Event Abstract Back to Event Surface modification by atmospheric pressure plasma deposition of HMDSO for anti-bacterial applications Yu-Chun Lin1 and Meng-Jiy Wang1 1 National Taiwan University of Science and Technology, Chemical Engineering, Taiwan Bacterial attachment, proliferation and colonization of bacteria on the surface of materials usually caused the formation of a biofilm[1]. For medical implants and devices, bacterial attachment adversely affects the functionality and limits the life -time of devices. In addition, the bacterial infection represents a common and substantial complication in the clinic, sometimes even leading to death. For food packing materials, the attachment of bacterial has seriously impact the food quality and productivity[2]. For marine equipment, microbial contamination on surface usually leading the attachment of the marine species to attach and proliferate, increasing the high cost for maintenance[3]. To address those problems, the antifouling and anti-microbial surfaces were considered to reduce the attachment of bacterial and the formation of biofilm. Therefore, the long-term efficacy of anti-bacterial properties possesses advantages for the applications. The SiOx films or matrix usually play an important role for releasing system due to the porous structure[4]-[6]. In this study, the matrices of SiOx were prepared by atmospheric pressure plasma jet (APPJ) deposition of hexamethyldisiloxane (HMDSO) with various deposition parameters such as deposition power and deposition time. The advantages of APPJ system were convenient and can be operated under ambient environment, not requiring vacuum system, and more effective[7]. The thickness of deposited thin films was modulated by the deposition time and the applied power of APPJ.The deposition rates of HMDSO films were 0.05, 0.46, 0.58, and 1.72 μm/min under the deposited power of 50, 100, 120, and 140 W, respectively (Fig. 1). The effects of deposition power were observed from the results of WCA measurementa, ATR-FTIRs and XPS. ATR-FTIR spectra showed that the reducing of Si-CH3 absorbance that was observed when increasing the deposition power. On the other hand, when increasing the deposition power, the surface wettability was switched from superhydrophilic to superhydrophobic. The oxidation reaction took place during the deposition processes which led to the changes of surface wettability. From the results of XPS analyses, at higher deposition power, the carbon content of deposition film was around 6%, lower than the deposition film prepared at low power deposition (13%). Alternatively, when increasing the deposition power, the oxygen content increased from 49.3 to 54.1%. The analytical results indicated that the deposition of the inorganic composition at high power and showed hydrophilic surface, due to the different level of oxidation reactions. In order to make sure the silver ions can be chelated by amine functional group, the sample was analyzed by ATR-FTIR. The result showed that the absorbance of amine functional group was reduced after chelating with silver ion[8],[9]. It is concluded that the HMDSO was successfully deposited on the substrate and revealed wide range of surface wettability, which was considered for release applications[10]-[12]. According to the agar plate tests, the hydrophilic HMDSO coating emerged inhibition zone at 8 hour cultivation, due to the silver ions can randomly penetrate through the hydrophilic barrier. Compared to the sample without HMDSO barrier, which showed largest inhibition zone (diameter: 2 cm) at 4 h culturing time. When increasing the inhibition period to 16 h, the reduction of inhibition zone for the sample without HMDSO barrier presented that the diameter of inhibition zone reduced to 1.3 cm. On the other hand, the sample with hydrophilic HMDSO coating performed continuously inhibition behavior, the inhibition zone would not decrease if the cultivation time increased. From the results of film thickness analyses, the film thickness also increased when increasing the deposition power at the same deposition time. However, the result of inhibition test indicated that the thicker film thickness showed the larger inhibition zone, which indicate ion release may limit by the barrier wettability. Ministry of Science and Technology; National Taiwan University of Science and Technology; Prof. Meng-Jiy Wang; Members in Lab. 503
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Mar 1, 2023
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