Synthesis of high refractive index polyamides containing thioether unit

Two kinds of aromatic dibenzoyl chloride monomer containing thioether unit 4,4′-Bis(4-chloroformylphenylthio)benzophenone (BP-DC) and 4,4′-thiodibenzoyl chloride (T-DC) were synthesized with two steps, which was reacted with diamine monomer containing thioether and amide unit to prepare a new kind of polyamide containing high quantity thio-ether group. The intrinsic viscosity of the polyamides was 0.76–0.90 dl/g obtained with optimum synthesis conditions. The polymers were found to have good optical properties: the optical transmittance of the aromatic polyamide film at 450 nm is higher than 80%, meantime the high quantity thio-ether unit provided the polymer with a high refractive index ranging from 1.691 to 1.696 and low birefringence of 0.007–0.008. At the same time the polymers had excellent thermal performance with glass transition temperature (T_g) of 226 °C–278 °C, initial degradation temperature (T_d) of 427 °C–439 °C. They showed improved solubility in polar aprotic solvents.     

Synthesis and characterization of a cross-linkable nonlinear optical polymer functionalized with a thiophene- and tricyanovinyl-containing chromophore

This paper reports a novel nonlinear optical polymer BP-AVT-TCV functionalized with a thiophene- and tricyanovinyl-substituted chromophore. BP-AVT-TCV was synthesized by the post-tricyanovinylation of an epoxy-based precursor polymer BP-AVT, and had a high molar functionalization degree of chromophore (70 mol.%). It had an enhanced glass transition temperature (T_g = 164 °C) compared with BP-AVT (T_g = 114 °C), and a high decomposition temperature (T_d,5% = 295 °C). BP-AVT-TCV was further cross-linked to achieve the three-dimensional (3D) network of thermosetting polyurethane (PU). The poled PU films revealed an electro-optic (EO) coefficient (γ₃₃) value of 21 pm/V at a wavelength of 1315 nm. The structures of the polymers were confirmed by FT-IR, UV–Vis, and ¹H NMR spectra.     

A novel,conjugated polymer containing fluorene,pyridine and unsymmetric carbazole moieties: Synthesis,protonation and electrochemical properties

An optically active, conjugated polymer bearing unsymmetric pendant carbazole chromophores was prepared via the Suzuki coupling of 9,9-dioctylfluorene-2,7-diboronic acid and a novel pyridine-containing compound. The polymer had a T_g of 192 °C and T_d10 at 437 °C under a nitrogen atmosphere and exhibited absorption bands at 320–400 nm and displayed an additional absorption bands at 380–480 nm after protonation with aq. HCl solution. The photoluminescence of the polymer shifted from 360–460 nm to 460–560 nm after protonation and the photoluminescence quantum yield of the polymer in THF solution was 0.88. The emission color of the polymer film changed from blue (439 nm) to yellow (551 nm) under an applied bias voltage of 2.5 V.     

Continuous aluminum oxide-mullite-hafnium oxide composite ceramic fibers with high strength and thermal stability by melt-spinning from polymer precursor

Continuous aluminum oxide-mullite-hafnium oxide (AMH) composite ceramic fibers were obtained by melt-spinning and calcination from polymer precursor that synthesized by hydrolysis of the aluminum isopropoxide, dimethoxydimethylsilane and hafnium alkoxide. Due to the fine diameter of 8–9 µm, small grain size of less than 50 nm and the composite crystal texture, the highest tensile strength of AMH ceramic fibers was 2.01 GPa. And the AMH ceramic fibers presented good thermal stability. The tensile strength retention was 75.48% and 71.49% after heat treatment at 1100 °C and 1200 °C for 0.5 h respectively, and was 61.57% after heat treatment at 1100 °C for 5 h. And the grain size of AMH ceramic fibers after heat treatment was much smaller than that of commercial alumina fibers even when the heat treatment temperature was elevated to 1500 °C, benefited by the grain size inhibition of monoclinic-HfO₂ (m-HfO₂) grains distributed on the boundary of alumina and mullite grains.     

Synthesis of poly(arylene benzimidazole) sulfone (PABIS) and preparation of hollow PABIS microspheres

4,4'‐Di(benzimidazolyl)benzene sulfone, as the monomer, is very readily available by the reaction of 4,4'‐dicarboxydiphenyl sulfone with o‐phenylenediamine, and poly(arylene benzimidazole) sulfone (PABIS) has been synthesized by the condensation polymerization of bis(4‐fluorophenyl) sulfone with di(benzimidazolyl)benzene sulfone via an N–C coupling reaction. The structure of the polymer was characterized by Fourier transform IR spectroscopy, ¹H NMR spectroscopy and elemental analysis, and the results showed agreement with the proposed structure. DSC and thermogravimetric measurements showed that PABIS possesses a high glass transition temperature (T_g = 321 °C) and good thermal stability with high decomposition temperature (T_d > 530 °C). Additionally, PABIS exhibits good solubility in most polar organic solvents. Based on the good chemical and physical properties, hollow PABIS microspheres with diameters in the range 0.3–1.8 mm were prepared by the micro‐liquid technique and the double‐layer latex technique. A new double T‐channel droplet generator was developed for continuous fabrication of controlled‐size hollow PABIS microspheres. The structures of the hollow PABIS microspheres were characterized, and they possessed equal wall thickness and good spherical symmetry. © 2013 Society of Chemical Industry     

Geometrical structures in solution and solid phase of poly(propargyl ester)s prepared by using a [Rh(norbornadiene)Cl]2-cocatalyst

Propargyl esters, HCCCH₂OCOC_nH_2n+1 (1: n = 3, 2: n = 5, 3: n = 9, and 4: n = 13), were polymerized using a [Rh(nbd)Cl]₂ catalyst and cocatalyst in an appropriate solvent at 0 °C and 40 °C. Number average molecular weights, M_n of the resulting polymers, poly(1)–poly(4), were 8000–54,000, and its dispersities (M_w/M_n)s and the yields were estimated to be 1.6–3.6 and ca. ～99%, respectively. These polymers were soluble in CHCl₃, CH₂Cl₂, and THF, and insoluble in CH₃OH and DMF. The amines, e.g., 2,6-dimethylpyridine and triethylamine worked well as the cocatalysts for the polymerization to give the yields, 93% and 88%, respectively. Further N,N-diethylaniline gave the maximum in cis%, 74%, although pyridine, aniline, pyrrole or imidazole did not work effectively. Remarkable line broadening phenomenon, LBP observed in the ¹H NMR spectra of poly(1) and poly(2) prepared at 0 °C or 40 °C, and poly(3) prepared at 40 °C was correlated with the polymerization temperature and the radical concentration generated in the polymer. The LBP was interpreted by the dipole–dipole interaction between the protons in the polymer and unpaired electrons due to carbon radicals generated by the rotational scission of the cis CC bonds during the polymerization. Their UV–vis spectral shape of poly(1)–poly(4) depended on the polymerization temperature and/or the alkyl chain length in the polymer. The XRD powder patterns of poly(3) prepared at 0 °C, and poly(4)s prepared at 0 °C and 40 °C showed layer crystal structures with a slightly bent herringbone confirmed by molecular mechanics calculation. The λ_max values of poly(4) prepared at 40 °C in methanol showed 317 nm and 340 nm in the solution and on the alumina, respectively.     

The design,synthesis and nonlinear optical properties of a novel,Y-type polyurethane containing tricyanovinylthiophene of high thermal stability

A novel, Y-type polyurethane containing 1-(2,4-dioxyethoxy)phenyl-2-{5-(2,2-dicyanovinyl)-2-thiophenyl}ethenes as nonlinear optical chromophores present within the polymer backbone, was prepared and characterized. The compound was soluble in common organic solvents and displayed thermal stability up to 260 °C and a glass transition temperature (T_g) of 163 °C. The second harmonic generation coefficient (d₃₃) of poled polymer films at the compound's fundamental wavelength of 1560 nm was ～3.72 × 10^?9 esu. Dipole alignment exhibited high thermal stability up to the T_g, and there was no decay in d₃₃ below 148 °C owing to the partial main-chain character of the polymer structure.     

Thermal expansion of bismuth magnesium tantalate and niobate pyrochlores

The thermal behavior of pyrochlores composing of Bi_1·5Mg_0.75M_1.5O_6.75 (M = Nb, Ta) (sp. gr. Fd-3m:2) was studied using the high-temperature X-ray powder diffraction in a wide temperature range of 30–1200 °C. At a temperature above 1080 °C both compounds thermally dissociate forming one of the reaction products MgMO₆ (M = Nb, Ta) whose reflexes are traced on X-ray diffraction patterns after cooling the sample down to room temperature. In the case of Bi_1·5Mg_0·75Nb_1·5O_6.75 orthoniobate α-BiNbO₄ forms at about 800–1020 °C as admixture. The thermal expansion analysis of Bi_1·5Mg_0.75M_1.5O_6.75 (M = Nb, Ta) showed that the compounds studied belong to slightly or moderately expanding materials. Thermal expansion for both compounds is isotropic. With a rise in temperature the unit cell parameter a and the thermal expansion coefficient (TEC) are increased uniformly and slightly for M = Ta (Nb): from 10.52822 (10.55325) Å (30 °C) up to 10.59181 (10.62801) Å (1050 °C) and from 3.8 (30 °C) up to 7.4 (8.9) × 10⁻⁶ °С⁻¹ at 800 °C respectively. The average TEC values in the range of 30–800 °C range are 5.6 (6.4) × 10⁻⁶ °C⁻¹ for M = Ta (Nb) respectively. Bi_1.5Mg_0.75Nb_1.5O_6.75 is characterized with the highest thermal expansion that may be related to the longer bond-length of Nb(Bi)–O in the polyhedra.     

Fluorinated poly(arylene ether sulfone)s for polymeric optical waveguide devices

Pentafluorophenyl sulfone was prepared by oxidation of pentafluorophenyl sulfide. Ethynyl terminated fluorinated poly(arylene ether sulfone) (EFPAESO) was synthesized via nucleophilic aromatic substitution from 4,4′-(hexafluoroisopropylidene) diphenol or 4,4′-(trifluoromethylphenylisopropylidene) diphenol with an excess of pentafluorophenyl sulfone, followed by reaction with 3-ethylnylphenol. The molecular weights (M_ns) of the polymers determined by GPC with polystyrene standard were in the range of 6,400-17,200 and polydispersities (M_w/M_ns) were in the range of 2.25-3.19. This EFPAESO showed very high thermal stability up to 479 °C for 5% weight loss in TGA in air. T_g of the polymer was changed from 148 to 196 °C after curing. The cured films showed good chemical resistance and high thermal-stability. At 1550 nm wavelength, the refractive indices of the copolymer films were in the range of 1.5037-1.5504 and birefringences were in the range of 0.0021-0.0025. The optical loss for EFPAESO was less than 0.37 dB/cm at 1550 nm wavelength.     

Viscoelastic and gas transport properties of a series of multiblock copolymer ionomers

A series of sulfonated poly(arylene ether sulfone) (BPSH-BPS) multiblock copolymer (MBC) ionomers were studied with respect to structure and physical properties. Ion exchange capacity (IEC_w) on a weight basis was constant for all MBC ionomers with controlled ionic and nonionic block lengths of 5k:5k, 10k:10k and 15k:15k. Viscoelastic properties were investigated as a function of block length, relaxation time, and temperature ranging from 200 °C to 250 °C. Relaxation time and glassy state modulus decreased with increasing ionic block length. Williams-Landel-Ferry (WLF) theory adequately modeled the viscoelastic changes in the BPSH-BPS MBC ionomers due to changes in time and temperature using a shift factor a_T. Small Angle X-ray Scatter (SAXS) revealed an average inter-chain d-spacing that increased with increasing ionic block length (21.1, 31.4 and 36.4 nm). The larger ionic domain size is attributed to an increase in bulk ionic density within an ionic domain. Bondi’s group contribution method predicts a lower fractional free volume (FFV) with increasing ionic block length. The 15k BPSH-BPS MBC ionomer had the lowest FFV of the series, which corresponds to the lowest hydrogen permeability of 2.46 Barrers at 30 °C and 4 atm.     

Si/B/C/N/Al precursor-derived ceramics: Synthesis,high temperature behaviour and oxidation resistance

The Si/B/C/N/H polymer T2(1), [B(C₂H₄Si(CH₃)NH)₃]_n, was reacted with different amounts of H₃Al·NMe₃ to produce three organometallic precursors for Si/B/C/N/Al ceramics. These precursors were transformed into ceramic materials by thermolysis at 1400 °C. The ceramic yield varied from 63% for the Al-poor polymer (3.6 wt.% Al) to 71% for the Al-rich precursor (9.2 wt.% Al). The as-thermolysed ceramics contained nano-sized SiC crystals. Heat treatment at 1800 °C led to the formation of a microstructure composed of crystalline SiC, Si₃N₄, AlN(+SiC) and a BNC_x phase. At 2000 °C, nitrogen-containing phases (partly) decomposed in a nitrogen or argon atmosphere. The high temperature stability was not clearly related to the aluminium concentration within the samples. The oxidation behaviour was analysed at 1100, 1300, and 1500 °C. The addition of aluminium significantly improved the oxide scale quality with respect to adhesion, cracking and bubble formation compared to Al-free Si(/B)/C/N ceramics. Scale growth rates on Si/B/C/N/Al ceramics at 1500 °C were comparable with CVD–SiC and CVD–Si₃N₄, which makes these materials promising candidates for high-temperature applications in oxidizing environments.     

The synthesis,photophysical and electrochemical properties of a series of novel 3,8,13-substituted triindole derivatives

The synthesis and properties of a series of new 3,8,13-substituted triindole derivatives 1a–1e are reported. The 3,8,13-substituted triindoles were thermally robust with high decomposition temperatures (≥405 °C) and high melt transitions (219 °C–373 °C). Compound 5e was crystallized in the monoclinic system with the space group P2₁/n. These compounds showed UV–Vis absorption (λ_max^Abs) in the range of 311–345 nm in DCM solution and 371–391 nm in solid state, and fluorescence maxima (λ_max^Em) in the range of 394–412 nm in DCM solution and 416–461 nm in solid state. The fluorescence quantum yields ranged from 0.27 to 0.58. The estimated electron affinities (LUMO levels) and estimated ionization potential (HOMO levels) of compounds 1a–1e are 3.54–3.71 eV and 5.12–5.48 eV, respectively. Quantum chemical calculations using DFT B3LYP/6-31G showed nearly identical LUMO (−0.72 to −1.10 eV) and HOMO (−4.65 to −4.84 eV) values. These results demonstrated that the new 3,8,13-substituted triindoles are promising thermally stable host materials for organic light-emitting diodes with reasonable hole mobility.     

Control of refractive index by annealing to achieve high figure of merit for TiO2/Ag/TiO2 multilayer films

We modified the refractive index (n) of TiO₂ by annealing at various temperatures to obtain a high figure of merit (FOM) for TiO₂/Ag/TiO₂ (45 nm/17 nm/45 nm) multilayer films deposited on glass substrates. Unlike the as-deposited and 300 °C-annealed TiO₂ films, the 600 °C-annealed sample was crystallized in the anatase phase. The as-deposited TiO₂/Ag/as-deposited TiO₂ multilayer film exhibited a transmittance of 94.6% at 550 nm, whereas that of the as-deposited TiO₂/Ag/600 °C-annealed TiO₂ (lower) multilayer film was 96.6%. At 550 nm, n increased from 2.293 to 2.336 with increasing temperature. The carrier concentration, mobility, and sheet resistance varied with increasing annealing temperature. The samples exhibited smooth surfaces with a root-mean-square roughness of 0.37–1.09 nm. The 600 °C-annealed multilayer yielded the highest Haacke's FOM of 193.9×10⁻³ Ω⁻¹.     

Optical and Microwave Dielectric Properties of Phase Pure (K0.5Na0.5)NbO3 Thin Films Deposited by RF Magnetron Sputtering

(K_0.5Na_0.5)NbO₃ (KNN) thin films have been deposited onto Pt/Ti/SiO₂/Si and quartz substrates by RF magnetron sputtering. The films were deposited at 400°C with the variation in oxygen mixing percentage (OMP) ratio from 0% to 100% and annealed at 700°C in oxygen atmosphere. The crystallinity of the films is found to be increased with increased OMP. Dielectric properties of the films were examined over the frequency range from 1 kHz to 1 MHz and the temperature range of 30°C to 400°C. The Curie temperature of the films was found to be in the range 369°C–373°C. For the first time, the split postdielectric resonator (SPDR) method was used to measure the microwave (10–20 GHz) dielectric properties of KNN thin films. The optical properties of as‐deposited and annealed KNN thin films were investigated by means of transmittance spectra. The optical bandgap is calculated by using the Tauc relation, and found to be in the range 4.34–4.40 eV and 4.29–4.37 eV for the as‐deposited and annealed films, respectively. The refractive index (n_700nm) of the films found to be in the range 1.98–2.01 and 1.99–2.07 for as‐deposited and annealed films, respectively. The refractive index dispersion is analyzed by using Wemple–DiDomenico (W–D) single‐oscillator model. The effect of annealing and OMP on the refractive index, packing density and W–D parameters has been investigated. The average single oscillator energy (E_o) and dispersion energies (E_d) of the annealed KNN thin films are in the range of 6.17–7.16 eV and 18.77–22.19 eV, respectively. AC‐conductivity of the annealed films was analyzed by using double power law. Ag/KNN/Pt thin films followed the ohmic conduction (J ∝ E^α, where α ~1) and the low leakage current density obtained for the deposited at 100% O₂ is 3.14 × 10^?5 A/cm² at 50 kV/cm.     

Interfacial microstructure characterization and strength evaluation of Si3N4/Si3N4 joints with Si–Mg composite filler for high-temperature applications

Silicon-nitride (Si₃N₄) components were joined under vacuum at 1100 °C for 10 min using Si–Mg composite fillers with Mg contents (X_Mg) that ranged from 0 at.% to 59 at.%. The Si₃N₄/Si₃N₄ joints were fabricated via Si layer formation at the joint interface; the molten Si–Mg liquid was transformed into a solid Si layer after Mg-evaporation-induced isothermal solidification. The joint tensile strength at room temperature increased considerably when X_Mg exceeded the liquidus composition of 37 at.% because of the enhanced densification/thinning of the Si layer. In these cases, some Mg atoms reacted with Si₃N₄ to form a fine-grained MgSiN₂-based layer, whereas relatively large (>0.1 μm) and smaller MgO precipitates (<10 nm) were observed in the Si layer. At a high X_Mg, the MgO precipitates were arranged in a network-like structure, which improved the fracture strength of the Si layer. The joints with a high strength at room temperature were examined using a three-point bending test at 1200 °C in air and endured a maximum fracture stress of ~200 MPa, which confirmed their potential for use in oxidizing atmospheres at least 100 °C above the bonding temperature.     

Synthesis of NiMn2O4 thin films via a simple solid-state reaction route

Herein, NiMn₂O₄ (MNO) spinel oxide thermistor films were synthesized on a SiO₂/Si substrate via annealing the electron beam evaporated Mn–Ni–Mn metal trilayers in air at different temperatures. The X-ray diffraction (XRD) results indicate that polycrystalline spinel-structured MNO thermistor films were formed. The surface particle size of the series MNO films quickly reduced from ~300 to ~120 nm with a temperature increase from 650 to 750 °C, and then, slowly reduced to 80 nm or even smaller with a temperature increase from 750 to 950 °C. Specifically, 750 °C anneal formed the spinel MNO film with largest B value of 5067 and Ea value of 0.4366. The proposed synthesis route for MNO spinel oxide film has been proven to be feasible.     

Synthesis, characterization and optical properties of cross-linkable poly(phthalazinone ether ketone sulfone)

Cross-linkable poly(phthalazinone ether ketone sulfone) bearing tetrafluorostyrene groups (PPEKS-FSt) has been prepared by copolycondensation reaction for optical waveguide applications. The resulting amorphous polymer exhibits good solubility in some common polar organic solvents (e.g., N,N′-dimethylacetamide, N-methyl-2-pyrrolidinone, chloroform) at room temperature, and can be easily spin-coated into thin films with good optical quality. The glass transition temperature (T_g) and the temperature of 1% weight loss (1% T_d) are 261 °C and 494 °C, respectively, which could be further increased by 31 °C and 14 °C upon thermal cross-linking. The cross-linked polymer thin films exhibit high refractive index (∼1.65, TE mode), high thermo-optic coefficient value (dn/dT) (−1.455 × 10⁻⁴/°C, TE mode), low optical loss (less than 0.24 dB/cm at 1310 nm) and relatively low birefringence (∼0.007).     

Effects of annealing temperature on the phase formation,optical, photoluminescence and magnetic properties of sol-gel YFeO3 films

YFeO₃ (YFO) thin films were deposited onto quartz substrates via sol-gel spin-coating technique and annealed at different temperature ranged between 650 and 900 °C. The impact of annealing temperature on the phase formation, microstructural, optical, photoluminescence (PL) and magnetic properties of the films were systematically investigated. X-ray diffraction analysis revealed an amorphous structure in film annealed at 650 °C and formation of hexagonal-YFO (h-YFO) phase in films annealed at 750–800 °C. The films annealed at 850–900 °C exhibited an orthorhombic-YFO (o-YFO) structure. Atomic force microscopy images of h-YFO films showed homogeneous surface with uniform particles size and shape. The particle size increased and had irregular shape in o-YFO films. The average particle size was 44 and 117 nm, while the root square roughness was 1.38 and 2.55 nm for h- and o-YFO films annealed at 750 and 850 °C, respectively. The optical band gap (E_g) was 2.53 and 2.86 eV for h- and o-YFO films annealed at 750 and 850 °C, respectively. The PL spectra of h-YFO films were red-shifted compared with that of o-YFO films. The PL emission related to near band edge was observed at 459.0 and 441.9 nm for h- and o-YFO films annealed at 750 and 850 °C, respectively. The magnetization was enhanced with the increasing of annealing temperature and has the value of 4.8 and 12.5 emu/cm³ at 5000 Oe for h- and o-YFO films annealed at 750 and 850 °C, respectively.     

Microstructure,mechanical and optical properties of MgAl2O4/MgAl2O4 joints bonded using CaO-Al2O3-SiO2 glass filler

Transparent MgAl₂O₄ ceramics were bonded by using CaO-Al₂O₃-SiO₂ (CAS) glass filler. The CAS glass filler exhibited the same thermal expansion behavior as MgAl₂O₄ ceramic and excellent wetting ability on the surface of MgAl₂O₄ ceramic. When the cooling rate of 15 °C/min was used, no interfacial reaction was observed and the amorphous brazing seam could be obtained. However, low joining temperature (1250 °C) led to the formation of pores and high joining temperature (1400 °C) resulted in the formation of cracks. Furthermore, the slow cooling rate of 5–10 °C/min induced the crystallization of CaAl₂Si₂O₈ and Mg₂Al₄Si₅O₁₈ due to the dissolution of MgAl₂O₄ substrate. The optimal flexural strength of 181–189 MPa was obtained when the joining temperature and cooling rate were 1300–1350 °C and 15 °C/min respectively. Moreover, the in-line transmittance of the joint at 1000 nm was 82.1%, which was slightly lower than that of MgAl₂O₄ ceramic (85.6%).     

Synthesis and characterization of poly(ether sulfone) copolymers

Poly(ether sulfone) copolymers I–V were synthesized by the nucleophilic substitution reaction of 4,4-dichlorodiphenyl sulfone with varying mole proportions of 4,4-isopropylidene diphenol (bisphenol A) and 4,4-dihydroxydiphenyl sulfone (bisphenol S) using sulfolane as the solvent in the presence of anhydrous K₂CO₃. The polymers were characterized by different physicochemical techniques. The glass transition temperature was found to decrease with increase in the concentration of bisphenol A units in the polymers. All polymers were found to be amorphous. Thermogravimetric studies showed that all the polymers were stable up to 400°C with a char yield of about 36% at 900°C in a nitrogen atmosphere. ¹³C-NMR spectral analysis reveals that bisphenol S-based triads are preferentially formed compared to bisphenol-A triads, indicating greater reactivity of bisphenol S toward dichlorodiphenyl sulfone. The overall activation energy for the thermal decomposition of bisphenol A-based polymer (1) is much higher than that of bisphenol S-based polymer ( II ). This was attributed to the modification of the backbone of polymer I during the initial cleavage of the C—CH3 bond of the isopropyledene group. Polymer II decomposes by cleavage of the C—SO2 bond. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 743–750, 1998