Tuning the thermoresponsiveness of weak polyelectrolytes by pH and light : Lower and upper critical-solution temperature of Poly(N,N-dimethylaminoethyl methacrylate)

Titelangaben

Plamper, Felix A. ; Schmalz, Alexander ; Ballauff, Matthias ; Müller, Axel H. E.:
Tuning the thermoresponsiveness of weak polyelectrolytes by pH and light : Lower and upper critical-solution temperature of Poly(N,N-dimethylaminoethyl methacrylate).
In: Journal of the American Chemical Society. Bd. 129 (2007) Heft 47 . - S. 14538-14539.
ISSN 1520-5126
DOI: https://doi.org/10.1021/ja074720i

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Abstract

The presence of multivalent counterions induces an upper critical solution temperature (UCST) in addition to the known lower critical solution temperature (LCST) of poly(N N -dimethylaminoethyl methacrylate) (PDMAEMA). The LCST-type cloud points can be adjusted by pH of the buffer, whereas the UCST-type cloud points can be adjusted by the concentration of trivalent counterions. High pH favors the LCST transition, whereas lower pH extends the UCST-type miscibility gap at constant concentration of trivalent counterions. By use of hexacyanocobaltate(III) as a trivalent counterion, we can even switch off again the UCST-behavior by UV-illumination (photoincluced dissolution).