Synthesis of a novel siloxane-based crosslink agent and its application in emulsion copolymerization of butyl acrylate and methyl methacrylate

Abstract

Improving water-based polymer`s properties using silicon compounds is strongly noticed nowadays. A novel siloxane-based crosslink agent was synthesized using oligomeric polydimethylsiloxane (PDMS) hydroxyl-terminated. The crosslinker was used for emulsion copolymerization of methyl methacrylate (MMA), butyl acrylate (BA), and acrylic acid (AA). Incorporation of the crosslinker in the structure of the copolymer increased the average latex particle size (from about 165 nm to 207 nm) and as a result of that, the viscosity of the latexes was dramatically decreased (from 212 cP to 83 cP). The crosslink density of the latexes, meanwhile, was raised (from about 7% to 60%). Electrostatic stability of the latexes was improved in the presence of the crosslinker (zeta potential from -31.7 mV to -49.5 mV and the average mobility of the latexes particles from -2.4 µm/s/V/cm to -3.8 µm/s/V/cm). The crosslinking agent affected both the initial decomposition temperature and residual weight fraction of the copolymer (from 388 °C to 406 °C and from about 0.5 w% to 12.4 w% respectively). Morphological study of the latexes was carried out using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) techniques. Addition of the crosslinker, lead to a decrease in the contact angle (from 70 to 39 degrees) of the latexes lm formed.