| This dissertation explores the use of atom transfer radical polymerization (ATRP) in the preparation of cross-linked networks of higher degree of control, as well as their applications to emerging classes of cross-linked materials. As examples, this dissertation discusses thermoresponsive hydrogels, self-healing polymeric coatings, ultra-thin polymer films, and thermoplastic elastomers. The introductory chapter provides an overview of the radical cross-linking chemistry and expected advantages of cross-linked networks prepared by controlled radical polymerizations. Chapters 2--4 describe the use of ATRP in preparing covalently cross-linked networks as well as in modifying network architectures. Also, the prepared polymer networks were examined as fast thermoresponsive and biomaterial-applicable hydrogels, using various evaluation techniques such as gravimetry, image analysis, and 1H-NMR spectroscopy. In Chapters 5--7, well-defined polymers with complex architectures were prepared by ATRP and used as building blocks of post-cross-linkable materials. In Chapter 5, self-healing polymer coatings based on reversible thiol-disulfide exchange reactions were investigated. The self-healing kinetics were measured using various AFM techniques. Based on the observation, the self-healing mechanism was proposed and the future directions on material design were sought. In Chapter 6, hyperbranched thermocurable polystyrenes were synthesized and examined their ultra-thin film forming capability. In Chapter 7, a physical cross-linking system based on block copolymer phase segregation was studied and examined as thermoplastic elastomers with superior thermomechanical properties. The studies presented in Chapter 2--7 are summarized and concluded in the final chapter, Chapter 8. |
