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We demonstrate the formation of highly ordered hexagonal arrays of hybridized polystyrene-poly(4-vinyl pyridine), PS-PVP, micelles with controllable size by solvent annealing techniques. Because the formation of hybridized micelles was prohibited in the mixture solutions of two different-sized PS-PVP micelles, single-layered films with bimodal self-assemblies of small and large micelles were fabricated from the mixture solutions by adjusting their mixing ratios. When the single-layered films were solvent annealed by saturated vapor of tetrahydrofuran (THF), on the other hand, small and large PS-PVP micelles in the bimodal self-assemblies merged together to form hybridized micelles. In addition, the hybridized micelles arranged themselves in a highly ordered hexagonal array, the diameter and center-to-center distance of which were precisely adjusted by varying the mixing ratio of small to large micelles in the bimodal assemblies.

We employed thin film blends of diblock copolymers with functional homopolymers as a simple strategy to incorporate organic functional materials into nanodomains of diblock copolymers without serious synthesis. A blend pair of polystyrene–poly(methyl methacrylate) (PS–PMMA) diblock copolymers and poly(vinylidene fluoride) (PVDF) was selected as a model demonstration because PVDF is a well-known ferroelectric polymer and completely miscible with amorphous PMMA. Thin films of symmetric PS–PMMA copolymers provided the nanometer-sized PMMA lamellae, macroscopically parallel to the substrate, in which PVDF chains were dissolved. Thus, amorphous PVDF chains were effectively confined in the PMMA lamellae of thin film blends. The location of PVDF chains in the PMMA lamellae was investigated by the dependence of the lamellar period on the volume fraction of PVDF, from which we found that PVDF chains were localized in the middle of the PMMA lamellae. After the crystallization of PVDF, however, some of PVDF migrated to the surface of the film and formed small crystallites.

The phase behavior of polystyrene-block-poly(n-pentyl methacrylate) copolymers [PS−PnPMA] having various block length ratios was investigated by rheology, transmission electron microscopy (TEM), and small-angle X-ray scattering (SAXS). All of the PS−PnPMA exhibited two transitions: the lower disorder-to-order transition (LDOT) and upper order-to-disorder transition (UODT) occurring at a lower and higher temperature, respectively. Thus, PS−PnPMA is characterized by a closed-loop type of phase behavior. As the volume fraction of PS in PS−PnPMA was decreased from 0.5 to 0.23, the microdomains observed between the LDOT and UODT changed from lamellae (LAM) to hexagonally packed cylinders (HEX) and finally to body-centered-cubic spheres (BCC), similar to other block copolymers exhibiting only an order-to-disorder transition. The rheological properties depended strongly on the type of microdomains within the closed-loop. The storage and loss moduli (G‘ and G‘ ‘) within the closed loop are the highest for a PS−P...

We investigated variations of the domain period of block copolymers by selective staining agents that are used for contrast enhancement in transmission electron microscopy. Employing thin films of symmetric diblock copolymers, homogeneous but selective staining was obtained throughout the film. Moreover, the thin film had a multilayered structure of parallel lamellae with the total film thickness quantized in terms of the lamellar period so that increments of the lamellar period by staining were conveniently and quantitatively evaluated as a function of staining time. In the case of a chemisorbed staining agent of osmium tetroxide for polybutadiene, the lamellar period in thin films of polystyrene-block-polybutadiene was gradually increased with staining time and had 22% increase at the saturation. Similar results were also obtained in the case of thin films of polystyrene-block-poly(methyl methacrylate) by ruthenium tetroxide and polystyrene-block-polyvinyl-pyridine by iodine.

We obtained perpendicular lamellar orientations in thin films of symmetric polystyrene- block -poly(methyl methacrylate), PS- b -PMMA, on self-assembled monolayers (SAMs) of 3-( p -methoxyphenyl)propyltrichlorosilane (MPTS) prepared on silicon wafers. In contrast to completely parallel lamellae on silicon wafers having a native oxide layer, perpendicular lamellae at the MPTS interface with parallel lamellae at the air interface were directly observed by transmission electron microscopy (TEM) in cross-sectional view. The perpendicular lamellae at the MPTS interface were attributed to the non-preferential (neutral) MPTS-covered substrate to both PS and PMMA blocks. The neutrality of the SAMs of MPTS was confirmed by the similar interfacial tension values of the SAMs of MPTS with PS and PMMA, estimated by contact angle measurements.

TlGaS2 single crystal were grown by using the Bridgman method. The deep levels of TlGaS2 single crystal were investigated by the TSC (thermally stimulated current) and PlCTS (photoinduced current transient spectroscopy) techniques. The activation energies of the four peaks observed from the TSC curve are (a) 0.18, (b) 0.23, (c) 0.36, and (d) 0.66 eV. Peaks a and b are located below the conduction band and peaks c and d are located above the valence band. The escape frequencies are calculated to be 2.9 × 106, 1.8 × 107, 3.4 × 107, and 5.6 × 1010 s−1, respectively. The PICTS spectra of TlGaS2 single crystal show four deep traps whose activation energies are calculated to be 0.17, 0.23, 0.35, and 0.65 eV, respectively.

Hexagonal arrangement of iron oxide nanoparticles was fabricated by utilizing a single-layered film of diblock copolymer micelles. The synthesis was directly performed on the solid substrate by oxygen plasma with preserving the dimensional order of micelles so that separate procedures for synthesis and deposition of nanoparticles were not necessary. Since the oxygen plasma treatment also eliminated polymers, pure patterns of iron oxide nanoparticles were obtained. Moreover, easy control over the size of nanoparticles enabled us to selectively create a ferrimagnetic or a superparamagnetic pattern of iron oxide nanoparticles without altering the fabrication process.

We demonstrated a self-assembly of two different kinds of nanoparticles simultaneously directed on a monolayer film of diblock copolymer micelles via physical and chemical arrangements. We first incorporated gold nanoparticles physically around the micelles of a monolayer film of PS-PVP micelles having a short-range hexagonal order. Iron oxide nanoparticles were then synthesized chemically in the PVP core area of the ordered micelles, resulting in a mosaic nanopattern of magnetic iron oxide nanoparticles surrounded by metallic gold nanoparticles. Thus, we were able to direct two kinds of nanoparticles to self-assemble in the specific positions as an example of controlled fabrication of nanometer-sized building blocks.

To identify the manganese related defect levels in GaSe, GaSe:Mn single crystals were grown with various Mn dopant levels using the Bridgman technique and the photoconductivity and photoluminescence properties were investigated. Peaks introduced by the manganese related defects were observed at 1.916 and 1.724 eV in the photoconductivity spectra and at 1.804 eV in the photoluminescence spectra at 80 K. These results allow the calculation of the energies of the A 1 and A 2 centers at 0.348 and 0.156 eV, respectively, above the valence band and a donor level at 0.112 eV below the conduction band. Also, we find that the A 1 and A 2 centers are pinned within the conduction band from measurements of the temperature dependence of the photoconductivity spectra.

Anomalous optical energy gap dependence of the noble Pb 1− x Cd x I 2 single crystal on the CdI 2 mol% has been investigated. The Bridgman method was utilized to grow sample crystals out of polycrystalline PbI 2 powder mixed with CdI 2 powder of various mol% in a vertical furnace. Analysis of the X-ray diffraction patterns shows that the Pb 1− x Cd x I 2 single crystal has the hexagonal close-packed layered structure. The optical energy gap of the Pb 1− x Cd x I 2 single crystal has its minimum value at 0.18 mol% and increases linearly for CdI 2 composition ratios higher than 1 mol%.