Surface Treatment of Nano Silica with an Amino Silane: The Effect of Treating Bath pH on the Surface Chemistry and Performance of Particle

In this work nano silica was treated by an amin silane at different pH conditions and analysed using different techniques. It was found that the pH of treating bath highly affected the grafting of silane on the surface leading to grafting ratios between 29 and58 percent. The zeta potentials changed from -7.1 mv for pristine silica to +5.5 mv and +18.01 mv for the lowest and the highest grafted particles respectively. The results showed that, the sample with higher grafting has better dispersion stability in solvents with higher hydrogen bonding parameter and lower polar parameter. The higher mechanical properties of the nano clear coats using a polyurethane filled with these particles may confirm the better dispersion and possibility of a physicochemical interaction between the surface modified silica and the matrix. The tensile strength, elongations at yield and break and micro indentation hardness as well as the Young modulus were used to show the improvement achieved in properties of modified particles containing resin. J. Color Sci. Tech. 4(2010), 71-82© Institute for Color Science and Technology.