De-Agglomeration and Dispersion Behavior of TiO2 Nanoparticles in Organic Media Using 3-Methacryloxypropyltrimethoxysilane as a Surface Modifier

Abstract

Titania (TiO2) nanopowder was de-agglomerated in butyl acetate (BAc) via a bead milling process in the presence of 3-methacryloxypropyltrimethoxysilane (MPS), and subsequently centrifuged to obtain the TiO2 nanoparticles dispersions with high transparency. The transparent TiO2 dispersions were further incorporated into various ultraviolet (UV)-curable formulations to examine the dispersion behavior of MPS-functionalized TiO2 (MPS-TiO2) nanoparticles in UV-curable organic media. Higher molar ratio of MPS/TiO2 causes better de-agglomeration of TiO2 nanoparticles in BAc, higher amount of MPS attached, and better stabilization of MPS-TiO2 nanoparticles, suggesting the excellent compatibility of MPS-TiO2 nanoparticles with BAc. However, a critical MPS-TiO2 load producing phase separation of MPS-TiO2 nanoparticles exists for the dispersion of MPS-TiO2 nanoparticles in UV-curable monomers or polyurethane (PU)/monomer mixtures. Higher fraction of PU in organic media leads to lower critical MPS-TiO2 load or even serious phase separation at extremely low TiO2 content. The lower the amount of the grafted MPS is, the higher the critical MPS-TiO2 load is. It implies that MPS-TiO2 nanoparticles are partially compatible with UV-curable monomers and incompatible with PU oligomer.