Abstract:
In this research, polyacrylatesiloxane (PAS) was prepared by seeded emulsion polymerization using the cyclosiloxanes (R-D4), obtained from silicone recycling, as a new reagent in PAS preparation. Moreover, in PAS preparation, silane coupling agents was used to modify polyacrylate to react with R-D4. Two different types of silane coupling agents, i.e. vinyltriethoxysilane (VTES) and 3-(trimethoxysilyl) propyl methacrylate (MPTMS) were varied in PAS preparation. The effect of temperature, time, the types of silane and silane contents used in PAS preparation were studied on the physical properties of PAS emulsion and its dried films. The results showed that the PAS emulsion can be prepared by using silane contents of 5-9% by wt at 80ºC for 7 hours under nitrogen atmosphere. It was found that the silane contents in PAS emulsion increased, the water contact angle increased resulting the hydrophobicity of coating films increased. Moreover, the coating films with VTES exhibited a higher water contact angle than those with MPTMS. Modified acrylic emulsion with VTES of 9% by wt provided water contact angle of 104.65° while the coating films with MPTMS showed lower water contact angle of 92.04°. Therefore, the PAS emulsion containing 9%wt of VTES was selected to prepare composite coating formulations to have hydrophobicity. The composite coating formulations were prepared by varying parameters such as the molar ratio of silane to R-D4 in PAS emulsion, amounts and types of fumed silica and organoclay, film fabrication methods (one pot and two pot), and types of substrates (glass and fiber cement board). Physical properties of composite coating films were investigated. The results showed that the composite coating films performed superhydrophobic surface with the one-pot coating formulation using 10 phr of organoclay (NC20A), 35 phr of fumed silica (FSH15) and PAS emulsion with 1:3 of mole ratios of VTES:R-D4 (PASVT9-13). The coating formulations were coated on glass and fiber cement board by dipping for 4 times. The water contact angles of glass surface and fiber cement surface coated with this composite coating formulation were 151.34 º and 150.88 º respectively.