Controlled syntheses of ’smart’ polymers are in the focus of our research. The polymers under study are water soluble or amphiphilic (i.e. containing both water soluble and insoluble structural units), polyelectrolytes (electrically charged polymers) and thermally responsive polymers. Thermally responsive polymers are ones which dissolve in water around room temperature but phase separate upon increasing (or decreasing) temperature. With these polymers it is possible to construct various materials from nanosized particles to macroscopic gels which compress upon increasing temperature and swell when temperature is lowered again. On the other hand, polyelectrolytes are used when materials are needed that respond to changes in pH or ionic strength.
Metallic nanoparticles (gold, silver, copper) stabilized with polymers as well as nano-clay based hybrid materials (nanocontainers) are prepared in the laboratory. Using e.g. thermoresponsive polymers it has been possible to prepare gold nanoparticles, which either disperses in water or precipitate. Nanosized metal particles have optical and electric properties which strongly differ from those of bulk materials.
Modern controlled polymerization reactions make it possible to adjust the molar mass and molar mass distribution in radical polymerization. These reaction types can also be used in constructive complex polymer architectures like block, graft or star polymers. One example as such polymers is star block copolymers synthesized in the laboratory. A star polymer is one where several chains are grown from one point.
Recently, stars with four or eight arms have been synthesized where the inner parts of the arms are insoluble in water but the outer parts comprise of extremely soluble polyelectrolyte chains. These kinds of polymers show very complex self-assembling behavior in water.
Published February 2, 2009
This project has been funded with support from the European Commission