Salt-induced structural behavior for poly(N-isopropylacryamide) grafted onto solid surface observed directly by AFM and QCM-D

Ishida N. and Biggs S. (2007) Salt-induced structural behavior for poly(N-isopropylacryamide) grafted onto solid surface observed directly by AFM and QCM-D. Macromolecules, 40 25: 9045-9052. doi:10.1021/ma071878e


Author Ishida N.
Biggs S.
Title Salt-induced structural behavior for poly(N-isopropylacryamide) grafted onto solid surface observed directly by AFM and QCM-D
Formatted title
Salt-induced structural behavior for poly(N-isopropylacryamide) grafted onto solid surface observed directly by AFM and QCM-D
Journal name Macromolecules   Check publisher's open access policy
ISSN 0024-9297
1520-5835
Publication date 2007-12-01
Year available 2007
Sub-type Article (original research)
DOI 10.1021/ma071878e
Open Access Status Not yet assessed
Volume 40
Issue 25
Start page 9045
End page 9052
Total pages 8
Place of publication Washington, DC, United States
Publisher American Chemical Society
Language eng
Formatted abstract
The salt-induced structural changes of an end-grafted poly(N- isopropylacrylamide) (PNIPAM) layer on a silica substrate were investigated in sodium sulfate solutions using an atomic force microscope (AFM) and a quartz crystal microbalance with dissipation (QCM-D). A PNIPAM layer was grafted onto the silicon wafer surface by free radical polymerization of NIPAM to obtain a high molecular weight polymer layer with low grafting density overall. AFM images of the coated surface were featureless at low salt concentrations commensurate with a brush-like layer. At salt concentrations ≥ 0.11 M, a large number of domain structures, with a characteristic size of ∼100 nm, were seen on the surface commensurate with a collapse of the brush-like layer into mushroom-like aggregates. This critical concentration for brush collapse is in good agreement with the concentration range of between 0.1 and 0.2 M, at which the phase transition of the bulk PNIPAM is reported. Both the frequency and the dissipation data obtained using a QCM-D also showed a significant change at this concentration indicative of the layer collapse. Further analysis of these data confirmed that the observed PNIPAM structural transition was caused by a collapse of the brush-like structure as a result of dehydration of the polymer chains.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Chemical Engineering Publications
 
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