Design of Novel Networked Polymer Architectures via Side-Chain Chemistry

Abstract

Significant efforts have been devoted to the precise control of polymer architectures and network properties, and among these strategies, we propose an approach centered on side‐chain chemistry. The first part of this work focuses on the design and synthesis of C1 poly(methylene)s bearing pendant benzoxazine units, enabled by a well-defined C1 polymerization pathway. This polymerization mode provides access to materials with higher functional-group density than their C2 analogues, thereby offering the potential for enhanced physicochemical properties. Extensive characterization, including chromatographic, spectroscopic, and thermal analyses, was conducted, and systematic optimization of the polymerization conditions was achieved through variations in catalyst identity and catalyst-to-monomer feed ratios. The benzoxazine moieties incorporated along the side chains further enable post-polymerization network formation via thermally induced ring-opening polymerization, resulting in structurally ordered and highly tunable polymer networks. This molecular design not only expands the synthetic scope of C1-based polymers but also demonstrates that benzoxazine side-chain chemistry provides a versatile platform for constructing architecturally unique polymer materials. The second part of this study introduces reprocessable bottlebrush polymer networks based on dynamic urethane bond exchange. Hydroxyl-functionalized bottlebrush polymers synthesized through a grafting-through strategy were crosslinked using a tri-isocyanate to form networks exhibiting vitrimer- like behavior governed by an associative urethane exchange mechanism. The resulting networks combine very low stiffness, sufficient mechanical strength, and excellent reprocessability. Rheological measurements, stress-relaxation experiments, and mechanical testing collectively reveal that side-chain chemistry and crosslinking density provide precise control over the dynamic behavior and bulk performance of the materials. Together, these two systems highlight how the deliberate design of side-chain functionalities can program the structure, dynamic properties, and macroscopic performance of networked polymer architectures. This work underscores the potential of such molecularly engineered systems for applications in adaptive soft materials, next-generation elastomeric networks, and recyclable polymer technologies.