Tuning Nanostructure Morphology and Gold Nanoparticle "Locking" of Multi-Responsive Amphiphilic Diblock Copolymers
Polymers and High Performance Materials
Reversible addition-fragmentation chain transfer (RAFT) polymerization was utilized to prepare multiresponsive, self-assembling amphiphilic poly [(N,N-dimethylaminoethyl methacrylate)(x)-b-(N-isopropylacrylamide)(y)] (DMAEMA(x)-b-NIPAM(y)). Controlling block lengths, solution pH, and NaCl concentration to elicit changes in the hydrophilic mass fraction resulted in specific. morphological changes upon thermally induced assembly. At y = 102 (68 wt % DMAEMA), DMAEMA(165)-b-NIPAM(102) Copolymers self-assemble into simple core-shell micelles (58 nm). Increasing y to 202 (48 wt % DMAEMA) leads to a mixture of spherical micelles (78 nm) and worm-like micelles (D = 50-100 nm, L = 400-500 nm). Further increasing y to 435 (36 wt % DMAEMA) produces vesicular structures (179 nm). Significantly, reversible assembly of these nanostructures from the present stimuli-responsive diblock copolymers can be accomplished directly in aqueous media without the necessity of dialysis or manipulation with cosolvents. Additionally, the associated nanostructures can be shell cross-linked above the critical aggregation temperature via the in situ formation of gold nanoparticles yielding assemblies with long-term aqueous stability.
Smith, A. E.,
Abell, T. U.,
Kirkland, S. E.,
Hensarling, R. M.,
McCormick, C. L.
(2009). Tuning Nanostructure Morphology and Gold Nanoparticle "Locking" of Multi-Responsive Amphiphilic Diblock Copolymers. Macromolecules, 42(8), 2958-2964.
Available at: http://aquila.usm.edu/fac_pubs/1174