Spontaneous Formation of Narrowly-Distributed Self-Assembly from Polyamidoamine Dendron-Poly(L-lysine) Block Copolymers Through Helix-Coil Transition of Poly(L-lysine) Block

The self-assembly of head-tail type block copolymers composed of polyamidoamine dendron head block and poly(L-lysine) (PLL) tail block was studied using a light scattering technique and transmission electron microscopy. A PLL tail block in a head-tail type block copolymer exhibits a coil-to-helix transition as a result of the change in solvent quality from water to methanol. When the PLL tail block takes a helical conformation in high methanol content, the resulting head-tail type block copolymer has a defined three-dimensional structure like that of a protein molecule. Self-assemblies of such block copolymers having a totally fixed molecular shape spontaneously form polymersome-like self-assemblies with an extremely narrow size distribution through converging to a thermodynamically stable assembling state. (C) 2009 Wiley Periodicals, Inc. J Polyrn Sci Part A: Polym Chem 47: 1217-1223, 2009