A straightforward method to synthesize a,o-telechelic poly(dimethylsiloxane)s

Abstract

One of the goals of polymer chemistry is developing new methodologies for the controlled synthesis of polymers with predictable, well-defined structures. Living anionic polymerization provides one of the best methodologies for synthesizing complex macromolecular structures such as a,o-telechelic polymers. These macromolecules are obtained by different synthetic methods, which usually involve the titration of alkyllithiums over double diphenyl ethylene derivatives (DDPE). In this work we report the synthesis of , telechelic PDMS by employing a novel bifunctional initiator, obtained from a commercial available siloxane precursor, poly(dimethylsiloxane) diglycidylether terminated (PDMS-DGE). The synthetic strategy involves the high-vacuum reaction of sec-BuLi+ with DPE, and subsequently with PDMS-DGE to promote the nuclephilic ring-opening of the epoxide ends. The resulting bifunctional initiator was then employed to polymerize hexamethly(cyclotrisiloxane) (D3) by using conventional anionic polymerization methods. From suitable terminating agents, silane (-SiH), vinyl (-CH=CH2), hydroxyl (-OH), trimethyl and even methacryloyl ended PDMS were obtained. From SEC analysis, narrow molar masses distributions (Mw/Mn < 1.3) and good control over the resulting number-average molar masses were observed. In addition, 1H-NMR and FTIR characterization confirmed the presence of the targeted functional groups in the resulting polymers.