Dresden 2014 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 54: Poster Session 3

CPP 54.23: Poster

Thursday, April 3, 2014, 15:00–19:00, P2

Stimuli-responsive reversible hydrogels from triblock polyelectrolytes and polyampholytes — •Margarita Dyakonova¹, Maria T. Popescu², Constantinos Tsitsilianis², Konstantinos Kyriakos¹, Sebastian Jaksch³, and Christine M. Papadakis¹ — ¹TU München, Physik-Department, Garching — ²University of Patras, Greece — ³JCNS at FRM II, Garching

We investigate the conformational properties of stimuli-responsive hydrogels from triblock polyelectrolytes PtBA-P2VP-PtBA (PtBA and P2VP are poly(tert-butylacrylate) and poly(2-vinylpyridine) and polyampholytes PAA-P2VP-PAA (PAA is poly(acrylic acid)) where the transitions are due to the neutralization of charged groups [1]. Hydrogels are formed at polymer concentrations as low as 0.4 wt%. The mechanical properties depend strongly on the pH value and the salt content [1].

We focus on the related structural changes of the hydrogels. SANS revealed a dependence of the hydrogel structure of the polyampholyte on charge asymmetry and revealed several transitions with increasing electrostatic interaction. Low charge asymmetry causes the collapse of the chain into a globule dominated by the fluctuation-induced attractions between oppositely charged moieties while at higher charge asymmetry, a network is formed. The latter has been confirmed for the polyelectrolyte system. These results demonstrate the origin of the strong changes in mechanical properties.