Non-Covalent Shape Quenching of Elastomers and Hydrogels
Mitchell Anthamatten
Associate Professor, Scientist, LLE
Dept. of Chemical Engineering, University of Rochester
Supramolecular polymers and networks formed by simple mixing can offer highly
ordered and responsive soft materials. We are studying elastomer networks that are
functionalized with reversibly associating side groups. Resulting materials contain both
permanent (covalent) and dynamic (non-covalent) net points. Experiments demonstrate
that reversible H-bonding interactions can effectively stabilize mechanically-strained
states. Unlike conventional shape-memory polymers, these elastomers contain dynamic
bonds and lack a well-defined shape recovery temperature. Evidence from dynamic
mechanical tests is applied to elucidate the underlying shape memory mechanism. Recent
studies have focused on H-bond dimerization within water-swollen environments, such a
hydrogel. RAFT techniques were applied to synthesize and study linear
poly(hydroxyethyl methacrylate) (polyHEMA) functionalized with ureidopyrimidinone
(UPy) side-groups. The presence of UPy side-groups significantly decreases equilibrium
water content and retards water swelling. The effect of side-groups on mechanical
properties will be discussed, and behavior will be contrasted to that of covalently
crosslinked samples.