Self-assembling quantum dots (QDs) have been obtained via the attachment of an outer corona of aromatic liquid crystalline (LC) dendrons to the surface of an inner alkylthiol corona encapsulating CdS nanoparticles. The dendronized CdS QDs form a cubic LC structure with an unusually low P2 1 3 symmetry. The anisotropic distribution of dendrons in the QD organic corona and in the P2 1 3 LC superlattice is thought to facilitate stacking interactions between the aromatic moieties. Moreover, the dendronized CdS QDs show LC structure-dependent photoluminescence quenching.

This study is focused on surface-modified Fe3O4@SiO2 particles with precisely controlled sizes and shapes applied in magnetorheological (MR) fluids. After the preparation of the monodisperse spindle-shaped and cubic Fe3O4@SiO2 particles, surface modification with dodecyltrimethoxysilane (DTM) was carried out via a silane coupling reaction to increase the dispersion stability of the particles. Afterward, MR fluids were prepared by mixing the DTM-modified Fe3O4@SiO2 particles with silicon oil. Transmission electron microscopy observations demonstrated that spindle-shaped Fe3O4@SiO2 particles could form a more stable chain-like structure than cubic Fe3O4@SiO2 particles upon application of an external magnetic field. The rheological measurements of MR fluids also indicated that the surface modification with DTM, the introduction of anisotropic shapes, and the increase in the particle size all played positive roles in the improvement in MR properties.

The surface-initiated atom transfer radical polymerization on α-Fe 2 O 3 fine particles controlled in size and shape is an efficient method to obtain monodispersed pseudo-polymer particles with anisotropic shapes; cubic-and spindle-shaped pseudo-poly(methyl methacrylate) and polystyrene particles have been successfully obtained. The pseudo-polymer particles form a free-standing orange-colored film with high transparency.Surface polymer modification of functional inorganic particles has attracted a great deal of attention to induce synergistic functions between polymers and inorganic materials.16 Surface-initiated atom transfer radical polymerization (ATRP) 712 is one of the most efficient methods to prepare such polymer-grafted inorganic particles. 1315 The resulting particles were covered by densely grafted polymers controlled in chain length. In particular, particles with a large polymer fraction could be regarded as pseudo-polymer particles. To date, sizecontrolled polymer particles with a spherical shape have been prepared through liquid-phase methods including emulsion polymerization, 16 dispersion polymerization, 16 and suspension polymerization.17 However, these techniques are inherently inapplicable for the preparation of polymer particles with anisotropic shapes because the resulting particles obtained by way of polymerization basically have an amorphous structure. In general, introduction of shape anisotropy into particles is achieved by control in the growth rate of the specific crystal planes of the particles. 1820 This means that the synthesis of shape-controlled particles is only applicable for crystalline particles. This is the reason why direct synthesis of polymerbased particles with anisotropic shapes has never been reported, so far. Up to date, shape-controlled polymer particles have been prepared with the use of a mechanical force or a template, such as microfluidic techniques, 21 lithography, 22 stretching method, 23,24 and particle replication in nonwetting template technology.25 Nevertheless, expensive equipment as well as tedious procedures were essential for previous studies, and there are large limitations to obtain size-and shape-controlled polymer particles. On the other hand, inorganic and organic crystalline particles, controlled in size and shape, can be obtained by control of the growth rate of specific crystal planes. In particular, a wide variety of inorganic crystalline particles have been prepared so far, and shape-induced functions have been also demonstrated. 1820,2628 In the present study, we focus our attention on the synthesis of polymer-grafted inorganic particles with anisotropic shapes because such polymer-coated particles can be regarded as pseudo-polymer particles controlled in size and shape. Scheme 1 represents our approach. As graft-polymerization, ATRP of methyl methacrylate (MMA) and styrene was carried out on the surface of α-Fe 2 O 3 fine particles with anisotropic shapes. Figure 1 shows FE-SEM images of the purposedesigned α-Fe 2 O 3 fine particles, F1, ...

Spindle-and disk-shaped pseudo-poly(methyl methacrylate) particles obtained by the surface-initiated atom transfer radical polymerization on α-Fe 2 O 3 or Fe 3 O 4 monodispersed fine particles exhibited lyotropic liquid-crystalline behavior in ionic liquids for a wide range of the mixing ratio. Effects of the size and shape of the particles on the lyotropic liquid-crystalline properties and the nanolevel self-organized structures have also been investigated. Keywords: Lyotropic liquid crystal | Monodispersed particle | Ionic liquidColloidal fluids of inorganic functional particles have attracted a great deal of attention 1,2 in material science and technology because introduction of fluidic property into inorganic materials has great potential for the development of novel-types of functional materials. 35 To date, various types of inorganic particle-based functional colloidal fluids have been extensively investigated and developed; nanoinks for printed electronics, 69 magnetorheological 10 and magnetic 11 fluids for magnetic devices, and hybrid lubricants to reduce interfacial friction 12 are the representative ones. For the development of the colloidal fluids, settling of the dispersed particles in the solvents is the most serious problem. 13 To prevent the sedimentation, extensive research has been carried out. 1416 In particular, to introduce high dispersion stability into inorganic particles towards hydrophilic organic solvents, polymer modification on the surface of the target particles is a useful technique. 17The surface-initiated atom transfer radical polymerization (ATRP) 18,19 of the inorganic particles is one of the most efficient methods to prepare such polymer-grafted inorganic particles. 20,21The resulting particles were covered with densely grafted polymers with controlled chain lengths. In our previous study, we developed an efficient procedure for the preparation of pseudo-poly(methyl methacrylate) (PMMA) particles with precisely controlled size and shape by the surface-initiated ATRP on size-and shape-controlled α-Fe 2 O 3 particles. 22 The resulting particles dispersed in common organic solvents such as THF, toluene, and CHCl 3 as primary particles. On the other hand, Watanabe et al. recently reported that surface PMMAmodified silica nanospheres exhibit high miscibility in 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) 30 However, effects of the particle size and shape as well as the grafted chain length of the particles on the resulting lyotropic LC phases have not yet been extensively investigated. In contrast, our developed pseudo-PMMA particles with an α-Fe 2 O 3 particulate core are the tailor-made particles because not only the size and shape of the particles but also the grafted chain length of the particles are precisely controlled.The purpose-designed iron oxide fine particles with PMMA chains on their surfaces were prepared by our established route. 22 As the α-Fe 2 O 3 particles, named Fn (n = 14), spindleshaped particles F1 and F2 with different in their particle me...