Raman spectroscopic study of CO₂ sorption process in poly methyl methacrylate

Abstract

Raman spectra of poly methyl methacrylate (PMMA) in contact with compressed CO2 were measured, to investigate effects of CO2 sorption on structure of the PMMA chain. The solubility and diffusivity of CO2 in PMMA were estimated from temporal variations of intensities of CO2 peaks. The PMMA structure was analyzed from temporal variations of vibrational energies of PMMA peaks. The results show that the vibration energies of CH stretching modes of PMMA increase with CO2 sorption, whereas those for skeletal vibration modes decrease. These energy shifts are attributed to elongational deformation of PMMA. The PMMA structure is deformed with stretching of the chains as a bundle. From energy shifts of the CO2 peaks, the size of the CO2 accommodated space between the bundles is estimated to be 1.6–1.9 nm. Furthermore, it was observed that the vibrational energies of the PMMA modes in foamed glassy PMMA differ from the values in glassy PMMA without foams. This result suggests that the local structure of the PMMA chain changes with the process of the CO2 sorption and/or foaming. The local structure of the PMMA chain might be one of the dominant factors governing the properties of cellular materials. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 831–842, 2008

Foaming behavior of 1-vinyl-2-pyrrolidone–methyl methacrylate copolymers under ScCO2

“…At this point, it is interesting to notice that the solubility of CO 2 in methacrylate-based polymers has been analyzed greatly in the last years. 18,19 The values of CO 2 sorption here reported are in agreement with those found in the literature (between 15 wt% and 25 wt% of CO 2 depending on the saturation pressure and temperature). However, the literature concerning the solubility data of CO 2 in poly(vinyl pyrrolidone)-based polymers is very limited.…”

Molecular confinement of solid and gaseous phases of self-standing bulk nanoporous polymers inducing enhanced and unexpected physical properties

“…Previous works discarded significant effect of the stretching of non-crosslinked polymer films on the conformation of the polymer chains [42], and no relationship can be found between the hoop stress occurring at the surface of the pores and the T g evolution (see Supplementary Information). On the other hand, CO 2 sorption can increase the radius of gyration of PMMA chains, thus inducing a local stretching of the molecules [43], thereby raising the thickness boundary at which the confinement is first observed. It should be noted that CO 2 sorption effects alone cannot explain the increase in T g , as several microporous PMMA samples made at high pressures experienced higher CO 2 uptakes than nanoporous 90/10 PMMA/MAM made at lower pressure (Table 1), and yet do not show a T g increment.…”

Nanoporous polymeric materials: A new class of materials with enhanced properties

“…A possible alteration of the fundamental properties of the base polymer due to the confinement of the polymer chains within the pore walls, or due to the stretching of the polymer chains induced during the manufacturing process [90], could be the cause of the different behaviors obtained. Nevertheless, more studies with different polymeric matrices are needed to understand, confirm or discard the contradictory tensile results that have been obtained up to now.…”