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Title: Phase behavior of (polyacrylamides + water) solutions: concentration, pressure and isotope effects
Authors: Azevedo, R. Gomes de 
Rebelo, L. P. N. 
Ramos, A. M. 
Szydlowski, J. 
Sousa, H. C. de 
Klein, J. 
Keywords: Liquid-liquid equilibria; Polyacrylamides; Polymeric aqueous solutions; Pressure effects; Isotope effects
Issue Date: 2001
Citation: Fluid Phase Equilibria. 185:1-2 (2001) 189-198
Abstract: Phase diagrams of poly(N-isopropylacrylamide) (PNIPAAM) as well as of hydrophilically-modified copolymers in aqueous solution were determined. A high-accuracy He-Ne Laser scattering technique was used for the detection of operational spinodal (sp) and cloud-point (cp) curves. Polymer concentration was varied from 0.5 to 20 wt.%. In the case of copoly(PNIPAAM/vinylsaccharide) several different chain lengths were considered. Pressure (up to 400 bar) and solvent isotope effects were studied. We predict a closed-loop type phase diagram for the copolymers, which presents an estimated hypercritical point in H2O solutions at Mw~0.5×105, although only lower critical solution temperature (LCST) is experimentally accessible. At lower molecular weights, the solutions are always in the one-phase region.
DOI: 10.1016/s0378-3812(01)00469-1
Rights: openAccess
Appears in Collections:FCTUC Eng.Química - Artigos em Revistas Internacionais

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