SYNOPSISA series of aromatic monomers bearing cationically polymerizable propenyl groups were prepared and characterized using the readily available starting materials: isoeugenol and o-ally1 phenol. Monomers with both propenyl and vinyl ether functional groups were also synthesized by the reaction of these starting materials with chloroethyl vinyl ether. The reactivity of the resulting monomers in photoinitiated cationic polymerization was studied using differential scanning photocalorimetry and photogel point measurements. Their thermal properties were determined using thermogravimetric analysis. 0 1994 John Wiley & Sons, Inc.

Keywords: hydrodimerization epoxy resins synthesis curing cationic photopolymerization INTRODUCTIONThe photoinitiated cationic polymerization of di-and multifunctional epoxides has been a long-term topic of investigation in this laboratory.' These polymerizations are of considerable current commercial interest since they are rapid, low-energy processes which are essentially pollution-free. Although a number of epoxy monomers are available from commercial sources, these materials are not specifically intended for use in cationic polymerizations. Consequently, these materials often contain undesirable impurities which inhibit cationic polymerizations or reduce their rates. In addition, the range of materials available is not sufficient to meet many of the mechanical and chemical requirements of many potential applications. For these reasons, current work in this laboratory has focused on the design and synthesis of novel multifunctional epoxide monomers by both conventional and unconventional routes.Recently Crabtree and his c o -~o r k e r s '~~ have developed a novel mercury photosensitized reaction by which olefins can be hydrodimerized in high yields in the presence of hydrogen gas to give branched alkanes. It was demonstrated by these workers that the reaction is very general and can be applied to olefins bearing a variety of different functional groups including unsaturated epoxides. The mechanism proposed by Crabtree and his co-workers for this hydrodimerization reaction is shown in Scheme 1. The reaction is carried out in a quartz vessel to which the alkene and a drop of mercury is added. The vessel is filled with hydrogen gas which is dissociated by photoexcited mercury atoms [ eqs.( 1 ) and ( 2 ) 1. Hydrogen atoms produced by the latter reaction add to the alkene generating carbon-centered free radicals [ eq. ( 3 ) ] which subsequently dimerize [ eq. (4)]. The reaction occurs only in the vapor state. As the dimer is formed, it becomes less volatile and remains in the liquid state at the bottom of the reaction vessel and is thus, largely protected from further reaction. However, during hydrodimerization dehydrodimerization also takes place as a side reaction by the abstraction of hydrogen atoms from the substrate and the product by photoexcited mercury atoms. This gives rise to a small amount of by-products with complex structures which are apparent by the pale yellow color of the product.This brief study was undertaken to determine whether the above photosensitized hydrodimerization reaction can be applied to the synthesis of novel difunctional epoxides. It was also of some interest to determine reactivity of these epoxides in photoinitiated cationic polymerization. EXPERIMENTAL Materials1,2-Epoxy-5-hexene, 1,2-epoxy-7-octene, and 1,2,7,8-&-epoxyoctane were used as purchased from the Aldrich Chemical Company. The photoinitiator, (4-octyloxyphenyl) phenyliodonium hexafluoroantimonate ( IV ) was prepared as previously de~cribed.~ 'H-NMR data were obtained in CDC13 with a VarianModel XL 200 spectrometer equ...