Metallogels form from Cu(II) ions and tetratopic ligand rctt-1,2-bis(3-pyridyl)-3,4-bis(4-pyridyl)cyclobutane. The tetrapyridyl cyclobutane has been synthesized in the organic solid state. The gel forms with a variety of counteranions and gels water. The hydrogel is thixotropic and is composed of nanoscale metal-organic particles (NMOPs), a high surface area of which likely accounts for the gelation of the polar aqueous medium. A shear stress profile of the thixotropic hydrogel gave a yield value of 8.33 Pa. A novel combination of atomic force microscopy (AFM) and scanning transmission X-ray microscopy (STXM) is used to assess the densities of individual NMOPs. A density of 1.37 g/cm(3) has been determined. A single-crystal X-ray diffraction study demonstrates the ability of the unsymmetrical cyclobutane 3,4'-tpcb to self-assemble with Cu(II) ions in [Cu(2)(hfac)(4)(3,4'-tpcb)](∞) (where hfac is hexafluoroacetylacetonate) to form a solvated 1D coordination polymer.

Most film coatings in the pharmaceutical industry are prepared using organic solvents or aqueous solvents. Due to different film-formation mechanisms, their properties are significantly different from each other. Curing can alter the microstructure of films by improving the coalescence of polymer particles for aqueous dispersion-based films or accelerating macromolecule relaxation for organic solvent-based films. The aim of this study was to investigate the effects of preparation methods and curing on the physicochemical properties of Kollicoat® SR30D and Kollicoat® MAE100P films. The film's properties, including water diffusion coefficient, mechanical properties, plasticizer loss, swelling behavior, and contact angle, were measured for uncured or cured aqueous dispersion-based or organic solvent-based films. The results indicated that curing decreased water diffusivities in films and increased film's tensile strength. Curing resulted in plasticizer loss from SR30D films but not from MAE100P films due to strong interaction between plasticizer and MAE100P. The surface of organic solvent-based films was more hydrophobic than that of aqueous dispersion-based films. The contact angle of organic solvent-based films was increased after curing possibly because curing decreased roughness of the film surface. Organic solvent-based SR30D films had better mechanical properties than the corresponding aqueous dispersion-based films because of higher degree of polymer-polymer entanglement in the organic solvent-based films. However, contradictory phenomena were observed in MAE100P films possibly due to a "core-shell" structure reserved in the aqueous dispersion-based MAE100P films. In summary, casting methods and curing have significant impact on the film properties due to different film structures, coalescence, or film relaxation, and other concurrent effects including evaporation of residue solvent and plasticizers.

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