Ring-opening polymerization of cyclic oligosiloxanes without producing cyclic oligomers

• 成果类型: Article
• 署名作者: Shi, Limiao; Boulegue-Mondiere, Aurelie; Blanc, Delphine; Baceiredo, Antoine; Branchadell, Vicenc; Kato, Tsuyoshi
• 署名单位: Universite de Toulouse; Universite Toulouse III - Paul Sabatier; Centre National de la Recherche Scientifique (CNRS); Autonomous University of Barcelona
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-10454
• DOI: 10.1126/science.adi1342
• 发表日期: 2023-09-01
• 页码: 1011-1014
• 关键词: block-copolymers; polydimethylsiloxane; hydrolysis; water

摘要

A long-standing problem associated with silicone synthesis is contamination of the polymer products with 10 to 15% cyclic oligosiloxanes that results from backbiting reactions at the polymer chain ends. This process, in competition with chain propagation through ring-opening polymerization (ROP) of cyclic monomers, was thought to be unavoidable and routinely leads to a thermodynamically controlled reaction mixture (polymer/cyclic oligosiloxanes = 85/15). Here, we report that simple alcohol coordination to the anionic chain ends prevents the backbiting process and that a well-designed phosphonium cation acts as a self-quenching system in response to loss of coordinating alcohols to stop the reaction before the backbiting process begins. The combination of both effects allows a thermodynamically controlled ROP of the eight-membered siloxane ring D-4 without producing undesirable cyclic oligosiloxanes.