A novel phenylethynyl-terminated siloxane:Synthesis and electron beam cure

The synthesis of a novel phenylethynyl-terminated siloxane polymer is described, by reaction of the amine-terminated siloxane with 4-phenylethynylphthalic anhydride. The oligomer (PET-PDMS) is electron beam (EB) curable, in contrast to the commercial phenylethynyl-terminated imide, PETI-5, probably as a result of increased polymer chain mobility arising from siloxane incorporation. Raman spectroscopy indicates that the cure mechanisms for electron beam and thermal cure of PET-PDMS are different. PET-PDMS appears to undergo chain scission under the influence of an electron beam. Differential scanning calorimetry of the EB cured polymer is also consistent with a mechanism involving cleavage of siloxane linkages. </jats:p