Abstract
We present a combined experimental and theoretical study on the role of copolymer architecture in the self-assembly of binary PEO-PCL mixtures in water-THF and show that altering the chain geometry and composition of the copolymers can control the form of the self-assembled structures and lead to the formation of novel aggregates. First, using transmission electron microscopy and turbidity measurements, we study a mixture of sphere-forming and lamella-forming PEO-PCL copolymers and show that increasing the molecular weight of the lamella-former at a constant ratio of its hydrophilic and hydrophobic components leads to the formation of highly curved structures even at low sphere-former concentrations. This result is explained using a simple argument based on the effective volumes of the two sections of the diblock and is reproduced in a coarse-grained mean-field model: self-consistent field theory (SCFT). Using further SCFT calculations, we study the distribution of the two copolymer species within the individual aggregates and discuss how this affects the self-assembled structures. We also investigate a binary mixture of lamella-formers of different molecular weights and find that this system forms vesicles with a wall thickness intermediate to those of the vesicles formed by the two copolymers individually. This result is also reproduced using SCFT. Finally, a mixture of sphere-former and a copolymer with a large hydrophobic block is shown to form a range of structures, including novel elongated vesicles.
Original language | English |
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Pages (from-to) | 5510-5519 |
Number of pages | 10 |
Journal | Macromolecules |
Volume | 44 |
Issue number | 13 |
Early online date | 16 Jun 2011 |
DOIs | |
Publication status | Published - 12 Jul 2011 |