木本油脂的微波辅助多碳碳官能化及UV固化应用基础研究

Deep processing and utilization of woody plant oils is very important for comprehensive utilization of forest resources and development of rural economy. In our previous project of National Natural Science Foundation, we found that synthesis of highly functional unsaturated ester (UE) macromonomers or oligomers from plant oil can lead to high-performance biobased unsaturated resins. Thus we believe that high unsaturated carbon-carbon (C=C) functionalization of woody plant oils is vital for preparation of high-performance biobased UV-curable materials. However, so far the study of high C=C functionalization of plant oils has a lot of shortcomings, such as lack of chemical routes, long reaction time, and too many side reactions. Therefore, in this project, we will explore new methods of high C=C functionalization of woody plant oils such as rubber seed oil and Wilsoniana fruit oil via microwave-assisted modification as well as the effect of citric acid molecule. Besides, reactions’ mechanism during the microwave-assisted modification will be carefully investigated to control products’ structures and obtain excellent UE prepolymers. Finally, structure-property relationships and UV-curing behaviors of the prepared bioresins will be studied. This study will provide new trend and methods for the high value-added utilization of woody plant oil resources, and give important fundamental studies for development and application of such high-performance UV-curable biomaterials.

木本油脂的深加工利用对促进林木生物资源的综合利用以及农村经济的发展具有十分重要的意义。基于已完成基金中合成高官能度的植物油基不饱和酯（Unsaturated Ester，简称UE）有利于获得高性能不饱和树脂这一发现，我们认为对木本油脂进行多碳碳官能化修饰研究，是制备高性能UV固化树脂的重要基础。然而，目前该研究中存在多官能化路线稀少，且反应时间长、副反应多等缺陷。因此，本项目将借助于微波辅助合成技术和柠檬酸分子的作用，对橡胶籽油、光皮树果油等木本油脂进行多碳碳官能化研究，并探索微波辅助改性的反应机理，以便对产物进行结构调控，获得优良的生物基UE光敏预聚体。另外，还将充分研究所得生物基UV树脂的结构性能关系及光固化动力学。本研究将为木本油脂资源的高值化利用提供新思路和新方法，并对高性能生物基UV固化材料的研发及应用具有重要的指导作用。

利用木本油脂制备光固化材料，对该类生物质资源的高值化利用、光固化材料产业的可持续发展以及环境保护等均具有重要的意义。本项目以木本油脂为原料，发展了两种基于微波技术的碳碳（C=C）官能化方法，合成了两类新型的植物油基不饱和酯光敏预聚体，进而制备了高性能或功能型光固化材料，并考察了其结构性能关系、光固化动力学及功能响应机制等，最后将其用于光固化涂料。结果表明：（1）微波合成技术可大幅提升植物油C=C官能化的效率。例如，柠檬酸改性法合成预聚体只用了30分钟，甲基丙烯酸缩水甘油酯（GMA）改性法则花费了25分钟。（2）桐油（TO）与马来酸酐（MA）反应时同时存在Diels–Alder加成和自由基共聚两种反应，且MA:TO越高，越倾向于自由基共聚反应。（3）所得预聚体的官能度较高：两种桐油-柠檬酸基光敏预聚体（TMCG1和TMCG2）的官能度分别为4.47和5.14个/甘油三酯（TG），而GMA改性桐油基预聚体（TMG）的官能度达3.81个/TG。（4）所得优化后桐油-柠檬酸基光固化材料具有高性能、高生物基含量的特征。例如，加入10%的愈创木酚基稀释剂光固化后，TMCG1材料的拉伸强度达16.6MPa，玻璃化转变温度（Tg）达74.1 oC，涂膜硬度为2H，生物基含量达72.4%。（5）所得优化后桐油-苹果酸基光固化材料具有高性能、高生物基含量、自修复、可回收加工、形状记忆等特征。例如，加入10%的苹果酸基稀释剂光固化后，TMG材料的生物基含量为55.1%，拉伸强度为7.1MPa，Tg为70.6 oC，划痕自修复率达93%，焊接后拉伸强度修复率达172%，第一次回收后拉伸强度修复率高达404%，形状固定率约98%。综上，本研究工作不但可为木本油脂转化为高性能或功能型光固化材料提供高效、绿色的新方法，而且可为这些材料的应用奠定一定的理论基础。