Helical Superstructures from Charged Poly(styrene)-Poly(isocyanodipeptide) Block Copolymers

Abstract

Amphiphilic block copolymers containing a poly(styrene) tail and a charged helical poly(isocyanide) headgroup derived from isocyano-L-alanine-L-alanine and isocyano-L-alanine-L-histidine were prepared. Analogous to low-molecular mass surfactants, these block copolymers self-assembled in aqueous systems to form micelles, vesicles, and bilayer aggregates. The morphology of these aggregates can be controlled by variation of the length of the poly(isocyanide) block, the pH, and the anion-headgroup interactions. The chirality of the macromolecules results in the formation of helical superstructures that have a helical sense opposite to that of the constituent block copolymers. The great variety of morphologies displayed by these block copolymers and the fact that they are easily accessible from poly(styrene) and different types of peptides open new opportunities for applications in the fields of life and materials sciences.

Self‐Assembled Nanoreactors

“…Amphiphilic block copolymers, constructed from at least two blocks with different properties, tend to aggregate in solvents selective for one of the constituent blocks, thus resembling traditional surfactants. Analogous to surfactants, a range of morphologies can be observed when dispersions of amphiphilic copolymers are prepared, that is, micellar, 203 bilayer, 204 chiral, 205 and other architectures 206 (Figure 18). The driving force for the selfassembly is generally considered to be microphase separation of the insoluble blocks.…”

Preparation of block copolymer vesicles in solution

“…57 Evidence for the existence of the vesicle structures was given by cyro-transmission electron microscopy through direct visualization in solution and by osmotic experiments that showed the existence of an inner aqueous compartment. 57 Cornelissen et al 6 made an amphiphilic block copolymer with a head group composed of amino acids, that is, polystyrene-block-poly(isocyano-L-alanine-L-alanine) (PS 40 -b-PIAA 10 ). They produced collapsed vesicles ranging in size from tens to hundreds of nanometers with a bilayer thickness of 16 nm in a sodium acetate buffer solution.…”

A monolithic hydro/organo macro copolymer actuator synthesized via interfacial copolymerization

“…36 For example, the binary cooperative effect 37,38 of the hydrophilic segments and hydrophobic segments cause the polymer chains to assemble into aggregates in aqueous solutions, with the hydrophobic segments twisting and coiling to entangle each other via hydrophobic interactions as the core. 39 Under certain conditions, the aggregates are able to transform among various morphologies, [39][40][41][42] including spheres, rods, 43 vesicles, 44 tubules 45 and cubosomes 46 similar to actuators. Therefore, it seems feasible to combine a hydrogel with an organogel to fabricate a covalently connected macro-scale 'amphiphilic diblock copolymer aggregate,' whereby the two subunits of diverse physical and chemical properties realize macroscopical motion.…”