We have studied electrostatic layer-by-layer spraying assembly of inorganic/organic nanocomposite multilayered films consisting of Au nanoparticle (Au NP) and photosensitive polycation nitrodiazoresin (NDR). A uniform growth of the Au NP-based assembly film is revealed by UV−vis spectroscopy and AFM-film thickness measurements. We demonstrate that cross-linked films can be produced by UV irradiation which induces the conversion of originally ionic bonds into covalent ones. The nanostructure of the film such as the thickness and the fraction of Au NP can be tailored by the adsorption conditions. Thus, we find that the mechanical properties, which were measured using a buckling test method, can be tailored to a certain degree.

We studied the swelling of polyelectrolyte (PE) multilayers (PEM) in water (H2O) vapors. The PEM were made from polyanion poly(styrene sulfonate) (PSS) and polycation poly(diallyldimethylammonium chloride)-N-methyl-N-vinylacetamide (pDADMAC-NMVA). While PSS is a fully charged polyanion, pDADMAC-NMVA is a random copolymer made of charged pDADMAC and uncharged NMVA monomer units. Variation of the relative amount of these two units allows for controlling the charge density of pDADMAC-NMVA. The degree of swelling was studied as a function of the relative humidity in the experimental chamber (respectively water concentration in the gas phase) for PEM prepared from PSS and pDADMAC-NMVA with their different charge densities--100%, 89% and 75%. The films were prepared by means of spraying technique and consisted of six PE couples-PSS/pDADMAC-NMVA. Neutron reflectometry was applied as main tool to observe the swelling process. The technique allows to obtain in a single experiment information about film thickness and amount of water in the film. The experiments were complemented with AFM measurements to obtain the thickness of the films. It was found that the film thickness increases when the charge density of the polycation decreases. The swelling of the PEM increases with the relative humidity and it depends on the charge density of pDADMAC-NMVA. The swelling behavior is 2-fold, splitting up in a charge dependent mode with relatively little volume increase, and a second mode with high volume expansion, which is independent from charge density of PEM. The "swelling transition" occurs for all samples at a relative humidity about 60% and a volume increase of ca. 20%. The results were interpreted according to the Flory-Huggins theory which assumes a phase separation in PEM network at higher water contents.

Hybrid coatings are formed by dispersing inhibitor (benzotriazole) containing functionalized mesoporous silica nanoparticles throughout a polyester primer. They outperform the primer in corrosion tests both when intact and scratched. Adding the inhibitor directly (without encapsulation into nanoparticles) is found to be less effective. Given the afforded holistic protection, these hybrid coatings represent an excellent model for future coating design.

Freestanding ultrathin polyelectrolyte-multilayer membranes, transferred to topographically structured polydimethylsiloxane (PDMS), are used as mechanical sensors. Due to the membranes' semipermeability, high-molecular-weight molecules can be either entrapped inside them or excluded, thus generating an osmotic pressure. This leads to a deformation. We investigate the deformation as a function of the osmotic pressure and present an analytical theory that fully describes the data. Thus, osmotic pressures can be determined quantitatively. The individual osmotic-sensitive elements have only microscopic dimensions, and arrays can be easily produced.