Chemical Approach to Functional Artificial Opals

25th anniversary article: CVD polymers: a new paradigm for surface modification and device fabrication

Well-adhered, conformal, thin (<100 nm) coatings can easily be obtained by chemical vapor deposition (CVD) for a variety of technological applications. Room temperature modification with functional polymers can be achieved on virtually any substrate: organic, inorganic, rigid, flexible, planar, three-dimensional, dense, or porous. In CVD polymerization, the monomer(s) are delivered to the surface through the vapor phase and then undergo simultaneous polymerization and thin film formation. By eliminating the need to dissolve macromolecules, CVD enables insoluble polymers to be coated and prevents solvent damage to the substrate. CVD film growth proceeds from the substrate up, allowing for interfacial engineering, real-time monitoring, and thickness control. Initiated-CVD shows successful results in terms of rationally designed micro- and nanoengineered materials to control molecular interactions at material surfaces. The success of oxidative-CVD is mainly demonstrated for the deposition of organic conducting and semiconducting polymers.

Preparation of submicrometer-sized clusters from polymer spheres using ultrasonication

The fabrication of small assemblies of spherical colloidal particles is presented. Basic principles of the preparation of miniemulsions were combined with the concept originally described by Pine and co-workers for the preparation of clusters from microspheres. The application of ultrasonic emulsification limits the size distribution of the emulsion droplets and thus the statistical distribution of the number of particles per droplet. The small droplet sizes together with the use of building blocks in the submicrometer range leads to large yields of well-defined small clusters with diameters below 300 nm. Such clusters might serve to build novel promising materials that demand high complexity or special symmetries.

Nanodiamond particles forming photonic structures

Colloid suspensions of irregularly shaped, highly charged detonation nanodiamond particles are found to have unexpected optical properties, similar to those of photonic crystals. This finding is all the more surprising since the particles used in this work are far more polydisperse than those typically forming photonic crystals. Intensely iridescent structures have been fabricated using the centrifugation of aqueous suspensions of nanodiamonds.