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A facile approach for improving color purity is explored by the introduction of an angle-robust selective absorber (ARSA) into bottlebrush block copolymer (BBCP)-based one-dimensional (1D) photonic crystals (PCs). The BBCPs of poly[(3-(12-(

The homopolymers P1, P2 and P3 were successfully synthesized by direct CH–CH arylation polymerization in an eco-friendly one-step coupling reaction. They present n-type properties for potential applications as acceptor polymers.

The relationships between the structure and the property of donor–acceptor copolymers based on dithieno[3,2-b:2′,3′-d]pyrrole as a strong donor unit and isoindigo or thiazole as acceptor units are successfully studied.

This paper presents a state-of-the-art review in modeling approach of hardware in the loop simulation (HILS) realization of electric machine drives using commercial real time machines. HILS implementation using digital signal processors (DSPs) and field programmable gate array (FPGA) for electric machine drives has been investigated but those methods have drawbacks such as complexity in development and verification. Among various HILS implementation approaches, more efficient development and verification for electric machine drives can be achieved through use of commercial real time machines. As well as implementation of the HILS, accurate modeling of a control target system plays an important role. Therefore, modeling trend in electric machine drives for HILS implementation is needed to be reviewed. This paper provides a background of HILS and commercially available real time machines and characteristics of each real time machine are introduced. Also, recent trends and progress of permanent magnet synchronous machines (PMSMs) modeling are presented for providing more accurate HILS implementation approaches in this paper.

The amphiphilic conformation of α-helical peptides has important biological functions, such as ion transport, antifreeze, and innate immunity, which can be mimicked by alternating polyisocyanate copolymers. We synthesized poly(allyl isocyanate-alt-(S)-(-)-α-methylbenzyl isocyanate (P(AIC-alt-SMBIC)) and ammonium-containing P(AIC-alt-SMBIC) (N-P(AIC-alt-SMBIC)), ensuring the amphiphilic helical conformation. The benzyl group of SMBIC plays an important role in alternating copolymerization with its steric and electron-withdrawing effects, while AIC provides an alkene group capable of introducing a customized functional group. The P(AIC-alt-SMBIC) with predominantly alternating sequence was acquired at f

Three crosslinkers (1,4-diaminobutane, 1,8-diaminooctane, and 1,6-hexanediol) were selected to produce hydrogen-bonded networks using a simple and effective method. The effects of these crosslinkers on the arrangement of crystalline structures were successfully studied using X-ray diffraction and high-voltage electron microscopy. The hydrogen-bonded isoindigo-based small molecules with 1,4-diaminobutane showed the best performance, with a crystal structure showing long-range order, due to the more suitable length of the 1,4-diaminobutane chain. The hole mobility estimated from hole-only devices based on isoindigo was enhanced from 1.24 × 10

Three homopolymers were successfully synthesized by direct CH-CH arylation polymerization of thieno[3,4

Highly conductive and stable anion exchange membranes (AEMs) are important components of high-performance anion exchange membrane fuel cells (AEMFCs). Here, we report the use of crosslinked poly(arylene ether sulfone) (PAES) AEMs containing quaternary ammonium (QA) and triazolium cations. The crosslinked PAES-triazole-hydroxide membrane (cPAES-TA-OH) had a higher ion exchange capacity (IEC) than that of the non-crosslinked membrane (PAES-TA-OH) owing to the presence of triazolium cations. The IEC values of cPAES-TA-OH and PAES-TA-OH were 1.75 and 1.31 meq/g, respectively. The IEC value affects the water uptake and swelling ratio of a membrane. The water uptake and swelling ratio of cPAES-TA-OH were higher than those of PAES-TA-OH at 30 °C and 80 °C. In addition, hydroxide conductivity and membrane stability were enhanced by crosslinking; the hydroxide conductivity of cPAES-TA-OH was 92.1 mS/cm at 80 °C under 95% RH (in contrast to 86.2 mS/cm for PAES-TA-OH), and its conductivity retention was 67% after treating with 1M NaOH at 80 °C for 24 h (in contrast to 51% for PAES-TA-OH).

The influence of N-substituent and pKa of azole rings has been investigated for the performance of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). Imidazole, benzimidazole, and triazole groups were functionalized on the side chains of poly(phenylene oxide), respectively. Each azole group is categorized by their N-substituent into two types: unsubstituted and methyl-substituted azoles. The membranes with methyl-substituted azoles showed higher phosphoric acid (PA) doping levels with an average increase of 20% compared to those with unsubstituted azoles in the full-doped states. However, unsubstituted azoles more effectively improved the proton conductivity and the membrane with unsubstituted imidazole (IMPPO-H) showed a high anhydrous proton conductivity of 153 mS/cm at 150 °C. In contrast, the membranes with methyl-substituted azoles showed a higher PA retention with an average increase of 81% compared to those with unsubstituted azoles. The higher PA retention of methyl-substituted azoles also led to the higher fuel cell performance with the maximum increase of 95% in the power density. It was also revealed that higher pKa of azoles enhanced the PA retention and the fuel cell performance. Based on the experimental results of PA retention and density functional theory calculations, the PA loss mechanism was also proposed.

We prepared a poly(pyrrole : biphenyldisulfonic acid : pyrrole (Py:BPDSA:Py)) nanocomposite of molybdenum disulfide (MoS2), P(Py:BPDSA:Py)-MoS2, with high crystallinity. The composite is synthesized by oxidative polymerization of Py:BPDSA:Py as a two-monomer-connected precursor (TMCP) linked by ionic bonding on a molybdenum disulfide (MoS2) monolayer. The chemical, structural and morphological characterization of this composite is confirmed by Raman spectroscopy, FT-IR, X-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS), and scanning electron microscopy (SEM). The crystal structure is analysed by X-ray diffraction (XRD) and high-voltage electron microscopy (HVEM), which shows a face-centered cubic (FCC) crystal structure for the composite. Nitrogen adsorption–desorption isotherms show an improved specific surface area (91.3 m2 g−1). The electrochemical properties of the composite with a unique crystal structure and a large specific surface area are analysed through cyclic voltammetry (CV), which shows a specific capacitance of 681 F g−1 demonstrating that the composite can be used as an efficient electrode active material for electrochemical energy storage systems.

A high-molecular-weight poly(styrene-co-2-(dimethylamino)ethyl methacrylate-co-acrylonitrile) (ABC)-type terpolymer with a high tensile strength (7.36 MPa) was synthesized using free radical polyme...

High-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) are operated between 120 °C and 180 °C. As a result, they cannot employ Nafion® as an electrode ionomer because the proton conductivity of Nafion® is very low without water. In this study, new polymers (poly(phenylene oxide), PPO) with a phosphate group including methyl phosphonic acid (PPO-MPA) or 6-oxohexyl phosphonic acid (PPO-HPA), which show good proton conductivities, are applied as ionomers and binders to form an electrode. In addition, vinylphosphonic acid (VPA) is investigated as an electrode additive. The PPO-MPA electrode shows a lower wetting angle than that of the PPO-HPA electrode. After the addition of VPA, the PPO-MPA electrode becomes more hydrophobic, whereas the PPO-HPA electrode becomes more hydrophilic. In the FT-IR spectra of the PPO-MPA electrode, the peak associated with the PO32− asymmetric stretch is more blue-shifted than the peak of the polyvinylidene difluoride electrode at a high temperature due to increased amounts of released protons from PPO-MPA, indicating that the binder with a phosphate group improved the proton conductivity of the ionomer in the HT-PEMFC. At 0.2 A/cm2, the performance of the membrane electrode assembly (MEA) using the PPO-MPA cathode increases from 0.55 V to 0.59 V by the introduction of VPA, whereas that using the PPO-HPA cathode decreases from 0.61 V to 0.57 V, which exhibits the same propensity as the hydrophobicity change. The value of charge transfer resistance at 0.6 V estimated by fitting of the electrochemical impedance spectra follows the same trend as the MEA performance. This is attributed to a change in catalyst coverage by phosphoric acid in the electrode by the addition of VPA and not a change in proton conductivity. The possibility of new polymer binders for the HT-PEMFC is demonstrated, and the MEA performance is shown to be influenced by the incorporation of VPA, which is accounted for the change in hydrophobicity of the electrode.

Iridium complex-incorporated monodisperse particles are prepared via surfactant-free emulsion polymerization. For this process, a vinyl-substituted iridium complex (IrV) is synthesized and copolyme...

Despite the importance of structure and properties in organic mixed conductors, there exist very few material systems where the effects of relative crystallinity, crystallite size, and doping conce...

A blend of poly(3-hexylthiophene) (P3HT) and poly(n-hexyl isocyanate-block-2-vinylpyridine) (PHIC-b-P2VP) in a common solvent shows the formation of long-range (micrometer-scale) nanowires of P3HT ...

A well-ordered polymer nanocomposite was prepared as a supercapacitor electrode based on sulfonated graphene oxide (SGO) and a two-monomer-connected precursor (TMCP). Biphenyldisulfonic acid (BPDSA...

Atomically thin molybdenum disulfide (MoS2) films were synthesized on a SiO2/Si substrate by metal-organic chemical vapor deposition (MOCVD). Raman spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy studies reveal the double-atomic-layer structure and the surface element composition of the MOCVD-grown MoS2 films. The photoluminescence measurement demonstrates a strong emission peak with a bandgap of 685.1 nm, attributed to highly efficient radiative transition at the double atomic layer. The contact resistance between the doubleatomic-layer MoS2 film and metal electrode was measured using the transmission-line modeling method. A Ti/Au electrode forms an ohmic contact with the double-atomic-layer MOCVD-grown MoS2 film, exhibiting a resistivity of 100 kΩ. The field-effect transistor based on the double-atomiclayer MoS2 film exhibits an electron mobility of 1.3×10−4 cm2/V·s and an on/off ratio of 6.5×102 at room temperature.

Background. Bacteremia is a major nosocomial infection that frequently occurs in trauma patients, increasing morbidity and mortality. The aim of this study was to identify risk factors and to describe epidemiological patterns for early onset (EOB) and late onset (LOB) bacteremia after trauma.Methods. We retrospectively reviewed medical records of all trauma patients admitted to the surgical intensive care unit and general ward between January 2011 and December 2015. The information was collected for each patient and recorded in a computer database: early onset bacteremia (EOB) was defined as when onset occurred within 7 days after trauma, and late onset bacteremia (LOB) was defined as when onset occurred after 7 days from trauma.Results. Thirty-four patients of 859 (4%) developed bacteremia during their hospital stay: 4 (11.8%) developed EOB, 26 (76.4%) LOB, and 4 (11.8%) patients developed both of them. Sixty events of bacteremia happened to these patients: 9 (15.0%) EOB and 51 (85.0%) LOB. Gram-positive cocci were isolated more frequently than Gram-negative bacilli in both groups. Gram-positive cocci were more frequently isolated in EOB than in LOB; otherwise, there was no statistical significance (77.8% vs. 64.7%,p=0.683). Central line-associated blood stream infection (CLABSI) and surgical site infection (SSI) were the most common identified source for LOB. Presence of liver (OR: 2.66,p=0.035) and pelvic injury (OR: 2.25,p=0.038), gastrointestinal tract perforation (OR: 5.48,p=0.002), and massive transfusion (OR: 3.36,p=0.006) represented risk factors for bacteremia.Conclusions. Presence of pelvic and liver injury on arrival in emergency department, gastrointestinal tract perforation, and massive transfusion within the first 24 hours after trauma appears to be significant risk factors for bacteremia.

We present the facile synthetic platform for the production of amphiphilic bottlebrush block copolymers bearing pyridine pendants through combination of living anionic polymerization (LAP), ring-op...

Well-defined ambipolar block copolymers containing carbazole, oxadiazole moieties, and only one homoleptic iridium(III) complex between the carbazole and oxadiazole blocks were successfully synthesized by sequential living anionic polymerization with controlled molecular weights (Mw), a narrow molecular weight distribution (Mw/Mn < 1.15), and a high conversion yield (98–100%). The optimum conditions for the successful controlled synthesis of an oxadiazole-containing the homopolymer of poly(2-phenyl-5-(6-vinylpyridin-3-yl)-1,3,4-oxadiazole) have been established by controlling the nucleophilicity strength of the carbanion. In addition, the location and concentration of the homoleptic iridium(III) complex were controlled by linking it to 1,1-diphenylethylene, which exhibits monoaddition characteristics in the main chain of the block copolymer.

Two kinds of donor-acceptor π-conjugated copolymer based on poly{[

Mie backscattering-based coloration of water-dispersed polymer particles is investigated. Diluted colloids and light absorber-added colloids are individually prepared to study the scattering properties. Light absorber-added colloids show ~2.9-fold higher colour saturation than diluted colloids because of the effective elimination of Mie forward scattering. Mechanism of selective extraction of Mie backscattering-based colour in the presence of light absorbers is explained by path length difference of Mie forward and backscattering. Using stimuli-responsive polymer particles, Mie scattering colour-based sensors that respond to pH and heavy metal ions are prepared.

A supramolecular aggregate with molecular-level ordering, is prepared by the hydrogen-bonding self-assembly of poly(4-(4-vinylphenylpyridine)) (P4VPPy) and 1,1′-ferrocenedicarboxylic acid (FDA) in dimethyl sulfoxide (DMSO) using a solvent vapor thermal annealing process. Co-dissolving P4VPPy and FDA in DMSO leads to hydrogen bonding between the pyridine and carboxylic acid. This is confirmed by Fourier transform-infrared spectroscopy and X-ray photoelectron spectroscopy. The crystalline morphology of the resulting thin films are investigated by high-voltage electron microscopy coupled with X-ray diffraction, which reveals that hydrogen bonding assisted self-assembly of P4VPPy and FDA results in precise arrangements of both the polymer chains and FDA molecules providing a highly ordered material with a face-centered cubic crystal structure. The X-ray spectra shows crystalline peaks with d spacing in the (100) direction and supports the high-voltage electron microscopy results. Furthermore, P4VPPy also interacts with 2,6-naphthalenedicarboxylic acid (NTDA), 1,4-benzenedicarboxylic acid (BZDA) and 1,2-ethanedicarboxylic acid (EDA) separately, and these structures are compared with the ordering behavior of P4VPPy⋯FDA.

In this paper, impedance modeling of a DC microgrid system consisting of a source and load converter, including an input filter, is performed. Impedance-based modeling has been used to derive mathematical models of the output impedance of the source converter and the input impedance of the load converter. The correlation between the converter interaction and system stability is analyzed based on the mathematical model. An impedance-based stability analysis is used to determine the system stability by analyzing the interactions among the converters in the DC microgrid system. Middlebrook's stability criterion, which uses the impedance transfer function, is applied to determine system stability. Moreover, in this paper, a stability enhancement control algorithm is proposed to resolve the system instabilities resulting from interaction among the converters and the distortion caused by the harmonics emanating from the AC input. The proposed stability enhancement control algorithm consists of a feed-forward type virtual impedance (VI) and a proportional-resonant (PR) controller. The validity of the proposed method is demonstrated by the results of the response characteristics in the frequency domain, and the effectiveness of the proposed control algorithm is verified via simulations and prototype experimental models.

Metal-free anionic polymerization of n-hexyl isocyanate (HIC) catalyzed by phosphazene bases in THF at −98 °C under 10−6 Torr was attempted to obtain poly(n-hexyl isocyanate) (PHIC) peptide mimics with a high purity. tert-Butylimino-tris(dimethylamino)phosphorene (t-BuP1), 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ5,4λ5-catenadi(phosphazene) (t-BuP2), and 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)-phosphoranylidenamino]-2λ5,4λ5-catenadi(phosphazene) (t-BuP4) with the characteristic orders of basicity and bulkiness (t-BuP1 < t-BuP2 < t-BuP4) were used as catalysts to activate N-phenethyl-3-phenylpropanamide ((PhEt)2OCNH, PEPPA). Only t-BuP2 and t-BuP4 generated the initiating amidate anions paired with each phosphazenium cation, which produced PHICs with MWs higher than the theoretical ones and characteristic ranges of dispersities. A moderately low dispersity was achieved by t-BuP2. The anionic polymerization of HIC catalyzed by t-BuP2 with molar feed ratios of the monomer to the initiator ([HIC]0/[PEPPA]0) within the range 207–801 produced PHICs with high yields (96.9–98.7%) and high MWs (Mn = 44.1–174 kDa, Đ = 1.37–1.64) that were linearly controlled by the feed ratios, even though no polymers were obtained by t-BuP1, and the products whose production was catalyzed by t-BuP4 had unpredictable MWs and high dispersities (Đ = 1.82–2.20).

Fabrication of high-conductivity ion exchange membranes (IEMs) is crucial to improve the performance of non-aqueous vanadium redox flow batteries (NAVRFBs). In the present work, anion exchange membranes with high-conductivity were fabricated by aligning ion channels of the polymer electrolyte impregnated in porous polytetrafluoroethylene (PTFE) under electric fields. It was observed that the ion channels of the polymer electrolyte were uniformly orientated in the atomic-force microscopy image. Its morphological change could minimize detouring of the transport of BF4− ions. The results showed through-plane conductivity was improved from 12.7 to 33.1 mS cm−1. The dimensional properties of the fabricated membranes were also enhanced compared with its cast membrane owing to the reinforcing effect of the substrate. Especially, the NAVRFB assembled with the optimized membrane showed increased capacities, with a 97% coulombic efficiency and 70% energy efficiency at 80 mA cm−2. Furthermore, the optimized membrane made it possible to operate the NAVRFB at 120 mA cm−2. Its operating current density was 120 times higher than that of a frequently used AHA membrane for RFBs.

Herein, we report significantly enhanced mechanical properties and thermal conductivity of polyimide (PI) by incorporating a small amount (0.01 wt %) of individualized boron-doped high-quality graphene as a filler. The boron-doped expandable graphite (B-EG) was synthesized by mixing boric acid (H3BO4) with expandable graphite (EG) and thermally treating the mixture at 2450 °C for 30 min using a graphite furnace in an argon atmosphere. The boron-doped graphene (B-g) was prepared by the solution-phase exfoliation of B-EG with an ultrasonication process, which is a method to obtain individualized graphene as well as few-layer graphene. The PI nanocomposites were prepared using the obtained graphene. The PI nanocomposites synthesized with high-quality B-graphene (B-g) showed enhanced mechanical properties and thermal conductivity compared to those of pure PI due to the doping effects and strong interfacial interactions between graphene and the PI matrix.

Self-healing polyurethane with disulfide bonds was synthesized using polycarbonate diol as a soft segment, and methylene diphenyl diisocyanate and 2-hydroxyethyl disulfide as a hard segment. Well-developed phase separation as the hard segments increased was confirmed by Fourier transform infrared spectra. The X-ray diffraction data showed that the crystallinity of the polycarbonate with a semicrystalline structure decreased as the HS increased, which affected the thermal, mechanical, and thermomechanical properties of the PU block copolymer. As the hard segments increased, the yield point on the strain-stress curve disappeared, and the mechanical properties (elongation at break and breaking stress) and the shape recovery rate of SHPU improved. The increase in the physical crosslinking between the hard segments contributed to improving shape recovery and mechanical properties. In particular, self-healing polyurethane with 30, and 35 wt% hard segments showed excellent self-healing ability at 80 C, while the self-healing ability for self-healing polyurethane with 40 wt% hard segments was decreased. The increase of the hard segment restricted the movement of the soft segment, thus the self-healing ability of SHPU with 40 wt% HS was decreased. It could be concluded that self-healing polyurethane synthesized using semicrystalline PC diol has a significant effect on shape recovery and self-healing efficiency due to the crosslinks between the hard segments.

The self-healing polyurethane films have received significant attention due to their unique shape memory behaviors and the hydrogen bonding arising from the urethane linkages. However, it is still a challenge to develop self-healing polyurethane with transparent, high impact resistance, and excellent shape recovery and mechanical properties. In particular, polycarbonate-based polyurethane shows transparency, weatherability and excellent mechanical properties. In this work, transparent self-healing polyurethane film with robust mechanical properties (breaking stress of 26 MPa and elongation at break of 630%) was synthesized by controlling the different molecular weight of the polycarbonate diol and incorporating dynamic disulfide bonds for reversibility. As a result, the self-healing polyurethane film showed an excellent self-healing ability with 98% healing efficiency and excellent shape memory ability with a recovery efficiency of ˃92%. In addition, we have identified a potential application for the self-healing flexible substrate in flexible electronics because of their stable electrical resistance even upon mechanical deformation.

Well-controlled polystyrene-polymethacrylate bottlebrush block copolymers (BBCPs) of ultrahigh molecular weight using ω-end-norbornyl polystyrene as the macromonomer for the first block were synthesized by combining living anionic polymerization (LAP) and ring-opening metathesis polymerization (ROMP). The ω-end-norbornyl polystyrene (NB-PSt), poly(tert-butyl methacrylate) (NB-PtBMA), poly(methyl methacrylate) (NB-PMMA), and poly(benzyl methacrylate) (NB-PBzMA) macromonomers (MMs) were synthesized by the LAP. The ROMP of the MMs led to poly(NB-g-St) (molecular weight, Mn = 1515 kDa, and dispersity, Ð = 1.12), poly(NB-g-tBMA) (Mn = 1470 kDa, Ð = 1.49), poly(NB-g-MMA) (Mn = 1128 kDa, Ð = 1.42), and poly(NB-g-BzMA) (Mn = 941 kDa, Ð = 1.16) bottlebrush homopolymers at degree of polymerization (DP) of 500. Synthesis of the BBCP, P(NB-g-St)-b-P(NB-g-tBMA) was well-controlled with high molecular weight and a low dispersity (Mn = 3002 kDa, Ð = 1.17) with a total DP of 976. The self-assembly of the resulting BBCP films revealed periodic lamellar morphologies with characteristic photonic crystal properties.