SYNTHESIS OF CATIONIC UV-CURABLE POLYSILOXANES AND PROPERTIES OF THE CURED FILMS OF THEIR COMPOSITES WITH EPOXY RESIN

Abstract

By means of a platinum-catalyzed hydrosilylation reaction,2,2,3,4,4,4-hexafluorobutyl methacrylate(HFMA) and allyl glycidyl ether(AGE) in different proportions were used to react with polymethylhydrosiloxane(PMHS) in turn,then with different fluorine contents,three kinds of cationic UV-curable polysiloxanes containing fluorinated/epoxy side groups(EFPS) were obtained.Their chemical structures were characterized by FTIR,1H-NMR and 13C-NMR.By respectively mixing the three synthesized polysiloxanes with a selected UV-curable epoxy resin(E51),a series of cured composite films were prepared via cationic photopolymerization under UV irradiation.The thermal stability,surface energy and water resistance property of these cured composite films were analyzed by means of TGA,surface contact angle test and water absorption ratio test.The results indicated that after the introduction of the cationic UV-curable epoxy groups into the side chains of PMHS,the obtained EFPS had more crosslinkable groups,leading to relatively high crosslink degree between the EFPS and the selected epoxy resin.When a quantity of the EFPS was added into epoxy resin matrix,in the presence of fluorine and silicon,the temperature values of the 5% mass loss(T5%) and the 50% mass loss(T50%) of the cured composite films increased to 337.7℃ and 463.6℃,respectively,and their residual weight at 600℃ increased to 25.6%.The calculated surface energy values of the cured films decreased from 44.1 mJ/m2 to 15.3 mJ/m2,and the water absorption ratios were lower than 0.5%.By scanning electron microscopy measurements,the cross-section morphology of the cured composite films showed that the EFPS and the selected epoxy resin was compatible.