Upgrade Traditional KOH Catalyzed Ring-Opening Polymerization of Cyclosiloxanes to More Efficient Process by Adding Catalytic Phosphazenium Salt as Cocatalyst

IF 5.1 1区化学 Q1 POLYMER SCIENCE

Macromolecules Pub Date : 2025-01-30 DOI:10.1021/acs.macromol.4c0238810.1021/acs.macromol.4c02388

Xiaoyu Guo, Zhedong Li, Jinfeng Shi, Chuanli Ren, Na Zhao* and Zhibo Li*,

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引用次数: 0

Abstract

The development of efficient catalyst to overcome the limitation of equilibrium ring-opening polymerization (ROP) of cyclosiloxanes represents the most appealing solution to resolve the back-biting side reaction and high energy consumption during the traditional polysiloxane production. In this contribution, equilibrium polymerization of octamethylcyclotetrasiloxane (D₄) catalyzed by KOH at high temperature was shifted to more efficient polymerization at ambient conditions via fast kinetics and back-biting suppressing by adding a catalytic amount of phosphazenium salt as cocatalyst. Polydimethylsiloxanes (PDMSs) were synthesized in high conversion (≥90%) by bulky phosphazenium salt P₅Cl/KOH catalyzed ROP of D₄ at room temperature in THF solution. The ratio of P₅Cl could be lowered to 0.001 mol % of D₄, and the back-biting reactions were negligible as evaluated by in situ ¹H NMR characterization of the polymerization system. Kinetics investigations suggested that the fast and controlled manner of the ROP was promoted by the P₅Cl/KOH combination. Furthermore, bulk ROP of D₄ and octaphenylcyclotetrasiloxane (P₄) catalyzed by activated phosphazenium salt P₅OMe conveniently afforded PDMSs with different molecular weights (up to 1616 kg mol^–1) and poly(dimethylsiloxane-co-diphenylsiloxane) (PMPS) copolymers with different diphenylsiloxane contents (8.4–63.8 mol %) at 100 °C. The good random characteristic of PMPS copolymers were thoroughly verified by ¹H/²⁹Si NMR and thermodynamic measurements.

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来源期刊

Macromolecules 工程技术-高分子科学

CiteScore

9.30

自引率

16.40%

发文量

942

审稿时长

2 months

期刊介绍： Macromolecules publishes original, fundamental, and impactful research on all aspects of polymer science. Topics of interest include synthesis (e.g., controlled polymerizations, polymerization catalysis, post polymerization modification, new monomer structures and polymer architectures, and polymerization mechanisms/kinetics analysis); phase behavior, thermodynamics, dynamic, and ordering/disordering phenomena (e.g., self-assembly, gelation, crystallization, solution/melt/solid-state characteristics); structure and properties (e.g., mechanical and rheological properties, surface/interfacial characteristics, electronic and transport properties); new state of the art characterization (e.g., spectroscopy, scattering, microscopy, rheology), simulation (e.g., Monte Carlo, molecular dynamics, multi-scale/coarse-grained modeling), and theoretical methods. Renewable/sustainable polymers, polymer networks, responsive polymers, electro-, magneto- and opto-active macromolecules, inorganic polymers, charge-transporting polymers (ion-containing, semiconducting, and conducting), nanostructured polymers, and polymer composites are also of interest. Typical papers published in Macromolecules showcase important and innovative concepts, experimental methods/observations, and theoretical/computational approaches that demonstrate a fundamental advance in the understanding of polymers.