Computer Simulations of Block Copolymer Nanocomposite Systems

Branas, Javier Dıaz (2019) Computer Simulations of Block Copolymer Nanocomposite Systems. PhD thesis, University of Lincoln.

Computer Simulations of Block Copolymer Nanocomposite Systems
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Item Type:Thesis (PhD)
Item Status:Live Archive


Block copolymers and nanoparticles are elements of the soft matter family which includesdeformable materials and is increasingly part of industry and biological applications. Blockcopolymer melts can self-assemble into well-ordered, periodic structures in the mesoscale. Fur-thermore, block copolymers are perfect scaffolds to locate colloidal nanoparticles and, when appli-cable, control their orientation. Nonetheless, the co-assembly of colloids within block copolymersis not that of simple passive fillers. Instead, the presence of particles can greatly disturb the orig-inal block copolymer structure leading to a true collective behaviour where several length scalescompete, along with entropic and enthalpic mechanism of assembly. To study such a complexproblem, computer programs are used. Cell Dynamic Simulation provide an efficient methodto study hybrid block copolymer/nanoparticle systems in the mesoscale, combining a continu-ous approach to the phase separation of block copolymers with colloids, which are individuallytreated following Brownian Dynamics. Using this method, a series of experimental results havebeen reproduced. Moreover, it has been used to study otherwise complex open questions such asthe full phase diagram of block copolymer morphologies in the presence of an arbitrary numberof particles with arbitrary chemical characteristic. Colloids have been found to segregate withinthe block copolymer structures dictated by their chemical properties, size, shape and concen-tration in the system. At high concentrations nanoparticles can greatly disturb the polymericmorphology and interesting cases of aggregation and phase-separation have been found. Neutralnanoparticles 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 blockcopolymer interface, which makes them ideal to segregate in layers at block copolymer inter-faces. Chemically inhomogeneous nanoparticles have been also found to assemble into complexconfigurations when mixed with block copolymers. In order to achieve relevant box sizes, anefficient CDS scheme is used. Furthermore, a parallel scheme using FORTRAN Coarrays hasbeen used, which allows to simulate up to tens ofμm sized systems, which is considerably largerthan previously reported simulations of block copolymer nanocomposite systems.

Divisions:College of Science > School of Mathematics and Physics
ID Code:39308
Deposited On:23 Dec 2019 16:15

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