Synthesis and properties of segmented poly(ether-urethanes) with specially designed and symmetrically chain-folding poly(N-alkylurethane) hard segments

摘要

The study of a series of segmented poly(ether-urethanes) with highly flexible poly(oxytetra-methylene) soft segments and especially designed, molecularly uniform poly(N-alkylurethane) hard segments based on piperazine and 1,4-butanediol bischloroformate has shown that size, shape and perfection of the hard domains can be varied by both the primary structure of the urethane chain and the sample history. Depending on the conformation or the stereogeometry of the built-in central constitutive hard segment unit, chain-extended or chain-folded hard segment crystallization, i.e., the formation of cylindrical or lamellar shaped hard domains can be achieved. These thermoplastic elastomers exhibit distinctly different properties which correlate systematically with the supermolecular structure and the corresponding hard segment architecture, respectively.