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A structural investigation of composite films of self-assembling stearate ions (C18) in layered double hydrotalcite clay (LDH) was carried out by means of X-ray diffraction (XRD) analysis, gas chromatography (GC), elemental analysis, thermogravimetry (TG), differential thermal analysis (DTA), and inductive coupled plasma emission spectrometric analysis (ICP-AES). From these detailed characterization studies, it was found that C18 forms a well-aligned bilayer structure within the inorganic LDH layers absorbed by the H2O monolayers with a tilt angle of approximately 29° from the right angle of the layers. Moreover, two-dimensional XRD analysis shows the guest anions to be arranged in a distorted hexagonal packing orientation along the lateral axis.

The self-assembly of sodium stearate and its homologs ( >C12) in hydrotalcite (LDH) interlayers was found to change reversibly between mono- and bilayer structures with a ratio changing continuously within a range of 70 °C and 5 °C in stoichiometric intercalations in aqueous dispersion. The bilayer structure was more stable than the monolayer, judging from the fact that bilayer aggregations were formed even in high temperatures with the addition of excess amounts of guest stearates over the anion exchange capacity (AEC). Hydrophobic interaction was determined to be the key factor for the formation of a bilayer assembly.

The present study is an investigation of a reversible thermal color change induced in lamella hybrids of poly(diacetylenecarboxylates) incorporated in layered double hydroxide (LDH) nanosheets. These poly-[m,n]/LDH hybrids prepared by the photo- or gamma-ray-induced polymerization of diacetylenecarboxylates, i.e., CH(3)(CH(2))(m)()(-)(1)CC-CC(CH(2))(n)()(-)(1)CO(2)(-) (mono-[m,n]), and intercalated in LDH lamella sheets, were observed to develop colors ranging from yellow to blue. The change in color was found to depend greatly on the alkyl carbon numbers of the mono-[m,n] (m,n = 10,11; 5,11; 10,5; 16,1) values. Moreover, the conformational alignment of the mono-[m,n] within the LDH was observed to be a crucial factor in color development, which was greatly affected by the intercalation degrees and extent of poly(ene-yne) linkage elongation of the polymers. For the poly-[m,n]/LDH hybrids investigated, a reversible color change was found to occur repeatedly and remarkably for the poly-[10,11]/LDH hybrid. This color change occurred at temperatures between ca. 20 and 80 degrees C back and forth from purple red to bright orange, in stark contrast to the irreversible color change for poly-[10,11] without LDH. Moreover, DSC and Raman spectroscopic studies of the LDH hybrids showed that the thermochromic temperature corresponded to the phase transition temperature of 80 degrees C. XRD analysis also indicated that the poly-[m,n]/LDH hybrid could retain its lamella structure during such thermochromic color changes, enabling conformational recovery in the polymer chains by a cooling down of the hybrids to temperatures lower than the transition temperature, while the nonhybrid poly-[10,11] powders exhibited an irreversible color change at 60 degrees C, above which the polymer powder turned amorphous.

NaNbO(3) thin films prepared by the sol-gel method had homogeneous microstructure with an average grain size of 15-25 nm and exhibited photoinduced hydrophilic conversion under UV irradiation. However, the films had little photocatalytic oxidation activity under UV irradiation. This is the first observation that NaNbO(3) undergoes photoinduced hydrophilicity under UV irradiation.

The dispersion of clay−diarylethene hybrid materials into an ionic biopolymer, gelatin, was investigated for the successful preparation of highly functional photochromic films. A mixture of the gelatin and the clay−diarylethene hybrid material dispersed in aqueous N,N-dimethylformamide (DMF) was cast on a glass plate. The film obtained after drying at 50 °C was transparent in the visible light region and showed highly reversible coloration and decoloration by alternative irradiation with UV light of around 300 nm and visible light of around 600 nm. X-ray diffraction analysis indicated that the diarylethene molecules were able to remain in the clay interlayers without spilling into the bulk gelatin matrix. Moreover, UV−visible polarized spectroscopic analysis revealed the clay−diarylethene hybrid materials to be oriented essentially parallel to the glass plate, indicating that the diarylethene molecules are aligned as inclined interdigitated monolayers within the clay interlayers.

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