title: A novel non-aqueous sol-gel route for the in situ synthesis of high loaded silica-rubber nanocomposites.
abstract: Silica-natural rubber nanocomposites were obtained through a novel non-aqueous in situ sol-gel synthesis, producing the amount of water necessary to induce the hydrolysis and condensation of a tetraethoxysilane precursor by esterification of formic acid with ethanol. The method allows the synthesis of low hydrophilic silica nanoparticles with ethoxy groups linked to the silica surface which enable the filler to be more dispersible in the hydrophobic rubber. Thus, high loaded silica composites (75 phr, parts per hundred rubber) were obtained without using any coupling agent. Transmission Electron Microscopy (TEM) showed that the silica nanoparticles are surrounded by rubber layers, which lower the direct interparticle contact in the filler-filler interaction. At the lowest silica loading (up to 30 phr) silica particles are isolated in rubber and only at a large amount of filler (>60 phr) the interparticle distances decrease and a continuous percolative network, connected by thin polymer films, forms throughout the matrix. The dynamic-mechanical properties confirm that the strong reinforcement of the rubber composites is related to the network formation at high loading. Both the improvement of the particle dispersion and the enhancement of the silica loading are peculiar to the non-aqueous synthesis approach, making the method potentially interesting for the production of high-loaded silica-polymer nanocomposites.
authors.affiliation: Dip. Scienze dei Materiali, INSTM, University of Milano-Bicocca, Via R. Cozzi 53, 20125 Milano, Italy. roberto.scotti@unimib.it laura.wahba@mater.unimib.it.
authors.forename: Laura
authors.initials: L
authors.lastname: Wahba
authors.forename: Massimiliano
authors.initials: M
authors.lastname: D'Arienzo
authors.forename: Sandra
authors.initials: S
authors.lastname: Dirè
authors.forename: Raffaella
authors.initials: R
authors.lastname: Donetti
authors.forename: Thomas
authors.initials: T
authors.lastname: Hanel
authors.forename: Franca
authors.initials: F
authors.lastname: Morazzoni
authors.forename: Markus
authors.initials: M
authors.lastname: Niederberger
authors.forename: Nadia
authors.initials: N
authors.lastname: Santo
authors.forename: Luciano
authors.initials: L
authors.lastname: Tadiello
authors.forename: Roberto
authors.initials: R
authors.lastname: Scotti