Authors Melnichenko, Y.B. ; Kiran, E. ; Heath, K. ; Salaniwal, S. ; Cochran, H.D. ; Stamm, M. ; Van Hook, W.A. ; Wignall, G.D.
Title Comparison of the behaviour of polymers in supercritical fluids and organic solvents via small-angle neutron scattering
Date 29.05.2000
Number 9242
Abstract Small-angle neutron scattering has been used to study the effect of temperature and pressure on the phase behaviour of semidilute solutions of polymers dissolved in organic and supercritical solvents. Above the theta temperature (T[Theta]), these systems exhibit a "good solvent" domain, where the molecules expand beyond the unperturbed dimensions in both organic solvents and in CO2. However, this transition can be made to occur at a critical "theta pressure" (P[Theta]) in CO2 and this represents a new concept in the physics of polymer-solvent systems. For T < T[Theta], and P < P[Theta], the system enters the "poor solvent" domain, where diverging concentration fluctuations prevent the chains from collapsing and allow them to maintain their unperturbed dimensions.
Publisher Journal of Applied Crystallography
Citation Journal of Applied Crystallography 33 (2000) 682-685
Tags chain collapse polystyrene poor

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