Rojcharin ChantarachindawongWasutap LuangtipPongpan ChindaudomTanakorn OsotchanToemsak SrikhirinMahidol UniversityThailand National Electronics and Computer Technology Center2018-06-112018-06-112012-08-01Canadian Journal of Chemical Engineering. Vol.90, No.4 (2012), 888-8961939019X000840342-s2.0-84863548209https://repository.li.mahidol.ac.th/handle/20.500.14594/13909The formation of scratch-resistant coating film prepared from colloidal silica and a polysiloxane matrix was investigated. Methyltrimethoxysilane (MTMS) was hydrolysed and mixed with silica sol (SiO 2 ) at various compositions to form the hybrid hard-coating nanocomposite film. The hydrolysed MTMS (polysiloxane) acts as the polymeric binder that is covalently linked to the colloidal silica surface and provides adhesion for the scratch resistant coating film to the substrate. The ratio between the polymeric matrix and the SiO 2 nanoparticles was found to play a major role in controlling the coating film appearance and its resistance to scratching. At a SiO 2 content < 30wt.%, the agglomeration of the hydrolysed polysiloxane was observed and caused the opacity of the coating film. At a SiO 2 content > 70wt.%, there was not enough polysiloxane to act as a binder for the SiO 2 , therefore a shrinkage upon solidification of the coating film caused cracking within the nanocomposite film. The optimum ratio was found to be at 40wt.%≤SiO 2 ≤60wt.%, where the films had a transparent, crack free hard coating, with excellent scratch resistance, good adhesion and very good environmental resistance. The nanoindentation revealed that the nanocomposite film, at the optimum loading, possessed a higher strength with a higher SiO 2 loading. Film properties, including hardness, scratch resistance, adhesion and environmental resistance were also examined. The morphology of nanocomposite films was identified by atomic force microscopy (AFM) and scanning electron microscopy (SEM). © 2011 Canadian Society for Chemical Engineering.Mahidol UniversityChemical EngineeringArticleSCOPUS10.1002/cjce.21631