Quantification of interfacial structure at nanoscale and its relationship with viscoelastic glass transition of SiO2/elastomer nanocomposites

Abstract

The interfacial structure and chain segment dynamics of nanofiller/polymer composites play an important role in their macroscopic properties. Nevertheless, the mechanisms on the effects of nanofiller on the chain segment dynamics and the glass transition temperature (Tg) of nanocomposites are still controversial. In this study, the interfacial structure (thickness and nanomechanical properties) of silica (SiO2)/solution polymerized butadiene styrene rubber (SSBR) composites were quantified by using quantitative nanomechanical mapping technique of atomic force microscopy. The quantitative relationship between the degree of graft of coupling agent (CA) on SiO2 and interfacial structure was built up. The formation mechanism of interfacial structure in SiO2/SSBR composites with different degree of graft on SiO2 was revealed. A new insight on the effect of interfacial interaction of polymer nanocomposites on their chain segment dynamics and Tg was proposed. With the increase in degree of graft, the interfacial thinkness largely increases, the dispersion of SiO2 is more homogeneous, and the total area of interfacial SSBR layer largely increases, resulting in the significant decrease in chain density of SSBR matrix, and thus a significant decrease in Tg. This study provides guidance for the interfacial design of high performance polymer nanocomposites for their wider application in industry.