These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Thermo-reversible swelling of thin hydrogel films immobilized by low-pressure plasma.
    Author: Schmaljohann D, Beyerlein D, Nitschke M, Werner C.
    Journal: Langmuir; 2004 Nov 09; 20(23):10107-14. PubMed ID: 15518501.
    Abstract:
    Thin films of graft copolymers consisting of poly(N-isopropylacrylamide) (PNiPAAm) or poly(N,N-diethylacrylamide) (PDEAAm) as polymer backbone and poly(ethyleneglycol) as side chains were cross-linked on fluoropolymer substrates by low-pressure plasma treatment. All immobilized polymers exhibit a lower critical solution temperature between 34 and 40 degrees C. The swelling and collapsing of the hydrogels was examined with temperature-dependent spectroscopic ellipsometry. Two time ranges of swelling were observed: a fast 'dynamic' and a slow 'equilibrium' swelling. The dynamic swelling occurs within minutes or less, whereas the equilibrium swelling needs several days to complete. The surface-bound hydrogels show a shift in the transition temperature toward lower temperatures compared with the behavior in solution. Full reversibility of the dynamic swelling/collapsing was found, but the temperature scan exhibits a hysteresis between heating and cooling cycles. The PNiPAAm-containing hydrogels show a sharper transition compared to the PDEAAm-containing hydrogels, which is almost linear over a wide temperature range.
    [Abstract] [Full Text] [Related] [New Search]