Functionalization of mesoporous silica with oligoisoprene brushes: Application as charge for elastomers reinforcement

The interfacial interaction between mesoporous silica nanoparticles (MSN) and natural rubber was successfully improved by surface modification of hydrophilic silica using oligoisoprene brushes. This approach involved grafting 3-aminopropyltriethoxy silane (APTES) onto the silica surface, achieving a grafting efficiency of 13.22 % and generating amine groups. The long polyisoprene chains of natural rubber were selectively cleaved using an optimized oxidative reaction, resulting in the formation of short oligomers with carbonyl chain ends known as Carbonyl Telechelic Natural Rubber (CTNR), having a molecular weight of 4100 g/mol. The CTNR oligomers were subsequently linked to APTES-modified silica via a Schiff's base reaction, imparting hydrophobicity to the silica surface and enhancing its compatibility and dispersion within the natural rubber matrix. Two conditions, MSN@CTNR1 and MSN@CTNR2, were investigated, exhibiting grafting efficiencies of 10.66 % and 4.70 %, respectively. The functionalized silica particles from MSN@CTNR1 were examined and incorporated at varying proportions into rubber latex, leading to the formation of thin films. Surprisingly, films containing 1 part per hundred rubber (phr) functionalized silica had better mechanical and thermal properties than films containing unmodified silica. This study underscores the potential of MSN, whose surfaces are modified by grafting oligoisoprene brushes, to enhance the crosslinking points and serve as innovative additives in the formulation of composite rubber films. Furthermore, these findings highlight the prospects of utilizing modified silica nanoparticles as coating additive materials, enabling the enhancement of properties and performance in rubber-based composites, thereby paving the way for the development of advanced coating applications in diverse industries.