Solid-State 13C NMR Study of Thermotropic Poly(bibenzoates). 2. Poly(triethylene glycol p,p'-bibenzoate)

摘要: Several samples of thermotropic poly(triethylene glycol p,p'-bibenzoate) (PTEB) with different thermal histories have been analyzed by DSC, X-ray scattering, and solid-state 13 C 1 H NMR. This polymer can be quenched into the smectic LC state becomes semicrystalline (0.39 crystalline fraction) upon annealing for 12 days at 85 °C (sample 85A). Also, 33 months ambient temperatures RTA1) yields a 31%-crystalline sample, owing to T g 20°C. By NMR, spectra fraction these two are isolated. These spectra, in aromatic region, very similar ; however, aliphatic region there significant differences which probably originate from conformational within spacer. DSC data show contrast melting points RTA1 85A samples. Small-angle synchrotron NMR spin diffusion data, combined crystallinity values, yield picture relatively thin crystallites, about 3 repeat units thick sample 2 so is some question as whether crystallites enough express their undistorted habit isolated point difference attributed crystal thicknesses, opposed polymorphism. Synchrotron taken layer spacing that spacings persist all samples, or annealed. Yet definite changes accompany crystallization. In view nature narrow width peaks suggests periodicity must encompass both noncrystalline (NC) regions. Selected relaxation measurements also bear out notion molecular mobility regions NC similar, although not identical. Finally, spectral observations carbons suggest one possibilities : either spacer conformation interior differs near crystal/NC interface A split peak line supports