Controlled functionalization of crystalline polyolefins and their application in soluble polymer support

摘要

Functionalization of polyolefins has been recognized as a useful methodology for the generation of new materials with a wide range of applications. Recently, crystalline or semi-crystalline polyolefins have drawn increasing attention in both industrial and academic fields as one of the most interesting engineering plastics, due to their remarkable physical and mechanical properties. This dissertation describes: (1) novel methods for the direct postfunctionalization of crystalline polyolefins to introduce functionality, (2) characterizations for the functionalized polymers to analyze their structures, molecular-weight properties, thermal properties, and hydrophilicity, and (3) an application of the modified crystalline polystyrene as a soluble polymer support for recyclable catalysts in green chemistry.Chapter 1 describes the controlled iridium-catalyzed C-H activation of commercial polystyrenes having three types of tacticity. The resulting boronic group in the polymers was further converted into other versatile groups such as hydroxy and aryl groups via subsequent modifications. Chapter 2 addresses the preparation of a soluble syndiotactic polystyrene-supported phosphine ligand. The Suzuki-Miyaura cross-coupling was effectively accomplished with the polymer-supported palladium complex, which was recovered quantitatively and recycled several times without any loss of activity and the addition of fresh base. In Chapter 3, controlled electronic aromatic bromination of syndiotactic polystyrene was studied. The brominated polymer could serve as a precursor for polyolefins having variable functionalities. Chapter 4 describes the synthesis of hydroxy-functionalized isotactic poly(1-butene) using controlled and regioselective rhodium-catalyzed C-H functionalization and subsequent oxidation. Atom transfer radical polymerization could generate a polar or amphiphilic graft copolymers from the functionalized crystalline polyolefin.