Study of water adsorption in PolyN-isopropylacrylamide) thin films using fluorescence emission of 3-hydroxyflavone probes
Morris, Cheryl Szczupak, Boguslaw Ryder, Alan G.
Morris, Cheryl
Szczupak, Boguslaw
Ryder, Alan G.
Loading...
Repository DOI
Publication Date
2010
Type
Article
Downloads
Citation
Morris,C.,Szczupak,B.,Klymchenko,A.S.,Ryder,A.G. (2010) 'Study of water adsorption in PolyN-isopropylacrylamide) thin films using fluorescence emission of 3-hydroxyflavone probes'. Macromolecules, 43 (22):9488-9494.
Abstract
The noncontact measurement of water uptake in microscale , thermoresponsive poly(N-isopropylacrylamide) thin films is challenging. We assessed the efficacy of three different 3-hydroxyflavone (3-HF)-based fluorophores to monitor water uptake in pNIPAM thin films close to the lower critical solution temperature (LCST) at 25 and 37 °C. These 3-HF fluorophores undergo excited-state intramolecular proton transfer, yielding emission from normal (N*) and tautomeric (T*) excited-state forms. The emission intensity ratio, log(IN*/IT*), and N* band position are environmentally sensitive. Water adsorption in pNIPAM thin films follows a nonlinear, two-phase process: at low relative humidity, the adsorbed water disrupts polymer-fluorophore hydrogen bonding, yielding small changes in log(IN*/IT*) ratios and overall intensity; at higher relative humidity, these intensity parameters (but not fluorescence lifetime) change dramatically, indicating a larger change in local polarity. These probes are thus sensitive indicators of water uptake in pNIPAM.
Funder
Publisher
ACS Publications
Publisher DOI
10.1021/ma102152j
Rights
Attribution-NonCommercial-NoDerivs 3.0 Ireland