Structure and Properties of Nano-SiO2/Acrylic Composite Emulsion with Interpenetrating Networks Prepared via Soap-Free Emulsion Polymerization

Abstract

The nano-SiO2/acrylic composite emulsion with the structure of interpenetrating networks was prepared by introducing nano SiO2 particles formed in situ with the hydrolyzation of traethylorthosilicate in the soap-free emulsion polymerization of acrylate. The structures, morphologies, particle size, thermal and mechanical properties of composite emulsion were characterized with FTIR, TEM, particle size analyzer, thermal analyzer, and tensile-testing machine. Influence of reactive emulsifier on the water resistance, particle size and its distribution of composite emulsion was studied. And influence of different added amount of tetraethyl orthosilicate (TEOS) on the thermal and mechanical properties of composite emulsion was investigated. Results show that water resistance of composite emulsion is increased in comparison with the emulsion prepared with the conventional emulsion polymerization and the average particle size is small and its distribution is good. SiO2 inorganic network acts as the crosslinked point in the acrylic polymer network, and covalently linked with organic phase. Thermal stability and pendulum hardness of composite emulsion are strengthened with the increase of the added amount of TEOS. However, tensile strength and broken elongation of film first is increased and then decreased with the increase of the added amount of TEOS. The tensile strength and broken elongation of film reach its maximum value when the added amount of TEOS is 4.5% and 3.0%, respectively.