3D打印用光敏型有机硅弹性体的可控构建及其性能调控

Photopolymers are the preferred 3D printing materials for high-precision products, due to excellent rheology property and instant light curing characteristic. With the wide application of UV-curing 3D printing, the consumption of photopolymers is rapidly increasing. However, there are some urgent problems in the UV-curing of photosensitive resin, such as surface oxygen inhibition, high volume shrinkage and serious solvent pollution. Moreover, there are also some shortcomings for photosensitive elastomers, such as complicated synthesis process, slow curing rate and bad anti-ultraviolet aging property. Thiol-ene reaction can still be effectively carried out even under normal atmosphere, and the UV-cured products have better dimensional stability and toughness. Hyperbranched polymers have low viscosity, small volume shrinkage and strong adhesion. Based on the theoretical conceptions and methods of molecular design to perform the 3D network structures between soft/rigid segments at molecular scale for photosensitive elastomer, so this project intends to take advantages of thiol-ene reaction and hyperbranched polymer to synthesize different types of photosensitive silicone polymer, and then construct novel and environmental friendly UV-curable compositions for 3D printing. By utilizing the click chemistry, various crosslinked network structures of polysiloxane are controllable constructed, and more the curing dynamics were investigated in detail. At the same time, the development laws of cross-linked network structure changing with molecular structures of silicone polymers and the curing conditions are explored. Moreover, the structure-performance relationships between the distribution and density of crosslinked network structure and mechanical properties, viscoelasticity and volume shrinkage are clarified. At last, the applicable characteristic parameters and molding conditions of UV forming materials are optimized in 3D printing process. This project constructed a novel and environmental friendly UV-curing system suitable for 3D printing, which will effectively contribute the technological progress and widen application of photosensitive polymers, and also has important theoretical significance and application value.

随着光固化3D打印的广泛应用，光敏聚合物的用量快速增加。然而，光敏树脂固化过程中存在体积收缩、溶剂污染等问题；光敏弹性体存在制备工艺复杂、耐紫外性能差等缺点。巯基-烯点击反应固化制品的体积收缩小，韧性好；超支化聚合物粘度低，反应活性高。本项目拟将巯基-烯点击反应和超支化聚合物的优点集于一身，在分子尺度上设计光敏弹性体软/硬链段之间的三维网络架构，合成不同分子结构的光敏有机硅树脂，构建环境友好的光固化体系，制备适合3D打印的光敏有机硅弹性体耗材。通过点击反应可控构建聚硅氧烷交联网络，对其固化反应动力学进行系统研究；探究交联网络结构与聚合物分子结构及固化工艺的变化规律；厘清交联网络的结构形态与密度同力学性能、粘弹性、体积收缩间的构-效关系；优化3D打印实体材料的特性参数与成型条件。本项目拟构建合成的环境友好的光固化体系，将有力地促进3D打印技术的进步和应用拓展，具有重要的理论意义和应用价值。

随着光固化3D打印的广泛应用，光敏聚合物的用量快速增加。然而，光敏树脂固化过程中存在体积收缩、溶剂污染等问题；光敏弹性体则存在制备工艺复杂、耐紫外性能差等缺点。巯基-烯点击反应固化制品的体积收缩小，韧性好；超支化聚合物粘度低，反应活性高。有鉴于此，本项目首先通过水解—缩聚反应合成了具有不同分子结构的巯基聚硅氧烷（PDMS-SH），并借助FT-IR、1H NMR、13C NMR、29Si NMR等对其分子结构进行了系统表征与分析，优化获得了最佳制备条件；然后将PDMS-SH与不同分子结构的乙烯基聚硅氧烷（PDMS-Vi）、自由基光引发剂（PI）配伍，借助巯基-烯光点击反应在分子尺度上可控构建光敏弹性体“软/硬”链段之间的三维网络架构，并利用实时红外、photo-DSC和光流变学等原位检测技术对光固化成型过程中官能团转化率、反应速率、固化热以及凝胶点等反应动力学参数进行了深入研究；最后，将光敏弹性体配方应用于SLA型光固化3D打印成型，优化了3D打印实体材料的特性参数与成型条件，并对光固化聚硅氧烷网络的结构形态及其交联密度、力学强度等性能间的构效关系进行了系统研究，开发出了适合光固化3D打印的光敏有机硅弹性体配方。因此，本项目利用巯基—烯光点击反应可控构建了光固化3D打印有机硅弹性体体系，并对其光固化动力学及制品性能的构效关系进行了系统研究，这将有力地促进光固化3D打印技术的进步和应用拓展，具有重要的理论意义和应用价值。