Lixin Sun, Yanan Sun, Chenliang Tang, Fangfei Xin, Chuanxing Wang, Lei Xu, Li Ding and Yuetao Liu*,
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Initiator Activation and Active Chain End Stabilization Strategy via the Dual Hydrogen Bond for the Controlled Synthesis of Poly(fluorosiloxane)
Poly(fluorosiloxane) (PMTFPS) holds significant potential for applications in coatings, sealing materials, and sensors. A main barrier to high-precision PMTFPS, particularly PMTFPS with a narrow molecular weight distribution, is the severely backbiting side reactions during anionic ring-opening polymerization (AROP) of trimethyl trifluoropropyl cyclotrisiloxane (D3F) monomers. To address this issue, we developed a binary organocatalytic system based on sodium hexamethyldisilazane (NaHMDS) and indolecarbazole (ICZ). In this system, the sodium salt (NaICZ) generated during the reaction activates the initiator benzyl alcohol (BnOH), forming an initiating system that features dual hydrogen bonding and exhibits low nucleophilicity (with a nucleophilicity index of 4.05 eV). Mechanistic analysis demonstrated that introducing ICZ as a hydrogen bond donor increases the activation energy barrier of the chain initiation rate-determining step (ΔG = 13.23 kcal/mol) and enhances the stability of the active center (E = −18.80 kcal/mol), effectively suppressing backbiting reactions.
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.
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