Silicone rubber films were modified by the consecutive grafting of 2-(diethylamino)ethyl methacrylate (DEAEMA) and N-vinylcaprolactam (NVCL) using direct method on two steps with gamma-rays. The effect of absorbed dos...Silicone rubber films were modified by the consecutive grafting of 2-(diethylamino)ethyl methacrylate (DEAEMA) and N-vinylcaprolactam (NVCL) using direct method on two steps with gamma-rays. The effect of absorbed dose and monomer concentration on grafting degree was determined. The grafted samples were verified by FTIR-ATR spectroscopy and swelling;thermal properties were analyzed by DSC and TGA. The stimuli-responsive behavior was studied by swelling and/or DSC. Thermo- and pH-sensitive films of (PP-g-DEAEMA)-g-NVCL presented a pH critical at 3.2 and LCST around 63.5℃.展开更多
A new method has been established to graft vinyl monomers onto silk fabrics by ultraviolet rays without any initiator or photosensitizer, in an attempt to improve undesirable properties of the materials with increased...A new method has been established to graft vinyl monomers onto silk fabrics by ultraviolet rays without any initiator or photosensitizer, in an attempt to improve undesirable properties of the materials with increased wrinkle recovery, better dyeing ability and color-fastness, and higher resistance to photo-yellowing, etc. In this work, ef- fectiveness of different types of UV devices and experimental conditions of the photo-induced graft-copolymeri- zation were investigated to control the influential factors on the grafting yield and properties of the graft-copolymer. Surface characteristics and structure changes, thermal properties and wrinkle resistance of grafted silk fabrics were studied. The grafted silk fabrics showed improved properties in crease resistance, dyeing ability and color-fastness, and heat stability as well. In detail, graft-copolymerization of 2-(Dimethylamino)ethyl methacrylate onto silk fabrics can make silk fabrics undergo from slight to drastic changes in their dyeing behavior, i.e., rate of dyeing and uptake of acid dyes. Different reaction systems of the same monomer can lead to reverse dyeing properties, indicating not only the function but also the structure affects the properties of grafted silk fab- rics, especially the color-fastness. The UV light graft copolymerization method is of significance in silk industrial applications in terms of the facility cost, operation convenience and grafting efficiency, in comparison to Co 60 γ-ray and electron beam irradiation facilities.展开更多
A novel well-defined water-soluble macromonomer based on 2-(dimethylamino) ethyl methacry-late(DMAEMA) was synthesized by using functional initiators such as potassium alcoholate of trimethylol-propane allyl ether via...A novel well-defined water-soluble macromonomer based on 2-(dimethylamino) ethyl methacry-late(DMAEMA) was synthesized by using functional initiators such as potassium alcoholate of trimethylol-propane allyl ether via oxyanion-initiated polymerization. GPC and 1H NMR studies confirmed that themacromonomers had narrow molecular weight distribution and each Poly(DMAEMA) chain contained apolymerizable allyl group. The macromonomers were highly surface active in aqueous media. They havepotential applications in preparation of surface-clean and functional latexes both as effective stabilizers andas co-monomers.展开更多
Since tertiary amines （Cα-H） can be oxidized by peroxides and transition metal cations in high oxidation states into Ca2＋ radicals to initiate vinylic polymerizations of methacrylates, Cu2＋ and 2-（N,N-dimethylam...Since tertiary amines （Cα-H） can be oxidized by peroxides and transition metal cations in high oxidation states into Ca2＋ radicals to initiate vinylic polymerizations of methacrylates, Cu2＋ and 2-（N,N-dimethylamino）ethyl methacrylate （DMAEMA） form a polymerizable redox initiating pair, in which DMAEMA serves as an intrinsically reducing inimer. CuSOa-catalyzed aqueous self-initiated radical polymerizations of DMAEMA were successfully performed at ambient temperature via a continuous Cu2＋-tertiary amine redox initiation based on catalyst regeneration in the presence of O2. The polymerization kinetics was monitored by gas chromatography and the structure of PDMAEMA was characterized by gel- permeation chromatography, nuclear magnetic resonance spectroscopy, laser light scattering and online intrinsic-viscosity analysis. Both the monomer conversion and the molecular weight of PDMAEMA increase with the reaction while the molecular weight distribution maintains rather broad, as the Cu2＋-DMAEMA redox-initiation leads to linear PDMAEMA chains with terminal methacryloxyl moieties, and the Cu2＋-PDMAEMA redox-initiation results in branched chains. The branched topology forms and develops only for the high-MW components of the PDMAEMA. Our results provide a facile strategy to prepare branched polymers from such commercially available intrinsically reducing inimers using a negligible concentration of regenerative air-stable catalysts.展开更多
文摘Silicone rubber films were modified by the consecutive grafting of 2-(diethylamino)ethyl methacrylate (DEAEMA) and N-vinylcaprolactam (NVCL) using direct method on two steps with gamma-rays. The effect of absorbed dose and monomer concentration on grafting degree was determined. The grafted samples were verified by FTIR-ATR spectroscopy and swelling;thermal properties were analyzed by DSC and TGA. The stimuli-responsive behavior was studied by swelling and/or DSC. Thermo- and pH-sensitive films of (PP-g-DEAEMA)-g-NVCL presented a pH critical at 3.2 and LCST around 63.5℃.
文摘A new method has been established to graft vinyl monomers onto silk fabrics by ultraviolet rays without any initiator or photosensitizer, in an attempt to improve undesirable properties of the materials with increased wrinkle recovery, better dyeing ability and color-fastness, and higher resistance to photo-yellowing, etc. In this work, ef- fectiveness of different types of UV devices and experimental conditions of the photo-induced graft-copolymeri- zation were investigated to control the influential factors on the grafting yield and properties of the graft-copolymer. Surface characteristics and structure changes, thermal properties and wrinkle resistance of grafted silk fabrics were studied. The grafted silk fabrics showed improved properties in crease resistance, dyeing ability and color-fastness, and heat stability as well. In detail, graft-copolymerization of 2-(Dimethylamino)ethyl methacrylate onto silk fabrics can make silk fabrics undergo from slight to drastic changes in their dyeing behavior, i.e., rate of dyeing and uptake of acid dyes. Different reaction systems of the same monomer can lead to reverse dyeing properties, indicating not only the function but also the structure affects the properties of grafted silk fab- rics, especially the color-fastness. The UV light graft copolymerization method is of significance in silk industrial applications in terms of the facility cost, operation convenience and grafting efficiency, in comparison to Co 60 γ-ray and electron beam irradiation facilities.
文摘A novel well-defined water-soluble macromonomer based on 2-(dimethylamino) ethyl methacry-late(DMAEMA) was synthesized by using functional initiators such as potassium alcoholate of trimethylol-propane allyl ether via oxyanion-initiated polymerization. GPC and 1H NMR studies confirmed that themacromonomers had narrow molecular weight distribution and each Poly(DMAEMA) chain contained apolymerizable allyl group. The macromonomers were highly surface active in aqueous media. They havepotential applications in preparation of surface-clean and functional latexes both as effective stabilizers andas co-monomers.
基金financially supported by the National Natural Science Foundation of China(No.20674033)Natural Science Foundation of Jiangsu Province(No.BK2008142)Scientific Research Foundation for the Returned Overseas Chinese Scholars(State Education Ministry)
文摘Since tertiary amines （Cα-H） can be oxidized by peroxides and transition metal cations in high oxidation states into Ca2＋ radicals to initiate vinylic polymerizations of methacrylates, Cu2＋ and 2-（N,N-dimethylamino）ethyl methacrylate （DMAEMA） form a polymerizable redox initiating pair, in which DMAEMA serves as an intrinsically reducing inimer. CuSOa-catalyzed aqueous self-initiated radical polymerizations of DMAEMA were successfully performed at ambient temperature via a continuous Cu2＋-tertiary amine redox initiation based on catalyst regeneration in the presence of O2. The polymerization kinetics was monitored by gas chromatography and the structure of PDMAEMA was characterized by gel- permeation chromatography, nuclear magnetic resonance spectroscopy, laser light scattering and online intrinsic-viscosity analysis. Both the monomer conversion and the molecular weight of PDMAEMA increase with the reaction while the molecular weight distribution maintains rather broad, as the Cu2＋-DMAEMA redox-initiation leads to linear PDMAEMA chains with terminal methacryloxyl moieties, and the Cu2＋-PDMAEMA redox-initiation results in branched chains. The branched topology forms and develops only for the high-MW components of the PDMAEMA. Our results provide a facile strategy to prepare branched polymers from such commercially available intrinsically reducing inimers using a negligible concentration of regenerative air-stable catalysts.
