Jump to main content
Jump to site search
Access to RSC content Close the message box

Continue to access RSC content when you are not at your institution. Follow our step-by-step guide.


Issue 31, 2012
Previous Article Next Article

Structural evolution in a biphasic system: poly(N-isopropylacrylamide) transfer from water to hydrophobic ionic liquid

Author affiliations

Abstract

The structural evolution of payload transfer in biphasic systems is significant but difficult to accurately follow over the whole process. The dynamic transfer of homopolymer poly(N-isopropylacrylamide) (PNIPAM) from water to a hydrophobic IL (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C2MIM][NTf2]) phase was investigated by in situ react infrared (IR) spectroscopy to reveal the detailed transfer process and structural changes of PNIPAM, water and [C2MIM][NTf2]. Compared with the corresponding binary systems, this work summarizes the four-step transfer behavior and the interactions among the components according to IR spectroscopy and multivariate curve resolution (MCR). At the initial stage, only some water diffuses into the hydrophobic IL in the form of a symmetric 1 : 2-type hydrogen bonded (anion⋯H2O⋯anion) species while most of the PNIPAM molecules are preserved in the water layer in the form of aggregates. Afterwards, the water molecules are bonded with PNIPAM in the aggregated state and they start to transfer together into the IL layer in the second stage where PNIPAM is changed into unfolding structures with complex interactions such as H2O⋯PNIPAM⋯anion, and meanwhile water structures of anion⋯(H2O)n⋯anion form due to further diffusion of water. After these stages, water molecules continue to dissolve in the IL although the polymer transfer is completed, and they are inclined to form further water clusters (H2O)n as deduced from the increase of OH region (3500–3300 cm−1) absorption. Finally, all of the components (PNIPAM, water and IL) coexist in the homogeneous IL phase with the aid of complex hydrogen bond and electric charge interactions.

Graphical abstract: Structural evolution in a biphasic system: poly(N-isopropylacrylamide) transfer from water to hydrophobic ionic liquid

Back to tab navigation

Supplementary files

Article information


Submitted
26 Jun 2012
Accepted
30 Sep 2012
First published
29 Oct 2012

RSC Adv., 2012,2, 11850-11857
Article type
Paper

Structural evolution in a biphasic system: poly(N-isopropylacrylamide) transfer from water to hydrophobic ionic liquid

H. Lai, Z. Wang and P. Wu, RSC Adv., 2012, 2, 11850
DOI: 10.1039/C2RA21288A

Social activity

Search articles by author

Spotlight

Advertisements