Kinetic/mechanistic aspects of radical polymerization: homogeneous and heterogeneous systems

Abstract

The objective of this Thesis is to develop new contributions to the fundamental knowledge in the area of kinetics and mechanism of radical polymerization. Polymer science, the study of large molecules, is one of the most important subjects, which has led to the development and production of numerous of our commodities and household items such as plastics, fibres, elastic materials, paints, adhesives, and even electronic applications. The popularity and importance of polymer products has all through the ages been a sufficient impetus to improve various polymerization techniques, not only conventional bulk or solution homogeneous systems, but also various specific conditions such as heterogeneous systems, polymerization under microwave (MW) irradiation, as well as controlled/living radical polymerization. Regardless of the specific techniques, the understanding of kinetics and mechanism is of prime concern. Despite the far-reaching achievements thus far, the subject of radical polymerization is of course far from complete. Radical polymerization itself has been advancing and new techniques and new interests are continuously emerging. In this Thesis, the on-going argument of the possible influence of MW irradiation on the kinetics of radical polymerization was experimentally investigated precisely with the model monomer of styrene. The kinetics of emulsion polymerization of styrene, one of the most precisely studied heterogeneous systems was studied to investigate the practical limit of the particle size in which the standard kinetic concept of ’zero-one theory’ is valid. A theoretical study is described for the kinetics of nitroxide-mediated polymerization (NMP) of styrene in under heterogeneous conditions of miniemulsion polymerization, where the influence of the particle size ’compartmentalization’ and ingredient partition are successfully combined for the first time. Finally, the elemental reactions of chain transfer to solvent were investigated for the conventional radical polymerization and NMP for the combination of N-isopropylacrylamide (NIPAM) monomer and dimetylformamide (DMF) solvent, not only in order to evidence the chain transfer to solvent reaction for this particular case, but also to gain a general understanding on how such side reactions influence the polymerization process.