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Self-assembled nanostructures of block copolymer : the impact of macromolecular architecture

Oleg Borisov Institut des Sciences Analytiques et de Physico-Chimie pour l’Environnement et les Matériaux, Pau

Applications of block copolymer nanostructures in soft nanotechnology and in medicine impose, as general requirements, precise control over dimensions and morphology of the nanostructures in combination with pronounced stimuli-responsive properties.
The statistical thermodynamic theory enables us to predict how the morphologies of the self-assembled structures can be on purpose tuned by varying not only the intra-molecular solvophilic/solvophobic balance, but also by changing macromolecular architecture, i.e., replacing conventional linear block copolymers by miktoarm starlike, linear-cyclic and linear-dendritic block copolymers. In particular, we focus on structural properties of micelles formed upon self-assembly of linear-dendritic block copolymers. We demonstrate that both hydrodynamic dimensions and aggregation number in such micelles decrease as a function of degree of branching of the dendron blocks whereas the number of potentially functionalizable exposed to the solution terminal groups of the corona-forming dendron blocks increases. This result may have important implication for design of linear-dendritic block copolymer micelles with smart functionalities for targeted drug delivery. Furthermore, the theory predicts that copolymers with dendronized coronal block demonstrate weaker tendency to form wormlike micelles or polymersomes as compared to homologous linear diblock copolymers. Dendronization of the associating block leads to the opposite effect.
Polymeric nanoparticles with non-conventional multicompartment structure, including asymmetric Janus particles, patchy spherical or wormlike micelles or polymersomes can be obtained upon assembly of triblock terpolymers comprising three chemically different blocks in selective solvent. These particles may serve as building blocks for hierarchically assembled materials. Our theoretical model enables us to predict morphology of the assemblies (number and shape of different nano-domains) as a function of the terpolymer composition and interaction parameters. The theoretical predictions are supported by experimental data.