Microstructure Analysis of Poly(cyclopentene carbonate)s at the Diad Level

The spectroscopic assignment of poly(cyclopentene carbonate)s at the diad level was performed by using two kinds of model compounds: isotactic and syndiotactic dimers of cyclopentene carbonate unit. By comparing the signals in the carbonyl region, we concluded that the signals at 153.85 and 153.78 ppm in the 13C NMR spectrum of poly(cyclopentene carbonate) were attributed to m-diad and r-diad, respectively. The signals at 82.61 and 82.53 ppm in the 13C NMR spectrum were assigned to m-diad and r-diad peak of methine resonance, respectively. It was found that the carbonate carbon signals were sensitive toward the stereocenters on adjacent epoxide ring-opening units. The syndiotactic and isotactic diads matched well with the microstructures of the stereoregular poly(cyclopentene carbonate)s that were prepared by using chiral dinuclear Co(III) complex catalysts.