Workshop on Soft Matter - Responsive Polymer Architectures
Uli Jonas
Macromolecular Chemistry, University of Siegen, Germany
10:00 - 10:40 Thursday 07 February 2019 PH01150 The term "reconfigurable" or "programmable" soft matter represents an emerging concept in science and technology, where the chemical, physical and functional properties of materials can be switched between well defined states by external stimulation, for example by temperature changes or by irradiation with light. Manifold examples are found in the animate nature, such as phototaxis of plants (like the head of the sunflower following the sun), and at present the challenge in research aims at harnessing such powerful behavior in artificial matter by merging the specific responsive functionality of molecules with a complex structural hierarchy.
Towards this aim we have synthesized a range of thermoresponsive, watersoluble polymers with either a lower critical- (LCST) or an upper critical solution temperature (UCST) by controlled radical polymerization methods. By means of the controlled polymerization method (RAFT and ATRP) specific end group functionalizations can be achieved. Upon variation of the temperature these polymers show a characteristic transition of their solubility and consequently of the coil dimensions in the aqueous phase, becoming soluble above their UCST, or insoluble above the LCST due to polymer coil collapse. These polymers show already a complex aggregation behavior in the solution state, which specifically depended on the end group functionalization. Concomitantly, the aggregation state and superstructure formation (micellar and vesicular aggregates) depends on the external thermal stimulation. The different polymers were also endowed with photoreactive groups that allow crosslinking upon irradiation with light. This photocrosslinking strategy enables immobilization of the transient state when changing external conditions.
|
Institute of Solid State Physics
