Using grafting-to method to synthesize polyethylene glycol polymer brushes on the surface of modified glass substrate

• Main Authors: Chun-Wei Chen, 陳俊瑋
• Other Authors: Tai-Chou Lee
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/17298354178499742306

碩士 === 國立中正大學 === 化學工程所 === 98 === We use grafting-to approach in this study, looking for an easier way to prepare and control the surface density of the polymer brushes on the substrate. Polyethylene glycol (PEG) was chosen as a model system to be grafted onto mixed self-assembled monolayers(SAMs). We explored the grafting density and thickness of polymer brushes as a function of number of grafting points which were varied by using mixed SAMs. These mixed SAMs were composed of MPS((3-mercaptopropyl) trimethoxysialne) and OTS(octadecyltrichlorosialne). The coverage of MPS was adjusted by immersion time and concentration, measured by water contact angle and X-ray photoelectron spectroscopy (XPS). The functional group at the end of PEG chain was changed from -OH to -Br, detected by Br 3d using XPS. This –Br end group can graft to MPS which had an end group of –SH through C-S coupling reaction using (HMIM)CuI(HMIM=1-hexyl-3-methyl-imidazol-2-ylidene) catalyst, justified by Fourier transform - Infrared spectroscopy and C 1s spectrum of XPS. The grafting density, calculated according to the literature, was reduced if the MPS coverage was lower. However, the thickness was almost the same while varying the ratio of MPS/OTS. The surface morphology was also studied using AFM. When the grafting density is higher, the surface of polymer brush is flatter, suggesting that less aggregates were generated. This study demonstrates that the density of polymer brush can be easily controlled by a simple surface modification.