POLYLACTONES .29. PREFERENTIALLY SYNDIOTACTIC POLY(BETA-(R,S)-BUTYROLACTONE) OBTAINED BY RING-OPENING POLYMERIZATION WITH TRIPHENYLTIN METHOXIDE OR DIPHENYLTIN DIMETHOXIDE

Triphenyltin methoxide (Ph3SnOMe) and diphenyltin dimethoxide (Ph2Sn(OMe)2)-initiated polymerizations of beta-(RS)-butyrolactone were conducted in bulk at 50 and 75-degrees-C. The low catalytic reactivity of the initiator prevented lower temperatures. The stereosequences of the isolated poly(beta-(RS)-butyrolactones) were analyzed by C-13 NMR spectroscopy and characterized by the ratio of isotactic and syndiotactic diads (i/s-ratios down to 0,4/1,0 were found). With Ph3SnOMe relatively high molecular weights (eta(inh) = 0,3 dL/g, M(w)BAR almost-equal-to 25000-30000) were obtained but the stereoselectivity of the polymers obtained with both Ph3SnOMe and Ph2Sn(OMe)2 is not higher than that with BU3SnOMe (published previously). Selected poly(beta-(R,S)-butyrolactone) samples were characterized by IR spectra, WAXS powder patterns and DSC measurements.