Filler-coupling agent-matrix interactions in silica/polymethylmethacrylate composites

Abstract

The interactions of the silane coupling agent methacryloxypropyltrimethoxysilane (MPS) with both fumed silica and a polymethylmethacrylate (PMMA) resin matrix were investigated using thermogravimetric analysis and Fourier transform infrared spectroscopy. OX 50 fumed silica was silanated with MPS at concentrations of 1% and 5% in aqueous ethanol (95%), acetone, and anhydrous toluene. Methyl methacrylate was polymerized with the silanated fumed silica (5% wt/wt) to form composites. The amount of MPS adsorption on the fumed silica and the amount of PMMA attached to the silanated fumed silica were determined by thermogravimetric analysis. MPS could be removed from the fumed silica after washing with methanol, but not after it underwent a drying process at 25 degrees C under vacuum. After vacuum drying at 25 degrees C, two types of adsorbed silane were found, i.e., firmly adsorbed and loosely adsorbed silane. The loosely adsorbed silane could desorb from silica and be incorporated into the polymer matrix through copolymerization with monomeric methyl methacrylate, resulting in crosslinking of the matrix. When the silanated silica was dried at 110 degrees C for 2 h, the loosely adsorbed silane was removed and the amount of firmly adsorbed silane increased. There was a positive correlation between the amount of firmly adsorbed MPS and the amount of PMMA attachment. The highest efficiency for PMMA attachment was found when MPS was adsorbed as a monolayer, because the loosely adsorbed silane did not contribute to the bonding of PMMA, and this suggested that not all of the double bonds of the MPS were accessible for reaction with the methacrylate monomer. Drying at 110 degrees C may also decrease the number of unsaturated double bonds of MPS.

Reinforcement of flowable dental composites with titanium dioxide nanotubes

“…This method is carried out in an anhydrous environment [36]. Amines can also be used as catalysts to promote adsorption of silane.…”

Farklı kimyasal ortamların indirekt kompozitlerin sertlik ve aşınma dirençlerine etkisi

“…Liu ve ark. 36 , silanizasyonun, dental kompozitleri güçlendirmek amacıyla cam doldurucu partikül ve çeşitli metakrilat bileşimler arasında kovalent bağ formasyonu ile kullanıldığını bildirmişlerdir. Silan uygulaması sonucunda kompozitlerin aşınmaya karşı dirençli bir yapı oluşturduğunu bildirmişlerdir; dolayısıyla çalışmamızda Signum'daki aşın-manın az olması silanize yapısından kaynaklanabilir.…”

Light curable dental composites designed with colloidal crystal reinforcement

“…We followed a silanization procedure reported in our previous publications [25,26]. Briefly, silica spheres were stirred for two hours in a 1 wt% MPS solution in acetone, where the amount of MPS silane molecules was 3 times that of the calculated silanol groups on the silica surface with an assumed silanol density of 5 nm −2 [27].…”