Quantitative analysis of branched high-density polyethylene content using far-infrared spectroscopy.

This study describes a simple method for estimating the content of branched high-density polyethylene using spectroscopy including the terahertz region. Herein, we prepared samples by blending high-density polyethylene with a blend ratio of 0 %-100 % of branched and linear polyethylene. Then, the terahertz absorption spectra of these samples were recorded from 600 to 50 cm (18-1.

Visualization of isothermal crystallization and phase separation in poly[(R)-3-hydroxybutyrate]/poly(L-lactic acid) by low-frequency Raman imaging.

The visualization of the variation of the inter/intra molecular interaction (C = O⋯CH) between poly[(R)-3-hydroxybutyrate] (PHB) and poly-L-lactic acid (PLLA) in the PHB/PLLA miscible blend during phase separation and crystallization process was successfully investigated using Raman imaging. Images of the blend were developed using high- and low-frequency Raman spectra acquired during the isothermal crystallization of the blend, and both of them were compared. The low-frequency region allowed to observe the changes in the hydrogen bonds between the molecular chains in the blend during phase separation and crystallization via a band at 75 cm derived from PHB.

Room-temperature quantum coherence of entangled multiexcitons in a metal-organic framework.

Singlet fission can generate an exchange-coupled quintet triplet pair state TT, which could lead to the realization of quantum computing and quantum sensing using entangled multiple qubits even at room temperature. However, the observation of the quantum coherence of TT has been limited to cryogenic temperatures, and the fundamental question is what kind of material design will enable its room-temperature quantum coherence. Here, we show that the quantum coherence of singlet fission-derived TT in a chromophore-integrated metal-organic framework can be over hundred nanoseconds at room temperature.

Morphologies of Comb-like Polyacrylic Acid/Polyacrylate Copolymers as Functions of the Degree of Derivatization with -CH Side Chains.

Polymers with crystallizable side chains have numerous applications, and their properties depend on their crystal morphologies and phase separation. Structural analysis on a wide spatial scale plays an important role in controlling the thermal properties and higher-order structures of these polymers. In this study, we elucidated the melting and crystallization processes of copolymers with varying crystallizable side-chain fractions over a wide spatial range.

Combined X-ray Reflectivity and Infrared Study of the Effect of Hydrogen Bonding of the OH Group on the Relaxation Behavior in Ultrathin Polyvinylphenol Films on SiO.

Utilizing X-ray reflectivity and infrared reflection absorption spectroscopy (IR-RAS), we have investigated the thermal expansion and contraction of ultrathin polyvinylphenol (PVPh) films supported on a silicon (100) substrate capped with an amorphous SiO layer. Despite being known to form strong interactions with the SiO surface, the thin PVPh films showed a reduction in the glass-transition point , similar to the behavior of polystyrene thin films deposited on SiO. We explored the relationship between thermal expansivity and film thickness using well-annealed films and found that it decreases with film thickness in the range below twice the radius of gyration of a polymer chain (2) in the glassy state.

Intermolecular Interaction of Tetrabutylammonium and Tetrabutylphosphonium Salt Hydrates by Low-Frequency Raman Observation.

Semi-clathrate hydrates are attractive heat storage materials because the equilibrium temperatures, located above 0 °C in most cases, can be changed by selecting guest cations and anions. The equilibrium temperatures are influenced by the size and hydrophilicity of guest ions, hydration number, crystal structure, and so on. This indicates that intermolecular and/or interionic interaction in the semi-clathrate hydrates may be related to the variation of the equilibrium temperatures.

A Study of C=O…HO and OH…OH (Dimer, Trimer, and Oligomer) Hydrogen Bonding in a Poly(4-vinylphenol) 30%/Poly(methyl methacrylate) 70% Blend and its Thermal Behavior Using Near-Infrared Spectroscopy and Infrared Spectroscopy.

Inter- and intramolecular hydrogen bonding and their temperature-dependent changes in a poly(4-vinylphenol)/poly(methyl methacrylate)(PVPh 30%/PMMA 70%) blend were investigated using near-infrared (NIR) and infrared (IR) spectroscopy. Band assignments of the fundamentals and first overtones of the OH stretching mode of a free OH group and OH groups in C=O···HO and OH···OH (dimer, trimer, and oligomer) hydrogen bonding of PVPh 30%/PMMA 70% were carried out by comparison between its NIR and IR spectra and comparison with NIR and IR spectra of phenol. The comparison of the NIR spectra of the PVPh 30%/PMMA 70% blend (hereafter, we denote it as PVPh30%) with the corresponding IR spectra reveals that to observe bands arising from the free OH and OH···OH dimer, which is a weaker hydrogen bonding, NIR is better while to investigate bands originating from OH groups in the OH···O=C and OH···OH (oligomer) hydrogen bonds, which are stronger hydrogen bonding, IR is better.

Solvent effect on the competition between weak and strong interactions in phenol solutions studied by near-infrared spectroscopy and DFT calculations.

Near-infrared (NIR) spectra of phenol in a series of non-aromatic and aromatic solvents were recorded to study the competition between various types of solute-solute and solute-solvent interactions. Depending on the phenol concentration, the free OH and OH involved in the OH⋯OH interactions in the dimers and higher associates are present in cyclohexane solutions. On the other hand, free OH does not appear in Cl-containing solvents since at a low phenol content the OH groups participate in the OH⋯Cl interactions.

Water-induced conformational changes in the powder and film of ε-poly(L)lysine studied by infrared and Raman spectroscopy.

In this study, we have investigated the water absorption-induced structural changes and thermal behavior of ε-poly(L)lysine-hydrochloride (EPLHCl) in the powder and film samples using infrared (IR) and Raman spectroscopy. An X-ray diffraction measurement reveals that the crystal structure of ε-poly(L)lysine (EPL) is similar to that of the γ-crystal of nylon-6. The powder form of EPLHCl absorbs water from the air and solidifies into a film (18% water content).

Attenuated Total Reflection-Far-Ultraviolet Spectroscopy and Quantum Chemical Calculations of the Electronic Structure of the Top Surface and Bulk of Polyethylenes with Different Crystallinities.

In this study, we explored the electronic structure of the surfaces of polyethylene samples having different crystallinities using attenuated total reflection (ATR) far-ultraviolet (FUV) spectroscopy and quantum chemical calculations. Specifically, the ATR-FUV spectra of five types of high-density polyethylene (HDPE), six types of linear low-density PE (LLDPE), and seven types of low-density PE (LDPE) were obtained. All the spectra contained an intense band near 156 nm and a broad band between 180 and 190 nm.

Visualization of Inter- and Intramolecular Interactions in Poly(3-hydroxybutyrate)/Poly(L-lactic acid) (PHB/PLLA) Blends During Isothermal Melt Crystallization Using Attenuated Total Reflection Fourier Transform infrared (ATR FT-IR) Spectroscopic Imaging.

Inter- and intramolecular interactions in multicomponent polymer systems influence their physical and chemical properties significantly and thus have implications on their synthesis and processing. In the present study, chemical images were obtained by plotting the peak position of a spectral band from the data sets generated using in situ attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopic imaging. This approach was successfully used to visualize changes in intra- and intermolecular interactions in poly(3-hydroxybutyrate)/poly(L-lactic acid) (PHB/PLLA) blends during the isothermal melt crystallization.

Study of changes in water structure and interactions among water, CH, and COO groups during water absorption in acrylic acid-based super absorbent polymers using Raman spectroscopy.

The interactions of acrylic acid-based super absorbent polymers (SAPs) with water and the hydrogen bonding of water within its three-dimensional network were studied using Raman spectroscopy. The Raman spectra of SAP solutions suggested that both the COO and CH groups of SAPs interact with water. The Raman spectra of pure water and those of SAPs containing approximately 40, 50, and 60% water exhibited a broad band corresponding to the OH-stretching mode of water in the 4000-3000 cm region.

Caregiver-reported dementia as a predictor of oral health among patients receiving home-visit dental treatment: A retrospective cohort study.

Objective: To assess caregiver-reported dementia as a risk factor for retained roots, an indicator of poor oral hygiene, among patients receiving home-visit dental treatment in Japan.

Methods: The medical records of 231 dentate patients who received home-visit dental treatment (covered by public medical insurance) for more than 2 years were retrospectively analyzed. The number of teeth and retained roots at the initial and final examinations were obtained from the dental charts, and the "change in the number of retained roots from initial to final examination" was determined.

Low temperature polytetrafluoroethylene (PTFE) coating improves the appearance of orthodontic wires without changing their mechanical properties.

A strong esthetic demand exists for white-colored rather than metallic-colored dental appliances. Polytetrafluoroethylene (PTFE), which is chemically stable with extremely low friction, is a suitable white-colored coating for dental appliances. In the conventional PTFE coating process, base materials are heated to approximately 400°C, which could change their mechanical properties.

A Study on Blend Ratio-dependent Far-IR and Low-frequency Raman Spectra and WAXD Patterns of Poly(3-hydroxybutyrate)/poly(4-vinylphenol) Using Homospectral and Heterospectral Two-dimensional Correlation Spectroscopy.

An intensive analysis of far-infrared (far-IR), low-frequency Raman, and wide angle X-ray diffraction (WAXD) data has been performed by two-dimensional correlation spectroscopy (2D-COS) as a function of the blend ratio of poly(3-hydroxybutyrate)/poly(4-vinylphenol) (PHB/PVPh). Homospectral 2D-COS revealed that a weak band at 128 cm in the far-IR spectra appeared more clearly in the 2D correlation spectra. Heterospectral 2D-COS (far-IR/low-frequency Raman and far-IR/WAXD) provided very important results that were hardly detected in the conventional 2D-COS.

Plasma Polymerization of Acrylic Acid for the Tunable Synthesis of Glassy and Carboxylated Nanoparticles.

Polymer nanoparticles (NPs) can be highly attractive in numerous applications, including biomedicine, where the use of inorganic matter may be detrimental for living tissues. In conventional wet chemistry, polymerization and functionalization of NPs with specific chemical groups involves complex and often numerous reactions. Here, we report on a solvent-free, single-step, low-temperature plasma-based synthesis of carboxylated NPs produced by the polymerization of acrylic acid under the conditions of a glow discharge.

Changes in the Electronic Transitions of Polyethylene Glycol upon the Formation of a Coordinate Bond with Li, Studied by ATR Far-Ultraviolet Spectroscopy.

This study investigates the electronic transitions of complexes of lithium with polyethylene glycol (PEG) by the absorption bands of solvent molecules via attenuated total reflectance spectroscopy in the far-UV region (ATR-FUV). Alkali-metal complexes are interesting materials because of their functional characteristics such as good ionic conductivity. These complexes are used as polymer electrolytes for Li batteries and as one of the new types of room-temperature ionic liquids, termed solvation ionic liquids.

Low-Frequency Vibrational Modes of Nylon 6 Studied by Using Infrared and Raman Spectroscopies and Density Functional Theory Calculations.

Far-infrared (FIR) and low-frequency Raman bands in the 90?400 cm region of crystalline nylon 6 in ? form were assigned based on comparisons of experimental spectra and quantum mechanical calculations. A fragment methodology was applied in the calculations for explicit consideration of interchain interactions and crystal symmetry. The main features in both Raman and FIR spectra were reproduced well, which enabled the band assignments based on density functional theory and the significant improvement of the conventional assignments for which there had been a big dispute.

Rydberg transitions as a probe for structural changes and phase transition at polymer surfaces: an ATR-FUV-DUV and quantum chemical study of poly(3-hydroxybutyrate) and its nanocomposite with graphene.

We investigated the surface (<50 nm) of poly(3-hydroxybutyrate) (PHB) and its nanocomposite with graphene by attenuated total reflection far- and deep-ultraviolet (ATR-FUV-DUV; 145-300 nm; 8.55-4.13 eV) spectroscopy and quantum mechanical calculations.

Stress-induced crystal transition of poly(butylene succinate) studied by terahertz and low-frequency Raman spectroscopy and quantum chemical calculation.

We measured terahertz (THz) and low-frequency Raman spectra of Poly (butylene succinate) (PBS) which shows the crystal transition from α to β by stretching. For the assignment of the absorption peaks in the low-frequency region, we performed quantum chemical calculations with Cartesian-coordinate tensor transfer (CCT) method. Four major peaks appeared in the THz spectra of PBS at around 58, 76, 90, and 100cm, and in the low-frequency Raman spectra a peak was observed at 88cm.

Controlled Terahertz Birefringence in Stretched Poly(lactic acid) Films Investigated by Terahertz Time-Domain Spectroscopy and Wide-Angle X-ray Scattering.

We report a correlation between the dielectric property and structure of stretched poly(lactic acid) (PLA) films, revealed by polarization-sensitive terahertz time-domain spectroscopy and two-dimensional (2D) wide-angle X-ray scattering (WAXS). The experiments evidence that the dielectric function of the PLA film becomes more anisotropic with increasing draw ratio (DR). This behavior is explained by a classical Lorentz oscillator model assuming polarization-dependent absorption.

Terahertz Imaging of the Distribution of Crystallinity and Crystalline Orientation in a Poly(ɛ-caprolactone) Film.

The distribution of crystallinity and the crystalline orientation of a poly(ɛ-caprolactone) (PCL) film have been studied using terahertz (THz) imaging. Terahertz images were developed by using the intensity ratio of the two spectral peaks at 1.42 and 2.

Low-Frequency Vibrational Modes of Poly(glycolic acid) and Thermal Expansion of Crystal Lattice Assigned On the Basis of DFT-Spectral Simulation Aided with a Fragment Method.

Low-frequency vibrational modes of lamellar crystalline poly(glycolic acid) (PGA) were measured on Raman and far-infrared (FIR) spectra. Among the observed bands, an FIR band at ∼70 cm and a Raman band at 125 cm showed a gradual lower-frequency shift with increasing temperature from 20 °C to the melting point at ∼230 °C. Their polarization direction was perpendicular to the chain axis of PGA.

Inhibitory effects of geranium essential oil and its major component, citronellol, on degranulation and cytokine production by mast cells.

We investigated the effects of geranium essential oil (GEO) on anaphylaxis. GEO can exert antioxidant and anti-inflammatory effects, but its roles in allergic reactions are incompletely understood. Here, we used mouse cells to show that GEO inhibited the degranulation of cultured mast cells (CMCs).