Effects of SBA-15 and its content on MMA solution polymerization and PMMA composites

Abstract

An ordered mesoporous material, such as SBA-15 was considered as a promising reinforcement agent for polymeric materials due to its large surface area and uniform pore structure. In this paper, poly(methyl methacrylate) (PMMA)/SBA-15 composites were prepared by in situ free-radical solution polymerization of MMA in the presence of SBA-15. The effects of SBA-15 content on solution polymerization and the properties of the final polymer composite were investigated. The PMMA molecular weight and its distribution in PMMA/SBA-15 composites were determined by gel permeation chromatography. Fourier-transform infrared spectra, X-ray diffraction, thermal gravimetric analysis (TGA), differential scanning calorimeter and dynamic mechanical analysis were used to characterize the structure and properties of the composites. The morphology of the composites was observed by scanning electric microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the monomer conversion dropped off, but the polymer average molecular weight increased upon the introduction of SBA-15 into solution polymerization process. When compared with pure PMMA, the storage modulus of the composites was improved and the highest improvement was acquired at 1 wt% of SBA-15, based on the monomer feed content. The glass transition temperatures of the composites were increased slightly. TGA results confirmed that the thermal stability of the composite was not influenced much and a higher degree of terminal vinyl groups was formed in the product of polymerization. SEM and TEM images indicated that SBA-15 particles were incorporated into the polymer matrix.