Tuning Dispersity by Photo-Induced ATRP: Monomodal Distributions with ppm Copper Concentration.

Abstract

Dispersity significantly affects the properties of polymeric materials. However, current methods that control the polymer dispersity are limited to bimodal molecular weight distributions, adulterated polymer chains or low end-group fidelity and rely on feeding reagents, flow-based or multicomponent systems. Herein, we report a simple batch system to overcome these limitations by exploiting photo-induced ATRP as a convenient and versatile technique to control dispersity of both homopolymers and block copolymers. By varying the concentration of the copper complex, a wide range of monomodal molecular weight distributions can be obtained (Đ = 1.05-1.75) where the Mn and Mw can be tuned on demand. In all cases, high end-group fidelity could be attained as exemplified by MALDI-ToF-MS and efficient block copolymer formation (monomodal, Ɖ = 1.1-1.5). Importantly, our approach utilises ppm levels of copper (as low as 4 ppm), can be tolerant to oxygen and exhibits perfect temporal control, representing a major step forward in tuning polymer dispersity for various applications.