POLY 407 |
| Self-assembling ABA triblock copolymers consisting of poly(oxalzoline), (A blocks) and poly(dimethylsiloxane-co-methylhydrosiloxane), (B-block) were synthesized by cationic ring-opening polymerization and functionalized via polymer-analogous hydrosilylation reactions with an ω-alkenyl substituted, potassium ion-selective 18-crown-6 ether molecule. The self-assembly of these block copolymers into vesicles was studied using a drop formation technique. A strong tendency to coalescence was observed under formation conditions, i.e. in the absence of external stimuli. By virtue of possessing supramolecular crown-ether receptors these systems exhibit unique properties to appropriate stimuli, specifically K+ and Na+ ions. When subjected to high concentrations of K+ or Na+ ions the coalesced vesicles rupture due to osmotic stress and then reform into microtubules. Alternatively when subjected to high concentrations of Mg2+ ions the vesicles rupture as in the earlier case but reform back into vesicles. Preliminary 1HNMR indicates that stiffening of the crown ether ring upon ion complexation is probably responsible for the change in shape.
|
|
Synthetic and Biological Macromolecules for Emerging Nanotechnologies
6:00 PM-8:00 PM, Tuesday, August 21, 2007 BCEC -- Exhibit Hall - B2, Poster
Sci-Mix
Division of Polymer Chemistry |
