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Single polymer chain elongation of poly(N-isopropylacrylamide) and poly(acrylamide) by atomic force microscopy

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.1021/jp000459f
AuthorSearch for: ; Search for: ORCID identifier: https://orcid.org/0000-0002-2480-6821; Search for: ; Search for:
FormatText, Article
Subjectnoncovalent interactions; polymer chains; solution chemistry; thermoresponsive polymers; urea
Abstract
The nanomechanical properties of poly(N-isopropylacrylamide) (PNIPAM) and poly(acrylamide) (PAAM) in deionized water and 8 M urea aqueous solution were studied by using an atomic force microscopy based techniquesingle-molecule force spectroscopy (SMFS). Different force−extension traces were obtained in both systems. They could be normalized and superimposed, respectively. The force curves of PNIPAM and PAAM in 8 M urea aqueous solution could be fitted by extended freely jointed chain (FJC) model separately. These facts indicate that single polymer chain stretching was obtained. Moreover, the elasticities of PNIPAM and PAAM in pure water and in 8 M urea aqueous solution were compared. It is worthy to be pointed out that for PAAM in deionized water, a deviation from the extended FJC model at the middle regime (from ∼50 to 450 pN) in the force curve was found. When 8 M urea aqueous solution was used as buffer solution, the deviation disappeared and the force curve could be fitted with extended FJC model. This result may be related to the fact that PAAM could form certain intramolecular hydrogen bonding in water. After the PNIPAM sample was heated to 33 °C, above its LCST, more signals were observed in one stretching. This could be attributed to the fact that polymer chains form more contact points with the glass substrate after thermal treatment. In addition, another way just different from the normal one to do the SMFS experiment was also provided.
Publication date
PublisherAmerican Chemical Society
In
  • The Journal of Physical Chemistry B 104, no. 44 (1 November 2000): 10258–10264.
LanguageEnglish
Peer reviewedYes
NRC publication
This is a non-NRC publication

"Non-NRC publications" are publications authored by NRC employees prior to their employment by NRC.

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Record identifier3a8ee80c-819c-4b2c-b5a9-49aa964ac7c9
Record created2023-04-04
Record modified2023-04-05
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