Novel Functional Polymers via Ring-Opening Metathesis Polymerization (ROMP) and Post-ROMP Modification

Abstract

Functional polymers play a pivotal role in advanced materials research owing to their diverse applications in electronics, optics, and other research and industrial fields. The ability to design and synthesize polymers with precisely tailored structures and properties is therefore of central importance. Among the various synthetic methodologies, ring-opening metathesis polymerization (ROMP), in combination with post-polymerization modification (PPM), has emerged as a versatile and powerful strategy for constructing novel functional polymeric systems. The research presented in this thesis centers on the use of ROMP and PPM in the controlled synthesis of new functional polymers and the study of their structural and physical properties. In Chapter 1, an overview of ROMP and PPM is provided with emphasis on their application to the synthesis of various functional polymeric materials. Chapter 2 describes the study on a novel chlorine-substituted poly(acetylene). As a monomer, cis-3,4-dichlorocyclobutene, was prepared and subsequently polymerized using a ruthenium-based olefin metathesis catalyst (the Grubbs 3rd generation catalyst). The resulting poly(cis-3,4- dichlorocyclobutene) underwent elimination to afford the chlorine-substituted poly(acetylene). The electrical conductivity of the chlorine-substituted poly(acetylene) was measured and determined to be on the order of 10–5 Ω−1 cm−1, a value comparable to those reported for organic semiconductors. In addition, both block and random copolymers were also synthesized and characterized, exhibiting good solubility in organic solvents along with valuable electronic properties. Chapter 3 describes the synthesis and study of new norbornene-based sulfur-containing polymer derivatives, poly(thianorbornene dicarboximide). A series of exo-7-thiabicyclo[2.2.1]hept-5- ene-2,3-dicarboximides were synthesized and polymerized using molybdenum-based olefin metathesis catalyst (Schrock’s catalyst). The ROMP reactions of these monomers proceeded in a controlled manner, enabling the tailoring of molecular weight and chain extension. The polymers were characterized using various techniques, and their refractive indices were found to have higher value than those of poly(norbornene) derivatives. To further demonstrate the monomer versatility, copolymerization reactions with norbornene were carried out and analyzed. As a PPM, treatment with base led to ring- opening hydrolysis, affording a polymer soluble in aqueous media.