Relation between chemical composition of sols and surface free energy of inorganic-organic films

摘要

The presented study deals with relation between chemical composition of precursor sols and surface free energy of inorganic-organic films. Inorganic-organic films were prepared from precursor sols in tetraethoxysilane (TEOS) - triethoxy(octyl)silane (OTES) - distilled water - nitric acid - isopropyl alcohol system. The fifteen sols were prepared, where the ratio of K=x(OTES)/(x(TEOS)+x(OTES)) varied from 0 to 0.5 and ratio of R=x(H2O)/(x(TEOS)+x(OTES)) varied from 2 to 6. The relationship between chemical composition and surface free energy of inorganic-organic films was quantified by model selection approach. Model, which describes the studied relationship in the best way, was selected on the basis of Akaike information criterion. Based on the analysis of selected (the best describing) model, it was found out that the surface free energy as well as its dispersion and polar component are dependent only on K ratio in observed range of K and R values. Form the physico-chemical aspect, the observed dependences of surface free energy, its dispersive and polar component on chemical composition of precursor sols are explained by the influence of octyl groups on the sequences of hydrolysis and condensation reactions leading to formation of particles in precursor sol. In addition, the arrangement of octyl groups is used for explanation of particles arrangement on film surface.