene (water content 3.5 x 10 -2 mole/liter) was carried out in a wide range of dose rate between 1.2 x 10 3 and 1.8 x 10 7 rad/sec, and compared with the polymerization of the moderately dried styrene (water content 3.2 x 10 -3 mole/liter). Molecular weight distribution curves of the polymerization products showed that they were generally consisted of four parts, namely, oligomers, radical, cationic, and super polymers. Contributions of the four constituents to the polymerization and the number average degrees of polymerization (DP) of the four kinds of polymers were calculated by the graphical analysis of the curves. The rate of radical polymerization and DP of radical polymers are independent of the water content; the dose rate dependences of the polymerization rate and DP agree with the well known square root and inverse square root laws, respectively, of the radical polymerization of styrene. The rate of ionic polymerization is directly proportional to the dose rate, but it decreases, at a given dose rate, inversely proportional to the water content of styrene. DP of ionic polymer is independent of the dose rate but decreases with increasing water content. The super polymer of DP about 10 4 is not formed in the case of the moderately dried styrene. G values for the initiating radical and ion formation are calculated to be independently of the dose rate and water content, 0.66 and 0.027, respectively. It was suggested that oligomer was formed in the early stage by the interaction of cation with anion and only those cations which had survived underwent polymerization. 10 figures, 4 tables

Ingenious route for ultraviolet-induced graft polymerization achieved on inorganic particle: Fabricating magnetic poly(acrylic acid) densely grafted nanocomposites for Cu{sup 2+} removal

Energy Technology Data Exchange (ETDEWEB)

Zhou, Qi, E-mail: roundzking@163.com [School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai, 200444 (China); Luo, Wenjun [Faculty of Material and Chemistry, China University of Geosciences, Wuhan, 430074 (China); Zhang, Xing [School of Environmental and Chemical Engineering, Shanghai University, 333 Nanchen Road, Shanghai, 200444 (China)

2017-08-15

Highlights: • A novel PAA brushes-decorated magnetic adsorbent was prepared successfully. • The preparation approach was simple, rapid, and efficient. • Densely polymer grafting can be achieved on inorganic substrate by the method. • The g-MNPs exhibits an outstanding adsorption performance for Cu{sup 2+}. • The Cu{sup 2+}-saturated adsorbent can be separated and regenerated easily. - Abstract: In this study, ultraviolet (UV)-induced graft technology is improved to be successfully applied on inorganic substrate for fabricating a novel poly(acrylic acid) (PAA) brushes-decorated magnetic nano-composite particles (g-MNPs) as a potential adsorbent toward Cu{sup 2+} ion. The most fascinating features of the resultant g-MNPs are the abundant and highly accessible carboxyl groups present in PAA brushes and the rapid separation from the medium by magnetic field after adsorption. Through the new and high-efficiency surface-initiated polymerization route, the densely PAA brushes was successfully immobilized on the MNPs surface with a high grafting yield of 88.3%. Excitingly, the g-MNPs exhibited an exceptional performance for Cu{sup 2+} adsorption, e.g., ultrahigh adsorption capacity (up to 152.1 mg g{sup −1}), rapid adsorption rate (within 30 min) and low residual concentration (below 1.3 ppm). Full kinetic and isotherm analysis as well as thermodynamic study were also undertaken, the results showed that Cu{sup 2+} adsorption followed Langmuir isotherm and the pseudo-second-order kinetic model, the adsorption rate was controlled by two sequential periods of external and intraparticle diffusion. According to the calculated value of thermodynamic parameters, the Cu{sup 2+} adsorption onto g-MNPs was a spontaneous endothermic process. Furthermore, the excellent reusability of the resultant adsorbent was also confirmed, which can keep above 95% adsorption capacity and desorption rate in 8 consecutive cycles.

Synthesis of a hollow fiber type porous chelating resin containing the amide oxime group by radiation induced graft polymerization for the uranium recovery

International Nuclear Information System (INIS)

Hori, Takahiro; Saito, Kyoichi; Furusaki, Shintaro; Sugo, Takanobu; Okamoto, Jiro.

1986-01-01

A hollow fiber type porous chelating resin containing amide oxime as a functional group was synthesized and used as an adsorbent for the recovery of uranium. Hollow fiber type porous polyethylene was used as a base polymer. Acrylonitrile was grafted onto it by the radiation-induced graft polymerization. By changing the reaction time, four kinds of graft polymer were obtained. The degree of grafting ranged from 79 % to 127 %. Each resin was soaked in hydroxylamine solution, and the cyano group was converted to amide oxime group. By elemental analysis, the amount of nitrogen introduced on the graft polymer resin in amidoximation was determined to range from 4.3 mmol to 8.5 mmol per 1 g of base polymer. Most of the nitrogen is considered to belong to the amide oxime group. The pore radius, which was initially distributed broadly from about 500 A to 10000 A for the base polymer, was changed to about 1000 A with narrow distribution by the grafting. The pore volume was 1.2 ∼ 1.4 cm 3 per 1 gram of the amide oxime resin, which was about half of that of the initial base polymer. But the pore volume per 1 g base polymer of the amide oxime resin increased with an increase in the grafting degree, e.g. 4.5 cm 3 /g base polymer at 127 % of grafting degree. Specific surface area, which was 30 m 2 /g in base polymer, decreased with an increase in the grafting degree, e.g. 15 m 2 /g at 127 % of grafting degree. Both the amounts of the adsorbed hydrochloric acid and the adsorbed copper were about 1.5 times of the amount of nitrogen introduced in the amidoximation. The reason is considered to be caused by the formation of hydroxamic acid and amide from the measurements of the IR spectra. The amount of uranium adsorbed on the resin was 64 % of the amount of nitrogen introduced in the amidoximation. (author)

Self-Propagating Frontal Polymerization in Water at Ambient Pressure

Science.gov (United States)

Olten, Nesrin; Kraigsley, Alison; Ronney, Paul D.

2003-01-01

Advances in polymer chemistry have led to the development of monomers and initiation agents that enable propagating free-radical polymerization fronts to exist. These fronts are driven by the exothermicity of the polymerization reaction and the transport of heat from the polymerized product to the reactant monomer/solvent/initiator solution. The thermal energy transported to the reactant solution causes the initiator to decompose, yielding free radicals, which start the free radical polymerization process as discussed in recent reviews. The use of polymerization processes based on propagating fronts has numerous applications. Perhaps the most important of these is that it enables rapid curing of polymers without external heating since the polymerization process itself provides the high temperatures necessary to initiate and sustain polymerization. This process also enables more uniform curing of arbitrarily thick samples since it does not rely on heat transfer from an external source, which will necessarily cause the temperature history of the sample to vary with distance from the surface according to a diffusion-like process. Frontal polymerization also enables filling and sealing of structures having cavities of arbitrary shape without having to externally heat the structure. Water at atmospheric pressure is most convenient solvent to employ and the most important for practical applications (because of the cost and environmental issues associated with DMSO and other solvents). Nevertheless, to our knowledge, steady, self-propagating polymerization fronts have not been reported in water at atmospheric pressure. Currently, polymerization fronts require a high boiling point solvent (either water at high pressures or an alternative solvent such as dimethyl sulfoxide (DMSO) (boiling point 189 C at atmospheric pressure.) Early work on frontal polymerization, employed pressures up to 5000 atm in order to avoid boiling of the monomer/solvent/initiator solution. High

Albumin grafting on polymer surfaces by gamma-irradiation

International Nuclear Information System (INIS)

Kamath, K.R.; Park, K.; DeMeo, D.

1993-01-01

Polymeric biomaterial surfaces were modified by albumin grafting to improve their blood compatibility. Albumin molecules were functionalized by introduction of double bonds. The functionalized albumin was covalently attached to polypropylene fibers, polycarbonate, and poly(vinyl chloride) by gamma-irradiation. ESCA and ATR/FTIR analysis of the control and grafted surfaces was conducted. Albumin grafting efficiency was found to be dependent on the gamma-irradiation time and the concentration of albumin as indicated by platelet adhesion studies. The grafted albumin molecules were not displaced when exposed to blood for prolonged time period. Finally, PLEXUS oxygenators grafted with albumin using this approach showed a significant reduction in platelet adhesion when compared to control

Polymerization Initiated at the Sidewalls of Carbon Nanotubes

Science.gov (United States)

Tour, James M.; Hudson, Jared L.

2011-01-01

A process has been developed for growing polymer chains via anionic, cationic, or radical polymerization from the side walls of functionalized carbon nanotubes, which will facilitate greater dispersion in polymer matrices, and will greatly enhance reinforcement ability in polymeric material.

Preparation of poly (methyl methacrylate)/nanometer calcium carbonate composite by in-situ emulsion polymerization

Institute of Scientific and Technical Information of China (English)

史建明; 包永忠; 黄志明; 翁志学

2004-01-01

Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate (nano-CaCO3) surface modified with (-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.

Radiation-induced grafting polymerization of MMA onto polybutadiene rubber latex

International Nuclear Information System (INIS)

Peng Jing; Wang Maolin; Qiao Jinliang; Wei Genshuan

2005-01-01

The grafting of methyl methacrylate (MMA) onto polybutadiene rubber latex by the direct radiation method was carried out. The effects of monomer concentration, absorbed dose and dose rate of gamma rays on the grafting yield were investigated. The graft copolymers were characterized by transmission electron microscopy (TEM), FTIR spectroscopy, and differential scanning calorimetry. TEM photographs revealed that the core-shell structures of latex particles are formed at low MMA content, and with the increasing of MMA content, the semi-IPN-like structure with core-shell could be developed due to the high gel fraction of polybutadiene (PBD) seed particles. In addition, infrared analysis confirmed that MMA could be grafted onto PBD molecular chains effectively under appropriate irradiation conditions. The interfacial adhesion between PBD rubber (core) and PMMA (shell) phases could be enhanced with the increase of MMA concentration

Generic Top-Functionalization of Patterned Antifouling Zwitterionic Polymers on Indium Tin Oxide

NARCIS (Netherlands)

Li, Y.; Giesbers, M.; Zuilhof, H.

2012-01-01

This paper presents a novel surface engineering approach that combines photochemical grafting and surface-initiated atom transfer radical polymerization (SI-ATRP) to attach zwitterionic polymer brushes onto indium tin oxide (ITO) substrates. The photochemically grafted hydroxyl-terminated organic

Grafting of acrylamide onto synthetic co polyamide by gamma irradiation

Energy Technology Data Exchange (ETDEWEB)

Hamoud, M R; Qamhieyh, E A [Chemistry Dept., College of Ibn Al-Haitham Baghdad university-Adhamiyah-Baghdad- (Iraq)

1995-10-01

Grafted copolymer was prepared by using gamma irradiation to graft acrylamide onto polymeric molecule prepared by interfacial condensation between two diamine molecules like 1,2 diamino propane and 1,6 diamino-hexane in aqueous layer with sebacoyl chloride in organic layer. The resulted co polyamide was grafted with acrylamide using gamma irradiation. The optimum conditions of grafting reaction were found, also various factors such as the effect of solvents, redox systems and the role water on the radiochemical grafting were studied. Many techniques were used in the characterization of the copolymer before and after grafting. 8 figs.,.

Surface functionalization of solid state ultra-high molecular weight polyethylene through chemical grafting

Science.gov (United States)

Sherazi, Tauqir A.; Rehman, Tayyiba; Naqvi, Syed Ali Raza; Shaikh, Ahson Jabbar; Shahzad, Sohail Anjum; Abbas, Ghazanfar; Raza, Rizwan; Waseem, Amir

2015-12-01

The surface of ultra-high molecular weight polyethylene (UHMWPE) powder was functionalized with styrene using chemical grafting technique. The grafting process was initiated through radical generation on base polymer matrix in the solid state by sodium thiosulfate, while peroxides formed at radical sites during this process were dissociated by ceric ammonium nitrate. Various factors were optimized and reasonably high level of monomer grafting was achieved, i.e., 15.6%. The effect of different acids as additive and divinyl benzene (DVB) as a cross-linking agent was also studied. Post-grafting sulfonation was conducted to introduce the ionic moieties to the grafted polymer. Ion-exchange capacity (IEC) was measured experimentally and is found to be 1.04 meq g-1, which is in close agreement with the theoretical IEC values. The chemical structure of grafted and functionalized polymer was characterized by attenuated total reflection infrared spectroscopy (ATR-FTIR) and thermal properties were investigated by thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Thermal analysis depicts that the presence of radicals on the polymer chain accelerates the thermal decomposition process. The results signify that the chemical grafting is an effective tool for substantial surface modification and subsequent functionalization of polyethylene.

Grafting of poly[(methyl methacrylate)-block-styrene] onto cellulose via nitroxide-mediated polymerization, and its polymer/clay nanocomposite.

Science.gov (United States)

Karaj-Abad, Saber Ghasemi; Abbasian, Mojtaba; Jaymand, Mehdi

2016-11-05

For the first time, nitroxide-mediated polymerization (NMP) was used for synthesis of graft and block copolymers using cellulose (Cell) as a backbone, and polystyrene (PSt) and poly(methyl metacrylate) (PMMA) as the branches. For this purpose, Cell was acetylated by 2-bromoisobutyryl bromide (BrBiB), and then the bromine group was converted to 4-oxy-2,2,6,6-tetramethylpiperidin-1-oxyl group by a substitution nucleophilic reaction to afford a macroinitiator (Cell-TEMPOL). The macroinitiator obtained was subsequently used in controlled graft and block copolymerizations of St and MMA monomers to yield Cell-g-PSt and Cell-g-(PMMA-b-PSt). The chemical structures of all samples as representatives were characterized by FTIR and (1)H NMR spectroscopies. In addition, Cell-g-(PMMA-b-PSt)/organophilic montmorillonite nanocomposite was prepared through a solution intercalation method. TEM was used to evaluate the morphological behavior of the polymer-clay system. It was demonstrated that the addition of small percent of organophilic montmorillonite (O-MMT; 3wt.%) was enough to improve the thermal stability of the nanocomposite. Copyright © 2016 Elsevier Ltd. All rights reserved.

Proficiency feasibility of multi-walled carbon nanotubes in the presence of polymeric surfactant on enhanced oil recovery

Science.gov (United States)

Nezhad, Javad Razavi; Jafari, Arezou; Abdollahi, Mahdi

2018-01-01

Enhanced heavy oil recovery methods are widely utilized to increase oil recovery. For this purpose, polymer and surfactant flooding have been used extensively. Recently, polymeric surfactant flooding has become an attractive alternative to sole polymer flooding due to their capability of providing an increase in solution viscosity and a decrease in interfacial tension, which are both beneficial for efficiency of the process. Applying nanoparticles as an additive to polymer solutions is a method to improve viscosity and alter rock wettability. Therefore, in this research, multi-walled carbon nanotube (MWCNT) was mixed with a polymeric surfactant of polyacrylamide-graft-lignin copolymer (PAM-g-L) synthesized via radical grafting reaction. Moreover, several solutions with different concentrations of nanoparticles with PAM-g-L were prepared. The solutions were injected into a micromodel to evaluate the PAM-g-L flooding efficiency in presence of the multi-walled carbon nanotubes. The results of micromodel flooding showed that increasing MWCNT concentration results in lower sweep efficiencies; and consequently, oil production will decrease. Therefore, MWCNT along with PAM-g-L has an unacceptable performance in enhanced heavy oil recovery. But data of wettability tests revealed that MWCNT can change the wettability from oil-wet to water-wet. In addition, the combination of the PAM-g-L and MWCNT in a solution will cause more water-wet condition.

Radiation induced graft copolymerization of vinyl monomers onto synthetic polymeric films

International Nuclear Information System (INIS)

Chauhan, G.S.; Kaur, Inderjeet; Misra, B.N.

1997-01-01

Polyethylene (PE) and polyamide (PA) films have been modified by radiochemical grafting of methylacrylate (MA), ethylacrylate (EA), methyl methacrylate (MMA) and ethyl methacrylate (EMA) in aqueous medium in air. Grafted films show increased area and lower thermal stability. The swelling behaviour of these films vary as a function of percent grafting (P g ). (author). 8 refs., 1 tab

Effect of storage conditions on graft of polypropylene non-woven fabric induced by electron beam

Energy Technology Data Exchange (ETDEWEB)

Lee, Jin Young; Jeun, Joon Pyo; Kang, Phil Hyun [Radiation Research Dvision for Industry and Environment, Korea Atomic Energy Research Institute, Jeongeup(Korea, Republic of)

2015-05-15

In this study, we fabricated effect of storage conditions on graft of polypropylene (PP) non-woven fabric induced by electron beam. The electron beam irradiations on PP non-woven fabric were carried out over a range of irradiation doses from 25 to 100 kGy to make free radicals on fabric surface. The radical measurement was established by electron spin resonance (ESR) for confirming the changes of the alkyl radical and peroxy radical according to effect of storage time, storage temperature and atmosphere. It was observed that the free radicals were increased with irradiation dose and decreased with storage time due to the continuous oxidation. However, the radical extinction was significantly delayed due to reduced mobility of radicals at extremely low temperature. The degree of graft based on the analysis of ESR was investigated. The conditions of graft reaction were set at a temperature: 60 degrees Celcius, reaction time: 6 hours and styrene monomer concentration: 20 wt%.

Graft copolymerization of N-vinyl-2-pyrrolidone onto pre-irradiated poly(vinylidene fluoride) powder

International Nuclear Information System (INIS)

Xu Chenqi; Huang Wei; Zhou Yongfeng; Yan Deyue; Chen Shutao; Huang Hua

2012-01-01

Graft copolymerization of N-vinyl-2-pyrrolidone (NVP) onto 60 Co γ-ray pre-irradiated poly (vinylidene fluoride) (PVDF) powder was investigated to find out the relationship between the degree of grafting (DG) and various factors, including monomer concentration, irradiation dose, reaction time, catalyst and so on. The DG can be calculated by comparing the amount of nitrogen element in the resulting copolymer (PVDF-g-PVP) powder with that in PVP on the basis of element analysis. The presence of PVP in the resulting PVDF powder was confirmed by the comparative studies of pristine PVDF and grafted PVDF powder through Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), thermo gravimetric analyzer (TGA) and differential scanning calorimetry (DSC), respectively. When the reaction was performed at the monomer concentration of 20% (vol.) and the absorbed dose of 40 kGy for 3 h in water, the max. DG of 17.7% was obtained. - Highlights: ► We modify pristine PVDF powders with NVP by the pre-irradiated graft polymerization. ► The various factors influencing the degree of grafting are investigated in detail. ► The optimal condition of graft polymerization is obtained. ► The polymerization is processed at 20% (vol.) of NVP and 40kGy for 3 hours in water. ► The maximum degree of grafting is 17.7 % at such a condition.

Time-resolved small-angle neutron scattering study on soap-free emulsion polymerization

Energy Technology Data Exchange (ETDEWEB)

Motokawa, Ryuhei [Research Group of Soft Matter and Neutron Scattering, Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Koizumi, Satoshi [Research Group of Soft Matter and Neutron Scattering, Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan)]. E-mail: koizumi@neutrons.tokai.jaeri.go.jp; Hashimoto, Takeji [Research Group of Soft Matter and Neutron Scattering, Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Nakahira, Takayuki [Department of Applied Chemistry and Biotechnology, Chiba University, Chiba-shi, Chiba 263-8522 (Japan); Annaka, Masahiko [Department of Chemistry, Kyushu University, Fukuoka 812-8581 (Japan)

2006-11-15

We investigated an aqueous soap-free emulsion polymerization process of Poly(N-isopropylacrylamide)-block-poly(ethylene glycol) by ultra-small-angle and time-resolved small-angle neutron scattering methods. The results indicate that the compartmentalization of chain end radicals into solid-like micelle cores crucially leads to the quasi-living behavior of the radical polymerization by prohibiting recombination process.

Thermo-responsive poly(N-isopropylacrylamide)-grafted hollow fiber membranes for osteoblasts culture and non-invasive harvest

Energy Technology Data Exchange (ETDEWEB)

Zhuang, Meiling, E-mail: zhuangmeiling2006@126.com; Liu, Tianqing, E-mail: liutq@dlut.edu.cn; Song, Kedong, E-mail: kedongsong@dlut.edu.cn; Ge, Dan, E-mail: gedan@dlut.edu.cn; Li, Xiangqin, E-mail: xiangqinli@163.com

2015-10-01

Hollow fiber membrane (HFM) culture system is one of the most important bioreactors for the large-scale culture and expansion of therapeutic cells. However, enzymatic and mechanical treatments are traditionally applied to harvest the expanded cells from HFMs, which inevitably causes harm to the cells. In this study, thermo-responsive cellulose acetate HFMs for cell culture and non-invasive harvest were prepared for the first time via free radical polymerization in the presence of cerium (IV). ATR-FTIR and elemental analysis results indicated that the poly(N-isopropylacrylamide) (PNIPAAm) was covalently grafted on HFMs successfully. Dynamic contact angle measurements at different temperatures revealed that the magnitude of volume phase transition was decreased with increasing grafted amount of PNIPAAm. And the amount of serum protein adsorbed on HFMs surface also displayed the same pattern. Meanwhile osteoblasts adhered and spread well on the surface of PNIPAAm-grafted HFMs at 37 °C. And Calcein-AM/PI staining, AB assay, ALP activity and OCN protein expression level all showed that PNIPAAm-grafted HFMs had good cell compatibility. After incubation at 20 °C for 120 min, the adhering cells on PNIPAAm-grafted HFMs turned to be round and detached after being gently pipetted. These results suggest that thermo-responsive HFMs are attractive cell culture substrates which enable cell culture, expansion and the recovery without proteolytic enzyme treatment for the application in tissue engineering and regenerative medicine. - Highlights: • PNIPAAm-grafted HFMs exhibited thermoresponsive characteristic. • The OB cells could adhere and spread well on the surface of PNIPAAm-grafted HFMs. • PNIPAAm-grafted HFMs do not significantly impact ALP activity and OCN protein expression level of OB cells. • Cell could be detached from PNIPAAm-grafted HFMs when temperature decreased from 37 °C to 20 °C.

Control of Polymer Nanostructure and Functionality via Radiation Grafting

International Nuclear Information System (INIS)

Palmese, G.R.

2006-01-01

Radiation grafting provides a useful means for controlling polymer structure and performance. Particularly, it is appropriate for combining materials with distinct thermodynamic characteristics chemically at interfaces. Therefore polymeric materials that generally will not mix - i.e hydrophilic and hydrophobic polymers - can be combined efficiently using radiation based methods. This is of particular importance when attempting to form polymer-polymer nanocomposites where the thermodynamic penalty associated with high specific interfacial surface area is very large. Generally, the combination at small scales of such distinct materials is appropriate when specific functionality is desired while maintaining structural performance characteristics. In such cases the hydrophilic polymer lends functional characteristics such as ionic conductivity, self-healing, and actuation, while the hydrophobic polymer component provides structural stability. In this communication a summary of our recent work concerning the use of radiation grafting for the synthesis of nanostructured functional materials is given. Examples to be discussed include toughing of polymeric systems, the synthesis polymeric and inorganic nanotubes, and the design of permeation selective membranes. These examples will be used to demonstrate the effectiveness of radiation grafting techniques for controlling polymer properties and small-scale structure

Synthesis of Specific Nanoparticles for Targeting and Imaging Tumor Angiogenesis Using Electron-Beam Irradiation

Energy Technology Data Exchange (ETDEWEB)

Rizza, G.; Deshayes, S.; Maurizot, V.; Clochard, M. -C.; Berthelot, T.; Baudin, C.; Déléris, G., E-mail: giancarlo.rizza@polytechnique.edu [Commissariat à l' énergie atomique (CEA), Institut Rayonnement Matière de Saclay (IRaMIS), B.P. 52, 91191 Gif Sur Yvette Cedex (France)

2010-07-01

We have succeeded to synthesize PVDF nanoparticles by nanoemulsion polymerization and their functionalization with a peptide that presents an anti-angiogenic activity. Resulted nanoparticles present a radius of 60 nm. From FESEM images and light scattering measurements, we deduced that they were spherical and monodisperse. The alkyl radicals induced from electron beam irradiation combine immediately with the oxygen to form peroxide radicals. Because of a high specific area and small crystallite size, the radical decay with time is evidenced from EPR measurements. Despite this radical decay, electron beam irradiation allows us to graft PAA by radical polymerization onto freshly irradiated PVDF nanoparticles and then to immobilize CBO-P11 by click chemistry via a spacer arm. Evidences of grafting were shown using HRMAS NMR and MALDI-TOF mass spectrometry. Nanoparticles functionalized with an angiogenesis-targeting agent are an attractive option for anti-tumor therapy.

Synthesis of Specific Nanoparticles for Targeting and Imaging Tumor Angiogenesis Using Electron-Beam Irradiation

International Nuclear Information System (INIS)

Rizza, G.; Deshayes, S.; Maurizot, V.; Clochard, M.-C.; Berthelot, T.; Baudin, C.; Déléris, G.

2010-01-01

We have succeeded to synthesize PVDF nanoparticles by nanoemulsion polymerization and their functionalization with a peptide that presents an anti-angiogenic activity. Resulted nanoparticles present a radius of 60 nm. From FESEM images and light scattering measurements, we deduced that they were spherical and monodisperse. The alkyl radicals induced from electron beam irradiation combine immediately with the oxygen to form peroxide radicals. Because of a high specific area and small crystallite size, the radical decay with time is evidenced from EPR measurements. Despite this radical decay, electron beam irradiation allows us to graft PAA by radical polymerization onto freshly irradiated PVDF nanoparticles and then to immobilize CBO-P11 by click chemistry via a spacer arm. Evidences of grafting were shown using HRMAS NMR and MALDI-TOF mass spectrometry. Nanoparticles functionalized with an angiogenesis-targeting agent are an attractive option for anti-tumor therapy

Thermoresponsive Poly(2-oxazoline) Molecular Brushes by Living Ionic Polymerization: Kinetic Investigations of Pendant Chain Grafting and Cloud Point Modulation by Backbone and Side Chain Length Variation

KAUST Repository

Zhang, Ning

2012-04-17

Molecular brushes of poly(2-oxazoline)s were prepared by living anionic polymerization of 2-iso-propenyl-2-oxazoline to form the backbone and subsequent living cationic ring-opening polymerization of 2-n- or 2-iso-propyl-2-oxazoline for pendant chain grafting. In situ kinetic studies indicate that the initiation efficiency and polymerization rates are independent from the number of initiator functions per initiator molecule. This was attributed to the high efficiency of oxazolinium salt and the stretched conformation of the backbone, which is caused by the electrostatic repulsion of the oxazolinium moieties along the macroinitiator. The resulting molecular brushes showed thermoresponsive properties, that is, having a defined cloud point (CP). The dependence of the CP as a function of backbone and side chain length as well as concentration was studied. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Physical properties of agave cellulose graft polymethyl methacrylate

Energy Technology Data Exchange (ETDEWEB)

Rosli, Noor Afizah; Ahmad, Ishak; Abdullah, Ibrahim; Anuar, Farah Hannan [Polymer Research Centre (PORCE), School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi Selangor (Malaysia)

2013-11-27

The grafting polymerization of methyl methacrylate and Agave cellulose was prepared and their structural analysis and morphology were investigated. The grafting reaction was carried out in an aqueous medium using ceric ammonium nitrate as an initiator. The structural analysis of the graft copolymers was carried out by Fourier transform infrared and X-ray diffraction. The graft copolymers were also characterized by field emission scanning electron microscopy (FESEM). An additional peak at 1732 cm{sup −1} which was attributed to the C=O of ester stretching vibration of poly(methyl methacrylate), appeared in the spectrum of grafted Agave cellulose. A slight decrease of crystallinity index upon grafting was found from 0.74 to 0.68 for cellulose and grafted Agave cellulose, respectively. Another evidence of grafting showed in the FESEM observation, where the surface of the grafted cellulose was found to be roughed than the raw one.

Radiation-initiated graft polymerization of methyl acrylate onto chrome-tanned sheepskin

International Nuclear Information System (INIS)

Kaldirimci, C.; Bas, N.

1982-01-01

Radiation grafting method was applied to obtain leather-polymer composite. Grafting of methyl acrylate onto chrome-tanned, bluestock sheepskin was investigated under the initiatory effect of 60 Co radiation of 0.20 11.50 Mrad. The percent of grafting was determined and water adsorption and shrinkage temperature measurements were carried out. It was shown that 2-4 Mrad is convenient to produce leather-polymer composite. (author)

Versatile antifouling polyethersulfone filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive.

Science.gov (United States)

Zhao, Yi-Fan; Zhang, Pei-Bin; Sun, Jian; Liu, Cui-Jing; Yi, Zhuan; Zhu, Li-Ping; Xu, You-Yi

2015-06-15

Here we describe the development of versatile antifouling polyethersulfone (PES) filtration membranes modified via surface grafting of zwitterionic polymers from a reactive amphiphilic copolymer additive. Amphiphilic polyethersulfone-block-poly(2-hydroxyethyl methacrylate) (PES-b-PHEMA) was beforehand designed and used as the blending additive of PES membranes prepared by phase inversion technique. The surface enriched PHEMA blocks on membrane surface acted as an anchor to immobilize the initiating site. Poly(sulfobetaine methacrylate) (PSBMA) were subsequently grafted onto the PES blend membranes by surface-initiated atom transfer radical polymerization (SI-ATRP). The analysis of surface chemistry confirmed the successful grafting of zwitterionic PSBMA brushes on PES membrane surface. The resulted PES-g-PSBMA membranes were capable of separating proteins from protein solution and oil from oil/water emulsion efficiently. Furthermore, the modified membranes showed high hydrophilicity and strongly antifouling properties due to the incorporation of well-defined PSBMA layer. In addition, the PES-g-PSBMA membranes exhibited excellent blood compatibility and durability during the washing process. The developed antifouling PES membranes are versatile and can find their applications in protein filtration, blood purification and oil/water separation, etc. Copyright © 2015 Elsevier Inc. All rights reserved.

Radical-Scavenging Activity of Thiols, Thiobarbituric Acid Derivatives and Phenolic Antioxidants Determined Using the Induction Period Method for Radical Polymerization of Methyl Methacrylate

Directory of Open Access Journals (Sweden)

Seiichiro Fujisawa

2012-04-01

Full Text Available The radical-scavenging activities of two thiols, eight (thiobarbituric acid derivatives and six chain-breaking phenolic antioxidants were investigated using the induction period method for polymerization of methyl methacrylate (MMA initiated by thermal decomposition of 2,2’-azobisisobutyronitrile (AIBN and monitored by differential scanning calorimetry (DSC. The induction period (IP for the thiols 2-mercaptoethanol (ME and 2-mercapto-1-methylimidazole (MMI was about half that for phenolic antioxidants. Except for the potent inhibitor 5,5-dimethyl-2-thiobarbituric acid (3, the IP for thiobarbituric acid derivatives was about one tenth of that for phenolic antioxidants. The IP for 1,3,5-trimethyl-2-thiobarbituric acid (1 and 5-allyl-1, 3-dimethyl-2-thiobarbituric acid (7 was less than that of the control, possibly due to inhibition by a small amount of atmospheric oxygen in the DSC container. The ratio of the chain inhibition to that of chain propagation (CI/CP for the thiols and thiobarbituric acid compounds except for 1, 3 and 7 was about 10 times greater or greater than that for phenolic compounds. A kinetic chain length (KCL about 10% greater than that of the control was observed for 1, suggesting that 1 had chain transfer reactivity in the polymerization of MMA. The average molecular weight of polymers formed from thiobarbituric acid derivatives is discussed.

Polymeric flocculant based on cassava starch grafted polydiallyldimethylammonium chloride: Flocculation behavior and mechanism

Energy Technology Data Exchange (ETDEWEB)

Razali, M.A.A.; Ariffin, A., E-mail: srazlan@usm.my

2015-10-01

Graphical abstract: - Highlights: • Flocculation performance of cassava grafted polyDADMAC was studied. • Turbidity and TSS removal increased with increasing grafting percentage. • The grafted polymer showed good removal in acidic and neutral region. • Zeta potential results pointed to the charge neutralization mechanism. • Flocs increased with increasing grafting percentage and molecular weight. - Abstract: In this work, flocculation properties of cassava starch grafted polydiallyldimethylammonium chloride (polyDADMAC) with different grafting percentages were investigated. Flocculation performance was evaluated in simulated kaolin suspension. The grafting percentages used were 1.76 %, 14.84 %, and 21.98 %. The effectiveness of the flocculation was measured based on the reduction of the turbidity and total suspended solids (TSSs), zeta potential measurements, particle size, and atomic force microscopy imaging. Grafted polymers improved the removal rate of turbidity and TSS compared with gelatinized starch, and the removal rate increased with increasing grafting percentage and dosage.

Polymeric flocculant based on cassava starch grafted polydiallyldimethylammonium chloride: Flocculation behavior and mechanism

International Nuclear Information System (INIS)

Razali, M.A.A.; Ariffin, A.

2015-01-01

Graphical abstract: - Highlights: • Flocculation performance of cassava grafted polyDADMAC was studied. • Turbidity and TSS removal increased with increasing grafting percentage. • The grafted polymer showed good removal in acidic and neutral region. • Zeta potential results pointed to the charge neutralization mechanism. • Flocs increased with increasing grafting percentage and molecular weight. - Abstract: In this work, flocculation properties of cassava starch grafted polydiallyldimethylammonium chloride (polyDADMAC) with different grafting percentages were investigated. Flocculation performance was evaluated in simulated kaolin suspension. The grafting percentages used were 1.76 %, 14.84 %, and 21.98 %. The effectiveness of the flocculation was measured based on the reduction of the turbidity and total suspended solids (TSSs), zeta potential measurements, particle size, and atomic force microscopy imaging. Grafted polymers improved the removal rate of turbidity and TSS compared with gelatinized starch, and the removal rate increased with increasing grafting percentage and dosage

Surface grafted polymer brushes: potential applications in dengue biosensors

Energy Technology Data Exchange (ETDEWEB)

Baratela, Fernando Jose Costa; Higa, Olga Zazuco, E-mail: ozahiga@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Faria, Henrique Antonio Mendonca de; Queiroz, Alvaro Antonio Alencar de, E-mail: alencar@unifei.edu.br [Universidade Federal de Itajuba (UNIFEI), Itajuba, MG (Brazil). Instituto de Fisica e Quimica

2013-07-01

A polymer brush membrane-based ultrasensitive biosensor for dengue diagnosis was constructed using poly(hydroxyethyl methacrylate) (PHEMA) brushes immobilized onto low density polyethylene (LDPE) films. LDPE surface films were initially modified by Ar{sup +} ion irradiation to activate the polymer surface. Subsequently, graft polymerization of 2-hydroxyethyl methacrylate onto the activated LDPE surface was carried out under aqueous conditions to create patterned polymer brushes of PHEMA. The grafted PHEMA brushes were characterized by Fourier transform-infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle analysis. The SEM observations showed that selective surface activation with Ar+ implantation and graft polymerization on the selectively activated surface had occurred. The PHEMA brushes were electrically characterized in the presence of concentrations of human immunoglobulin (IgG). The proposed amperometric biosensor was successfully used for determination of IgG in physiologic samples with excellent responses. (author)

Surface grafted polymer brushes: potential applications in dengue biosensors

International Nuclear Information System (INIS)

Baratela, Fernando Jose Costa; Higa, Olga Zazuco; Faria, Henrique Antonio Mendonca de; Queiroz, Alvaro Antonio Alencar de

2013-01-01

A polymer brush membrane-based ultrasensitive biosensor for dengue diagnosis was constructed using poly(hydroxyethyl methacrylate) (PHEMA) brushes immobilized onto low density polyethylene (LDPE) films. LDPE surface films were initially modified by Ar + ion irradiation to activate the polymer surface. Subsequently, graft polymerization of 2-hydroxyethyl methacrylate onto the activated LDPE surface was carried out under aqueous conditions to create patterned polymer brushes of PHEMA. The grafted PHEMA brushes were characterized by Fourier transform-infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and contact angle analysis. The SEM observations showed that selective surface activation with Ar+ implantation and graft polymerization on the selectively activated surface had occurred. The PHEMA brushes were electrically characterized in the presence of concentrations of human immunoglobulin (IgG). The proposed amperometric biosensor was successfully used for determination of IgG in physiologic samples with excellent responses. (author)

Characterization of poly(Sodium Styrene Sulfonate) Thin Films Grafted from Functionalized Titanium Surfaces