Versatile synthesis of self-assembling ABA triblock copolymers with polymethyloxazoline A-blocks and a polysiloxane B-block decorated with supramolecular receptors

BACKGROUND: Self-assembling amphiphilic block copolymers with incorporated, biologically relevant functionalities have received limited attention, partly due to the fact that biomolecules are not robust enough to synthetic manipulation, do not lend themselves readily to systematic studies due to their complexity and leach rather quickly from a vesicle or membrane when physically incorporated. Synthetic supramolecules are used as biomolecule mimics in functional membranes. RESULTS: Reaction conditions were established for the synthesis of a tosyl-terminated siloxane end-blocker, which serves as molecular weight control in the synthesis of polydimethylsiloxane (PDMS) and poly(dimethylsiloxaneco-methylhydrosiloxane) [P(DMS-co-MHS)] copolymers. Hydrosilylation reactions were investigated for the covalent coupling of synthetic supramolecules (18-crown-6 ether, hydroxybenzoate) to the polymer backbone using the methylhydrosiloxane repeat units as the anchor moiety. Using P(DMS-co-MHS) or derivatized P(DMSco-MHS) copolymers as macroinitiator for the ring-opening polymerization of 2-methyl-4-hydroxy-oxazoline led to the formation of poly[(dimethylsiloxane-co-methylhydrosiloxane)-block-oxazoline] [P(DMS-co-MHS-b-Ox)] ABA triblock copolymers with defined PDMS to PMHS ratios and controlled molecular weights. CONCLUSION: Derivatized P(DMS-co-MHS-b-Ox) ABA triblock copolymers synthesized using a novel versatile procedure undergo vesicle formation upon electroformation with vesicle diameters ranging from 2 to 10 μm. The size of the vesicle depends on the overall polarity of the macromolecule.  2008 Society of Chemical Industry Supplementary electronic material for this paper is available in Wiley InterScience at http://www.interscience.wiley.com/jpages/ 0959-8103/suppmat/