Modeling and Characterization of Chain Polymerization Reactions for Multifunctional Monomers

点击翻译按钮获取中文摘要

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.