Synthesis of a Novel ABC Triblock Copolymer with a Rigid-Rod Block via Atom Transfer Radical Polymerization

Complex liquid-crystal nanostructures in semiflexible ABC linear triblock copolymers: A self-consistent field theory

We show that two series of ABC linear triblock copolymers possess sequences of order-to-order phase transitions between microphase-separated states, as the degree of flexibility of the semiflexible middle B-blocks varies. The spatial and orientational symmetries of these phases, some of them containing liquid-crystal ordering, are analysed in comparison with related structures previously determined experimentally and theoretically. A theoretical framework based on the self-consistent field treatment of the wormlike-chain model, which incorporates the Flory-Huggins and Maier-Saupe interactions in the free energy, is used here as a basic foundation for numerical calculations. We suggest that tuning the flexibility parameter, which reduces to the concept of degree of polymerization in the coil-like limit and characterizes the chain-persistency in the rod-like limit, provides a promising approach that can be used to design the resulting microphase-separated structures in semiflexible copolymer melts.

Functional Polyether-based Amphiphilic Block Copolymers Synthesized by Atom-transfer Radical Polymerization

This review deals with the synthesis, physical properties, and applications of amphiphilic block copolymers based on hydrophilic poly(ethylene oxide) (PEO) or hydrophobic poly(propylene oxide) (PPO). Oligomeric PEO and PPO are frequently functionalized by converting their OH end groups into macroinitiators for atom-transfer radical polymerization. They are then used to generate additional blocks as part of complex copolymer architectures. Adding hydrophobic and hydrophilic blocks, respectively, leads to polymers with amphiphilic character in water. They are surface active and form micelles above a critical micellization concentration. Together with recent developments in post-polymerization techniques through quantitative coupling reactions (‘click’ chemistry) a broad variety of tailored functionalities can be introduced to the amphiphilic block copolymers. Examples are outlined including stimuli responsiveness, membrane penetrating ability, formation of multi-compartmentalized micelles, etc.