The surface energy and structure of graft layers of a comb-shaped LC polymer

For the graft layers of LC polymer prepared by postpolymerization of a meso gen-containing acrylic monomer on the substrates of fluoro-containing polym ers, the energy characteristics of the surface were determined by the conta ct angle method. It was Shown that, within the studied region of the layer thicknesses (2-15 mu m), the energy characteristics are independent of the synthetic conditions and the nature of a substrate involved in the process of grafting polymerization. The thermal annealing of the samples at a tempe rature higher than the isotropization temperature of the LC polymer, leads to a sharp decrease in the polar component of the surface tension from 10.6 to 4.5 mJ/m(2). Uniaxial orientation gives rise to a change in the surface characteristics of the graft layers in the direction opposite to that of t hermal annealing: the polar constituent increases to 13.1 mJ/m(2), while th e dispersion constituent decreases to 27.1 mJ/m(2). The experimental eviden ce is related to the concentration of CN groups in the surface layers of th e graft polymer. The scheme was suggested for the structure of the LC polym er layer which takes into consideration various conditions of the polymer s ynthesis.