Synthesis and characterization of poly(methacrylates) containing spiroacetal and norbornene moieties in side chain

A four‐step synthetic strategy was applied to achieve novel methacrylic monomers. 5‐Norbornene‐2,2‐dimethanol was prepared from a Diels–Alder reaction of cyclopentadiene and acrolein, followed by the treatment of the adduct with an HCHO/KOH/MeOH solution. The resulting 1,3‐diol (1) was then acetalized with different aromatic aldehydes having OH groups on the ring to produce four spiroacetal derivatives. The reaction of methacryloyl chloride with the phenolic derivatives led to four new methacrylic monomers that were identified spectrochemically (mass, FTIR, ¹H‐NMR, and ¹³C‐NMR spectroscopy). Free radical solution polymerization was used to prepare novel spiroacetal–norbornene containing polymethacrylates, which were characterized by FTIR and ¹H‐NMR spectroscopy and differential scanning calorimetry and thermogravimetric thermal analysis. Gel permeation chromatography was performed to determine molecular weight averages and polydispersity. The polymethacrylate having naphthalenic nuclei was recognized to be the highest molecular weight polymer (M̄_n = 12144, η_inh = 0.80 dL/g) with the highest thermal stability. All the polymers showed good solubility in a variety of common organic solvents. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 30–38, 2000     

Synthesis,characterization, and comparison of self‐doped,doped, and undoped forms of polyaniline,poly(o‐anisidine), and poly[aniline‐co‐(o‐anisidine)]

Polyaniline (PANI), poly(o‐anisidine), and poly[aniline‐co‐(o‐anisidine)] were synthesized by chemical oxidative polymerization with ammonium persulfate as an oxidizing reagent in an HCl medium. The viscosities, electrical conductivity, and crystallinity of the resulting polymers (self‐doped forms) were compared with those of the doped and undoped forms. The self‐doped, doped, and undoped forms of these polymers were characterized with infrared spectroscopy, ultraviolet–visible spectroscopy, and a four‐point‐probe conductivity method. X‐ray diffraction characterization revealed the crystalline nature of the polymers. The observed decrease in the conductivity of the copolymer and poly(o‐anisidine) with respect to PANI was attributed to the incorporation of the methoxy moieties into the PANI chain. The homopolymers attained conductivity in the range of 3.97 × 10^?3 to 7.8 S/cm after doping with HCl. The conductivity of the undoped forms of the poly[aniline‐co‐(o‐anisidine)] and poly(o‐anisidine) was observed to be lower than 10^?5 J/S cm^?1. The conductivity of the studied polymer forms decreased by the doping process in the following order: self‐doped → doped → undoped. The conductivity of the studied polymers decreased by the monomer species in the following order: PANI → poly[aniline‐co‐(o‐anisidine)] → poly(o‐anisidine). All the polymer samples were largely amorphous, but with the attachment of the pendant groups of anisidine to the polymer system, the crystallinity region increased. The undoped form of poly[aniline‐co‐(o‐anisidine)] had good solubility in common organic solvents, whereas doped poly[aniline‐co‐(o‐anisidine)] was moderately crystalline and exhibited higher conductivity than the anisidine homopolymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Synthesis and characterization of new cardo poly(bisbenzothiazole)s from 1,1‐bis(4‐amino‐3‐mercaptophenyl)‐4‐tert‐butylcyclohexane dihydrochloride

A new monomer 1,1‐bis(4‐amino‐3‐mercaptophenyl)‐4‐tert‐butylcyclohexane dihydrochloride, bearing the bulky pendant 4‐tert‐butylcyclohexylidene group, was synthesized from 4‐tert‐butylcyclohexanone in three steps. Its chemical structure was characterized by ¹H NMR, ¹³C NMR, MS, FTIR, and EA. Aromatic poly(bisbenzothiazole)s (PBTs V) were prepared from the new monomer and five aromatic dicarboxylic acids by direct polycondensation. The inherent viscosities were in the range of 0.63–2.17 dL/g. These polymers exhibited good solubility and thermal stability. Most of the prepared PBTs V were soluble in various polar solvents. Thermogravimetric analysis showed the decomposition temperatures at 10% weight loss that were in the range of 495–534°C in nitrogen. All the PBTs V, characterized by X‐ray diffraction, were amorphous. The UV absorption spectra of PBTs V showed a range of λ_max from 334 to 394 nm. All the PBTs V prepared had evident fluorescence emission peaks, ranging from 423 to 475 nm with different intensity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2000–2008, 2006     

Preparation,photoisomerization, and microfabrication with two‐photon polymerization of crosslinked azo‐polymers

We report the preparation, photoisomerization properties, and three‐dimensional (3D) microstructure fabrication with two‐photon polymerization of crosslinked azo‐polymers. A series of bi‐acrylate‐substituted azobenzene derivatives were designed and synthesized as the monomers and/or crosslinkers of the crosslinked azo‐polymers. The doping concentration of the derivatives in pre‐polymer resins was significantly increased due to the introduction of bulky tert‐butyl and flexible alkyl chains. The double‐exponential dynamics of trans‐to‐cis photoisomerization of the azo‐polymers indicated the coexistence of different processes for the azobenzene moieties in the polymeric crosslinked networks. The crosslinked azo‐polymers exhibited ideal “on–off” switching performance in the highly reversible trans–cis–trans isomerization cycles. Furthermore, we prepared a photoresist containing the azobenzene derivative for 3D microstructure fabrication based on two‐photon polymerization. A woodpile photonic crystal with a photonic bandgap at telecommunication wavelength region was successfully fabricated with the azobenzene‐containing photoresist, which would open the way for the design and manufacturing of miniature optical communication devices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2947–2956, 2013     

Electropolymerization and properties of 3,4‐ethylenedioxythiophene backbone polymer with tetrathiafulvalene as pendant

Three 3,4‐ethylenedioxythiophene (EDOT) derivatives, including an EDOT‐tetrathiafulvalene (TTF) derivative, were synthesized by Steglich esterification of carboxylic acids with hydroxymethyl EDOT (3,4‐ethylenedioxythiophene methanol). The UV spectra showed that there was no distinctive intramolecular interaction for the EDOT–TTF monomer between the EDOT and the TTF moieties in the ground state; however, the cyclic voltammetry responses implied that such intramolecular interaction occurred. Electropolymerization in excessive potential could bring in strong overoxidation effects and degradation in the polymer film. The polymers were simulated using density functional theory with Gaussian03 package and the optimized HOMO and LUMO state were figured out. The conductivity of TTF‐polymer was 6 S·cm^?1 obtained by galvano station and 4.8 × 10^?3 S·cm^?1 obtained by potentiostatic electropolymerization after doping with 7,7,8,8‐tetracyanoquinodimethane. The results indicated that this polymer was a reasonable candidate for conducting materials and it was meaningful to increase the conductive dimensions of TTF polymers by chemical doping. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Thiophene‐ and silarylene‐containing polyesters. Resonance effect on conductivity after polarization in an external electric field

Polyesters were synthesized by direct polycondensation of thiophene‐2,5‐dicarboxylic acid and five different silarylene‐containing diphenols using a tosyl chloride/pyridine/N,N‐dimethylformamide system as a condensing agent. Polymers were obtained in good yields and were characterized using Fourier transform infrared and NMR (¹H, ¹³C, 135‐DEPT and ²⁹Si) spectroscopy and elemental analysis. All polymers were completely soluble in aprotic organic polar solvents such as dimethylformamide, dimethylsulfoxide and N‐methyl‐2‐pyrrolidone. The range of effective mass of the polymers (m/z) was 1 × 10⁵–2 × 10⁵, determined using electrospray ionization mass spectrometry. Asymmetry and steric hindrance prevented dense packing of the polymeric chains, showing glass transition temperatures between ? 78 and ? 51 °C and loss of thermal stability at 177–199 °C (10% weight loss). Additionally, the melting points of the polyesters were found to be in the range 62–67 °C. Because of this, the samples were semi‐solid at room temperature. The optical band gaps of the polymers were observed between 4.54 and 4.48 eV, corresponding in all cases to insulator behavior. The molecular structure of the samples was studied using X‐ray diffraction, showing a degree of order that was associated with two monoclinic lattices. Additionally, the conductivity was studied using a two‐point method with contacts on top of polymer films. Prior to the electrical measurement, the samples were polarized in an external electric field of 0.8 to 6.4 V cm^?1, and the alignment of the dipoles increased the electrical conductivity. Copyright © 2012 Society of Chemical Industry     

Effect of Nitrogen‐Doping on Detonation and Stability Properties of CL‐20 Derivatives from a Theoretical Viewpoint

Six nitrogen‐doping CL‐20 derivatives were designed and investigated as energetic materials at B3LYP/6‐31G** level based on the density functional theory method. Results show that nitrogen‐doping derivatives exhibit high crystal densities (1.98∼2.18 g cm⁻³) and positive heats of formation (451.68∼949.68 kJ mol⁻¹). Among nitrogen‐doping derivatives, 2,4,6,8,10,12‐hexanitro‐2,4,6,8,9,10,12‐heptaazaisowurtzitane(A1), 2,4,6,8,10,12‐hexanitro‐2,3,4,6,8,9,10,12‐octaazaisowurtzitane(B1) and 2,4,6,8,10,12‐hexanitro‐1,2,3,4,6,8,9,10,12‐nonaazaisowurtzitane(C1) possess better detonation velocity and pressure than CL‐20, and A1 gives the best performance (D _K‐J•A1=9.6 km s⁻¹; P _K‐J•A1=43.07 GPa). Moreover, the specific impulse, brisance, and power of N‐doping CL‐20 derivatives are also higher than that of CL‐20. The thermal stability and sensitivity of nitrogen‐doping molecules were analyzed via the bond dissociation energy (BDE ), the characteristic height (h₅₀) and electrostatic sensitivity (E _ES). The results indicate that the stability of A1, B1 and 2,4,6,8,10,12‐hexanitro‐1,2,3,4,6,7,8,9,10,12‐decaazaisowurtzitane(D1) is comparable with that of CL‐20. Considering detonation performance and stability, A1 and B1 may be promising candidates as energetic materials with superior detonation performance and favorable stability.     

Chromophoric poly(urea‐urethane)s with pendent 3‐hydroxynaphthalene group: Synthesis and characterization

The reaction of 4‐(3‐hydroxynaphthalene)‐1,2,4‐triazolidine‐3,5‐dione ( 3HNTD ) with n‐propylisocyanate was performed at different molar ratios. The resulting monosubstituted urea and disubstituted urea‐urethane derivatives were obtained in high yields and were used as model compounds for polymerization reactions. 3HNTD as a monomer was used in the preparation of heterocyclic poly(urea‐urethane)s to produce photoactive polymers, by polycondensation with different diisocyanates in N,N‐dimethylacetamide (DMAc) solution. Chromophoric heterocyclic polymers containing naphthalene group, obtained in quantitative yields, possessed inherent viscosities in the range of 0.14–0.38 dL/g. The resulting poly(urea‐urethane)s is insoluble in most organic solvents, but easily soluble in polar solvents such as dimethyl sulfoxide (DMSO), DMAc, and N‐methylpyrrolidone (NMP). The polymers were characterized by IR, ¹H‐NMR, elemental analysis, and TGA. Fluorimetric and UV–vis studies of the monomer as well as polymers were performed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of electrically conducting copolymer of aniline and o‐bromoaniline using methane sulfonic acid as dopant

Polyaniline (PAN), poly(o‐bromoaniline) (POBA), and poly(aniline‐co‐o‐bromoaniline) (PABA) were synthesized by oxidative coupling. These polymers are protonated by 10–20% methane sulfonic acid (MSA) and 1M HCl. The new polymer bases have greater solubility than that of PAN in common polar organic solvents; PAN–MSA was observed to be the most thermally stable of these polymers. POBA is associated with residual quinoid diimine units as illustrated in the IR and UV‐vis spectra, after reduction with hydrazine dihydrochloride. Both the doping agents cause a downward shift of the quinoid absorption in the IR spectra. MSA‐ and HCl‐doped PAN and PABA polymers exhibit a coil‐like conformation in DMSO, whereas only MSA‐doped PAN and PABA show an “expanded coil‐like” conformation in m‐cresol with a “free carrier tail” above 800 nm in their electronic spectra. XPS spectra indicated the presence of covalent bromine in the POBA and PABA polymers. Bromine retention was greater in the homopolymer as evidenced by the IR studies after aging at 350°C. Compared to HCl, MSA is found to be a more effective dopant, enhancing the conductivity of the copolymers by 10²–10³ times in magnitude. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2662–2669, 2002     

High temperature‐insensitive ferro‐/piezoelectric properties and nanodomain structures of Pb(In1/2Nb1/2)O3–PbZrO3–Pb(Mg1/3Nb2/3)O3–PbTiO3 relaxor single crystals

For rhombohedral (R) Pb(In_1/2Nb_1/2)O₃–PbZrO₃–Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ (PIN–PZ–PMN–PT) relaxor single crystal, high temperature‐insensitive behaviors under different external stimuli were observed (remnant polarization P_r from 30°C to 180°C and piezoelectric strain d₃₃* from 30°C to 116°C). When electric field E ≥ 50 kV/cm in the case of an activation field E_a = 40‐50 kV/cm was applied, it was found that the domain switching was accompanied by a phase transition. The high relaxor nature of the R phase PIN–PZ–PMN–PT was speculated to account for the large E_a and high piezoelectric response. The short‐range correlation lengths extracted from the out‐of‐plane (OP) and in‐plane (IP) nanodomain images, were 64 nm and 89 nm, respectively, which proved the high relaxor nature due to In³⁺ and Zr⁴⁺ ions entering the B‐site in the ABO₃‐lattice and enhancing the disorder of B‐site cations in the R phase PIN–PZ–PMN–PT. The switching process of R nanodomain variants under the step‐increased tip DC voltage was visually revealed. Moreover, the time‐dependent domain evolution confirmed the high relaxor nature of the R phase PIN–PZ–PMN–PT single crystal.     

Synthesis and characterization of new arylamine chitosan derivatives

The synthesis of new chitosan derivatives and their complete characterization by elemental analysis, Fourier transform infrared, thermogravimetric analysis, and cross‐polarity/magic‐angle‐spinning ¹³C NMR is described. A chitosan that was 96.5% deacetylated and had a viscosimetric molecular weight of 131,000 g/mol was prepared. N‐(3,5‐Diethylaminobenzoyl) chitosan with a degree of substitution of 29% and N‐(4‐ethylaminobenzoyl) chitosan with a degree of substitution of 60% were obtained. Such derivatives could be used as metal‐chelating polymers, as flocculants, and in biomedical applications because of the aryl amine moieties in their structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 807–812, 2004     

Electrical Conductivity of SiOCN Ceramics by the Powder‐Solution‐Composite Technique

SiOCN ceramics have been prepared by the polymer pyrolysis method. The preceramic polymers were synthesized from a polysiloxane cross‐linked with two different N‐containing compounds: a silazane or a ternary amine. The corresponding SiOCN ceramics were obtained by pyrolysis in nitrogen atmosphere at five different temperatures from 1000°C to 1400°C. The electrical conductivity of the powdered SiOCN ceramic samples was determined by the powder‐solution‐composite technique. The results show an increase in room temperature AC conductivity of three orders of magnitude, from ≈10^?5 (S/cm) to ≈10^?2 (S/cm), with increasing pyrolysis temperature from 1000°C to 1400°C. Furthermore, the electrical conductivity of the amine‐derived SiOCN is three to five times higher than that of the silazane‐derived ceramic at each pyrolysis temperature. The combined structural study by Raman spectroscopy and chemical analysis suggests that the increase of electrical conductivity with the pyrolysis temperature is due to the sp³‐to‐sp² transition of the amorphous carbon phase. The higher conductivity of the amine‐derived SiOCN is also discussed considering features like the volume% of the free‐carbon phase and its possible N‐doping.     

Synthesis and swelling properties of crosslinked poly(orthosilicate)s from cyclohexanedimethanols

Condensations of cyclohexanedimethanol derivatives with tetraethyl orthosilicate in the proper stoichiometric ratio produce crosslinked poly(orthosilicate)s. Synthesized crosslinked polymers have swelling abilities in common organic solvents such as tetrahydrofuran (THF), dichloromethane, benzene and acetone. All these polymers are moderately thermally stable and possess solvent uptake abilities that are not only good and fast but are also regenerable. FTIR, solid‐state ¹³C, ²⁹Si‐NMR and thermal methods were used to characterize these synthesized polymers. The effects of different cyclohexanedimethanol derivatives on the properties of polymers were also examined. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122:1182–1189, 2011     

New polyurethane cationomers with naphthyl and phenyltriazene pendants: Synthesis and properties

Two new diols bearing triazene moiety, 1‐(α‐naphthyl)‐3,3‐di(2‐hydroxyethyl) triazene‐1 (NT‐D) and 1‐phenyl‐3,3‐di(2‐hydroxyethyl) triazene‐1 (PT‐D), were synthesized from aromatic amines and diethanolamine. These monomers were used as chain coextenders in the two‐step addition reaction between poly(tetramethylene oxide) diol, 2,4‐tolylene diisocyanate, and N‐methyldiethanolamine to obtain photosensitive polyurethanes of elastomer type. Triazene polyurethane cationomers with chlorine counterions were prepared via a quaternization reaction of the above polymers with benzyl chloride. All polyurethanes had a quantity of triazene units between 7.02 and 8.93 wt % polymer, and the content of ammonium quaternary groups in the cationic ones was of 30.56 meq/100 g naphthyl triazene polyurethane cationomer (PUC‐NT) and 30.19 meq/100 g phenyl triazene polyurethane cationomer (PUC‐PT), respectively. Photobehavior of the triazene units in all polymers under continuous Hg‐lamp irradiation was similar to that found for monomers, when both chromophores were transformed during UV irradiation. It is concluded that the PT‐D acts as a more efficient sensitizer in the UV light‐induced reaction but the photolysis in elastomeric films was lower than that observed in solution. The presence of quaternary ammonium structure on the same polymer backbone decreases the constant rates of photolysis. Because the triazene polyurethanes become crosslinked during UV irradiation could be assessed as potential negative‐resist polymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2599–2605, 2004     

Boric acid binding studies with diol containing polyethylenimines as determined by 11B NMR spectroscopy

Three water‐soluble polymers incorporating increasing levels of 2,3‐dihydroxy propyl attached to polyethylenimine (PEI) backbone were synthesized, characterized by NMR, and investigated for their ability to bind boric acid (BA). ¹¹B NMR spectroscopy showed that BA interacted with the polymeric 2,3‐dihydroxy propyls by forming borate monoester and borate diesters in the boron concentration range of 100–1000 ppm and at 0.0775M polymer. Borate monoester species predominated for low functionalization levels (33% of the PEI amines functionalized), whereas borate diester species dominated for the higher functionalized polymers (66–100% of the PEI amines functionalized). All three polymers showed that 100% of the BA was bound as a mixture of borate mono‐ and diesters at 100‐ppm boron. The overall best performer based on total borate ester formation was the 2/3‐PEI, with a binding K_d of 631 at 200 ppm boron. Borate ion concentration was measured from the ¹¹B NMR chemical shift of the BA/borate peak and it decreased as 1/3‐PEI > 2/3‐PEI > 3/3‐PEI. Variable temperature ¹¹B NMR showed drastic reduction of borate ester species at 65°C. Thus, PEI polymers, as the ones investigated in this work, are reasonable candidates for the selective recovery and recycle of BA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4411–4418, 2006     

Synthesis and characterization of new 4‐tolyldiphenylamine derivatives for hole transporting polymers

New hole transport polymers have been synthesized by condensation polymerization of 4‐tolyldiphenylamine (TDPA) with various types of aldehyde. The reaction conditions have been investigated to yield polymers with high molecular weight. It is found that the molecular weight and yield of the TDPA–aldehyde polymers strongly depend on the electron donor–acceptor nature of the substituent on the aromatic ring of the aldehyde monomer. Structural characterization by ¹H NMR spectroscopy shows that the addition condensation reaction occurs exclusively at the para position of TDPA. The electrochemical and optical properties of polymers have been investigated by cyclic voltammetry and UV–vis spectroscopy. Cyclic voltammograms of all polymers show well‐defined pairs of reduction and oxidation peaks, indicating that the polymers are electrochemically active. All polymers show low conductivities of magnitude 10^?14 S cm^?1. Differential scanning calori‐metry measurements reveal that TDPA–aldehyde polymers exhibit glass transitions in the range 170–230 °C. These polymers possess good solubility and the films show sufficient morphological stability. © 2001 Society of Chemical Industry     

Investigations on electric properties and domain structures of Nd-doped 0.70Pb(Mg1/3Nb2/3)O3–0.30PbTiO3 relaxor ferroelectric ceramics with high piezoelectric properties

Although rare earth neodymium (Nd) doping is common in Pb(Mg1/3Nb2/3)O₃–PbTiO₃ (PMN–PT) single crystals, it is rarely reported in PMN–PT ceramics. To explore the effect of Nd doping on PMN–PT ceramics, PMN–30PT:xNd³⁺ (x = 0%, 1%, 2%, and 3%) relaxor ferroelectric ceramics were fabricated using a solid-state method via two-step sintering. An enhanced piezoelectric charge coefficient (d₃₃) of ∼870 pC/N and a high piezoelectric strain coefficient (d₃₃*) of ∼1025 pm/V were achieved for x = 2%. Through Rayleigh analysis of polarization–electric field (P–E) hysteresis loops under small electric fields, it was found that the dielectric property was mainly influenced by the intrinsic contribution (local lattice distortion). Furthermore, by investigating domain configurations, high piezoelectric properties were found to be associated with the domain size reduction and local structural heterogeneity. The results indicate that the PMN–30PT:xNd³⁺ ceramics is a promising material for electronic devices, and that rare earth Nd doping is an efficient strategy for improving the electronic performance of Pb-based relaxor ferroelectrics.     

Direct (hetero)arylation polymerization for the synthesis of donor–acceptor conjugated polymers based on N‐benzoyldithieno [3,2‐b:2′,3′‐d]pyrrole and diketopyrrolopyrrole toward organic photovoltaic cell application

In this research, new donor–acceptor (D‐A) photovoltaic polymers were synthesized from dithieno[3,2‐b:2′,3′‐d]pyrrole electron donor derivatives, including N‐benzoyldithieno[3,2‐b:2′,3′‐d]pyrrole and N‐(4‐hexylbenzoyl)dithieno[3,2‐b:2′,3′‐d]pyrrole, in combination with the electron deficient unit 2,5‐bis(2‐ethylhexyl)‐3,6‐di(thiophen‐2‐yl)‐2,5‐dihydropyrrolo[3,4‐c]pyrrole‐1,4‐dione via direct (hetero)arylation polymerization. The D‐A conjugated polymers obtained were characterized via ¹H NMR, gel permeation chromatography, Fourier transform infrared spectroscopy, DSC, XRD, photoluminescence and UV–visible methods. In addition, these D‐A polymers were used as activated layers in bilayer and bulk heterojunction structures for the fabrication of organic photovoltaic cells. © 2019 Society of Chemical Industry     

New polymer syntheses. IX. Synthesis and properties of new conducting polyazomethine polymers containing main chain cycloalkanone and pyridine moieties

Novel polyazomethines containing cycloalkanones or pyridine moieties were synthesized by the polycondensation of 2,5‐bis(m‐aminobenzylidene)cyclopentanone (BMAP, IV), 2,6‐bis(m‐aminobenzylidene)cyclohexanone (BMAH, V), 2,6‐bis(p‐aminobenzylidene)cyclohexanone (BPAH, VI), and 2,6‐bis(m‐aminostyryl)pyridine (BMAS, VIII) diamines with terephthalaldehyde in EtOH at 25°C. These polymers were yellow to orange in color, had reduced viscosities up to 1.42 dL/g, and had electric conductivities as high as 10⁻¹¹–10⁻¹² S cm⁻¹. All the polyazomethines were insoluble in common organic solvents but dissolved completely in concentrated sulfuric acid. However, they were readily hydrolyzed in concentrated H₂SO₄. X‐ray diffraction diagrams showed that the crystallinities of the polyazomethines were low. These azomethine polymers showed high thermal and thermooxidative stability and exhibited no appreciable decomposition up to 400°C in air. The electronic spectra of the polymers indicated a large bathochromic shift of the π–π* absorption band (∼360 nm) that was due to the presence of CN bonds in the polymer main chain. Doping with iodine dramatically raised the conductivity and produced dark brown to black colored semiconductive polymers with a maximum conductivity on the order of 10⁻⁷ S cm⁻¹. Furthermore, the morphology of selected examples of the four polyazomethines was examined by scanning electron microscopy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1218–1229, 2000     

Formation of pervaporation membranes from polyphosphazenes having hydrophilic and hydrophobic pendant groups: Synthesis and characterization

A series of new polyphosphazene polymers were synthesized using three different pendant groups with the goal of probing structure–function relationships between pendant group substitution and polymer swelling/water flux through thin dense films. Formation of polymers with relative degrees of hydrophilicity was probed by varying the stoichiometry of the pendant groups attached to the phosphazene backbone: p‐methoxyphenol, 2‐(2‐methoxyethoxy)ethanol, and o‐allylphenol. The polymers in this study were characterized using NMR, thermal methods, and dilute solution light‐scattering techniques. These techniques revealed that the polymers were amorphous high polymers (M_w = 10⁵–10⁷) with varying ratios of pendant groups as determined by integration of the ¹H‐ and ³¹P‐NMR spectra. Thin dense film membranes were solution‐cast with azo‐bis(cyclohexane)carbonitrile included in the matrix and crosslinked using thermal initiation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 422–431, 2001