Decoration of nanoparticles by specific functional groups provides means of controlling their aggregation and self-assembly into ordered morphologies. We study the photocontrollable self-assembly of the azobenzene-functionalized nanoparticles using coarse-grained molecular dynamics simulations. With no illumination applied, a monodomain smectic morphology is formed only via cooling the isotropic system at a sufficiently slow rate. Quenching the system below the smectic–isotropic transition results in formation of a polydomain glass-like state with restricted dynamics of nanoparticles. Upon irradiation with appropriate wavelength and intensity, the azobenzenes undergo trans–cis–trans photoisomerization cycles which unlock the interdomain links and induce uniaxial orientation of domains with their local director perpendicular to the polarization axis of irradiation. As demonstrated by the simulations, this transition can speed up essentially the self-assembly of decorated nanoparticles from the isotropic to the monodomain smectic phase, both via gradual cooling down and via quenching in a broad temperature interval below the smectic–isotropic transition.

We consider a mesoscale model for nano-sized metaparticles (MPs) composed of a central sphere decorated by polymer chains with laterally attached spherocylinder. The latter mimics the mesogenic (e.g., cyanobiphenyl) group. Molecular dynamics simulations of 100 MPs reveal the existence of two novel morphologies: uCol h (hexagonal columnar arrangement of MPs with strong uniaxial order of mesogens collinear to the columns axis) and wCol h [the same arrangement of MPs but with weak or no liquid crystalline (LC) order]. Collinearity of the LC director and the columnar axis in uCol h morphology indicates its potentially different opto-mechanical response to an external perturbation as compared to the columnar phase for the terminally attached mesogens. Preliminary analysis of the structures of both phases is performed by studying the order parameters and by visualisation of the MPs arrangements. Different mechanisms for the mesogens reorientation are pointed out for the cases of their terminal and lateral attachment. MotivationColloid particles, polymers and LC molecules represent main building blocks of soft matter physics [1]. When two or more of such blocks are combined into a MP, the latter forms a meta-material that exhibits a range of new morphologies and new effects that are not observed for any of its pure constituents. Examples to mention are: LC elastomers, LC dendrimers, decorated nanoparticles and others [2][3][4][5][6][7], all of these having already found a number of applications in thermo-and photo-controlled elasticity, plasmonic resonance, photonics and medicine. Most applications rely on the symmetry of the equilibrium morphology, in which each constituent is "responsible" for particular property of a meta-material. For instance, its elasticity is usually controlled by a polymer subsystem, optical properties are governed by both the behaviour of mesogens and the arrangement of gold nanoparticles (if any). Therefore, the type of mutual arrangement of the constituent parts is crucial regarding the new potential applications of each particular meta-material.Let us concentrate on the MPs built out of a spherical core decorated by polymer chains (spacers) each ending by a mesogen. The core mimics either a solid nanoparticle (e.g., gold nanoparticle [6,7]) or averaged in time shape of a dendritic scaffold [4,5]. It was found experimentally that the most important aspects of decoration are as follows: the surface density of mesogens on the outer shell of MP, the length of a spacer, and the exact way mesogens are attached chemically to the spacer [4][5][6][7][8][9][10][11]. In particular, both terminal and lateral attachment can be realised chemically [4,5,[8][9][10][11] [depicted schematically in figure 1 (a) and (b)] and the difference between the morphologies observed in these two cases are in the focus of this study.

We consider the coarse-grained modelling of patchy ligand shell nanoparticles with liquid crystalline ligands. The cases of two, three, four and six symmetrically arranged patches of ligands are discussed, as well as the cases of their equatorial and icosahedral arrangement. A solution of decorated nanoparticles is considered within a slit-like pore with solid walls and the interior filled by a polar solvent. The ligands form physical cross-links between the nanoparticles due to strong liquid crystalline interaction, turning the solution into a gel-like structure. Gelation is carried out repeatedly starting each time from a freshly equilibrated dispersed state of nanoparticles. The gelation dynamics and the range of network characteristics of the gel are examined, depending on the type of patchy decoration and on the solution density. Emphasis is given to the theoretical prediction of the type of decoration and the solution density most suitable for producing a uniformly cross-linked and highly elastic gel structure.

By means of molecular dynamics simulations we study formation of the wall-to-wall percolation cluster in the solution of decorated nanoparticles in a pore. The model takes into account photo-switching between unpolar trans and polar cis-isomers of azobenzene. This leads to either colloidal dispersion of the particles or their aggregation in a polar solvent. The dynamics of percolation cluster formation is analysed by applying a pulse-like illumination. We found that the wall-to-wall percolation is subject to the competition between nanoparticles aggregation, wall adsorption and microphase separation of the nanoparticles.

We consider a solution of nanoparticles in a pore with one of its walls being a liquid crystalline polymer brush. Both nanoparticles' ligands and the brush molecules side chains contain the same liquid crystalline groups. The system is studied using the molecular dynamics simulations. At both cases of a low and high brush density, the aggregation between the pairs of nanoparticles in a bulk and between the brush molecules prevail. However, we found a specific brush density when the nanoparticles are adsorbed more readily on a brush than aggregate in a bulk. A set of density profiles as well as the dynamical properties of nanoparticles are analysed in all cases considered.