Search

We analyzed edible potato starch and observed the interaction between its granular structure and water molecules. We studied the changes caused by gelatinization during heating and stirring using microscopy, micro‐FT‐IR spectroscopy, and X‐ray scattering techniques. A wide range of spatial scales was revealed using these various techniques. The rate of gelatinization varied significantly and was dependent on the starch concentration. The process of adsorption of water on starch molecules was studied using the humidity‐controlled FT‐IR spectroscopy technique. Furthermore, by comparing the X‐ray scattering profiles of dry and wet granules, the 9‐nm repeat “cluster” structure was studied. A gradual collapse of the granules occurred during the processes of heating and stirring. A clustered smectic structure and a smectic‐like structure were observed in the opaque gel after gelatinization. Upon further heating, a transparent gel was obtained after the melting of the cluster., We analyzed edible potato starch and observed the interaction between its granular structure and water molecules. A wide range of spatial scales was revealed using various techniques such as X‐ray scattering and FT‐IR measurements. We could succeed gelatinization and gelation process with a wide spatial scale.

Hairy particles consisting of polyisoprene-b-polystyrene (PI-b-PS) were synthesized by polymerization-induced self-assembly (PISA) based on a living anionic polymerization method. The molecular agg...

A strategy to obtain chiral silica using an achiral stereoregular polymer with polyhedral oligomeric silsesquioxane (POSS) side chains is described herein. The preferred helical conformation of the POSS-containing polymer could be achieved by mixing isotactic polymethacrylate-functionalized POSS (it-PMAPOSS) and a chiral dopant. The array structure of POSS molecules, which are placed along the helical conformation, is memorized even after removing the chiral dopant at high temperatures, leading to a chiral silica compound with exclusive optical activity after calcination.

High-density syndiotactic poly(methyl methacrylate) (st-PMMA) brushes form a helical structure and encapsulate fullerene molecules in their helical cavities, leading to a PMMA brush/fullerene inclusion complex. The brushes recognize the size of guest molecules and spontaneously adapt their helical diameter to the guest molecules. Both polymer brush/C60 and polymer brush/C70 inclusion complex on the flat substrate were characterized on the basis of grazing incidence wide-angle X-ray diffraction (GIWAXD) measurements, and it is revealed that the main chains oriented perpendicular to the substrate. Moreover, high-density st-PMMA brushes grafted onto nanoparticles efficiently separate C70 molecules from the mixture of C60 and C70 solution. Even after 5× repeating process, the selectivity for C70 molecules remains at 99%.

PCPDTBT, a copolymer of cyclopentadithiophene and benzothiadiazole, is a locally ordered low-bandgap donor–acceptor conjugated polymer that has been used as a hole-transport material for polymer blend solar cells. In this study, the short-range order structure of PCPDTBT in spin-coated PCPDTBT/conjugated polymer blend films has been characterized to elucidate aggregation behaviors that arise when a locally ordered conjugated polymer is blended with other polymers. UV–vis absorption spectroscopy and grazing-incidence wide-angle X-ray scattering measurements revealed that short-range ordering of PCPDTBT is promoted when it is diluted in an amorphous conjugated polymer matrix, poly­(3-methyl-4-hexylthiophene-2,5-diyl) (P3M4HT). In a PCPDTBT/P3M4HT blend film with 10 wt % PCPDTBT, the fraction of PCPDTBT chains that form aggregates increases from 51% (in neat film) to 78%, and the correlation length of the ordered PCPDTBT chains extends from 4.6 nm (in neat film) to 7.7 nm in the chain backbone direction. The polymer matrix-assisted ordering can be explained in terms of suppression of both undesired overlap and interpenetration of PCPDTBT chains; both processes can derange the self-aggregated single-chain order of PCPDTBT. This short-range ordering enhancement would be significant for the design of efficient charge carrier transport in thin-film devices such as polymer/polymer blend solar cells that use low-bandgap donor–acceptor conjugated polymers with various blend ratios as hole- and electron-transport materials.

In order to investigate the effects of bulky substituents on the crystal structures and packing modes, N-benzyl (Bn) and N-2-phenylethyl (EtPh) substituents are introduced in bisthienoisatin (BTI),...

Upon extending a hydrophobic polymer chain from the end of a preceding hydrophilic chain in aqueous solutions, the resultant block copolymers may eventually undergo self-assembly. Further chain propagation continues in the newly formed hydrophobic polymer rich domain. This process is often referred to as polymerization-induced self-assembly (PISA). Its kinetics are determined by the polymerization and the micelle formation/growth, which may influence each other, possibly leading to a highly complex process of structural development. In this study, we examined PISA in aqueous solution on the reversible addition fragmentation chain transfer (RAFT) dispersion polymerization of poly(N-acryloylmorpholine)-b-poly(N-acryloylthiomorpholine). Using in situ small-angle X-ray scattering (SAXS) and nuclear magnetic resonance spectroscopy (NMR), the polymerization and micelle formation were observed. In the analysis, because the time scale of the micelle formation/growth is much shorter than that of the polymerization, the polymerization and micelle fomarion/growth can be decoupled. Thus, these were separately analyzed in depth, and a combination of the kinetics of RAFT polymerization and the simple scaling theory of the micellar structures can quantitatively describe the overall micellar structural development during PISA. This study provides an unprecedented insight into the processes underlying PISA and deepens our quantitative understanding of it.

We have successfully performed X-ray diffraction measurements of the liquids octamethylcyclotetrasiloxane (OMCTS, a quasi-spherical-shaped molecule) and

Studies on the effectiveness of substances such as drugs and cosmetics that act on the skin require structural evidence at the molecular level in the stratum corneum to clarify their interaction with intercellular lipid and soft keratin. For this purpose, when applying the substances to the stratum corneum X-ray diffraction experiment is one of the powerful tools. To detect minute structural changes in a stratum corneum sample, using a "solution cell", dynamic synchrotron X-ray diffraction measurements were performed when applying aqueous solution of the substances to the stratum corneum: (1) It was found that a surfactant, sodium dodecyl sulfate, significantly disrupted the long-period lamellar structure. (2) To study the effects of water, structural modifications of the short-period lamellar structure and the soft keratin in corneocytes were measured as a function of time. At the initial water content of 15 wt%, the spacings of the short-period lamellar structure and the soft keratin increased toward those at the water content of 25 wt%, that is a key water content in the stratum corneum. (3) Nanoparticles composed of assembly of amphiphilic molecules are one of the leading pharmaceutical formulations. When the nanoparticles were applied, a new assembly of amphiphilic molecules originated from the nanoparticle appeared. This phenomenon suggests that the formation of the new assembly at the surface of skin is concerned with the release of the drug from the nanoparticles. (4) When ethanol was applied to the stratum corneum, only the liquid state in the intercellular lipid matrix was dissolved. After the removal of ethanol from this stratum corneum, the ordered hydrocarbon-chain packing structures appeared. From this fact we would propose that the liquid state region is the main pathway for hydrophobic drugs with a small molecular weight in connection with the so-called 500 Da rule. Here, not only the technique but also the background to these studies and the characteristic results obtained from these studies are explained.