Photopolymerization of vinyl-containing liquid silizane preceramic monomers copolymerized with thiol monomers,based on a step-growth radical polymerization mechanism,is a novel,rapid,inexpensive and simple tech-nique ...Photopolymerization of vinyl-containing liquid silizane preceramic monomers copolymerized with thiol monomers,based on a step-growth radical polymerization mechanism,is a novel,rapid,inexpensive and simple tech-nique for producing preceramic structures from liquid pre-cursors.The kinetics of alkyl 3-mercptopropionate-vinyl silizane under UV irradiation is investigated by using real-time Fourier transform infrarcd(FT-IR)and photo-dif-ferential scanning calorimetry(photo-DSC).The experi-mental results show preliminarily that:(1)about 80%conversion of vinyl group has been achieved in the pres-ence of a low concentration photoinitiator under UV irra-diation;(2)by increasing the functionalities of the thiol group,the peak rate of copolymerization increases and the final conversion of the vinyl group decreases;(3)the copolymerization is primarily a bimolecular radical ter-mination process;(4)the copolymerization is first-order,i.e.,its rate is proportional to the vinyl group concentra-tion and independent of the concentration of thiol group.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.20574056)Military Equipment Foundation of Defence(No.9140A12070106HK0338)the Doctorate Foundation of Northwestern Polytechnical University(No.CX200614).
文摘Photopolymerization of vinyl-containing liquid silizane preceramic monomers copolymerized with thiol monomers,based on a step-growth radical polymerization mechanism,is a novel,rapid,inexpensive and simple tech-nique for producing preceramic structures from liquid pre-cursors.The kinetics of alkyl 3-mercptopropionate-vinyl silizane under UV irradiation is investigated by using real-time Fourier transform infrarcd(FT-IR)and photo-dif-ferential scanning calorimetry(photo-DSC).The experi-mental results show preliminarily that:(1)about 80%conversion of vinyl group has been achieved in the pres-ence of a low concentration photoinitiator under UV irra-diation;(2)by increasing the functionalities of the thiol group,the peak rate of copolymerization increases and the final conversion of the vinyl group decreases;(3)the copolymerization is primarily a bimolecular radical ter-mination process;(4)the copolymerization is first-order,i.e.,its rate is proportional to the vinyl group concentra-tion and independent of the concentration of thiol group.
