Synthesis of monomers that expand on polymerization. Synthesis and polymerization of 3,9-dimethylene-1,5,7,11-tetraoxaspiro[5.5]undecane

A spiro ortho-carbonate containing two double bonds, 3,9-dimethylene-1,5,7,11-tetraoxaspiro[5.5]undecane (III) was prepared from 2-methylene-1,3-propanediol (VI). The structure of the monomer was indicated by its elementary analysis as well as its infrared and NMR spectra. When the crystalline monomer was polymerized with Lewis acids such as trifluoride etherate as catalysts, soluble polymer with a high molecular weight was obtained. The infrared and NMR spectra indicated that the polymer was an alternating copolymer of ether and carbonate having double bonds. When the usual monomers such as vinyl chloride and styrene polymerize, shrinkage occurs. However, this monomer underwent expansion on polymerization.