How polymer surface diffusion depends on surface coverage

doi:10.1021/ma062104l

CORC > 化学研究所 > 中国科学院化学研究所

	How polymer surface diffusion depends on surface coverage
	Zhao, Jiang ; Granick, Steve
刊名	MACROMOLECULES
	2007-02-20
卷号	40 期号:4 页码:1243-1247
ISSN号	0024-9297
DOI	10.1021/ma062104l
英文摘要	Measurements are presented of how surface diffusion of flexible polymers at the solid-liquid interface is controlled by surface coverage. Surface coverage is varied over the full range from dilute to saturated surface coverage. The method of measurement is fluorescence correlation spectroscopy (FCS), and the systems are poly(ethylene oxide) (PEG) and dextran adsorbed onto methyl-terminated self-assembled monolayers in buffered aqueous solution. A detailed study of PEG (M(w) = 10 800 g mol(-1)) shows nonmonotonic behavior. The translational diffusion coefficient (D) at first increases with increasing surface concentration, presumably because the number of adsorption sites per molecule decreases as chains switch from pancake to loop-train-tail conformation. Excellent fits to behavior characteristic of a single diffusion process argue against aggregation or crystallization in the adsorbed state. In-situ ellipsometry measurements appear to rule out conformation changes to a hypothetical helical structure, as this would introduce birefringence to the adsorbed polymer layer causing deviations from the observed linear growth of apparent layer thickness with increasing surface coverage. For all three samples studied (PEG of M(w) = 10 800 and 20 000 g mol(-1) and also dextran with M(w) = 10 000 g mol(-1)), D at surface coverages larger than the estimated surface overlap concentration slow by 1 order of magnitude, presumably reflecting crowding and entanglement with neighboring chains.
语种	英语
出版者	AMER CHEMICAL SOC
WOS记录号	WOS:000244160800064
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/62813]
专题	中国科学院化学研究所
通讯作者	Granick, Steve
作者单位	1.Univ Illinois, Dept Mat Sci & Engn, Urbana, IL 61801 USA 2.Univ Illinois, Dept Chem, Urbana, IL 61801 USA 3.Univ Illinois, Dept Phys, Urbana, IL 61801 USA 4.Chinese Acad Sci, Inst Chem, Joint Lab Polymer Sci & Mat, State Key Lab Polymer Phys & Chem, Beijing 100080, Peoples R China
推荐引用方式 GB/T 7714	Zhao, Jiang,Granick, Steve. How polymer surface diffusion depends on surface coverage[J]. MACROMOLECULES,2007,40(4):1243-1247.
APA	Zhao, Jiang,&Granick, Steve.(2007).How polymer surface diffusion depends on surface coverage.MACROMOLECULES,40(4),1243-1247.
MLA	Zhao, Jiang,et al."How polymer surface diffusion depends on surface coverage".MACROMOLECULES 40.4(2007):1243-1247.