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Zwitterionic polymer-based dual thermoresponsive micelles were synthesized. Structural investigations revealed that they exhibit both liquid–liquid phase separation and coil–globule transition and the size scale of each transition is different.

Reverse osmosis (RO) membranes are becoming popular as energy saving and environmentally friendly materials for the desalination of water. Toward the rational design of RO membranes, we performed contrast-variation neutron scattering measurements and atomistic molecular dynamics (MD) simulations on polyamide/water systems with various water contents and deuteration ratios. The experimental and computational structure factors showed good agreement for all the systems examined. The structure of the water-rich polyamide/water system obtained from MD calculation showed that the water clusters are well connected to each other, and a relatively large number of water molecules are present at a distance over 3 A from the polyamide. The partial radial distribution functions were calculated, and strong interactions were observed between water and the carboxyl group in polyamide. Thus, the water permeability of the RO membrane can be expected to improve when more carboxyl groups are introduced. In addition, the polyamide–polyamide interaction was found to be equal to or smaller than the polyamide–water interactions and relatively weak in the water-rich system. Reverse osmosis membranes have been playing a main role for the desalination of water in the world. Hydration structure of polyamide functional layer of the membrane was studied via neutron scattering and atomistic molecular dynamics simulations. Experimental and computational structure factors, S(Q), of the polyamide/water system showed good agreement. Water clusters in water-rich system were well connected to each other and formed channel-like structure. Polyamide–water interactions and polyamide-polyamide interactions, which are thought to be important to enhance the performance of the membranes, were examined in detail.

Simultaneous differential scanning calorimetry (DSC) and luminescence (LUM) measurements of polyacrylonitrile revealed that a precursory reaction progresses below the well-known endothermic cyclization reaction (i.e., peak temperature ca. 280 °C). The intensity of LUM increased above 90 °C, which is around the glass transition temperature. After the peak at 180–190 °C, the LUM intensity decreased with temperature up to 250 °C, i.e., below the onset temperature of cyclization reaction. Thermal signals cannot be seen on the DSC curve in the temperature range of the LUM peak. The activation energy (Ea) estimated from the heating rate dependence of the LUM peak temperatures was 122 kJ mol−1. However, the Ea obtained from the well-known exothermic peak temperatures of DSC measurements was 190 kJ mol−1. Electron spin resonance and nuclear magnetic resonance also support the chemical structure of the luminescence species. FT-IR and X-ray diffraction were also performed to confirm the change in chemical and physical structural. Finally, ab initio calculations suggest that thermally stable heterocyclic radical species with two to four fused six-membered rings are the main products of the precursory reaction.

Polyvinyl pyrrolidone (PVP) is well known as a biocompatible polymer used in the fields of medical devices and pharmaceuticals, and is associated with intermediate water, which is said to play an important role in developing the biocompatibility of medical materials. The states of water molecules interacting with PVP, i.e., the non-freezing water, slow and fast intermediate water are classified using 2H NMR. The non-freezing water is directly hydrogen-bonded to ca. 1.5 amide groups of PVP. The slow intermediate water interacts with PVP indirectly through non-freezing water. It then shows slow diffusion dynamics and forms cubic-form ice during cold crystallisation, while the fast intermediate water can diffuse as fast as free water, and can freeze to form normal hexagonal-form ice. Statement of significance For many of the medical materials, including artificial organs such as dialysis membranes and artificial blood vessels, polymers are used. Biocompatibility of polymer is an important property for materials used in medical devices and medicine. Although there are lots of studies about surface design of materials in terms of hydrophilicity, charge, or morphology, the unified expression factor of biocompatibility have not been clear. Recently, it is suggested that water molecules, especially intermediate water, on materials surface play important roles in the development of biocompatibility. However, the characteristics of the intermediate water have not been understood. It is important issues to be solved in the development of new and high-performance biocompatible polymer materials based on the concept of intermediate water. In present study, we have investigated the intermediate water on polyvinyl pyrrolidone (PVP), which is biocompatible polymer widely used in medical device and medicine. Differential scanning calorimeter (DSC), X-ray diffraction (XRD), and various nuclear magnetic resonance (NMR) methods for PVP aqueous solutions were performed in order to clarify the physical properties of the intermediate water. We found that the intermediate water has structural order and diffusive mobility just between free water and non-freezing water. These features of intermediate water are induced by structural interaction with polymer. The knowledge from present study expected to provide guidance for the design of biocompatible materials.

Differential scanning calorimetry and fast scanning chip calorimetry heating experiments were carried out in a wide range of rates of temperature change from 0.2 to 60,000 K s−1 for isothermally crystallized polyamide 6. Multiple melting peaks were observed. With increasing heating rate, the highest-temperature endotherm shifts toward lower temperatures and finally disappears due to suppression of the reorganization. The critical heating rate to suppress reorganization was 15–50 times higher than the critical cooling rate to cause complete vitrification. On heating at rates higher than the critical heating rate to suppress reorganization, there were observed two melting processes of different kinetics. Four possible assignments were considered regarding the two crystal populations. These are (i) crystals grown during primary and secondary crystallization, (ii) crystals grown in the bulk and nucleated at the surface/substrate, (iii) crystals, which are subjected to different local stress originating from heterogeneities in interlamellar regions, and (iv) the crystal/mesophase polymorphism. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2126–2138

The lamellar thickness distribution (LTD) of not-reorganized linear polyethylene was calculated on the basis of the melting point distribution using fast scanning calorimetry (FSC) by applying the following precautions. First, by taking sufficiently small sample mass and thickness, the influence of thermal lag during fast-heating is thought to be negligible. Second, by fast-heating, reorganization and cold crystallization are strongly hindered or even suppressed. Third, the influence of superheating has been accounted for and corrected by deconvolution of the FSC curve using the calculated melting kinetics of single-sized lamellae consisting of folded-chain crystal. Under such precautions, the resulting FSC heating curve reflects the melting point distribution of metastable-but-not-reorganized folded-chain crystals. Finally, the Gibbs–Thomson equation was applied to calculate the LTD from the melting point distribution. The average lamellar thickness calculated was in good agreement with that determined b...

The thermal behavior of polyacrylonitrile (PAN) has been investigated using X-ray diffraction, differential scanning calorimetry (DSC), and ultrafast DSC. In conventional DSC, it is difficult to prevent the concurrent occurrence of the exothermic reactions of PAN with melting. However, in the ultrafast DSC curve, the exothermic peak due to these reactions disappears over the temperature range 0–400 °C at heating rates above 250 °C s −1 . Alternatively, the glass transition and the melting of PAN are observed over the temperature range 109–129 °C and 335–362 °C, respectively. Moreover, upon cooling from the molten state at a rate of −7500 °C s −1 , PAN crystallization is observed at 204 °C. These findings were observed repeatedly during heating and cooling measurements. From the extrapolation analysis, the zero-entropy-production melting temperature of PAN is found to lie in the temperature range 320–350 °C. Finally, the equilibrium melting temperature of PAN is estimated to be ca. 465 °C.

X-ray scattering measurements of an expanded liquid Se(80)Te(20) mixture in the temperature range between 300 and 1000 °C and at pressures of 10, 200, and 1600 bar have been carried out. The reverse Monte Carlo simulation and Voronoi-Delaunay void analyses have been applied to clarify the relationship between the voids and chain geometries in the intermediate scale near the semiconductor to metal (SC-M) transition at 800 °C under 200 bar accompanied by a shrinkage of molar volume. The structure of the liquid mixture can be envisaged in terms of a packing of covalently bonded chains and interstitial voids. The thermal expansion leads to a decrease in the number of chains around a chain and is compensated for by empty spaces (voids). The packing density of helical chains decreases and so voids supported by chains increase with rising temperature. At high temperature the shortening of chains and frequent transfer of lone pair electrons on Se (or Te) atoms cause modification of the helical chain to ring and zigzag chain conformations. The stacking of zigzag chains, joined to layers above 800 °C, leads to the formation of metallic domains separated by voids. The shrinkage of molar volume near the SC-M transition arises through the progressive filling of the voids around chains with (Se, Te)(5, 6, 7, 8) rings.

X-ray diffraction measurements were carried out for liquid iron near the melting temperature and atomic configurations were constructed from the structure factor $S(Q)$ obtained, by reverse Monte Carlo modeling and Monte Carlo simulation with the effective pair potential deduced by the inverse method. The bond-orientational order parameter ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{W}}_{6}$ calculated from the atomic configurations obtained from both simulations indicates a pronounced icosahedral ordering, and the fraction of nearly icosahedral configurations is estimated to be approximately 14% in liquid iron. These experimentally obtained results seem consistent with recent results of ab initio molecular-dynamics simulation for liquid iron [P. Ganesh and M. Widom, Phys. Rev. B 77, 014205 (2008)].

AMATERAS is a very suitable spectrometer for investigation of diffusion dynamics of solutions and also for obtaining the dynamic structure factor S(Q,E) over large Q region. The aim of this paper is to investigate the diffusion dynamics of water molecules in the 1-propanol aqueous solution with small amount of KCl. The S(Q,E) for 1-propanol solutions with and without KCl were obtained. The result shows that the diffusion constant D is slightly larger for KCl containing solution than that without KCl.

After the analysis of the quasi-elastic neutron scattering (QENS) spectra of lower alcoholic aqueous solutions, we found that the parameter α, which is the number fraction of hydrophobic hydrating water molecules, has an important role in describing the dynamics and other properties of these solutions. The diffusion coefficient D was obtained from QENS spectra using the relaxing cage model, and D was found to have the same linear relation against α for ethyl alcohol, n -propyl alcohol, i -propyl alcohol, and t -butyl alcohol (with a small deviation) aqueous solutions. The excess molar volume and average hydration number of these solutions could also be expressed with common parameters, which are independent of the alcohol species.

The dynamics of water molecules in the n-propyl alcohol-water mixtures is investigated by using quasielastic neutron scattering measurements. The dynamic structure factor S(Q,E) obtained from incoherent scattering of hydrogen atoms of water is fitted with jump diffusion and relaxing cage models. The diffusion constant obtained from the relaxing cage model, which gives better fitting with S(Q,E), shows better agreement to the experimental value than that of jump diffusion model. The dependence of translational relaxation time tau(T)(Q) and stretched exponent beta(T)(Q) on the fraction of hydrophobic hydrating water molecules in the solution is discussed.

Quasielastic neutron scattering has been used to investigate the hydration of alcohol clusters in tert -butyl alcohol–water mixture. The measurements were made in a range of alcohol concentration, ...