A hybrid block copolymer(BCP) nanocomposite computational model is proposed to study nanoparticles(NPs) with a generalised shape including squares, rectangles and rhombus. Simulations are used to study the role of anisotropy in the assembly of colloids within BCPs, ranging from NPs that are compatible with one phase, to neutral NPs. The ordering of square-like NPs into grid configurations within a minority BCP domain was investigated, as well as the alignment of nanorods in a lamellar-forming BCP, comparing the simulation results with experiments of mixtures of nanoplates and PS-b-PMMA BCP. The assembly of rectangular NPs at the interface between domains resulted in alignment along the interface. The aspect ratio is found to play a key role on the aggregation of colloids at the interface, which leads to a distinct co-assembly behaviour for low and high aspect ratio NPs.
Nanocomposite materials made of block copolymer (BCP) and nanoparticles display properties which can be different from the purely polymeric matrix. The resulting material is a crossover of the original properties of the BCP and the presence of the assembled nanoparticles. A mesoscopic study using cell dynamic simulations is reported, to quantitatively describe the structural properties of such hybrid materials. The most relevant parameters are identified to be the fraction of nanoparticles in the system and its chemical affinity, while the nanoparticle size with respect to the BCP length scales plays a role in the assembly. The morphological phase diagram of the BCP is constructed for nanoparticles with chemical affinity ranging from A-compatible to B-compatible for a symmetric A-B diblock copolymer. Block-compatible nanoparticles are found to induce a phase transition due to changes in the effective concentration of the hosting phase, while interface-compatible particles induce the appearance of two new phases due to the saturation of the diblock copolymer interface.
The presence of nanoparticles in a diblock copolymer leads to changes in the morphology and properties of the matrix and can produce highly organized hybrid materials. The resulting material properties depend not only on the polymer composition but also on the size, shape, and surface properties of the colloids. The dynamics of this kind of systems using a hybrid mesoscopic approach has been studied in this work. A continuum description for the polymer is used, while colloids are individually resolved. The method allows for a variable preference of the colloids, which can have different sizes, to the different components the block copolymer is made of. The impact that the nanoparticle preference for either, both, or none of the blocks has on the collective properties of nanoparticle–block copolymer composites can be analyzed. Several experimental results are reproduced covering colloid‐induced phase transition, particles' placement within the matrix, and the role of incompatibilities between colloids and monomers.
Block copolymer melts self-assemble in the bulk into a variety of nanostructures, making them perfect candidates to template the position of nanoparticles. The morphological changes of block copolymers are studied in the presence of a considerable filling fraction of colloids. Furthermore, colloids can be found to assemble into ordered hexagonally close-packed structures in a defined number of layers when softly confined within the phaseseparated block copolymer. A high concentration of interface-compatible nanoparticles leads to complex block copolymer morphologies depending on the polymeric composition. Macrophase separation between the colloids and the block copolymer can be induced if colloids are unsolvable within the matrix. This leads to the formation of ellipsoid-shaped polymer-rich domains elongated along the direction perpendicular to the interface between block copolymer domains. * Electronic supplementary information (ESI) available.
Simulations and experiments of nanorods (NRs) show that co-assembly with block copolymer (BCP) melts leads to the formation of a superstructure of side-to-side NRs perpendicular to the lamellar axis. A mesoscopic model is validated against scanning electron microscopy (SEM) images of CdSe NRs mixed with polystyrene-blockpoly(methyl methacrylate). It is then used to study the co-assembly of anisotropic nanoparticles (NPs) with a length in the same order of magnitude as the lamellar spacing. The phase diagram of BCP/NP is explored as well as the time evolution of the NR.NRs that are slightly larger than the lamellar spacing are found to rotate and organise side-to-side with a tilted orientation with respect to the interface. Strongly interacting NPs are found to dominate the co-assembly while weakly interacting nanoparticles are less prone to form aggregates and tend to form well-ordered congurations.Block copolymer (BCP) melts can self assemble into well-ordered mesophases, 14 which are repeated periodically with a domain size H 0 , typically of the order of 1 − 300 nm. 5 This periodicity makes BCPs excellent matrices to host nanoparticles (NPs), which can be localised in specic regions of the phase-separated BCP. 6,7 Mixtures of BCPs and colloids have long been studied using theory 8,9 simulations 1012 and experiments 13,14 due to the interesting behaviour resulting from the co-assembly of selective nanoparticles and phase-separated block copolymer. Nanorods (NR) have attracted considerable attention as constituents of functional polymer nanocomposite materials. 15 The orientational degree of freedom of anisotropic colloids introduces new possibilities of BCP/NP co-assembly, thanks to the intrinsic ordered structures of the neat BCP (lamellar, cylindrical, etc). For instance, gold NRs have been found to orient along the lamellar domain axis when conned in one of the symmetrical phases. 16,17 Similarly, gold NRs template the direction of the cylindrical domains in an asymmetrical diblock copolymer mixture. 18 Ordered arrays of aligned NRs were achieved by Thorkelsson 19,20 in the co-assembly of BCP and anisotropic
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