A New Class of Polyethers-Poly(1,4-Dichloro-2,3-Epoxybutane)s - Synthesis, Mechanism and Property Aspects

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Abstract The cationic ring opening polymerization and copolymerization of the cis and trans isomers of 1,4-dichloro-2,3-epoxybutane (CD and TD) with an iBu3Al - 0.7 H2O catalyst at -78°C has led to an interesting new class of polyethers containing 50% chlorine. The crystalline, racemic diisotactic polymer, obtained from CD in quantitative yield, has the most interesting combination of properties. It has a high melting point (235°C), a high glass transition (95°C), crystallizes readily from the melt, is unusually stable to heat and light, can be melt-processed up to 270°C, is flame resistant, has good barrier properties for air and water, and has good electrical properties. Its main deficiency is poor impact strength which can be overcome by orientation and other methods. This polymer is derived from low-cost raw materials, i.e. Cl2, butadiene, and O2. The interesting combination of properties of the CD polymer combined with its potential moderate cost should lead to such uses as flame resistant plastics, fibers, films and coatings. The CD polymer crystallizes with a helical chain conformation which appears to persist in the melt and in solutions and which appears to influence the crystallization and glass transition behavior of CD polymer and copolymers. The cationic polymerization of CD to highly stereoregular diisotactic polymer has unusual mechanistic aspects. A possible polymerization mechanism is proposed.