Spontaneous alternating copolymerization of 1-silyloxy-1,3-dienes and unsaturated cyclic anhydrides

1-Silyloxy-1,3-dienes, i.e., 1-butadienyloxytrimethylsilane (BdTMS) or 1-butadienyloxytert -butyldimethylsilane (BdTBDMS) and unsaturated cyclic anhydrides, containing maleic anhydride (MAn), citraconic anhydride (CAn), and itaconic anhydride (IAn) were found to form charge transfer complexes (CTC) in benzene. Equilibrium constants, K, of the complexes were calculated by the Benesi-Hildebrand equation using UV spectroscopy to be 0.4 -1.0. Spontaneous copolymerizations of silyloxydienes with unsaturated cyclic anhydrides were established from 25 to 75 mol% of BdTMS in the feed. All polymers obtained had molar composition of 50/50 irrespective of feed molar ratios. Interestingly, molar ratio of 1,4- and 3,4-addtion structure seems to be influenced by K of CTC. Desilylation and successive lactonization of poly(BdTMS-alt-MAn) were conducted. Conversions of lactonization were beyond Flory's limit (86.5%) being nearly 100% due to intramolecular reactions of neighboring hydroxyl groups and cyclic anhydride in alternating copolymers.