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

Felix A Plamper; Alexander Schmalz; Matthias Ballauff; Axel H E Müller

doi:10.1021/ja074720i

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

J Am Chem Soc. 2007 Nov 28;129(47):14538-9. doi: 10.1021/ja074720i. Epub 2007 Nov 7.

Authors

Felix A Plamper¹, Alexander Schmalz, Matthias Ballauff, Axel H E Müller

Affiliation

¹ Makromolekulare Chemie II, Universität Bayreuth, D-95440 Bayreuth, Germany.

PMID: 17985892
DOI: 10.1021/ja074720i

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 (photoinduced dissolution).