Compartmentalized nanoparticles in aqueous solution through hierarchical self-assembly of triblock glycopolymers

Abstract

Amphiphilic block copolymers can elegantly assemble in water to form well-defined nano-objects and through smart design of the polymers it is possible to efficiently prepare functional materials for biomedical applications such as drug carriers. Linear triblock terpolymers add an additional level of complexity to the process. The assembly can proceed in a step-wise manner, collapsing one block at a time and producing materials with segregated domains in the nanometer scale. Here we present the self-assembly of a pH-responsive and sugar-functionalized linear triblock terpolymer PGlcEA-b-PBuA-b-P4VP in aqueous solution. Initially the polymer forms small spherical micelles with a poly(butylacrylate) core and a corona composed by the two outer blocks. Subsequent exchange of the solvent to aqueous solution at different pH value causes aggregation into bigger particles triggered by the segregation of the poly(4-vinylpyridine) block. Morphologies include large patchy spherical particles and caterpillar-type structures and are strongly influenced by the acidity of the solution. We determine the best conditions for the preparation of the aggregates and study their stability to ageing and temperature variation with particular focus on the “caterpillars”. Our results demonstrate that a hierarchical self-assembly can be useful to expand the morphological diversity of polymeric nanoparticles in aqueous solution bearing bioactive surface functionalities.