Future Directions

Research into block copolymer nanoparticles and nanostructures is a relatively new area, but has created a vast amount of interest due to their versatility. Block copolymer nanoparticles and nanostructures have become so popular because their size, structure, properties, and surface chemistry can all be designed to suit the intended purpose.

The ability to generate compartmentalized volumes at the nanometer level is one of the fundamental motifs used by cells in synthesizing biomolecules and performing the biochemical processes necessary for their function. This motif has been recently reassembled using block copolymer micelles and vesicles as nanoreactors.

Nanoreactors have been prepared by the incorporation of a channel protein into the membrane of block copolymer vesicles. The design of hybrid nanoreactors that comprise membrane proteins stabilized with block copolymer membrane for energy conversion applications. Recently, Vriezema et al. have demonstrated that block copolymer vesicles containing enzymes can be used to perform one-pot multi step reactions. Block copolymer vesicles containing enzymes, one in the aqueous inner compartment and one in the bilayer, have also been used for enzymatic ring-opening polymerization of lactones in water.

It has been shown that this approach can be readily expanded into nonaqueous solvent. In particular, the recent reports of block copolymer nanostructures in ionic liquid and the ability of micelles to shuttle from an aqueous solvent to an ionic liquid as a function of temperature, link block copolymer technology with more sophisticated synthetic routes.

Block copolymer structures can also be used to mimic the ability of biomolecules to convert chemical energy into mechanical energy. An ABA copolymer, where the B block is pH sensitive, assembles into cubic micellar phases whose d-spacing and hence, the size of the whole gel can be tuned by a chemical oscillator. More recently Topham et al. exploited phase separation in a pH sensitive triblock copolymer to create an antagonistic swelling gel. Powered by pH oscillations, this system uses a poly(acid) gel attached to a poly(base) gel where as one swells the other contracts, creating a force in the same fashion that muscles work antagonistically in the body .

Possible applications for the block copolymer nanostructures encompass many areas, from delivery vectors, tissue engineering scaffolds, artificial muscles and nanoreactors, to fuel cells and water purification systems. However, despite all the research conducted so far, there is still a great deal left to explore, with the only limitation being our creativity.