Modeling and Characterization of Chain Polymerization Reactions for Multifunctional Monomers

从多官能团单体形成高交联聚合物通常伴随着聚合物结构的异质性，反应动力学的自加速和自减速，形成玻璃态聚合物，体积收缩相对于平衡的延迟，以及达到最大官能团转化率。多功能单体的聚合物提供了许多优点，因为它们形成了具有高机械和热完整性的高度交联的聚合物以及溶剂吸收率低(即吸湿性)。其中许多材料在很大的波长范围内对光也是透明的。这些聚合物特性使这些材料成为光纤涂层、激光视盘涂层、非球面透镜、牙科材料、印刷油墨和非线性光学材料的理想应用。这项工作从理论和实验两方面阐述了固化条件(如温度、单体官能度和类型、引发速度和类型)与固化后聚合物最终性能之间的关系。由于聚合物的行为强烈依赖于聚合物的结构和性能，因此将开发模型来提供一个框架，适用于链式聚合的固化工艺。该框架将预测温度、引发速率和类型等反应条件的影响，以及单体的特性和官能度对反应和聚合物的结构和性能的影响。目前耦合体积松弛和反应动力学的模型将被修改，以预测温度依赖性、解聚、离子聚合、以及通过反应扩散终止。将开发一个凝胶动力学模拟程序，用于预测聚合物的结构，包括分子量分布、凝胶点转化率、环化倾向、以及作为反应条件的函数的异质性。最后，反应进程和聚合物结构的实验表征将使用引发的多(甲基)丙烯酸酯的自由基聚合无论是通过热能还是紫外线辐射。通过这种方式，模型将得到验证。

The formation of highly crosslinked polymers from multifunctional monomers is typically accompanied by heterogeneity of the polymer structure, autoacceleration and autodeceleration of the reaction kinetics, formation of a glassy polymer, a delay in volume shrinkage with respect of equilibrium, and the attainment of a maximum functional group conversion. Polymers of multifunctional monomers afford a number of advantages in that they form a highly crosslinked polymer with high mechanical and thermal integrity as well as low solvent (i.e. moisture) absorption. Many of these materials are also transparent to light over a large wavelength range. These polymer properties make these materials desirable for applications as optical fiber coating, laser video disc coatings, aspherical lenses, dental materials, printing inks, and nonlinear optical materials. This work addresses, from both a theoretical and an experimental basis, the relationship between cure conditions such as temperature, monomer functionality and type, and initiation rate and type to the final properties of the polymer after curing. Because the polymer behavior is strongly dependent on the polymer structure and properties, models will be developed to provide a framework, applicable to curing processes involving chain polymerization. This framework will predict the effect of reaction conditions such as temperature, initiation rate and type, and monomer characteristics and functionality on the reaction and on the polymer structure and properties. Current models coupling the volume relaxation and reaction kinetics will be modified to predict temperature dependence, depolymerization, ionic polymerizations, and termination by reaction diffusion. A kinetic gelation simulation will be developed and used to predict the polymer structure including the molecular weight distribution, the gel point conversion, the cyclization tendency, and the heterogeneity as a function of the reaction conditions. Finally, experimental characterization of the reaction progress and the polymer structure will be done using free radical polymerizations of multi(meth)acrylates initiated both thermally and by ultraviolet radiation. In this way the models will be verified.