Improved synthesis and properties of hydroxyl-terminated liquid fluorosilicone

The synthesis of hydroxyl-terminated poly(trifluoropropylmethyl) siloxane (PTFPMS-OH) by anionic ring-opening polymerization of 1,3,5-tris(trifluoropropylmethyl)cyclotrisiloxane (D3F) was studied in bulk using potassium hydroxide as an initiator in the presence of several reaction stabilizers. The promoting effect of the reaction stabilizers for the polymerization of D3F was investigated by GPC and NMR analyses. Results showed that the selected reaction stabilizers exhibited a significant promoting effect. This new process of polymerization produced well-defined alpha,omega-dihydroxylated polysiloxane in very high yields. The addition of reaction stabilizers could almost completely suppress back-biting reactions during the polymerization. It was found that there lies an exponential decay relationship between the molecular weight of PTFPMS-OH and amount of end-capping agent. Thus, by adjusting the reaction conditions strictly, the molecular weight of the fluorosilicone could be controlled accurately, and meanwhile a broad "terminate window" could be implemented. Thermogravimetic (TG) analysis indicated that PTFPMS-OH could be used in a wide range of operational temperatures. (C) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43220.