环氧液晶弹性体材料的制备与力学性能研究

传统的液晶弹性体材料多采用丙烯酸酯类或聚硅氧烷类分子,通过自由基聚合制备.然而由于自由基聚合易被氧气阻聚,固化过程收缩率高且内应力大,传统液晶弹性体材料的力学性能并不是很优异.为解决这一问题,本文合成了带有环氧基团的液晶单体和交联剂,使用碘鎓盐作为引发剂,通过光引发阳离子反应,用原位聚合交联法制备了环氧液晶弹性体材料.光引发阳离子聚合和传统自由基聚合相比,不受氧气影响且弹性体固化时体积收缩率小.对制备出的液晶弹性体材料的晶相和力学等性能进行探究和表征,发现其比传统的丙烯酸酯类或者聚硅氧烷类液晶弹性体材料具有更优异的力学性能,在清亮点以上,其弹性模量达到了0.92 MPa.

Synthesis and Mechanical Property Investigation of Epoxy Liquid Crystal Elastomer Material

Most of the traditional liquid crystal elastomers are based on polyacrylate or polysiloxane systems and prepared by thermal or photo-initiated free-radical polymerization.However,the free-radical polymerization is easily inhibited by oxygen,causing high volume shrinkage and large internal stress during the curing process.In order to address these drawbacks,we design and synthesize a new liquid crystal monomer and a crosslinking agent bearing epoxy groups.The epoxy liquid crystal elastomer is prepared by in situ cationic polymerization/crosslinking using iodonium salt as the photo-initiator.Compared with the traditional liquid crystal elastomers,the volume shrinkage is small during the photo-initiated cationic reaction and the photo-curing process will not be interfered by oxygen.The liquid crystallinity and mechanical properties of the epoxy liquid crystal elastomer material are systematically characterized.The results show that epoxy liquid crystal elastomer material prepared by photo-initiated cationic polymerization possess better mechanical properties than the traditional polyacrylate/polysiloxane liquid crystal elastomers.The elastic modulus reach 2.53 MPa at the temperature beyond the LC-to-isotropic phase transition.