Fabrication of chemically bonded polyacrylate/silica hybrid films with high silicon contents by the sol–gel method

Polyacrylate/silica hybrid latexes (PAES) with high silicon contents (up to 21%) were prepared by directly mixing colloidal silica with polyacrylate emulsion (PAE) modified by a silane coupling agent. Sol–gel-derived organic/inorganic thin films were obtained by addition of hydrophilic co-solvents to PAES and subsequent drying at room temperature. The effects of co-solvents and γ-methacryloxypropyltrimethoxysilane (KH570) content on the properties of PAES films were investigated. Dynamic light scattering (DLS) data indicated that the average diameter of PAES (96 nm) was slightly larger than that of PAE (89 nm). TEM photo revealed that colloidal silica particles were dispersed uniformly around polyacrylate particles and that some of the colloidal silica particles were adsorbed on the surface of PAE particles. The data of crosslinking degree and FT-IR spectra confirmed that the chemical structure of the PAES changed to form Si–O–Si-polymer crosslinking networks during the film formation. AFM photos, contact angle for water, and XPS analysis showed that the polyacrylate/inorganic hybrid films with high silicon contents were formed by the co-solvent-mediated, sol–gel method and that the Si-based polymers were uniformly distributed on the surface of the dried films. TGA data demonstrated that the PAES films display much better thermal stability than the PAE counterpart.

► The polymer/silica hybrid emulsions (PAES) with high silicon contents (up to 21%) were prepared by direct mixing of colloidal silica with PAE modified with KH570. ► TEM photos revealed that the colloidal silica was uniformly dispersed around the polyacrylate particles and some colloidal silica particles were adsorbed on the surface of PAE particles. ► AFM photos and XPS analysis of PAES films showed that the co-solvents promoted the sol–gel process of colloidal silica and the self-assembly on the film surface upon drying of emulsions. ► TGA curves demonstrated that the PAES film with 3 wt% KH570 and isobutanol as co-solvent displayed the best thermal stability.