Processing of nanocomposite foams in supercritical carbon dioxide. Part I: Effect of surfactant

• Published in: Polymer (Guilford) Vol. 51; no. 15; pp. 3436 - 3444
• Main Authors: NGO, Thi Thanh Van, Duchet-Rumeau, Jannick, Whittaker, Andrew K., Gerard, Jean-François
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 08.07.2010; Elsevier
• Subjects: Applied sciences; Carbon dioxide; Cellular; Chemical Sciences; Clay; Clays; Composites; Dispersions; Exact sciences and technology; Foam; Foams; Forms of application and semi-finished materials; Material chemistry; Nanocomposites; Nanomaterials; Nanostructure; Nucleation; Polymer industry, paints, wood; Polymers; Polystyrene; Surfactants; Technology of polymers; Foam; Polystyrene; Clay; Cell structure; Organic clay; Montmorillonite; Dispersion degree; In situ; Carbon dioxide; Experimental study; Cellular plastic; Free radical polymerization; Foaming process; Morphology; Preparation; Supercritical solvent; Styrene polymer; Nanocomposite; Plastics
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2010.05.039

Polystyrene-clay nanocomposites were prepared by in situ polymerization to achieve the better dispersion of lamellar silicates i.e. montmorillonite and fluorohectorite and were used to process foams with supercritical CO2. Clay–Polymer interactions were modulated by varying the surface treatment of clays: a physical interface was formed with the compatible surfactant showing aromatic groups (MMT-benz) and a chemical interface was created after reaction of methacrylate group (MMT-MHAB) with the styrene monomer. The dispersion of nanocomposites and the microstructure of resulting foams are very dependent on the quality of the clay/matrix interface. With the compatible clay, exfoliation of aromatic clay in polystyrene matrix is obtained at all scales. On the other hand, with the reactive clay, intercalated primary particles are obtained but the size of foam cells is the smallest and cell density is the highest. Our results suggest that the nucleation occurs primarily on physico-chemical nucleation sites that are the carbonyl group of the tethered copolymers synthesized on reactive clay and that present a strong affinity for CO2. The relaxation times determined by using solid-state NMR spectroscopy are consistent with the formation of the in situ copolymers. [Display omitted]