Discrete Cyclic\nPolymers with Uniform Chain Length

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