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Evidence for residual dipolar interactions in the polybutadiene domains of two poly(styrene−butadiene−styrene) block copolymers is shown at temperatures ranging from ambient to 90 °C. The two copolymers differ for the presence of a plasticizer, selectively compatible with the polybutadiene blocks. The evidence results from the analysis of ¹H transverse magnetization decays, ¹H pseudo-solid echoes, and ¹³C edited ¹H spectra. ¹H transverse magnetization decay data can be interpreted using a simplified network model, which provides the number N of statistical segments between cross-links. The analysis of decays and ¹H pseudo-solid echoes shows that the plasticizer induces a lowering of the entanglement density. These results are consistent with the information obtained from the ¹³C edited ¹H spectra.

The order and dynamics of the mesogenic groups in a series of side chain liquid crystal copolymers were investigated in their nematic phase through ²H NMR. The main chain is built with a variable content of randomly distributed acrylic and methacrylic units, while the mesogenic groups are based on a phenyl benzoate moiety which is labeled on one phenyl ring. The analysis of the orientational order together with the spectral densities J1(ω0) and J2(2ω0) revealed a certain degree of heterogeneity concerning both the order of the mesogens a and m respectively bound to the acrylic and the methacrylic monomers and their dynamics. In fact, mesogens m are more ordered than a and characterized by slower motions. The processes mainly contributing to relaxation proved to be the rotation of the phenyl ring about its para-axis and the spinning of the whole mesogenic unit.