title: Tuning the thermoresponsiveness of weak polyelectrolytes by pH and light: lower and upper critical-solution temperature of poly(N,N-dimethylaminoethyl methacrylate).
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).
authors.affiliation: Makromolekulare Chemie II, Universität Bayreuth, D-95440 Bayreuth, Germany.
authors.forename: Felix A
authors.initials: FA
authors.lastname: Plamper
authors.forename: Alexander
authors.initials: A
authors.lastname: Schmalz
authors.forename: Matthias
authors.initials: M
authors.lastname: Ballauff
authors.forename: Axel H E
authors.initials: AH
authors.lastname: Müller