Solid-state structure of comb-like polymers having n-octadecyl side chains .1. Cocrystallization of side chain with n-octadecanoic acid

Solid-state structures of comb-like polyacrylates (PAx) and polymethacrylates (Phx) having crystallizable n-octadecyl side chains and their blends with n-octadecanoic acid (C18) have been investigated by means of differential scanning calorimetry and X-ray diffraction methods. It is concluded that n-alkyl side chains of comb-like polymer cocrystallize with low-molecular-weight C18 by incorporation of C18 into hexagonal crystalline lattice. In the case of amorphous PMx, the addition of C18 can induce a formation of crystalline domain by the cocrystallization with the side chain. Differences in the crystallization behavior, such as fractions of crystallized methylene units and effects of thermal history, between PAx and PMx are found to be considerably large. These results are explained by the difference in the segmental mobility of main chain.