光热双重响应聚硅氧烷网络构筑及其固化行为与性能调控

Novel molecular structure and green curing method have become a hot issue of high performance polysiloxane materials. In this study, some novel polysiloxane compounds containing optical molecular switch in the backbone are prepared. The intramolecular structure of D-A adduct from the backbone of polysiloxane can be effectively controlled by means of stimulation of different light wavelengths to realize dual regulation of photo and heat, which can resolve the contradiction between thermal degradation (or recycle) and utilization of this materials under high temperature. Meanwhile, a new idea is proposed that regulating the structure of adjacent groups of alkynyl in backbone of polysiloxane to enhance curing reactivity so that it can be cured under low temperature in the absence of catalyst. In addition, the influence of molecular structure of reactant on curing reactivity and curing behavior are discussed in detail and a proper dynamic model and equation are established. Furthermore, the effects of light stimulation under different temperature on viscoelasticity, thermodynamic and mechanical properties are explored. And the performance changes (glass transition temperature, modulus and mechanical strength) between original crosslinked polysiloxane and remoldable polymer under different cycles of heat and light are studied. These results and achievements will enrich the present curing theory of silicone materials, be valuable and meritorious to the further design, development and application of novel polysiloxane materials, especially for degradable and recyclable materials and re-moldable thermosetting materials, in the thoughts and foundational data.

集成新型结构，绿色固化方法于一体是功能性有机硅材料研究热点和方向。本项目设计系列主链结构中嵌入光学分子开关的聚硅氧烷预聚物，采用不同波长光调控主链结构中D-A加成物分子内构造，实现D-A逆向反应光热双控性，解决传统D-A型动态聚合物热解回收与高温环境无法使用之间矛盾；提出调控炔基邻近双官能团构造可有效提高其反应活性，实现无催化剂作用有机硅材料低温快速固化；探讨反应物分子结构与反应活性、固化工艺和固化动力学内在关联，拟建立适合该体系的动力学模型与方程；研究不同温度下光刺激变化对固化物热学性能、粘弹性、力学性能影响和不同光热循环次数对原始态交联聚合物与热解重塑后固化物性能（玻璃化温度Tg、模量和力学强度）变化关系。该项目研究成果，将丰富目前有机硅材料固化理论，为新型聚硅氧烷材料的研究和扩展应用提供新的方法和基础数据，对可降解回收和可重塑的热固性有机硅材料开发具有指导意义。

集成新型结构，绿色固化方法于一体是功能性有机硅材料研究热点和方向。本课题从分子水平设计系列结构中含有光-热功能性基团聚硅氧烷化合物，并引入无金属或无催化剂体系的交联反应，让材料在固化方式、热力学性能和可重塑性取得进展。该研究成果，不仅丰富目前有机硅材料固化理论，为新型功能化有机硅材料的开发和扩展应用提供新的方法和指导意义。具体研究内容如下：（1）合成并表征系列含光-热基团有机硅树脂，包括含D-A结构聚硅氧烷、含环氧基和双键聚硅氧烷；功能化交联剂和增强剂，包括含巯丙基聚硅氧烷、含叠氮基聚硅氧烷和聚倍半硅氧烷；（2）采用DSC法和流变学研究树脂体系固化反应和非等温动力学过程，并研究分子结构对其反应活性的影响，结果表明，基团电子效应对反应活性影响较大；（3）采用光-热外界刺激，有效调节有机硅材料力学性能、粘弹性、耐热性和可重塑性，构建分子结构-性能间关系。