Thermal Stability of Fluorinated Polydienes Synthesized by Addition of Difluorocarbene

Abstract

Linear PCHD and polyisoprenes with different microstructures and molecular weights are synthesized and chemically modifi ed to improve their thermal and chemical stability by forming a three-membered ring structure containing two C Ϫ F bonds. Pyrolysis of these fl uorinated polydienes proceeds through a two-stage decomposition involving chain scission, crosslinking, dehydrogenation, and dehalogenation. The pyrolysis leads to graphite-like residues, whereas their polydiene precursors decompose completely under the same conditions. The fl uorination of PCHD enhances its thermal stability. The stronger C Ϫ F bond along with high strain of the three-membered ring structure and formation of relatively stable free radicals play an important role in the thermal stability of fl uorinated polydienes.