In situ FT-IR spectroscopy has been used to study poly(methyl methacrylate) films subjected to high-pressure and supercritical CO2. Spectral changes indicate increased molecular mobility of ester groups due to the plasticization effect of CO2 on PMMA. This increase in PMMA segmental mobility has been used to impregnate Disperse Red 1 dye (DR1) into polymer film from a supercritical fluid solution. The enhanced diffusion process was observed in situ via FT-IR and UV/vis spectroscopy.
ABSTRACT:In situ ultraviolet-visible spectroscopy has been used to study diffusion of two azo-dyes in a CO 2 -swollen matrix of poly(methyl methacrylate) (PMMA). The diffusivity of both dyes can be tuned simply be changing the system pressure. Higher pressure of CO 2 enhances diffusion of a dye in PMMA. The diffusion of dyes in CO 2 -swollen PMMA can also be influenced by specific interactions. The partitioning of the dyes between the polymer phase and the fluid phase was measured, and the partition coefficients are large (10
Cosolvents exhibit significant effects on the partitioning behavior of dilute solutes between a supercritical CO 2 fluid phase and cross-linked siloxane-based polymers. A spectroscopic technique was developed and applied that allows us to measure the partition coefficients of both the cosolvents and solutes between the two phases. The Sanchez-Lacombe lattice fluid equation of state was extended to represent a two-phase, four-component system and was quantitatively successful in representing the volumetric and phase-equilibria properties of such systems. We then apply the model and our data to investigate the magnitudes of stationaryphase effects in supercritical fluid chromatography and explore opportunities to use the model for a priori prediction of separation.
A single Sanchez−Lacombe lattice fluid equation of state is used to model both phases for a
polymer−supercritical fluid−cosolvent system. This method represents well over a wide pressure
range both volumetric and phase equilibrium properties for a cross-linked poly(dimethyl siloxane)
phase in contact with CO2 modified by a number of cosolvents. A single adjustable binary
interaction parameter, obtained from swelling data of the polymer, is used to correlate both
polymer dilation and solvent sorption.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.