Photoinitiated Cationic Ring-Opening Polymerization of Octamethylcyclotetrasiloxane

Abstract

Photochemical techniques have recently been revitalized as they can readily be adapted to different polymerization modes to yield a wide range of complex macromolecular structures. However, the implementation of the photoinduced cationic methods in the polymerization of cyclic siloxane monomers has scarcely been investigated. Octamethylcyclotetrasiloxane (D4) is an important monomer for the synthesis of polydimethylsiloxane (PDMS) and its copolymers. In this study, the cationic ring-opening polymerization (ROP) of D4, initiated by diphenyl iodonium hexafluorophosphate (DPI), has been studied. Both direct and indirect initiating systems acting at broad wavelength using benzophenone and pyrene were investigated. In both systems, photochemically generated protonic acids and silylium cations are responsible for the polymerization. The kinetics of the polymerization are followed by viscosimetry and GPC analyses. The reported approach may overcome the problems associated with conventional methods and therefore represents industrial importance for the fabrication of polysiloxanes.

Progress in process parameters and mechanism research of polymer emulsion preparation

“…Mistry Bhavita 53 synthesized a halogen-terminated macromolecular initiator with good grafting ability by reacting vinyl-terminated polydimethylsiloxane (PDMS) with 3-chloropropyl mercaptan, for the synthesis of ABA-type block copolymers. Coban Zehra Gul 54 investigated the use of diphenyliodonium hexafluorophosphate (DPI) as an initiator to initiate the cationic ring-opening polymerization (ROP) of octamethylcyclotetrasiloxane (D4), resulting in the preparation of cationic emulsions. Przesławski Grzegorz 55 studied the use of benzoyl peroxide (BPO) as an oxidizing agent (initiator) and N , N -dimethyl-aniline (DMA) as a reducing agent (co-initiator) to investigate the properties of poly(methyl methacrylate) (PMMA) cement.…”