Logo JG-Universität MainzProf. Dr. Axel Müller


274. Plamper, F.A.; Ruppel, M.; Schmalz, A.; Borisov, O.V.; Ballauff, M.; Müller, A.H.E.: Tuning the Thermoresponsive Properties of Weak Polyelectrolytes: Aqueous Solutions of Star-Shaped and Linear Poly(N,N-dimethylaminoethyl methacrylate), Macromolecules 40, 8361 (2007)

We investigated the thermoresponsive behavior of aqueous solutions of star-shaped and linear poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA). The observed cloud points strongly decrease with increasing pH of the solution. This is explained by a weak charging of the star polymers with decreasing pH. A significant decrease of the cloud points with increasing molecular weight for high pH, i.e. for the almost uncharged state, was found to be virtually independent of the arm number and arm length. These findings are explained classical Flory-Huggins theory. The increase of cloud points upon charging is captured by introduction of an effective degree of polymerization. Polymers with shorter arms show slightly higher cloud points at low pH than polymers with longer arms. The intramolecular segment density also influences the observed apparent pKb values, leading to higher values for stars with higher arm numbers.

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Related links:
  • Project: DFG Mu896/25: pH- and temperature induced self-organization of bis- and tris-hydrophilic polymers and hybrid particles to hydrogels (SPP 1259 "Intelligente Hydrogele")
  • Project: SFB 481 TP A12: Structure Formation and Phase Equilibria in Concentrated Solutions of Charged Starpolymers

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