Small-angle X-ray scattering from semidilute solutions of poly(N-isopropylacrylamide) in 1-propanol–water mixtures has been measured in a poor-solvent regime. The binary and ternary cluster integrals of polymer segments were determined from the concentration dependence of the correlation length at several temperatures just below the lower critical-solution temperature. The contributions of the segment–segment interactions to the entropy S
int and enthalpy H
int have been calculated from the temperature dependence of interaction parameters (binary and ternary cluster integrals) and it has been found that both values are positive. The dependence of S
int on the concentration of propanol does not show a simple linear relationship.
On the amorphous layer in bone mineral and biomimetic apatite: A combined small- and wide-angle X-ray scattering analysis.