Development of Two-step Plasma Treatment Procedure Using Atmospheric Pressure Dielectric Barrier Discharge in Post-discharge Jet Region for Polylactide Surface Modification

• Main Authors: Yang, Yi-Wei, 楊宜偉
• Other Authors: Wu, Chong-Sin
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/22402635127568082339

博士 === 國立交通大學 === 機械工程系所 === 102 === A two-step plasma treatment procedure using the post-discharge jet region of atmospheric pressure (AP) nitrogen-based dielectric barrier discharge (DBD) was developed for better surface modification on Polylactide (PLA). The optimized plasma treatments were carried out in two steps in sequence, which include: 1) pretreatment plasma treatment to pretreat the surface using the N2 DBD jet with 0.1% addition of O2 in company with a moving speed of 1 cm/s for 40 passes, and 2) an ammonia plasma treatment to incorporate nitrogen-containing groups using the same N2 DBD jet, but with the addition of 5% NH3 and a moving speed of 2 cm/s for 80 passes. After applying the two-step plasma treatment, the X-ray photoelectron spectra (XPS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) analyses shows a remarkably enhanced nitrogen containing group, such as primary amine and primary amide, incorporation (N/C ratio of ~0.19) compared to that of either treatment alone. Moreover, the surface energy, contact angle and surface roughness are improved to 70.5 mJ/m2, 38˚ and 73.22 nm, respectively. These modified surface properties are confirmed to be very beneficial in improving cell growth on the PLA surface for mouse muscle myoblast cells (C2C12). On the other hand, the performance of surface modification and cell growth on two-step plasma treated PLAs implemented by electrodes with various lengths is investigated. the result shows that employing shortened electrodes allows not only an omission of water cooling system but also dramatic reduction of the plasma temperature down to 17℃ maximally compared to that using 5 cm electrode (52℃). Furthermore, 1 cm electrode would be chosen as the optimal approach for processing delicate medical devices owing to its low treatment temperature of 30℃ and greatly improved cell proliferation, which performs approximately 7% lowered optical density (OD) compared to that obtained by 5 cm electrode after 48 hours of culture. Lastly, a surface amination mechanism is proposed based on the observations of optical emission spectra (OES), atomic force microscope (AFM) and XPS analyses for explaining experimental observations.