Key Words:CATIONIC POLYMERIZATION; COPOLYSILOXANES; MACROMONOMERS; CHALLENGES; SILOXANES
Abstract:Precise synthesis of well-defined functional polysiloxanes on demand was challenging due to chain transfer and backbiting side reactions during ring-opening polymerization (ROP) of cyclosiloxane monomers. In this contribution, atrisphosphazene base (C3N3-Me-P3) with medium basicity and bulky molecular size was demonstrated as an effective organocatalystto realize the controlled ROP of hexamethylcyclotrisiloxane (D3). Linear poly(dimethylsiloxane)s (PDMSs) with different end-groups were successfully synthesized by C3N3-Me-P3-catalyzed ROP and the subsequent end-capping of the propagatingpolysiloxanes using diverse organochlorosilanes. Molecular characterizations by GPC,1H and29Si NMR, and matrix-assisted laserdesorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) verified the molecular weights (Mn= 3.7-16.5 kg/mol),narrow distributions (D <= 1.18), and well-defined structures of the resulting PDMSs. Moreover, kinetics investigations indicated that the ROP of D3catalyzed by C3N3-Me-P3proceeded in a fast and kinetically controlled manner. This work demonstrated an efficient strategy to make well-defined functional polysiloxane materials using phosphazene as an organocatalyst.
Volume:55
Issue:7
Translation or Not:no