The effect of shear on the alignment of the smectic A phase formed by a polyacrylate side chain liquid crystal polymer (SCLCP) has been investigated using small-angle X-ray scattering (SAXS) with simultaneous rheology. Large amplitude oscillatory shear led to a highly oriented state with the layer normal parallel to the neutral direction. The sample mosaic width obtained after large amplitude shear (⬃10°, Gaussian HWHM) was comparable to that obtained by magnetic alignment of the mesogens. The smectic phase was found to exhibit shear thinning, with a sharp reduction in both dynamic shear moduli upon application of shear. Cessation of shear led to a rapid recovery in the moduli to their initial values, although the anisotropy of the SAXS peaks relaxed more slowly. Nevertheless, a high degree of alignment was retained even after the relaxation period.
Посилання на статтю:
Polymer Communication Shear-induced layer alignment in the smectic phase of a side chain liquid crystal polymer / I.W. Hamley, P. Davidson, A.J. Gleeson // Polymer. – 1999. – N 40. – P. 3599–3603.