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ZnO-TiO2 composites co-doped with Er3+ and Yb3+ ions were successfully synthesized by powder-solution mixing method and their upconversion (UC) luminescence was evaluated. The effect of firing temperature, ZnO/TiO2 mixing ratio, and dopant concentration ranges on structural and UC luminescence properties was investigated. The crystal structure of the product was studied and calculated in detail by means of X-ray diffraction (XRD). Also, the site preference of Er3+ and Yb3+ ions in the host material was considered and analyzed based on XRD results and UC luminescence characteristics. Brightest UC luminescence was observed in the ZnO-TiO2:Er3+,Yb3+ phosphor fired at 1300 °C in which the system consisted of mixed phases; Zn2TiO4, TiO2, RE2Ti2O7 and RE2TiO5 (RE = Er3+ and/or Yb3+). Under the excitation of a 980 nm laser, the two emission bands were detected in the UC emission spectrum, weak green band centered at 544 and 559 nm, and strong red band centered at 657 and 675 nm wavelengths in accordance with 2H11/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+ ion, respectively. The simple chemical formula equations, for explaining the site preference of Er3+ and Yb3+ ions in host crystal matrix, were generated by considering the Zn2TiO4 crystal structure, its crystal properties, and the effect of Er3+ and Yb3+ ions to the host crystal matrix. The UC emission intensity of the products was changed by varying ZnO/TiO2 mixing ratios, and Er3+ and Yb3+ concentrations. The best suitable condition for emitting the brightest UC emission was 1ZnO:1TiO2 doped with 3 mol% Er3+, 9 mol% Yb3+ fired at 1300 °C for 1 h.

Photoresponsive behaviors of thermosensitive hydrogels containing carbon black (CB) were investigated by comparing experimental and simulation results. Poly( N -isopropylacrylamide-acrylamide) (PNIPAm) and poly( N -n-propyl-acrylamide) (PNNPAm) gels were employed as the matrix of photoresponsive hydrogels exhibiting a lower critical solution temperature (LCST) behavior without hysteresis and with hysteresis, respectively; CB-PNIPAm and CB-PNNPAm were used as photoresponsive hydrogels. The size and surface temperature behaviors of the photoresponsive hydrogels were measured under laser irradiation. The surface temperatures of irradiated both gels increased rapidly after the irradiation to a peak and then decreased exponentially. The CB-PNIPAm gel shrank and its size synchronized with the surface temperature rise and reached a constant between the shrunken and swelling states. The CB-PNNPAm gel first shrank, then re-swelled after going through a minimum value. The main different behaviors of the two gels could be explained by the hysteresis effect based on numerical simulation results. The numerical simulation results also demonstrated that photosensitive gels with hysteresis can be self-oscillator driven by stationary light sources.

We have successfully prepared thin films of PbBr-based layered perovskite having hole-transporting carbazole chromophore-linked ammonium molecules as an organic layer by a simple spin-coating from the N,N-dimethylformamide solution in which the stoichiometric amount of lead bromide and carbazole-linked ammonium bromides was dissolved. Their X-ray diffraction profiles exhibited that their layer structure formed (0 0 n)-orientation, where c-axis is perpendicular to the substrate plane. Their layer structure depended on the alkyl chain length of ammonium molecules. When methylene length of C5H10 was employed in the carbazole-linked ammonium molecules, highest orderliness of the layer structure was attained; higher-order X-ray diffraction peaks were observed in the layered perovskite films. In the layered pervskite film, in-plane conduction, namely conduction in the direction of the stacking of carbazole chromophore, was measured. For comparison, conductivity of poly(N-vinylcarbazole) (PVCBz) thin film was also measured. The conductivity of the layered perovskite thin film (1.8 × 10−10 Scm−1 at 303 K) was about three order of magnitude larger than that of the PVCBz thin film (5.3 × 10−14 Scm−1 at 303 K). Despite the much higher conductivity of the layered peroskite thin film, the activation energy of the conductivity of the layered perovskite thin film (1.44 eV) was about 2.4 times larger than that of the PVCBz thin film (0.61 eV). This phenomenon is probably due to difference in film morphology through considering the results of AFM observation.

PbBr-based layered perovskite film was successfully prepared by successive deposition of amphiphilic ammonium bromide monolayer which was formed on a subphase of saturated aqueous PbBr 2 solution. In this work, we studied the formation process of layered perovskite structure on the subphase while evaluating reflection spectra of amphiphilic ammonium monolayers and observing topographs of the monolayer using a scanning probe micrograph. The reflection spectra demonstrated that the layered perovskite structure was formed on the subphase of saturated aqueous PbBr 2 solution. From the reflection spectra and the AFM image, the reasonable formation process of the layered perovskite structure on the subphase was proposed.

New organic–inorganic nano-complexes were produced from a micelle of tri-block polymers; poly(styrene)-b-poly(2-vinylpyridine)- b-poly (ethylene oxide) (PS-PVP-PEO) and tungsten compounds such as tungstate (W 1 2− ), undecatungstophospate (PW 11 7− ) and undecatungstosilicate (SiW 11 8− ) in acidic aqueous solutions. The size and morphology of the complexes were characterized by measurements of dynamic light scattering, atomic force microscopy, and scanning electron microscopy. This complex is assembled mainly by the charge interaction between the inorganic polyanions and the positively charged PVP block in the PS-PVP-PEO molecule, which was confirmed by zeta-potential and fluorescence spectroscopic studies. In the absence of the inorganic anions, the zeta-potential of the micelle was +11 mV at pH 3 due to the positive charge of the PVP block. When the inorganic anion was mixed with the PS-PVP-PEO micelle, decrease in the zeta-potential due to charge neutralization occurred with incorporation of inorganic anions into the PS-PVP-PEO micelle. The minimum zeta-potential was 0, −33, and −35 mV for W 1 2− /PS-PVP-PEO, PW 11 7− /PS-PVP-PEO, and SiW 11 8− /PS-PVP-PEO complexes, respectively. Excess negative charge which occurred in the latter two complexes indicates that PS-PVP-PEO molecules bound PW 11 7− and SiW 11 8− by forces other than charge interaction. In addition, the incorporation of an inorganic polyanion into the micelle gave a new morphology to the micelle. In the absence of the polyanion, the PS-PVP-PEO micelles showed an extended conformation due to repulsive forces working among the positively charged PVP blocks. Addition of the polyanion caused the formation of shrunken forms of the micelles, since the charge repulsion was cancelled by the polyanion. This feature may be useful in developing a new type of functioning micelle.

The aggregation state of a mixed monolayer of cyanine dye and fatty acid during compression was investigated on the basis of surface pressure–area isotherm measurements, atomic force microscopic observations and spectroscopic measurements. The mixed monolayer was in a miscible state at all surface pressure values. The domains were formed in a matrix region by compression, which is probably due to ordering of molecular conformation. Compression at a surface pressure higher than the plateau pressure causes regularization of stacking of cyanine rings, resulting in the formation of J-aggregates.

The structure concerning the molecular aggregation in Langmuir-Blodgett (LB) films of pheophytine a (Phe- a ) has been studied by ultraviolet–visible (UV–Vis) and infrared (IR) spectroscopies and their morphology has been delineated by atomic force microscopy (AFM). UV–Vis spectra were measured for a chloroform (CHCl 3 ) solution of Phe- a , cast film from the CHCl 3 solution and six-layer LB films of Phe- a prepared in air and argon (Ar) atmospheres. A comparison of these UV–Vis spectra indicates the existence of two kinds of aggregates of Phe- a in the cast and LB films. One has a Qy band at 683 nm and another has a corresponding band at 700 nm. Soret bands of the cast and LB films also show a marked broadening. It is suggested from the UV–Vis measurements that the LB film prepared in the Ar atmosphere includes the aggregate with the 700 nm band at the highest ratio among the three kinds of films. On the other hand, the IR spectra of the solution, and cast and LB films resemble each other, suggesting that Phe- a exists in a monomer in them. Therefore, it seems that the aggregates are composed of stacked Phe- a monomers with a π – π interaction. AFM images for the LB films of Phe- a prepared in the air and Ar atmosphere reveal that they have very smooth and flat surface.

The aggregation structure of fatty acid monolayers on the water surface have been classified with respect to thermal ( T sp , T αc , T m ) and chemical (the degree of ionic dissociation of hydrophilic group) factors. In the case of amphiphiles with a non-ionic hydrophilic group, at T sp below T m , the monolayer is in a crystalline phase which is designated “the crystalline monolayer”. The crystalline monolayer is further classified into “the fusing-oriented crystalline monolayer” and “the randomly assembled crystalline monolayer” at T sp below and above T αc , respectively. At T sp above T m , the monolayer is in an amorphous phase which is designated “the amorphous monolayer”. In the case of amphiphiles with an ionic hydrophilic group, at T sp below T m , amphiphile molecules form “the compressing crystallized monolayer”, and T sp above T m , the monolayer is not crystallized by compression. Molecular-resolution images of molecules in the monolayers were successfully observed with an atomic force microscope (AFM) for the first time. A high mechanical stability of the monolayer is inevitably required for the non-destructive AFM observation of the fatty acid monolayer. For the preparation of the mechanically stable monolayer, the continuous compression method up to a low surface pressure and the multi-step creep method were used. Further, the Langmuir-Blodgett (LB) films with a homogeneous surface morphology could be constructed by the mechanically stable monolayers, and the morphological homogeneity was necessary for the construction of low-propagation loss LB film optical waveguides.

A two-dimensional ultrathin film was defined as being a film thinner than the dimension of an unperturbed Gaussian chain in the three-dimensional state. The segment density of an unperturbed chain in equilibrium in the two-dimensional solid state was investigated using a Monte-Carlo simulation. When the film thickness exceeds 30% of twice the radius of gyration of a three-dimensional unperturbed chain, the segment density is not particularly high in comparison with the three-dimensional state. This means that a polymer chain will behave as a two-dimensional unperturbed chain in the equilibrium state of a two-dimensional ultrathin film, as in a three-dimensional solid state. Therefore, the excess expansion of a polymer chain in a two-dimensional ultrathin polystyrene film with a thickness comparable to twice the radius of gyration of a three-dimensional unperturbed chain might arise from non-equilibrium characteristics. In addition, the relaxation behaviour of a two-dimensional ultrathin film of a styrenebutadienestyrene (SBS) triblock copolymer was investigated by transmission electron microscopy. The two-dimensional ultrathin SBS film contracted and decomposed into two phases (polystyrene and polybutadiene) from the one phase right after the film preparation. This indicates that the two-dimensional ultrathin film was in a distinct non-equilibrium state right after spreading a solution on the water surface.

In this study, self-pulsating microparticles have been successfully prepared using a pH-sensitive and permselective membrane system.

A too-dimensional ultrathin film was defined as a film with a dimension thinner than that of an unperturbed chain. The aggregation structure of the too-dimensional ultrathin polystyrene (PS) film prepared by the water casting method was examined. The radius of gyration of a PS chain in the two-dimensional ultrathin film was evaluated from SAXS and SANS measurements. The radius of gyration along the direction parallel to the fim surface was found to be larger than the radius of gyration of an unperturbed chain. The apparent occupied volume for a corresponding chain, which consists of overlapping of a noticed chain and surrounding chains, was calculated from the radius of gyration and film thickness

The preparation condition of polystyrene (PS) ultra thin film by a water casting method was investigated on the basis of transmission electron microscopic (TEM) observations. Homogeneous ultra thin films were prepared from a 0.2–2.0 wt% cyclohexanone solution of PS owing to moderate spreadability of the solution on the water surface. The spreading state of the solution on the water surface depending on the dissipation speed of solvent and entanglements among PS chains were in strong relation to formation of the homogeneous ultra thin film. X-Ray interference measurements revealed that the thickness of the ultra thin film was smaller than the dimension of an unperturbed PS chain. Such thinner film than the dimension of the unperturbed chain was defined as 2-dimensional ultra thin film in order to distinguish from 3-dimensional solid film. The radius of gyration of a polymer chain in the 2-dimensional ultra thin film was evaluated from small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS) measurements. PS chains in the 2-dimensional ultra thin film expanded along the direction parallel to the film surface.

Poly(vinyl alcohol) films (PVA) were soaked at 20°C in aqueous I-KI solutions with different iodine concentrations. Iodine sorption obeyed a Freundlich isotherm over a range of iodine concentration from 5×10−3 to 6×10−1 mol l−1. Changes in the PVA crystal lattice with iodine sorption showed that iodine molecules intrude into crystalline, as well as amorphous regrons to form a new “substitution type” crystal lattice. In this lattice, one PVA chain of a hydrogen-bonded pair in the original PVA cell is replaced by a polyiodine chain. The iodination increased the drawability of PVA films. It is not certain, however, whether the enhanced drawability is due to the plasticized amorphous phase alone, as is suggested by depression of the glass transition temperature, or also to the iodinated crystals.

The addition of halide salts into the subphase has caused formation of the layered perovskite structure in a Langmuir monolayer on the subphase containing lead bromide at a concentration three orders of magnitude lower than that in the conventional methods.

Electron diffraction studies of a [(dioctadecyl)carbamoylmethyl]guanidinium toluene-p-sulfonate (DG) monolayer reveal that the regularity of the molecular arrangement and the size of crystalline domains are controlled through binding of aqueous α,ω-dicarboxylates with various spacer lengths.

A monolayer of 2-amino-4,6-di(dodecylamino)-1,3,5-triazine 1 transferred from barbituric acid solution onto a mica plate is observed by atomic force microscopy (AFM) to show regularly arrayed terminal methyl groups of 1 as a result of hydrogen-bond networking.

The structure of a poly(vinyl alcohol) (PVA)-iodine complex was investigated by a resonance Raman spectroscopy, wide angle X-ray diffraction, small angle X-ray scattering, NMR and IR spectroscopies. The Raman spectra of swollen PVA films exhibited fundamental scattering at 164, 108, and 42 cm−1 with Ar+ ion and dye lasers as the excitation sources. The results of Raman spectra showed that only the I5− is formed in the complex, irrespective of the difference in the visible absorption spectra. The relative intensity of the peak at 65 ppm decreased with increasing amount of complex in the 13C NMR spectra. The absorbance of the infrared spectrum in the region of 2900–3300 cm−1 decreased with increased iodine concentration of the soaking solution, while the absorbance in the region of 3300–3700 cm−1 increased. These results show that some changes in the state of hydrogen bondings are induced by complexation. The weight of the PVA film increased rapidly by iodine sorption at the first stage and then decreased. The changes of the long period and volume took place rapidly, being followed by much slower increase in Young’s modulus. The ratio of the decrease in volume was much larger than that of the long period. It was assumed that the fast contraction in iodine-soaking was mainly due to the release of water out of membranes induced by iodine-sorption but not due to the complexation.

Extension induced iodine-poly(vinyl alcohol) (PVA) complexation was studied for PVA films with different degrees of hydration in very dilute iodine aqueous solutions. The complexation was reversibly induced by extension and its recovery. The strain energy required for the complexation was estimated to understand complexation enhancement by extension. The strain energy increased with the increase of temperature, and with the decrease of the iodine concentration, while it was almost independent of the degree of hydration. This extension induced complexation is considered to be due to the decrease in the entropy of PVA chains by extension.

PVA films with a wide span of hydration (swelling) were soaked at different temperatures in iodine aqueous solutions to make the iodine–PVA complex, with a particular concern for the effects of the degree of hydration (D.H.) on the complex formation. The visible absorption maximum λmax increased with D.H., while it decreased with temperature. The equilibrium amount of the complex increased with D.H. at a given concentration of iodine below 20-°C. However, the effects of D. H. on the amount of complex deteriorated with increasing temperature and at 45-°C became reversed to those at low temperature. When the samples soaked at 5-°C were heated in the solution, the amount of complex suddenly began to decrease at 20-°C; this corresponded to the sudden stress relaxation of water swollen PVA films. This transition seems to have great effect on the complexation.

Higher Order Structure and Thermo-Responsive Properties of Polymeric Gel with Crystalline Side Chains