Dresden 2014 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 28: (Hydro) Gels and Elastomers

CPP 28.7: Talk

Wednesday, April 2, 2014, 11:30–11:45, ZEU 222

Collapse and swelling of bulk polymers and polymer brushes studied by solid-state NMR — Ute Böhme and •Ulrich Scheler — Leibniz-Institut für Polymerforschung Dresden e.V.

Dynamic NMR, relaxation NMR and measurements of residual dipolar couplings via double quantum NMR gives acces to molecular mobility over a wide range of corellation times. Combined with the detection under high-resolution solid-state NMR applying CRAMPS signals of different functional groups and in particular the solvent can be separated. The separation of solvent dynamics from thepolymer is key to this investigation. Slow polymer chain dynamics clearly shows in proton transverse relaxation. The chains of collapsed poly(acrylic acid) brushes are significantly more mobile than in the bulk polymer. Upon the addition of water this dynamic difference becomes stronger and an even more mobile component appears in the brush. The temperature-dependent collapse of PNIPAM has been followed by various techniques. The combination of relaxation NMR with CRAMPS shows the polymer dynamics in the collapsed state as well. There is a continous variation of the chain dynamics over a wide temperature range around the transition temperature as shown inproton T1rho, which is very selective for motions in the kilohertz range.