Discrete Cyclic Polymers with Uniform Chain Length

This study presents a robust approach for synthesizing cyclic polyesters with precise chemical structures and uniform chain lengths. Discrete cyclic homopolymers and block copolymers, composed exclusively of repeat units without any molecular heterogeneities, were prepared using a modular approach that combined iterative growth and ring closure methods. The precise chemical structure rules out the inherent molecular uncertainties associated with molecular weight distribution and other defects. Due to topological constraints, the cyclic chains exhibit a higher glass-transition temperature compared to their linear counterparts. Meanwhile, an appreciable reduction in the lattice dimension and thermodynamic stability of the assembled structures was recorded in cyclic block copolymers. This study provides an ideal model system for a quantitative exploration of the critical contribution of the cyclic topology that has long been compromised by linear contaminants and statistical uncertainties.