A facile method of hydrophobic surface modification for acrylonitrile-styrene-acrylate terpolymer based on the out-migration property of metallic soaps

摘要

Graphical abstractDisplay OmittedHighlights•A hydrophobic surface is achieved with the assistance of metallic soap.•The materials added with metallic soaps show increased water contact angle.•Out-migrated hydrophobic groups contribute to the lower wetting behavior.•The hybrid composites perform excellent weather resistance.•ZnSt easily out-migrates to the surface than CaSt, MgSt and BaSt.AbstractHydrophobic surface modification is conducted in this study by using additives with long alkyl chains. Several kinds of metallic soaps, such as calcium stearate (CaSt), zinc stearate (ZnSt), magnesium stearate (MgSt) and barium stearate (BaSt) were employed. Polymer matrix is acrylonitrile-styrene-acrylate (ASA) terpolymer due to its wonderful weather resistance property. The surface chemical characterization was studied by Fourier transformed infrared (FTIR) technology and X-ray photoelectron spectroscopy (XPS). Carboxylate (OCO–) indexes of composites in both transmittance and reflection modes were calculated according to FTIR results. As to the ratio of carboxylate index in reflection mode to that in transmittance mode, the sample added with 5 wt% ZnSt shows a higher value of 8.77, and a much higher value of 14.47 for the sample added with 10 wt% ZnSt. The corresponding CC/ CH /CC peak areas of the samples added with 5 wt% or 10 wt% ZnSt are 75.4% and 77.3% respectively, much higher than other samples. This indicates ZnSt is much easier to out-migrate to material surface and therefore is more suitable for hydrophobic surface modification. In particular, the water contact angle of the ASA/ZnSt composite added with 10 wt% ZnSt significantly increased to 127o(40oincrease in comparison with pure ASA), successfully converting the surface wettability from hydrophilic to hydrophobic.