Direct observation of the phase transition for a poly(N-isopropylacryamide) layer grafted onto a solid surface by AFM and QCM-D

Naoyuki Ishida, Simon Biggs

Research output: Contribution to journalArticle

99 Citations (Scopus)

Abstract

The temperature-induced structural changes of a thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) layer grafted onto a silica substrate were inve7stigated in aqueous solution 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. By AFM imaging, the transition of the grafted PNIPAM chains from a brush-like to a mushroom-like state was clearly visualized: The surface images of the plate were featureless at temperatures below the LCST commensurate with a brush-like layer, whereas above the LCST, a large number of domain structures with a characteristic size of ∼100 nm were seen on the surface. Both frequency and dissipation data obtained using QCM-D showed a significant change at the LCST. 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.

Original languageEnglish
Pages (from-to)11083-11088
Number of pages6
JournalLangmuir
Volume23
Issue number22
DOIs
Publication statusPublished - Oct 23 2007
Externally publishedYes

Fingerprint

Quartz crystal microbalances
Brushes
quartz crystals
solid surfaces
microbalances
brushes
Microscopes
dissipation
Phase transitions
microscopes
Polymers
Free radical polymerization
Dehydration
Silicon wafers
polymers
Molecular weight
Silica
dehydration
Silicon Dioxide
free radicals

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry

Cite this

Direct observation of the phase transition for a poly(N-isopropylacryamide) layer grafted onto a solid surface by AFM and QCM-D. / Ishida, Naoyuki; Biggs, Simon.

In: Langmuir, Vol. 23, No. 22, 23.10.2007, p. 11083-11088.

Research output: Contribution to journalArticle

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