A Valid Way of Quasi-Quantificationally Controlling the Self-Assembly of Block Copolymers in Confined Space

To mimic nanostructures assembled by biomolecules in organic cells and achieve precise self-assembly of block copolymers, a simple but valid way is introduced to quasi-quantificationally control the aggregation numbers (N(agg)) of polymeric micelles. A three-dimensional and closed microconfinement similar to a cell is constructed by W/O inverse emulsion as the spot for self-assembly of the pH-responsive block copolymer poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP). The N(agg) values of the resulting polymeric micelles are effectively controlled by tuning the number of polymer chains encapsulated in isolated water pools. Micelles with different N(agg) values are successfully prepared and characterized by atomic force microscopy, transmission electron microscopy, and dynamic light scattering. When the number of polymer chains enclosed in a water pool (N(chain)) is less than the average N(agg) of normal micelles generated in bulk aqueous solution, the resultant aggregates formed in the confined spaces always have lower N(agg) as well as smaller sizes than the normal micelles do, while normal micelles predominantly form when N(chain)N(agg) (normal micelle).