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We fabricated actuators consisting of an ionic liquid gel electrolyte layer sandwiched between two nanofiber mat electrodes and studied the relationship between the polymer type of the nanofiber mat and the performance of the actuator. We selected poly(urethane) (PU), poly(methyl methacrylate) (PMMA), and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as the materials for the nanofiber mat electrodes. The performance of the actuator was determined on the basis of cyclic voltammetry and AC impedance measurements.
Copolymerization kinetics of methyl methacrylate and ethyl methacrylate by Cu(0)-mediated reversible deactivation radical polymerization was thoroughly explored. The copolymerization follows pseudo-first order kinetics in a highly controlled manner. Detailed kinetic studies revealed that two different monomers experience different enthalpic barriers in propagation, which strongly suggest that the copolymerization exhibits not perfectly, but nearly random composition. Further studies on glass transition and chain extension highlight the significance of these fundamental studies to predict thermal properties and to realize complex polymer architecture.
Large dielectric constants were measured for nylon 93. A displacement–electric hysteresis loop was obtained for a slowly cooled sample of nylon 93. The structure of nylon 93 was investigated in detail to clarify the origin of these unusual electric properties. The results obtained by X-ray diffraction, polarizing optical micrography, and differential scanning calorimetry indicated that α- and γ-crystals were formed in the slowly cooled and quenched samples, respectively, and the γ-crystals in the quenched samples were gradually changed into α-crystals by annealing.
Fully aromatic polyimide particles were obtained in a single step via the polycondensation of diethyl (hexafluoroisopropylidene)diphthalate and 4,4’-oxydianiline using polyvinylpyrrolidone (PVP) as a steric stabilizer in ethylene glycol. Since the monomers are soluble in ethylene glycol, but the polyimide is insoluble, the polyimide particles grew gradually during the polycondensation process. The particle size and size distribution were controlled by varying the molecular weight and amounts of PVP.
Benzoxazine bridged by a flexible polysulfide rubber chain (BLP) was conveniently prepared through the ring-opening addition of thiol-capped liquid polysulfide rubber (LP-3) and bisphenol-A/aniline-based benzoxazine (B-a). BLP was a highly viscous fluid at room temperature with a low curing temperature. After curing, the polymerized BLP (PBLP) presented excellent flexibility, outstanding thermal stability, and an extremely high char yield.
A soluble polysilsesquioxane containing macrocyclic structure (PSQ-MC) is successfully prepared by the hydrolytic condensation of a dual site-type silane coupling agent, i.e., bis{3-[3-(trimethoxysilyl)propylthio]propyl}phthalate (BTPP). PSQ-MC is assumed to be a polymer in which an 8-membered cyclic siloxane having two 23-membered rings is linked by a single siloxane bond. In addition, PSQ-MC could capture palladium ions.
The clear experimental results are revealed to confirm that a special type of a diluent can act as an agent of improving the crystallizability of poly(L-lactide) (PLLA). We conducted time-resolved SWAXS to follow the isothermal crystallization of PLLA. The WAXS result shows enhancing effects of the diluent on the crystallization of PLLA such as reducing induction period and accelerating crystallization. The growth of the crystalline lamellae in their thickness direction and the space filling by the stacks of crystalline lamellae are found to be accelerated in the presence of the diluent.
Isothermal crystallization of poly(glycolic acid) (PGA) was carried out using terahertz (THz) and infrared (IR) spectroscopy and simultaneous small-angle X-ray scattering (SAXS)/wide-angle X-ray diffraction (WAXD) measurements. The intensity of the absorption peak at 192 cm−1 increased before the increase in intensity of the peak at 65 cm−1 during the isothermal melt-crystallization process at 185 °C. This is due to a difference in the vibrational origins of these two bands. In addition, these THz bands appeared after the appearance of the SAXS and WAXD peaks
The dispersion state and aggregate structure of carbon black in polystyrene composites prepared by solvent casting suspensions in different dispersion media with different particle contents and their effects on the bulk rheological properties of the composites were investigated by transmission electron microscopy, ultrasmall-angle and small-angle X-ray scattering, and dynamic viscoelasticity measurements. The viscoelastic moduli of the melt polymer composites below and above the percolation limit varied with the dispersion medium, reflecting the difference in the macroscopic dispersion state and aggregate structure of carbon black in polystyrene.
The formation of multiple intramolecular hydrogen bonds (IHBs) is a reliable method for obtaining conjugated oligomers with helical secondary structures, and imidazole with both proton-accepting and proton-donating abilities plays an important role. On the basis of its optical properties in conjunction with DFT calculations, a conjugated oligomer composed of alternating imidazole and 1,4-dihydroxybenzene units was found to (1) form robust IHBs, (2) be susceptible to both acid and base treatment, and (3) potentially adopt a helical conformation.
Polythiourethane (PTU) elastomers, which are obtained by the reaction between polyol, diisocyanate, and dithiol, are expected to have some properties that polyurethanes (PUs) do not have. Herein, the microphase-separated structure and mechanical properties of the 1,4-bis(isocyanatomethyl) cyclohexane-based PTUs were investigated. It was revealed from the differential scanning calorimetry, small-angle X-ray scattering and dynamic viscoelasticity measurements that the PTUs possess a stronger degree of microphase separation and lower glass transition temperature of soft segment compared to that of PUs.
Time-resolved X-ray measurements during melting and analyses of samples heat treated near their melting temperature revealed a structural change of the melt-crystallized isotactic polypropylene. During melting at a heating rate of 5 K/min, we observed the appearance of a higher melting temperature peak due to lamellar thickening of the α1 crystal. Lamellar thickening was accompanied by an increase in central diffuse scattering of SAXS, suggesting that thickening occurred at random positions and caused disordering of lamellar stacking.
The change of ultra-small-angle X-ray scattering (USAXS) image after necking was taken for poly(ethylene terephthalate) (PET) and poly(phenylene sulfide) (PPS) fibers. USAXS pattern of PPS shows three streaks, which were meridional and equatorial streaks and total reflection. In addition to the three streaks observed for PPS, USAXS pattern of PET shows a layer-lined streak. Far stronger meridional streak of PPS means the periodic density deviation preliminary formed in the as-spun fiber, and the layer-lined USAXS streak of PET could be explained by the periodic bundle of a fibrillar-shaped smectic phase.
A poly(4-methylpentene-1) (P4MP1) film was prepared on a quartz substrate, which was a model system of interfaces in a filler-reinforced semicrystalline polymer composite. Grazing-incidence wide-angle X-ray diffraction measurements revealed that P4MP1 in the film after the isothermal crystallization formed a Form I crystal polymorph, in which the chain axis was oriented along the direction parallel to the quartz interface. Combining sum-frequency generation vibrational spectroscopy with molecular dynamics simulation enabled us to study the local conformation of P4MP1 chains at the quartz interface and the changes that occurred with isothermal crystallization.
The role of strain rate (\(\dot \varepsilon\)) in strain induced crystallization (SIC) of vulcanized natural rubber (NR) and synthetic isoprene rubber (IR) was studied by in-situ wide angle X-ray scattering (WAXS). The nucleation rate (I) was determined by measuring the slope on the plot of the scattering intensity (IX) as a function of time (t). Various I values were determined for various \(\dot \varepsilon\). On the plot of I vs. \(\dot \varepsilon\), we found that I is proportional to \(\dot \varepsilon\); I ∝ \(\dot \varepsilon\)
Conducting polymers were synthesized via in situ polymerization, using nanoclay bentonite sodium and its modified form. The polymer nanoclay modified form showed enhanced solubility compared to the original polymers and improved thermal stability, along with higher corrosion inhibition efficiency and aggregation-induced emission with luminescence dependent on the aggregate structure.
When bulk polymerization of MMA is conducted at room temperature, polymerization-induced phase separation occurs. Separation into MMA-rich and PMMA-rich phases coincides with the onset of the Trommsdorff effect. The highlighted region of the phase diagram represents a part of the phase state that depends upon the processing path: in one case (path 1), there are two phases present, in the other (path 2), the material is single-phase.
We investigated the crystallization dynamics of P3MB1 under isothermal condition by synchrotron radiation X-ray scattering and optical microscopy. At a crystallization temperature (Tc) of 297 °C, needle-like crystals consisting of stacked lamellae formed. As Tc increased, the number of lamellar branches decreased and morphological transition (spherulite → axialite → needle-like crystal) occurred. The suppression of lamellar branching was attributed to the low viscosity of the molten portion at Tc.
Changes in the aggregated structure of silica in styrene–butadiene rubber are measured with small-angle X-ray scattering under cyclic uniaxial elongation. We employ a spherical harmonics expansion approach to quantitatively analyze the anisotropic scattering data and to separate the anisotropic response of the silica’s configuration upon the elongation from the isotropic component. This study demonstrates that the combination of time-resolved small-angle scattering measurement and an analysis using spherical harmonics expansion is quite useful for exploring the structural response of filled rubber systems to an external deformation.
Grazing incidence wide-angle X-ray diffraction study of lamellar orientation in isotactic polypropylene thin films. Crystalline structure of isotactic polypropylene (iPP) thin films was investigated by means of grazing incident wide-angle X-ray diffraction, atomic force microscopy, and transmission electron microscopy. Flat-on mother lamellae with orthogonal daughter lamellae form in the thin film. We propose a lamellar growth model for iPP thin films in which the crystallization progresses flat-on mother lamellae at the substrate interface to out-of-plane growth of daughter lamellae from the mother lamellae.