kineticallyarrestedThe construction of hybrid systems −those involving multiple components exhibiting distinct physicochemical characteristics− through non-directional interactions results from a balance between self-organization and integrative co-assembly. The importance of hybrid systems relies on the fact that their properties can be readily modulated according to composition, affording access to a wide range of materials with distinct physicochemical properties.

Aside from the possibilities enabled by the combination of distinct building blocks, the level of complexity of aggregates from macromolecular amphiphiles can also be modulated through kinetic manipulation of the assembly process, yielding structures in different states of equilibrium. The non-ergodic character of these assemblies emphasizes the critical role of kinetic pathways of polymer assembly on aggregate functional and structural complexity.

We have demonstrated the solution co-assembly of architecturally distinct amphiphiles into kinetically-arrested nanoparticles through a large and rapid change in solvent quality. The amphiphiles examined differed in terms of hydrophilic block architecture (linear vs. dendron-based branched) and size. Nanostructures generated by rapid precipitation from homogeneous solution and high supersaturation were unlike equilibrium structures assembled in solution. Controlled variations in particle size were achieved by changes in amphiphile architecture, blend composition, and final solvent content. Amphiphiles distributed randomly within the nanoparticles, as assessed by labeling methods. The rapid co-assembly of macromolecular amphiphiles from solution is a robust and versatile strategy toward the formation of kinetically stable composite nanoparticles, with increasing functional and structural complexity according to the molecular characteristics of the building blocks.

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