FTIR in situ measurement of swelling and CO2 sorption in acrylic polymers at high CO2 pressures

A FTIR (Fourier Transform Infrared) microscope combined to a CO2 high-pressure cell has been used to determine simultaneously the CO2 uptake and the swelling of acrylic polymer systems, precursors of CO2-foamed polymers (PMMA), a triblock copolymer (MAM) and a PMMA/10 wt% MAM blend. Samples were saturated with supercritical CO2 (scCO(2)) up to high pressures (5, 10, 30 MPa) at 40 degrees C and 130 degrees C. The behavior upon pressure increase is indeed different at the two temperatures in the three systems, showing either a linear or a plateau shape. These two regimes are analyzed in view of literature. Addition of 10 wt% MAM copolymer led to a significant increase of CO2 uptake (23% for neat PMMA to 42% for the blend, 40 degrees C, 30 MPa). Such data are useful to find out, before foaming, the best routes to produce low-density and nanoporous polymer foams, using scCO(2) as foaming agent.