Abstract:

A high transmittance is the prerequisite for optically functional materials to be successfully used in practical applications. However, introduction of inorganic nanoparticles even at low contents into transparent polymers often leads to opaque nanocomposites due to light scattering caused by the nanoparticles because of the refractive index (RI) mismatch between nanoparticles and polymer matrices. This article reports for the first time a strategy for facile synthesis of highly transparent polymer nanocomposites by introduction of core–shell structured nanoparticles with the same RI. This strategy is based on the assumption that the core–shell structured nanoparticles can be regarded as integral nanofillers that have one refractive index in the polymer medium. In this study, core–shell structured silica–titania (S-T) nanoparticles were synthesized through coating titania with continuous feeding via hydrolysis of tetrabutyl orthotitanate (TBOT) to silica core preprepared according to Stöber’s method by base-catalyzed hydrolysis of tetraethylorthosilicate (TEOS) in ethanol solution. The transmittance of the S-T/epoxy nanocomposites synthesized by introduction of the S-T nanoparticles into a transparent epoxy matrix was studied as a function of the titania coating content. The optimal transmittance of the nanocomposite was successfully attained at the shell weight content of 36.5% in terms of the filler-matrix RI matching principle.