Heat stability and degradation of thermostable prepolymers in a controlledatmosphere - I: The heat cycle of propargylic monomer homopolymerization, and characterization of adducts

The liquid study of propargylic monomers during heat treatment has shown th e formation of secondary phenolic products in the reaction mixture. They ar e in the form of propargyl-phenol and chromene-phenol and could be the weak links in the thermal properties of the final polymer. Moreover, we note so me differences between the reactivities of the two monomers, probably relat ed to the nature of the central pivot of the skeleton. Solid state analyses by FTIR and sold state crossed polarization magic angl e spinning C-13 NMR have confirmed the structure of the final polymer, and the reaction paths proposed and have enabled the heat cycle used to be vali dated. Thermal analyses have shown that the fluorine pivot confers the best thermal properties on the crosslinked material and influences the reactivi ty and degradation mechanisms of the compounds. In addition, the degradatio n of the crosslinked compounds occurred as a single step for the dipropargy l ether of bisphenol A and as two steps for the dipropargyl ether of hexafl uorobisphenol A.