Polymer/clay nanocomposite foams prepared by CO₂

Polymeric foams are widely used in many applications. In this study, we prepared polymer/clay nanocomposite foams using carbon dioxide as the foaming agent. The effect of clay dispersion (intercalation vs. exfoliation), clay concentration and types of polymers on foam morphology were investigated. It was found that clay nanoparticles serve as an efficient nucleation agent. The nucleation efficiency is affected by both clay dispersion and polymer-clay-CO₂ interaction. By controlling nanocomposite composition and foaming conditions, PMMA nanocomposite foams with cell size as small as ∼0.4 μm and cell density as high as ∼10¹² cells/cc can be produced. These foams exhibit good combination of stiffness, toughness, weight saving and dimension stability. In addition, PLGA nanocomposites foams were also prepared and they can be used for tissue engineering scaffolds.