Oxazine Ring Substituted Benzoxazine Thermosets Smart Architecture Structure Property Relationship and Thermal Behavior

Abstract

Thermosetting polymers cater to various applications ranging from small to large scale industries. Phenol-formaldehyde polymers are the front runners among them. However, considering their limitations and environmental distresses, finding alternatives is the need of the hour. Incidentally, polybenzoxazines appeared as a potential replacement. In general, 1,3-benzoxazine (Bz) monomers undergo ring-opening polymerization (ROP) reactions under heat to form PBz. Despite exhibiting excellent properties such as low flammability, high mechanical strength, chemical and moisture resistance, flexibility in structural design, etc., and thus serving as an attractive material for high-end applications, efforts are in progress to overcome various associated drawbacks, for example, mass loss during curing, the requirement of high temperature for polymerization and lack of high-quality thermoset resins, dependence on petro-based resources, structural designing rationale, etc. The thesis broadly investigates the questions mentioned above and discusses the probable solutions in light of the latest fourth-generation oxazine ring-substituted benzoxazines, which include syntheses, characterization, and study of thermal and polymerization properties of monomers and polymers. To rationalize their thermal behaviour, molecular-level interactions have been evaluated, and mechanistic polymerization pathways have been proposed. These findings encourage the strategy of structural tailoring and investigating structure-property relationships as one of the promising routes to prepare high-temperature thermosets suitable for traditional and newer cutting-edge applications.