SYNTHESIS AND PHOTOINITIATED CATIONIC POLYMERIZATION OF ETHYLENE-7-PHENYL-1,4,6,9-TETRAOXASPIRO[4.4]NONANE

Synthesis of the asymmetrically substituted ethylene-7-phenyl-1,4,6,9- tetraoxaspiro[4.4]nonane monomer in four steps and its polymerization are described. The spiromonomer is liquid at room temperature. Photoin itiated cationic polymerization of ethylene-7-phenyl-1,4,6,9-tetraoxas piro[4.4]nonane at ambient temperature in bulk was investigated, using a cationic photoinitiator system based on l)[1,2,3,4,5,6-eta](1-(meth ylethyl)benzene)iron(I) hexafluorophosphate (Irgacure 261). Upon irrad iation, within 10 mon quantitative double ring-opening polymerization to a structurally well-defined poly(alkylene-carbonate-ketone) with mo lecular weight average M(w) of 27.000 (GPC) occurred. No elimination, vinylidene polymerization, or single ring-opening polymerization was d etected, as commonly observed in the case of free-radical initiation o f similar spiroorthocarbonates, spiroorthoesters, or methylenedioxolan es were detected. Despite quantitative double ring opening, no volume expansion occurred during polymerization. A volume shrinkage of 4.1% w as found. General structural prerequisites for expanding and pseudoexp anding monomer systems are discussed.