Organic–inorganic hybrids made from polymerizable precursors

Organic–inorganic hybrid films were prepared based on a recipe using organoalkoxysilanes’ ability to create an inorganic network combined with polymer network formation via radical polymerization of the organic groups. The starting mixtures included different triethoxysilanes (RTES), where the organic substitute (R) was varied from methyl- (MeTES), phenyl- (PTES), octyl- (OTES) to vinyl- (VTES). Additionally, films prepared using methacryloxypropyltrimethoxysilane (MPTS) were also investigated. Most of the formulations were enriched with tetraisopropyl orthotitanate (TIP). Based on phase diagrams, the limits of the one-phase liquid regions were determined for the initial (RTES–ethanol–water) ternary mixtures. Non-linear modifications of the refractive indexes versus water concentration, as well as the measured conductivity changes indicate that these apparent homogeneous systems are nanostructured as microemulsions. Based on the results of combined microscale (atomic force microscopy (AFM)) and macroscale (wettability, thermal analysis) investigations, it was possible to observe the internal structure and to explain the measured properties of the final composite films. The high resistance against solvent attack is based on the regular, granular-like structure of the end products. Heating the films (at temperatures above the thermal degradation range for the incorporated organics) forces the inorganic structures to collapse and undergo phase transformations

Structural and mechanical study of a self-assembling protein nanotube

We report a structural characterization of self-assembling nanostructures. Using atomic force microscopy (AFM), we discovered that partially hydrolyzed α-lactalbumin organizes in a 10-start helix forming tubes with diameters of only 21 nm. We probed the mechanical strength of these nanotubes by locally indenting them with an AFM tip. To extract the material properties of the nanotubes, we modeled the experiment using finite element methods. Our study shows that artificial helical protein self-assembly can yield very stable, strong structures that can function either as a model system for artificial self-assembly or as a nanostructure with potential for practical applications. © 2006 American Chemical Society