In-situ encapsulating MMT intermediate particles by suspension polymerization of poly (methyl methacrylate-co-styrene): preparation, tunable dispersion and properties

Abstract

Effectively encapsulating large size inorganic particles by polymeric materials is of great significance in making functional materials. In this paper, poly (methyl methacrylate-co-styrene)/montmorillonite (MMT) intermediate particles (PMMAS/I-MMT) were prepared by the suspension polymerization method. The chemical composition, dispersion behavior, particle size distribution and properties of PMMAS/I-MMT composite particles were characterized by energy dispersive spectrometer (EDS), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscopy (TEM), thermo-gravimetric analysis (TGA) and a laser particle analyzer. By using a step-by-step intercalation process of MMT clay and a careful separation process, the interlayer spacing of pristine Na-MMT was well tuned from 1.2 nm to 1.9 nm to provide I-MMT phase. MMT layers encapsulated in PMMAS copolymer were characterized by FTIR. XRD indicated that I-MMT interlayer spacing was further enlarged to 3.3 nm in the PMMAS composite with 3.0 wt% I-MMT loading and these composite films showed tunable and gradual exfoliation behavior, which was consistent with TEM analysis. The obtained volume average size of PMMAS/I-MMT composite particles had a narrow size distribution from 52.0 μm to 79.0 μm. The active layer exfoliations had greatly enhanced PMMAS thermal stability up to 453 °C by TGA, and the properties of its surface wetting and barrier against water were stably improved. Such encapsulated MMT composite particles may provide candidate materials for modifying fluid channels of petroleum engineering.