Grafting of high-density poly(ethylene glycol) monolayers on Si(111)

X. Y. Zhu, Y. Jun, D. R. Staarup, R. C. Major, S. Danielson, V. Boiadjiev, W. L. Gladfelter, B. C. Bunker, A. Guo

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102 Scopus citations

Abstract

A strategy has been developed for the grafting of poly(ethylene glycol) (PEG) monolayers onto the atomically flat Si(111) surface. This process involves the direct interaction of the HO-functional group on PEG with a chlorine-terminated silicon surface. The resulting monolayers show exceptional flatness, with mean roughness on the angstrom scale. Film thickness is determined by ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy. Results for different molecular weights reveal that the grafted PEG molecules are in a brushlike configuration at low molecular weight (MW = 200, 300) and a more coil-like configuration at higher molecular weight (MW = 1000, 2000). The surface density of grafted PEG molecules is significantly higher than those reported in the literature and decreases with increasing molecular weight, from 92% at MW = 300 to 35% at MW = 2000. Both the brushlike and the coil-like configurations show excellent properties of protein resistance.

Original languageEnglish (US)
Pages (from-to)7798-7803
Number of pages6
JournalLangmuir
Volume17
Issue number25
DOIs
StatePublished - Dec 11 2001

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