Controlling the self-assembly of binary copolymer mixtures in solution through molecular architecture

Autor: Greenall, M. J., Schuetz, P., Furzeland, S., Atkins, D., Buzza, D. M. A., Butler, M. F., McLeish, T. C. B.
Rok vydání: 2011
Předmět:
Zdroj: Macromolecules, 2011, 44 (13), pp 5510-5519
Druh dokumentu: Working Paper
DOI: 10.1021/ma2008546
Popis: 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.
Comment: 29 pages double-spaced including 11 figures, submitted to Macromolecules
Databáze: arXiv
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