CROSS-LINKING OF POLY(EPIBROMOHYDRIN) CONTAINING THE ARYL PROP-2-YNYLETHER TERMINATED SIDE-GROUP

Poly(epibromohydrin) (PEBH) was chemically modified using 1,8-diazabic yclo-(5.4.0)-7-undecene to catalyze the substitution of the bromine at om by 4-(propargyloxy)benzoic acid. The linear polyethers obtained sho wed a degree of substitution from 36 to 82% depending on the PEBH/Nu r atio. A model compound, aryl propargyl ether terminated monomer (II), was synthesized to study the crosslinking. Differential scanning calor imetry (DSC), IR, H-1 and C-13 NMR analysis showed that this process f irst involves a sigmatropic rearrangement reaction of the aryl proparg yl ether groups to form 2H-1-benzopyran structures which subsequently polymerize. Linear polymers undergo a similar process of crosslinking leading to thermostable polymers. The activation energies are independ ent of the degree of modification but the final thermal properties dep end on the crosslinking density.