Cationic polymerization of α,β‐disubstituted olefins. IV. Stereospecific polymerization of propenyl alkyl ethers catalyzed by BF₃·O(C₂H₅)₂ and Al₂(SO₄)₃–H₂SO₄ complex

Abstract

Abstract The cis ‐ and trans ‐propenyl alkyl ethers were polymerized by a homogeneous catalyst [BF 3 ·O(C 2 H 5 ) 2 ] and a heterogeneous catalyst [Al 2 (SO 4 ) 3 –H 2 SO 4 complex]. Methyl, ethyl, isopropyl, n ‐butyl and tert ‐butyl propenyl ethers were used as monomers. The steric structure of the polymers formed depended on the geometric structures of monomer and the polymerization conditions. In polymerizations with BF 3 ·O(C 2 H 5 ) 2 at −78°C., trans isomers produced crystalline polymers, but cis isomers formed amorphous ones except for tert ‐butyl propenyl ether. On the other hand, highly crystalline polymers were formed from cis isomers, but not from the trans isomers in the polymerization by Al 2 (SO 4 ) 3 –H 2 SO 4 complex at 0°C. The x‐ray diffraction patterns of the crystalline polymers obtained from the trans isomers were different from those produced from the cis isomers, except for poly(methyl propenyl ether). The reaction mechanism was discussed briefly on these basis of these results.