Mesoporous silica particles grafted with polystyrene brushes as a nucleation agent for polystyrene supercritical carbon dioxide foaming

In this study, spherical ordered mesoporous silica (s-OMS) was applied as a new type of nucleating agent in polystyrene (PS) foaming with supercritical CO 2 as a blowing agent. These s-OMS particles were modified by the selective grafting of PS brushes on the outside surface, by which the mesoporous structure inside particles could be maintained. Transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Brunauer–Emmett–Teller surface area analysis were used to characterize the structure of the original and modified particles; these indicated that the PS brushes were grafted on the outside surface and the inside porous structure were maintained. PS/s-OMS–PS composites were prepared by a solution blending method, and the s-OMS–PS particles could have been well dispersed in the PS matrix because of the surface modification. Subsequently, PS and composite microcellular foams were prepared by a batch foaming process, and the morphology characterization on these foams showed that the s-OMS particles exhibited an excellent heterogeneous effect on PS foaming. The heterogeneous effect became more significant when the foaming temperature or saturation pressure was low. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4308–4317, 2013