Temperature-pressure superposition in SANS Ξ for an A-b-B diblock copolymer

A temperature-pressure (T-P) superposition in scattering behavior for an A-b-B Diblock copolymer was studied. A symmetric dPS-b-PPrMA was synthesized by the sequential, anionic polymerization of d-styrene and n-propyl methacrylate in tetrahydrofuran (THF) at -78°C in the presence of LiCl under purified argon using sec-BuLi as an initiator. The results show that at lower temperatures, a weak and broad peak maximum at 0.18 nm^-1 is seen due to the correlation hole scattering by the compositional fluctuation of block copolymer in disordered state. The copolymer exhibits a baroplastic behavior, which yields diminishing Flory-Huggins effective interaction parameter with increase in pressure. The SANS interaction parameter is also predicted at any point in a given temperature-pressure window only with the minimal number of measurements by using the characteristic curve.