Facile One-Pot Route to Well-Defined Homotelechelic Polydimethylsiloxane (PDMS) Macroinitiators

Polydimethylsiloxane (PDMS)-based ABA triblock copolymers have been widely employed in applications ranging from biomedical devices, electronics, and microfluidics to templates for patterning. These materials are usually prepared by growing the A blocks from a presynthesized PDMS macroinitiator via controlled radical polymerization (CRP). The PDMS macroinitiators themselves are commonly synthesized via end-group functionalization of commercially available PDMS precursors, which often exhibit broad molecular weight distributions. Here, we report a one-pot strategy for synthesizing PDMS macroinitiators with narrow molecular weight distribution via the organocatalytic ring-opening polymerization of hexamethylcyclotrisiloxane (D3) and terminating the polymerization using chlorosilane end-cappers bearing CRP initiating groups. We report the efficient synthesis via hydrosilylation of chlorosilane end-cappers with atom transfer radical polymerization (ATRP) and nitroxide-mediated polymerization (NMP) initiators. The successful synthesis of well-defined ABA triblock copolymers via ATRP and NMP using the PDMS macroinitiators is confirmed by NMR spectroscopy and gel permeation chromatography (GPC) analysis.