基于光化学保护策略稳定型高精度硫醇-烯光敏树脂的构建及其在光固化快速成型中的应用研究

The polymerization shrinkage of photosensitive resins has become a bottleneck for improving the shaping accuracy of Stereolithography. Thiol-ene photosensitive resins have the potential to become the next generation of photosensitive resins for Stereolithography due to their low polymerization shrinkage and high reactivity. However, the further application of thiols in the related field is constrained because of its bad smell, poor stability as well as polymerization shrinkage. For this reason, this project is to synthesize a series of light-cleavable protected-thiol monomer and a series of ene monomers with open expending groups respectively so as to fabricate novel photo-sensitive resins for Stereolithography. A systematic study is also made of the light-cleavable thiol, open expending groups photo-cationic polymerization , and thiol-ene radicals photopolymerzation mechanism. Moreover, the regularity between physicochemical properties and the structure of resins is studied. Consequently, the structure-function relationship between monomer, the structure of resins and the properties of resins is established, which will provide a theoretical basis for regulating the properties of resins. Through this project, a series of low or zero polymerization shrinkage photosensitive resins for Stereolithography will be obtained, which may pave the way for improving the accuracy of Stereolithography.

光敏树脂的聚合收缩已经成为光固化快速成型精度进一步提高的瓶颈。硫醇-烯光敏树脂具有聚合收缩小、聚合活性高的优点，有望成为新一代光固化快速成型专用光敏树脂。但是，硫醇难闻的气味、较差的稳定性及一定程度的聚合收缩仍然制约其在该领域中的应用。为此，本项目拟分别合成含光去保护的新型硫醇单体和含膨胀开环单元的新型烯类单体，构建新型的光固化快速成型专用光敏树脂体系；系统的研究此光敏树脂体系中硫醇去保护光裂解反应、膨胀开环单元光照阳离子聚合，以及硫醇-烯自由基光照聚合机制及过程影响因素；并通过研究树脂理化性质与树脂结构之间的关联规律，从而建立单体、树脂结构与树脂的性能的构效关系，为调控树脂性能的提供理论基础。通过本项目的研究工作，力争获得一批低聚合收缩甚至无聚合收缩的光敏树脂，为进一步提高光固化快速成型的制造精度创造条件。

硫醇-烯光敏树脂具有聚合收缩较小、优异的抗氧阻聚效应，聚合活性高的优点，有望成为新一代光固化3D打印用光敏树脂。但是仍存在味道难闻，树脂稳定性差，机械强度低较等缺点，限制了这类光敏树脂在光固化快速成型中的进一步应用。在本项目的资助下，主要进行了如下的工作：1）利用商用硫醇单体与丙烯酸酯和乙烯醚等烯类，构建了稳定性良好的硫醇-烯光敏树脂用于3D打印，考察了不同烯类单体结构对硫醇-烯树脂各项性能的影响，评估了硫醇-烯光固化3D打印性能。2）合成了超支化硫醇单体，考察了这类单体在硫醇-烯光敏树脂的抗收缩性能，成功制备了非双酚A型正畸3D打印用硫醇-烯光敏树脂，在牙科修复领域显示一定的应用潜力。3）采用了硫醇-烯和硫醇-环氧正交反应，成功制备了稳定的硫醇/烯/环氧混杂型光敏树脂，通过光固化和热固化双重固化策略，显著提高了硫醇-烯光敏树机械性能和树脂的玻璃转化温度Tg，消除了3D打印后树脂的机械性能各向异性。4）合成了含有双螺环原碳酸酯结构的二元硫醇单体和二元甲基烯类单体。分别考察了这两类单体光照阳离子开环聚合和光照自由基开环聚合行为，并研究了这两类单体在硫醇-烯光敏树脂的中抗收缩性能。通过上述的研究，对于获得稳定性好，聚合收缩率低，打印精度高的新一代3D打印用光敏树脂提供了一定的研究基础和借鉴。