In this critical review we compare two geometries in partial wetting: a liquid drop on a planar substrate and a spherical particle at a planar liquid interface. We show that this comparison is far from being trivial even if the same physical interactions are at play in both geometries. Similarities and differences in terms of free energies and frictions will be discussed. Contact angle hysteresis, the impact of surface roughness and line pinning on wetting will be described and compared to selected experimental findings.

Vegetable oil based hybrid films were developed thanks to a novel solvent- and heating- free method at the air-water interface using silylated castor oil cross-linked via a sol-gel reaction. To understand the mechanism of the hybrid film formation, the reaction kinetics was studied in detail by using complementary techniques: rheology, thermogravimetric analysis, and infrared spectroscopy. The mechanical properties of the final films were investigated by nano-indentation, whereas their structure was studied using a combination of wide-angle X-ray scattering, electron diffraction, and atomic force microscopy. We found that solid and transparent films form in 24 hours and, by changing the silica precursor to castor oil ratio, their mechanical properties are tunable in the MPa-range by about a factor of twenty. In addition to that, a possible optimization of the cross-linking reaction with different catalysts was explored and finally, cytotoxicity tests were performed on fibroblasts proving the absence of film toxicity. The results of this work pave the way to a straightforward synthesis of castor-oil films with tunable mechanical properties: hybrid films cross-linked at the air-water interface combine an easy and cheap spreading protocol with the features of their thermal history optimized for possible future micro/nano drug loading, thus representing excellent candidates for the replacement of non-environment friendly petroleum-based materials.

The influence of surface-modification of TiO2-nanoparticles with phosphonic acid molecules on the structure of polymer nanocomposites has been studied by small-angle scattering and transmission electron microscopy. The grafting of phosphonic acids was done by phase transfer into chloroform, and polymer nanocomposites have been formulated by solvent casting with two polymers of slightly different hydrophobicity, PMMA and PEMA. By analyzing the shape of the scattering curves around the interparticle correlation peak, and in particular the depth of the correlation hole, information on nearest neighbor correlations between nanoparticles is obtained. While local nanoparticle arrangements are found to be independent of the global particle volume fraction, they are controlled by the degree of hydrophobicity of the alkyl phosphonic acid grafts with respect to hydrophobicity of matrix. Quantitative analysis of the correlation hole thus evidences the fine-tuning of local nanocomposite structure with phosphonic acids.

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Block copolymer assemblies are fascinating objects that have been studied for years. In this work, the PS-PNaSS-PS ABA triblock copolymer was synthesized by RAFT polymerization and self-assembled in a selective medium (THF/water). Various morphologies of aggregates were identified (spheres, cylinders, and vesicles) but we focused on large compound vesicles which gave birth to porous materials after solvent evaporation. The change in solvent composition upon drying was modeled and correlated to the change in morphology observed using microscopy techniques such as AFM, TEM and cryo-TEM. The large compound vesicles were found to partially fuse to form a bulk material before the vesicular compartments were opened to yield pores of about 30 nm.

We study the swelling and shrinking behavior of core-shell microgels adsorbed on silicon wafers. In these systems, the core is made of cross-linked poly(N isopropylmethacrylamide) and the shell consists of cross linked poly(N-n propylacrylamide). In suspension, these particles exhibit an extended linear swelling behavior in the temperature interval between the lower critical solution temperatures of the two polymers. Using ellipsometry and AFM, we show that this linear response is also observed in the adsorbed state.

The microstructure of polymer nanocomposites made with disordered silica filler (Zeosil(R) 1165MP) of industrial relevance and various coating agents is quantitatively analyzed using a combination of SAXS, TEM, and a recently developed structural model. The polymer matrix is formed by an end-functionalized styrene-butadiene statistical copolymer capable of covalent grafting on the silica nanoparticles. The effect of the coating agents with different alkyl chain length (C8, C12, and C18) on filler structure quantified in terms of aggregate formation, for different concentrations (up to 8%wt with respect to silica), and the effect of a commonly added catalyzer, DPG, are studied using the structural model. As a result we show that a strongly synergetic effect of both DPG and coating agent exist. Our findings open the road to a fundamental understanding and rational design of model and industrial nanocomposite formulation with optimized coating agents.