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Title: Computer simulations of block copolymer nanocomposite systems
Author: Branas, Javier Dıaz
ISNI:       0000 0004 8506 9743
Awarding Body: University of Lincoln
Current Institution: University of Lincoln
Date of Award: 2019
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Block copolymers and nanoparticles are elements of the soft matter family which includes deformable materials and is increasingly part of industry and biological applications. Block copolymer melts can self-assemble into well-ordered, periodic structures in the mesoscale. Furthermore, block copolymers are perfect scaffolds to locate colloidal nanoparticles and, when applicable, control their orientation. Nonetheless, the co-assembly of colloids within block copolymers is not that of simple passive fillers. Instead, the presence of particles can greatly disturb the original block copolymer structure leading to a true collective behaviour where several length scales compete, along with entropic and enthalpic mechanism of assembly. To study such a complex problem, computer programs are used. Cell Dynamic Simulation provide an efficient method to study hybrid block copolymer/nanoparticle systems in the mesoscale, combining a continuous approach to the phase separation of block copolymers with colloids, which are individually treated following Brownian Dynamics. Using this method, a series of experimental results have been reproduced. Moreover, it has been used to study otherwise complex open questions such as the full phase diagram of block copolymer morphologies in the presence of an arbitrary number of particles with arbitrary chemical characteristic. Colloids have been found to segregate within the block copolymer structures dictated by their chemical properties, size, shape and concentration in the system. At high concentrations nanoparticles can greatly disturb the polymeric morphology and interesting cases of aggregation and phase-separation have been found. Neutral nanoparticles can macro-phase separate into elongated clusters along the lamellar direction. Non-spherical particles such as nanorods or square-like particles have been studied in detail, finding highly ordered configurations of nanoparticles in accordance with recent experiments. Highly anisotropic nanoparticles have been found to display higher occupancy rate of the block copolymer interface, which makes them ideal to segregate in layers at block copolymer interfaces. Chemically inhomogeneous nanoparticles have been also found to assemble into complex configurations when mixed with block copolymers. In order to achieve relevant box sizes, an efficient CDS scheme is used. Furthermore, a parallel scheme using FORTRAN Coarrays has been used, which allows to simulate up to tens of μm sized systems, which is considerably larger than previously reported simulations of block copolymer nanocomposite systems.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available