Is there a molecular signature of the LCST of single PNIPAM chains as measured by AFM force spectroscopy?

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• 作者：Edit Kutnyanszky ; Anika Embrechts¹ ; Mark A. Hempenius ; G. Julius Vancso ; ^{g.j.vancso@utwente.nl}
• 刊名：Chemical Physics Letters
• 出版年：2012
• 期刊代码：7_00092614
• 类别：ph
• 出版时间：11 May, 2012
• 卷：535
• 期：Complete
• 页码：126-130
• 文件大小：588 K

摘要

The molecular stretching behavior of temperature responsive poly(N-isopropylacrylamide) (PNIPAM) chains was studied by atomic force microscopy based single molecule force spectroscopy. Force-extension curves obtained in water below and above the lower critical solution temperature, in the co-nonsolvent water/methanol mixture, and in dimethyl sulfoxide (H-bond blocking) follow the same trajectory, independently whether the chain was pulled from a collapsed or from a solvated state. This result indicates that for a single PNIPAM chain the formation of intrachain H-bonds in the precipitated state does not cause measurable chain stiffening at the single chain level.