ABSTRACT Syndiotactic poly(vinyl alcohol) (s-PVA) was successfully prepared from poly(vinyl trifluoroacetate) in 1956. S-PVAs with syndiotactic diad(s-diad) contents of 58 to 64 % were prepared up to 1960. The properties of those s-PVA i.e. the difficult dissolution in water, easy gelation of those aqueous solutions, high melting temperature, high thermal stability, strong color development with iodine, etc. were studied. Recently s-PVAs with s-diad contents of 64~72 % were derived from several vinyl ester monomers with bulky aliphatic acyl or many fluorine atom containing acyl groups and vinyl acetate through the polymerization in fluoroalcohols. The s-PVA with s-diad content of 72 % has the pentad syndiotactic sequence of 24%. The dimethylsulfoxide/water solutions of s-PVA form gels through the gelation with solid phase separation and liquid-liquid separation in accordance with temperature and concentration. The hydrogels can be used as drug release devices. The melting point of s-PVA with s-diad content of 65 % and the crystallinity of 0.97 % was 279 °C. The fibers with high tensile strengths of 2 ~ 6 GPa have been prepared. The blue color complex of s-PVA with iodine is made by incorporating iodine in aggregates of syndiotactic sequences in the s-PVA molecules.
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