Investigations into Structure-Property Relationships of Novel Polymers Synthesized Primarily from Bio-Renewable Resources

This dissertation investigates the synthesis and characterization of polymers primarily derived from renewable biomass sources, along with the structure-property influences on material properties. One polymer that has garnered interest as a promising value-added material is poly(2-vinylfuran) (PVF), an analog to styrene (S) derived from hemicellulose. Previous reports have determined the sole effective polymerization method to be through an emulsion. Investigations into this peculiar observation herein determined that compartmentalization of the propagating chains allows for radical propagation, which was found to be an order of magnitude faster than for styrene. Further analysis of kinetics and material properties of the resulting polymers were investigated. In an alternate thrust, biomass derived isohexides were studied in detail to determine the influence of the inherent stereocenters on resulting polymer properties. Novel polyurethanes were synthesized from isosorbide (IS) and isomannide (IM) derived diisocyanates, as well as 2,5-bishydroxymethylfuran (BHMF) in varying feed ratios. It was concluded that the difference in stereochemistry significantly influenced chain behavior and the presence of entanglements, contributing significantly to the observed mechanical behavior. In an alternate thrust, the reactivity differences of the two chiral alcohols on IS were utilized to synthesize various asymmetric monomers capable of chain growth polymerizations. The resulting polymers were of significantly higher molecular weight and showed interesting thermal behavior due to the rigidity of the isohexide core. An additional investigation was conducted into the mechanical and viscoelastic properties of poly(4-phenylcylcopentene) (P4PCP) and its hydrogenated counterpart (H2-P4PCP), which is a novel ethylene-styrene (ES) copolymer analog previously synthesized in our lab. Both polymers were found to be quite ductile with glasstomeric behavior due to the proximity of the Tg to room temperature (~17 °C). Both polymers were found to have quite high elastic recovery and polymer creep, indicating the greater contribution of viscous behavior to the overall polymers. The precise arrangement of styrene (S) units along the backbone along with the lack of atactic polystyrene (PS) homopolymers was found to significantly influence material properties compared to previously synthesized ES copolymers.