Optical pyrometry: A novel method for monitoring photopolymerization reactions, and, Synthesis, characterization and modification of epoxy- and hydroxy-functional microspheres produced by cationic suspension photopolymerization.

摘要

This thesis is divided into two parts. The first portion of this thesis work describes the development of optical pyrometry (OP) as a new analytical technique for monitoring of the progress of both free radical and cationic photopolymerizations in real-time. The second portion of this work involves the synthesis of functional microspheres via suspension photopolymerizations.; The OP method is rapid, reproducible and very easy to implement. Using this technique, a temperature profile of a photopolymerization can be obtained. The effects of the mass and reactivity of the monomer, light intensity, structures and concentrations of the photoinitiators and monomers, humidity, and the presence or absence of oxygen on various free radical and cationic photopolymerizations were examined using this method. The addition of sulfides to cationic polymerizations was investigated. The photoinitiated cationic ring-opening polymerizations of certain epoxides and 3,3-disubstituted oxetanes display the characteristics of frontal polymerizations. To characterize these frontal polymerizations, a modification of optical pyrometry was instituted. This method provides a simple, rapid means of following these fast polymerizations and quantitatively determining their frontal velocities.; The second part of this thesis describes a novel method for the synthesis and characterization of epoxy functional microspheres. This synthesis is rapid, one step, and capable of producing spherical particles ranging in size from 50 nm to 400 mum. The photopolymerizations were carried out both in aqueous and non-aqueous suspensions. A variety of experimental and compositional variables were examined to determine their effect on the particle size, distribution and epoxy content of the spheres including: initiator composition and concentration, sonication time, irradiation time, viscosity of both the monomer and suspending medium, and porogen composition. In addition, the microspheres were subjected to pyrolysis and their macrostructure was unchanged even after a 60% weight loss.; The surface modification of epoxy- and hydroxy-functional polymeric microspheres was investigated. A variety of chemical modifications via acid- and base-catalyzed addition reactions were performed. Mercaptans, amines, acid chlorides, alcohols, and water were reacted with the epoxy-functional microspheres, whereas acid chlorides and isocyanates were added to the hydroxy-functional microspheres.