Colloidal crystals surface

SILICA COLLOIDAL CRYSTAL SURFACE MODIFIED WITH CHARGEABLE ORGANIC MOLECULES... 

As an example of composite core/shell submicron particles, we made colloidal spheres with a polystyrene core and a silica shell. The polar vapors preferentially affect the silica shell of the composite nanospheres by sorbing into the mesoscale pores of the shell surface. This vapor sorption follows two mechanisms physical adsorption and capillary condensation of condensable vapors17. Similar vapor adsorption mechanisms have been observed in porous silicon20 and colloidal crystal films fabricated from silica submicron particles32, however, with lack of selectivity in vapor response. The nonpolar vapors preferentially affect the properties of the polystyrene core. Sorption of vapors of good solvents for a glassy polymer leads to the increase in polymer free volume and polymer plasticization32. 

Any study of colloidal crystals requires the preparation of monodisperse colloidal particles that are uniform in size, shape, composition, and surface properties. Monodisperse spherical colloids of various sizes, composition, and surface properties have been prepared via numerous synthetic strategies [67]. However, the direct preparation of crystal phases from spherical particles usually leads to a rather limited set of close-packed structures (hexagonal close packed, face-centered cubic, or body-centered cubic structures). Relatively few studies exist on the preparation of monodisperse nonspherical colloids. In general, direct synthetic methods are restricted to particles with simple shapes such as rods, spheroids, or plates [68]. An alternative route for the preparation of uniform particles with a more complex structure might consist of the formation of discrete uniform aggregates of self-organized spherical particles. The use of colloidal clusters with a given number of particles, with controlled shape and dimension, could lead to colloidal crystals with unusual symmetries [69]. 

Owing to the simphcity and versatility of surface-initiated ATRP, the above-mentioned AuNP work may be extended to other particles for their two- or three-dimensionally ordered assemblies with a wide controllabiUty of lattice parameters. In fact, a dispersion of monodisperse SiPs coated with high-density PMMA brushes showed an iridescent color, in organic solvents (e.g., toluene), suggesting the formation of a colloidal crystal [108]. To clarify this phenomenon, the direct observation of the concentrated dispersion of a rhodamine-labeled SiP coated with a high-density polymer brush was carried out by confocal laser scanning microscopy. As shown in Fig. 23, the experiment revealed that the hybrid particles formed a wide range of three-dimensional array with a periodic structure. This will open up a new route to the fabrication of colloidal crystals. 

Keywords wrinkling Thin-film Elastomeric polymer Polydimethylsiloxane Patterns Deformation Surfaces Self-assembly Polyelectrolyte multilayer films Thin-films Polymer brushes Colloidal crystallization Mechanical-properties Assembled monolayers Buckling instability Elastomeric polymer Tobacco-mosaic-virus Soft lithography Arrays... 

Allard M, Sargent EH, Lewis PC, Kumacheva E (2004) Colloidal crystals grown on patterned surfaces. Adv Mater 16 1360-1364... 

A template surface is usually needed in order to obtain colloidal crystals with orientations other than (111). When a substrate with the appropriate arrays of relief structures is used, the pits can serve as physical templates to confine and control the nucleation and growth of colloidal crystals that will exhibit a pre-specified spatial orientation, van Blaaderen and Wiltzius first demonstrated the use of lithographically defined surfaces as templates to grow specifically oriented colloidal crystals. They accomplished this by utilizing a slow sedimentation process and were able to produce crystals with either (100) or (110) planes oriented parallel to the supporting substrates.148 This work was followed by Yodh and coworkers... 

An inkjet printing of colloidal crystals was proposed by Frese et describing inkjet printing processes of monodispersed particles which are able to form two- or three-dimensional photonic crystals on the substrate surface by arranging in a closely packed lattice structure on the surface. The particle size was selected so that it will diffract light in the visible spectral region, i.e., particle size of 200-500 nanometers. In this work drop-on-demand inkjet printing techniques are utilized. 

Ward, M.D. Organic crystal surfaces structure, properties and reactivity. Curr. Opin. Colloid Interface Sci. 1997, 2 (1), 51-64. 

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