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Dynamics of regio-regulated Poly(4-methylthiazole-2,5-diyl) [HH-P4MeTz] wasinves tigated by solid-state 1H, 2D, 13C NMR spectroscopies, and differentialscanning calorimetry(DSC) measurements. DSC, 2D quadrupolar echo NMR, 13Ccross-polarization and magic-angle spinning(CPMAS) NMR, and 2D spin-echo(2DSE)CPMAS NMR spectroscopy suggest existence of a quasi-ordered phase in whichbackbone twists take place with weakened pi-stackings. Two-dimensional exchange2D NMR(2DEX) detected slow dynamics with a rate of an order of 10^2Hz for theCD_3 group in d_3-HH-P4MeTz at 288K. The frequency dependence of protonlongitudinal relaxation rate at 288K shows a omega^-1/2 dependence, which isdue to the one-dimensional diffusion-like motion of backbone conformationalmodulation waves. The diffusion rate was estimated as 3+/-2 GHz, which wasapproximately 10^7 times larger than that estimated by 2DEX NMR measurements.These results suggest that there exists anomalous dispersion of modulationwaves in HH-P4MeTz. The one-dimensional group velocity of the wave packet isresponsible for the behavior of proton longitudinal relaxation time. On theother hand, the 2DEX NMR is sensitive to phase velocity of the nutation ofmethyl groups that is associated with backbone twists. From proton T_1 and T_2measurements, the activation energy was estimated as 2.9 and 3.4 kcal/mol,respectively. These were in agreement with 3.0 kcal/mol determined byMoller-Plesset(MP2) molecular orbital(MO) calculation. We also performedchemical shielding calculation of the methyl-carbon in order to understandchemical shift tensor behavior, leading to the fact that a quasi-ordered phasecoexist with the crystalline phase.Comment: 14 pages, 11 figures, to appear in Phys.Rev.

physical review. b, condensed matter and materials physics

Dynamics of the quasiordered structure in the regioregulated<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>π</mml:mi></mml:math>-conjugated polymer poly(4-methylthiazole-2,5-diyl)

Dynamics of the quasiordered structure in the regioregulatedπ-conjugated polymer poly(4-methylthiazole-2,5-diyl)