The mechanism of formation of supported lipid layers from phosphatidylcholine and phosphatidylserine vesicles in solution on polyelectrolyte multilayers was studied by a variety of experimental techniques. The interaction of zwitterionic and acidic lipid vesicles, as well as their mixtures, with polyelectrolyte supports was followed in real time by micro-gravimetry. The fabricated lipid-polyelectrolyte composite structures on top of multilayer coated colloidal particles were characterized by flow cytometry and imaging techniques. Lipid diffusion over the macroscopic scale was quantified by fluorescence recovery after photobleaching, and the diffusion was related to layer connectivity. The phospholipid-polyelectrolyte binding mechanism was investigated by infrared spectroscopy. A strong interaction of polyelectrolyte primary amino groups with phosphate and carboxyl groups of the phospholipids, leading to dehydration, was observed. Long-range electrostatic attraction was proven to be essential for vesicle spreading and rupture. Fusion of lipid patches into a homogeneous bilayer required lateral mobility of the lipids on the polyelectrolyte support. The binding of amino groups to the phosphate group of the zwitterionic lipids was too weak to induce vesicle spreading, but sufficient for strong adsorption. Only the mixture of phosphatidylcholine and phosphatidylserine resulted in the spontaneous formation of bilayers on polyelectrolyte multilayers. The adsorption of phospholipids onto multilayers displaying quarternary ammonium polymers produced a novel 3D lipid polyelectrolyte structure on colloidal particles.

The assembly of polyelectrolyte multilayers and the formation of complexes in a solution of poly(diallyldimethylammonium chloride) (PDADMAC) and poly(acrylic acid) (PAA) have been studied as a function of pH. Quartz Crystal Microbalance with Dissipation (QCM-D) in combination with Ellipsometry shows that PAA-PDADMAC multilayers display a supralinear growth pattern at pH 3 with a corresponding change in the frequency response of more than 650 Hz for 17 polyelectrolyte layers.Atomic Force Microscopy (AFM) confirmed the formation of a 200 nm thick film. For pH values higher than 6, assembly is drastically reduced resulting in values below 150 Hz in the QCM-D for the same number of layers. Isothermal Titration Calorimetry (ITC) and Dynamic Light Scattering (DLS) were used to study complex formation. At pH 3, an exothermic heat of complex formation of À2.11 kcal mol À1 was measured. With increasing pH, the heat of complex formation has been seen to decrease. At pH 10, the heat of complex formation tends to be more endothermic and is approximately 0 at pH 13. The addition of urea to PAA at pH 13 resulted in an exothermic heat of complex formation of 1.41 kcal mol À1 during titration with PDADMAC, highlighting the role of hydrogen bonding with water of PAA in governing the interaction between PAA and PDADMAC.

A ligand design is proposed for transition metal nanoparticle (TMNP) catalysts in aqueous solution. Thus, a tris(triazolyl)-polyethylene glycol (tris-trz-PEG) amphiphilic ligand, 2, is used for the synthesis of very small TMNPs with Fe, Co, Ni, Cu, Ru, Pd, Ag, Pt, and Au. These TMNP-2 catalysts were evaluated and compared for the model 4-nitrophenol reduction, and proved to be extremely efficient. High catalytic efficiencies involving the use of only a few ppm metal of PdNPs, RuNPs, and CuNPs were also exemplified in Suzuki-Miyaura, transfer hydrogenation, and click reactions, respectively.

Understanding the relationship between the location of nanoparticles (NPs) in an organic matrix and their catalytic performances is essential for catalyst design. Here we show that catalytic activities of Au, Ag and CuNPs stabilized by dendrimers using coordination to intradendritic triazoles, galvanic replacement or stabilization outside dendrimers strongly depends on their location. AgNPs are found at the inner click dendrimer periphery, whereas CuNPs and AuNPs are encapsulated in click dendrimer nanosnakes. AuNPs and AgNPs formed by galvanic replacement are larger than precursors and only partly encapsulated. AuNPs are all the better 4-nitrophenol reduction catalysts as they are less sterically inhibited by the dendrimer interior, whereas on the contrary CuNPs are all the better alkyne azide cycloaddition catalysts as they are better protected from aerobic oxidation inside dendrimers. This work highlights the role of the location in macromolecules on the catalytic efficiency of metal nanoparticles and rationalizes optimization in catalyst engineering.

The ability to engineer surfaces at the supramolecular level by controlled integration of specific chemical units through substrate‐independent methodologies represents one of the new paradigms of contemporary materials science. Here, a method is reported to form multifunctional supramolecular coatings through simple dip‐coating of substrates in an aqueous solution of polyamine in the presence of phosphate anions. The chemical richness and versatility of polyamines are exploited as phosphate receptors to form thin functional films on a broad variety of substrates, ranging from metal to carbonaceous surfaces. It is shown that the simple derivatization of pendant amino groups of polyallylamine precursors with different chemical groups can endow films with predefined responsiveness or multiple functions—this translates into one‐pot and one‐step preparation of substrate‐adherent films displaying built‐in functions. It is believed that the flexibility, speed, and versatility with which this method provides such robust functional films make it very attractive for preparing samples of fundamental and technological interest.