Preparation of poly(methyl methacrylate)/clay nanocomposites using supercritical fluid process

Abstract

Organoclay-based poly(methyl methacrylate) (PMMA) nanocomposites were prepared using a chlorodifluoromethane (HCFC-22) solvent by the supercritical fluid process. Mechanical properties, transmission electron microscopy (TEM), wide angle X-ray diffraction (WAXD), and thermal stability were characterized for PMMA nanocomposites. Commercially available organoclays (ASM clay) treated with alkyl ammonium salt, such as Cloisite (R) 15A and Cloisite (R) 30B, were compared with lab-made organoclays (FSM clay); specifically, sodium montmorillonite modified with a fluorinated surfactant. Ultrasonic treatment in the preparation of FSM clay was also investigated. Since the fluorinated tail in FSM clay is compatible with HCFC-22, FSM clay processed with ultrasonication showed partial exfoliation for PMMA/FSM clay nanocomposite, resulting in better thermal and mechanical properties and higher glass transition temperature as opposed to the intercalation morphologies for PMMA/ASM clay.