Satoshi Koizumi

Bio: Satoshi Koizumi is an academic researcher from Japan Atomic Energy Agency. The author has contributed to research in topics: Small-angle neutron scattering & Neutron scattering. The author has an hindex of 30, co-authored 139 publications receiving 3045 citations. Previous affiliations of Satoshi Koizumi include Ibaraki University & University of Tsukuba.

An imaging plate neutron detector

Abstract: We have developed two kinds of imaging plate neutron detectors (IP-ND), where the neutron converters, 6 Li (tentatively, Nat Li was used) and Gd were mixed with photostimulated luminescence (PSL) materials on a flexible plastic support, and the dynamic range and spatial resolution of our IP-ND were successfully obtained as 1:10 5 and less than 0.2 mm, respectively, which are comparable to the ones of X-ray. The distinctive features of the IP-ND, where the IP-NDs of different neutron detection efficiency and converters were positively used, were found and discussed. The application of the IP-ND for neutron radiography was demonstrated.

Ordered structure in blends of block copolymers. 1. Miscibility criterion for lamellar block copolymers

Abstract: Morphology of binary mixtures of poly(styrene-block-isoprene) (SI) having different compositions (ps of the polystyrene block in SI and total molecular weights was investigated on the solution-cast film with toluene as a neutrally good solvent. In the range of the composition f PS =0.35-0.69 covered, the two SI copolymers were found to be totally miscible on the molecular level at all compositions, forming a single microdomain morphology, if their molecular weight ratio is smaller than about 5. They were found to be only partially miscible, if their molecular weight ratio is greater than about 10, forming macroscopically phase-separated coexisting labellar microdomains with different domain spacings

Ordered Structures of Block Copolymer/Homopolymer Mixtures. 5. Interplay of Macro- and Microphase Transitions

Abstract: Self-assembly in the solution-cast films of binary mixtures of poly(styrene-block-isoprene) (SI) and homopolystyrene (HS) in the dry brush regime was studied by means of transmission electron microscopy (TEM) and light scattering (LS). This self-assembly involves the interplay of the macrophase and microphase transitions. In the case of a low volume fraction of SI, the macrophase separation between SI and HS first takes place via spinodal decomposition (SD) during the solvent evaporation process. This process is subsequently followed by the microphase transition, forming microdomains inside the macrodomains rich in SI. The process is eventually frozen by vitrification

Thermosensitive Diblock Copolymer of Poly(N-isopropylacrylamide) and Poly(ethylene glycol) in Water: Polymer Preparation and Solution Behavior

Abstract: This investigation focused on the self-assembly of poly(N-isopropylacrylamide)-block-poly(ethylene glycol) (PNIPA-block-PEG) in water. A quasi-living radical polymerization technique including a Ce(IV) ion redox system enabled us to prepare block copolymers with relatively narrow molecular weight distributions. We distinguish five regions in the phase diagram: a transparent sol, opaque sol, transparent gel, opaque gel, and syneresis. By examining the extent of changes in the spectroscopic properties of a fluorescence probe, pyrene, as a function of block polymer concentration and/or temperature, we determined the critical association concentration as well as the partition coefficient Kv for pyrene. The spectroscopic properties indicate that the hydrophobicity around the probe starts to increase far below the demixing line of the PNIPA-block-PEG, a remarkable finding which suggests that even in the temperature region below the LCST temperature of a PNIPA block (∼32 °C), this block copolymer provides more ...

New Insight into Hierarchical Structures of Carbon Black Dispersed in Polymer Matrices: A Combined Small-Angle Scattering Study

Abstract: Using a combined ultra-small-angle and small-angle scattering (CSAS) method of neutrons and X-rays, we investigated hierarchical structures of carbon black (CB) highly loaded in polyisoprene (PI) and poly(styrene-random-butadiene) copolymer (SBR) under mechanical field (defined respectively as CB/PI and CB/SBR) as well as in toluene under a sonic field (defined as CB/toluene). In order to analyze each structure level comprising the hierarchical structures of CB from the CSAS profiles, we employed the unified Guinier/power-law approach proposed by Beaucage (J. Appl. Cryst. 1995, 28, 717). Furthermore, in order to extract not only sizes but also shapes of the structure elements, we developed a modified approach, in which the Guinier scattering function utilized in the Beaucage approach was replaced by a form factor of the corresponding structure. Comparison of the scattering profiles from CB/PI and CB/SBR with CB/toluene clarified that (i) the smallest structure elements of CB (that further form mass-fracta...

Progress, Challenges, and Opportunities in Two-Dimensional Materials Beyond Graphene

Abstract: Graphene’s success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in...

2D materials: to graphene and beyond

Abstract: This review is an attempt to illustrate the different alternatives in the field of 2D materials. Graphene seems to be just the tip of the iceberg and we show how the discovery of alternative 2D materials is starting to show the rest of this iceberg. The review comprises the current state-of-the-art of the vast literature in concepts and methods already known for isolation and characterization of graphene, and rationalizes the quite disperse literature in other 2D materials such as metal oxides, hydroxides and chalcogenides, and metal–organic frameworks.

Density multiplication and improved lithography by directed block copolymer assembly

Abstract: Methods to pattern substrates with dense periodic nanostructures that combine top-down lithographic tools and self-assembling block copolymer materials are provided. According to various embodiments, the methods involve chemically patterning a substrate, depositing a block copolymer film on the chemically patterned imaging layer, and allowing the block copolymer to self-assemble in the presence of the chemically patterned substrate, thereby producing a pattern in the block copolymer film that is improved over the substrate pattern in terms feature size, shape, and uniformity, as well as regular spacing between arrays of features and between the features within each array compared to the substrate pattern. In certain embodiments, the density and total number of pattern features in the block copolymer film is also increased. High density and quality nanoimprint templates and other nanopatterned structures are also provided.

Characterization techniques for nanoparticles: comparison and complementarity upon studying nanoparticle properties

Abstract: Nanostructures have attracted huge interest as a rapidly growing class of materials for many applications. Several techniques have been used to characterize the size, crystal structure, elemental composition and a variety of other physical properties of nanoparticles. In several cases, there are physical properties that can be evaluated by more than one technique. Different strengths and limitations of each technique complicate the choice of the most suitable method, while often a combinatorial characterization approach is needed. In addition, given that the significance of nanoparticles in basic research and applications is constantly increasing, it is necessary that researchers from separate fields overcome the challenges in the reproducible and reliable characterization of nanomaterials, after their synthesis and further process (e.g. annealing) stages. The principal objective of this review is to summarize the present knowledge on the use, advances, advantages and weaknesses of a large number of experimental techniques that are available for the characterization of nanoparticles. Different characterization techniques are classified according to the concept/group of the technique used, the information they can provide, or the materials that they are destined for. We describe the main characteristics of the techniques and their operation principles and we give various examples of their use, presenting them in a comparative mode, when possible, in relation to the property studied in each case.