SYNTHESIS AND CHARACTERIZATION OF GLYCIDYL AZIDE POLYMERS USING ISOTACTIC AND CHIRAL POLY(EPICHLOROHYDRIN)S

Isotactic and chiral glycidyl azide polymers (GAPs) have been synthesi zed by the reaction of isotactic and chiral poly(epichlorohydrin)s (PE CHs) with sodium azide in dimethylformamide at 95 degrees C. The azida tion does not affect the isotacticity of the chains, but the polymer b ackbone is degraded in the process; a GAP of high molecular weight (10 0 kg/mol) is nevertheless obtained. Despite the high isotacticity of t he polymer chains, the GAPs are not crystalline. Long reaction times f avor the branching and/or the cross-linking of the polymer. The isotac tic and chiral PECHs used as starting materials for the CAP syntheses have been prepared by the Vandenberg process using racemic or chiral m onomers, leading thus to partially ((RS)-PECH) or completely ((R)-or ( S)-PECH) isotactic polymers, respectively. They have been split into a soluble and an insoluble fraction by acetone extraction. The fraction ation of chiral PECH withdraws from the polymer the incompletely isota ctic chains coming from the presence of monomers of opposite configura tion in the chiral epichlorohydrin or from a defective polymerization process. The population of crystals remaining in the insoluble chiral PECH fraction is thus more homogeneous, leading to an improved crystal linity and a higher melting temperature.