Papers by Author: O. Nimittrakoolchai

Abstract: Two different viscous coating materials, which are Polydimethylsiloxane (PDMS) mixed with 10%wt of Dicumylperoxide (DCP), and Semifluorinate Silane (SFS), were applied to silicon micro-asperity. The cosine’s Young and viscosity of those coating materials are -0.3584,-0.3496 and 3.176x10-3, 1.339 x10-3 Pas, respectively. The rough surfaces with nine asperity shapes were studied. The results shown that, pillar shape has an effect on water contact angle (WCA): Stripe asperity cannot make the average WCA greater than 150. When consider the pillar asperity, the WCA falls between 152 and 157, which exhibits a superhydrophobic surface property. However, actual WCA of the micro-asperity coated with PDMS+10%wt of DCP is lower than that coated with SFS around 1 to 7. High viscous material makes the asperity size bigger than the design and decreases the WCA: the low viscous material is more suitable for coating on the asperities.

Abstract: In this paper, we report innovative gloves that are coated with hydrophobic film such that the outer surface of the gloves is hydrophobic. A coating precursor containing polymethyl hydrogensiloxane, silica nanoparticle, semifluorinated silane and Pt-catalyst was painted onto the gloves. The coated gloves were kept at room temperature for 12 h to make the film dry, and then tested for their chemical resistance with 10 M NaOH, conc. HCl, conc. H2SO4 and conc. HNO3 solutions, as well as the standard buffered solutions (pH = 1, 4, 10, and 12) at 25oC by dropping the chemicals onto the coated gloves. It was found that the nitrile gloves had similar contact angles to the latex gloves when tested with the standard buffered solutions while the nitrile gloves had higher contact angles compared to the latex gloves when tested with different aqueous-based hazardous chemicals. The nitrile gloves coated with the hydrophobic film showed high acid droplet contact angle, leaving behind much lesser damage from hazardous chemicals.

Abstract: Due to excellent photocatalytic and optical properties of titanium dioxide (TiO2), it has been applied in several products such as food packaging plastics, materials for vehicles or for buildings and sunscreen-protecting cosmetics. In this present work, the synthesized as well as commercial TiO2 was coated onto a household curtain fabric for anti-microbial and ultraviolet (UV) shielding functions. The coating was performed by inducing the deposition of TiO2 layer from the Ti precursor onto the fabric surface pre-treated with silane adhesive agent so as to improve the adhesion. Ag nanoparticles were also incorporated in some samples to further improve the antibacterial function. Anti-bacterial activities of the coated fabric were evaluated by standard qualitative test (the Kirby-Bauer test (AATCC 147)). Efficiency for UV shielding was evaluated by measuring a UV-Vis reflection of the coated fabrics both before and after subjecting to several washing cycles. The result showed that the TiO2-coated fabrics developed had potential as antibacterial and UV shielding for the curtain industry.

Abstract: Adhesion between TiO2 coatings and the fabrics was improved by using a silane adhesive agent. To investigate a suitable method of applying adhesive agent, two different coating methods were conducted. The silane was either mixed with Ti precursor for fabric dipping, or coated onto the fabrics before dipping them in a Ti precursor. The effect of Ti precursor, sol and colloid, on coating morphology was also studied. It was found that continuous coating with no cracking was obtained when the fabrics were pre-treated with the silane. The TiO2 coatings had good adhesion, regardless of the method of applying the adhesive agent. Thick, cracked coatings were obtained from Ti colloid precursor while continuous coating was obtained from the Ti sol precursor.