The development of microphase separation after temperature jumps in poly(N,N-diethylacrylamide) hydrogels was studied by means of small-angle neutron (SANS) and X-ray (SAXS) scattering. The curves of excess SANS and SAXS for temperature jumps from 25 to 30°C were different in character from those for jumps from 30 to 35°C. After the temperature jump from 25 to 30°C two polymer phases with different water content are formed (excess scattering intensity lex ~ q- 2, where q is the length of the scattering vector); however, after the jump from 30 to 35°C the dilute phase is formed by water droplets (pronounced two-phase structure, Ie~q-4). Photoelastic measurements on the equilibrium swollen samples indicate that correlations exist between side groups at temperatures greater than or equal to 33°C. The association of side groups leads to microsyneresis and to the differences observed in scattering behaviour.
Посилання на статтю:
SAXS, SANS and photoelasticity of poly(N, N-diethylacrylamide) networks: 1. Structure changes after temperature jumps / J. Plestil*, M. Ilavsky, H. Pospisil and D. Hlavata // Polymer. – 1993. – Vol 34. – P. 4846-4851.