Nuclear magnetic resonance studies on poly(t‐butylethylene oxide‐2‐D)

Properties and methods of synthesis of several optically active polyoxiranes and polythiiranes

“…The most interesting case found seemed to be that of t-butyl thiirane for which optically active and racemic polymers prepared by stereospecific initiators showed differences in the solubility and the melting point [42] and had two different types of crystalline structure [60]. In the case of t-butyl oxirane, the racemic polymer prepared using a stereospecific initiator was in major part (90%) insoluble in common solvents at room temperature, but was soluble on heating [5 1-52] , [90] . The crystalline structure of the racemic polymer was found to be different from that of methyl oxirane and methyl thiirane, with two R type polymer chains and two S type polymer chains per unit cell, which is optically inactive by optical compensation [91].…”

High‐resolution NMR spectrum of deuterated and undeuterated poly(propene sulfone)

“…Both the A and B protons are sensitive to tacticity, giving rise to five lines in the methylene spectrum of I11 and ten lines, consisting of four overlapping AB quartets, in the methylene spectrum of IV. From a consideration of the relative intensities of the peaks in the spectra of poly(propene-24 sulfone)s of different tacticities the following assignment to triad structures has been made: TA: 6.43 hi and i, 6.51 s and h,. The proportions of the four triad structures correspond to a single-parameter model for chain growth in which the probability of an isotactic placement u is 0.50 for the free-radical copolymerization of propene and sulfur dioxide, 0.55 for the ZnCOa-initiated polymerization of propene sulfide and 0.64 for the CdCOsinitiated polymerization of propene sulfide.…”

“…This appears to be the first reported case of a preferred mode of addition to an ethylenic bond in a free radically initiated polymerization. 6.06 hi, 6.12 i and s, 6.19 h,; TB:…”