Easily disrupted: Micelles of a new amphiphilic block copolymer that bear coumarin groups are sensitive to near infrared light by two-photon absorption of the chromophore. Disruption of the micelles under irradiation at 794 nm results in release of both photocleaved coumarin and encapsulated nile red from the hydrophobic core of micelle into aqueous solution, which results in opposing changes in fluorescence emission intensity.

The synthesis, solution and solid state self-assembly properties of a series of polyisoprene-b-poly(epsilon-benzyloxycarbonyl-L-lysine) PI-b-PZLys and polyisoprene-b-poly(L-lysine) PI-b-PLys block copolymers have been examined. The formation of stimuli-responsive micelles in water has been studied as a function of pH and ionic strength using static and dynamic light scattering, UV-circular dichroism and transmission electron microscopy. The observed change in the micelles dimensions has been directly attributed to the conformational transition in the secondary structure of polypeptide chains. In bulk, these rod-coil copolymers form self-assembled structures that have been characterized using DSC, DMA, WAXS and SAXS techniques. Hexagonal in lamellar (HL) and more interestingly hexagonal in hexagonal (HH) morphologies have been evidenced as a function of the chemical composition.

We demonstrate the use of atom transfer radical polymerization (ATRP) to graft polymers onto preformed shell cross-linked reverse micelles (SCRM). Reverse polymer micelles are first obtained in organic solvents and stabilized by cross-linking of the shell using the photoinduced dimerization of coumarin groups (>310 nm). The structurally locked SCRM are then used as micellar macroinitiators for further polymerization from their surface of monomers such as styrene and dimethylaminoethyl methacrylate (DMAEMA) via ATRP. The decoration of an outer corona of PDMAEMA renders the nanoparticles containing a hydrophilic core soluble in water, with the solubility being sensitive to changes in pH and temperature. In addition, such decorated SCRM are light-responsive. The photoinduced cleavage of cyclobutane bridges (<260 nm) leads to the de-cross-linking of the shell and thus the disintegration of the micellar aggregates. The characterization results, using size-exclusion chromatography (SEC), dynamic light scattering (DLS), and transmission electron microscope (TEM), show an excellent control over the reactions, the molar mass, and the polydispersity of SCRM before and after the surfaceinitiated ATRP. The "decoration" of SCRM offers a new route to designing stimuli-responsive polymer nanostructures that cannot be prepared through only block copolymer self-assembly.