Methacrylic diblock copolymers are prepared using reversible addition-fragmentation chain transfer (RAFT) chemistry at 70oC using an aqueous dispersion polymerization formulation. The first block is water-soluble poly(glycerol monomethacrylate), whereas the second block comprises water-insoluble poly(2-hydroxypropyl methacrylate). As it grows, the latter block becomes increasingly hydrophobic, which drives in situ self-assembly to form spherical nanoparticles of 25-100 nm diameter at 10% solids. Adjusting the copolymer curvature enables the morphology to be varied systematically from spheres to worms to vesicles. Phase diagrams are elucidated, which allows the reproducible synthesis of nanoparticles with predictable morphologies at up to 25% solids. If vesicles are targeted, the block copolymer morphology evolves from spheres to worms to vesicles during the polymerization. TEM studies reveal jelly-fish nano-structures that provide mechanistic insights regarding the worm-to-vesicle transition. The worm phase leads to shear-thinning, free-standing gels at 20oC but degelation occurs on cooling to 5oC due to a reversible worm-to-sphere transition.

Polymerization-induced self-assembly

245th National Meeting (2013)

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