Wettability of polydimethylsiloxane surface via acid treatment

• Main Authors: Hsiang-Yi Su, 蘇祥溢
• Other Authors: G. Steven Huang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/18648490032593894147

碩士 === 國立交通大學 === 奈米科技研究所 === 96 === This paper describes a novel chemical modification of polydimethylsiloxane (PDMS) surface by using H2SO4 solution and subsequently the result of modification was confirmed by contact angle of water drops, Scanning Electric Microscope (SEM), and Fourier Transform Infrared spectrometry (FTIR). Soon after the acid treatment, the contact angle of the modified PDMS surface was reduced greatly from 110∘to 38∘owing to the H2SO4 solution destroyed the original bonding of the PDMS and the grafting of hydroxyl functional groups on the molecular chains of the PDMS surface. However, after six-hour of aging, the hydrophilic surface formed from acid treatments not only recovered to a hydrophobic one but also formed a super-hydrophobic exterior. This result can be explained from two aspects: one is by the discovery of the generation of micro-submicro-nano structure which is similar to the lotus leaf, and we considered that the air trapping in rough micro-nano binary structures can significantly decrease the contact area between water and the PDMS surface to increase the contact angle, the other one is the diffusion of lower molecular weight species from the inner bulk to the surface. Regarding to the importance of wettability and wide applications of PDMS, the potential technology for modulating the wettability of PDMS surface would be valuable in the applications of biosensors and nano-/micro-fabrication.