title: Swelling of Poly(n-butyl methacrylate) Films Exposed to Supercritical Carbon Dioxide: A Comparative Study with Polystyrene.
abstract: We report here the swelling and relaxation properties of confined poly(n-butyl methacrylate) (PBMA) films having thicknesses of less than 70 nm under supercritical carbon dioxide (scCO2) using the X-ray reflectivity technique. Swellability is found to be dominant in thinner films compared to thicker ones as a consequence of the confinement-induced densification of the former. Swellability is proportionately increased with the density of the film. PBMA films exhibit a more significant swelling than do PS films, and their differences become more prominent with the increase in film thickness. A comparison between the results obtained for polystyrene (PS) and PBMA ultrathin films reveals that the swellability is dependent upon the specific intermolecular interaction between CO2 and the chemical groups available in the polymers. Owing to strong Lewis acid-base interactions with scCO2 and the lower glass-transition temperature (bulk Tg ≈ 29 °C), PBMA films exhibit a greater amount of swelling than do PS films (bulk Tg ≈ 100 °C). Though they reach to the different swollen state upon exposition, identical relaxation behavior as a function of aging time is evidenced. This unprecedented behavior can be ascribed to the strong bonding between trapped CO2 and PBMA that probably impedes the release of CO2 molecules from the swollen PBMA films manifested in suppressed relaxation.
authors.affiliation: Centre for Research in Nanoscience and Nanotechnology, University of Calcutta , Technology Campus, Block JD2, Sector III, Saltlake City, Kolkata, 700098 India.
authors.forename: Jayanta Kumar
authors.initials: JK
authors.lastname: Bal
authors.affiliation: LUNAM Université, IMMM, Faculté de Sciences, Université du Maine , UMR 6283 CNRS, Le Mans, Cedex 9 72000 France.|European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, 38043 Grenoble Cedex 9, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Beuvier
authors.affiliation: Laboratoire d'Ingénierie des MATériaux de Bretagne, Centre de Recherche , Rue de Saint Maudé, BP 92116, 56321 Lorient Cedex, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Vignaud
authors.affiliation: LUNAM Université, IMMM, Faculté de Sciences, Université du Maine , UMR 6283 CNRS, Le Mans, Cedex 9 72000 France.|Laboratoire d'Ingénierie des MATériaux de Bretagne, Centre de Recherche , Rue de Saint Maudé, BP 92116, 56321 Lorient Cedex, France.
authors.forename: Mohamed Souheib
authors.initials: MS
authors.lastname: Chebil
authors.affiliation: LUNAM Université, IMMM, Faculté de Sciences, Université du Maine , UMR 6283 CNRS, Le Mans, Cedex 9 72000 France.
authors.forename: Soumaya
authors.initials: S
authors.lastname: Ben-Jabrallah
authors.affiliation: Centre for Research in Nanoscience and Nanotechnology, University of Calcutta , Technology Campus, Block JD2, Sector III, Saltlake City, Kolkata, 700098 India.
authors.forename: Ikbal
authors.initials: I
authors.lastname: Ahmed
authors.affiliation: Laboratoire d'Ingénierie des MATériaux de Bretagne, Centre de Recherche , Rue de Saint Maudé, BP 92116, 56321 Lorient Cedex, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Grohens
authors.affiliation: LUNAM Université, IMMM, Faculté de Sciences, Université du Maine , UMR 6283 CNRS, Le Mans, Cedex 9 72000 France.
authors.forename: Alain
authors.initials: A
authors.lastname: Gibaud