PHOTOCALORIMETRIC ANALYSIS OF THE REACTIV ITY OF CROSS-LINKABLE POLYDIMETHYLSILOXANES

The synthesis of a model cyclic tetrasiloxane has been performed. The siloxane contained primary hydroxyl functions on which were grafted un saturations that were crosslinked under UV, or by a radical or a catio nic route. The grafts were acrylic, acrylate urethanes, vinyl and styr enic ethers. The synthesis was followed by a study of the reactivity o f these four oligomers by DCP (differential power compensated photocal orimetry), in order to compare the reactivity of styrenic polysiloxane s, which are a new class of UV crosslinkable polymers, to that of acry lic or vinyl ethers polysiloxanes. Thus, it was noticed that styrenic groups exhibit an average reactivity, but are as reactive by the catio nic as by the radical method. (C) 1997 Elsevier Science Ltd.