Rigid chain ribbon‐like metallopolymers

A set of new copolymers is here reported in which the repeating units are connected each other through Cu(II) metal centers. The coordination link is based on the bis‐chelating properties of salicylaldiminate groups of two different monomers. Due to their chemical structure, the two monomers afford, respectively, flexible and rigid repeating units in the metallocopolymers constitution upon coordination to copper centers. All the copolymers were soluble and easily processable. As shown by XRD analysis, rigid units' rich copolymers adopt a ribbon‐like structure in solid state in which highly planar strands of polymer stack thanks to π?π interactions, similarly to the polymer composed exclusively by rigid units. This behavior can be justified assuming the existence of a partial block character in copolymer constitution where long sequences of rigid units are alternated to sequences of flexible units. This assumption is supported also by DSC and UV–Vis analysis. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2412–2421     

Synthesis and characterization of new segmented polyurethanes with side‐chain,liquid‐crystalline chain extenders

Liquid‐crystalline, segmented polyurethanes with methoxy–biphenyl mesogens pendant on the chain extender were synthesized by the conventional prepolymer technique and esterification reaction. Two, side‐chain, liquid‐crystalline (SCLC) polyurethanes with mesogens having spacers of six and eight methylene units were prepared. The structures of the mesogenic units and SCLC polyurethanes were confirmed by Fourier transform infrared spectroscopy and ¹H NMR. Polymer properties were also examined by solubility tests, water uptakes, and inherent viscosity measurements. Differential scanning calorimetry studies indicated that the transition temperature of the isotropic to the liquid‐crystalline phase decreased with increasing spacer length. Wide‐angle X‐ray diffraction (WAXD) studies revealed the existence of liquid‐crystalline phases for both SCLC polyurethanes. Polarized optical microscopic investigations further confirmed the thermotropic liquid‐crystalline behaviors and nematic mesophases of both samples. Thermogravimetric analysis displayed better thermal stabilities for both SCLC polymers and indicated that the presence of mesogenic side chains may increase the thermal stability of segmented polyurethanes. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 290–302, 2004     

Studies of protection of iron corrosion by rosin imidazoline self‐assembled monolayers

A type of rosin imidazoline (IM) has been synthesized using rosin acid and diethylenetriamine (DETA) as raw materials. The monolayers of IM were assembled on the surface of iron. The monolayers of the IM inhibitor were characterized by electrochemical impedance spectroscopy (EIS), electrochemical polarization curves and double‐layer capacitance. Surface analysis was carried out to establish the mechanism of corrosion inhibition of iron by X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy. The IM inhibitor showed good inhibition efficiency for iron in 0.1 M H₂SO₄. The inhibition mechanism of IM inhibitor was interpreted using molecular simulation. Copyright © 2006 John Wiley & Sons, Ltd.     

Chlorine‐Induced Hydrogen‐Bonding Network of A Novel Dimer Based on Nickel and Tridentate Ligand: 3‐Hydrazine‐4‐amino‐1,2,4‐Triazole

The reaction of NiCl₂ and 3‐hydrazine‐4‐amino‐1,2,4‐triazole (Hatr) in the mixed solvent of EtOH and H₂O yielded a dimer compound ([Ni₂(Hatr)₂(H₂O)₂(EtOH)₂Cl₂]Cl₂·EtOH) with water and EtOH molecules coordinated to nickle ions. It crystallized in trigonal space group R‐3, a=b=29.67(1) Å, c=8.95(7) Å, β=120(1)°, as determined by single‐crystal X‐ray diffraction. Then, they were fully characterized by the IR spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG), and elemental analysis.     

Jacket‐like structure of donor–acceptor chromophores‐based conducting polymers for photovoltaic cell applications

Through the Stille coupling polymerization, a series of soluble acceptor/donor quinoxaline/thiophene alternating conducting polymers with a hole‐transporting moiety of carbazole as a side chain ( PCPQT ) has been designed, synthesized, and investigated. The UV–vis measurement of the charge‐transferred type PCPQT s of different molecular weights with low polydispersity exhibits a red shifting of their absorption maximum from 530 to 630 nm with increasing chain length (M_n: from 1100 to 19,200). The HOMO and LUMO energy levels of PCPQT can be determined from the cyclic voltammetry measurement to be ?5.36 and ?3.59 eV, respectively. Solar cells made from PCPQT/PCBM bulk heterojunction show a high open‐circuit voltage, V_oc of ～0.75 V, which is significantly higher than that of a solar cell made from conventional poly(3‐hexyl thiophene)/ PCBM as the active polymer PCPQT has lower HOMO level. Further improvements are anticipated through a rational design of the new low band‐gap and the structurally two‐dimensional donor–acceptor conducting polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1607–1616, 2010     

Interfacial reactions of nickel ion containing multilayers and nickel ultra‐thin films with an interpenetrating polymer network substrate

An interpenetrating polymer network (IPN) substrate was prepared by dip‐pulling a silicon wafer or glass plate into polymer precursors, followed by solidification at room temperature. The nickel ion containing Langmuir–Blodgett (LB) multilayers was subsequently fabricated onto the IPN substrate by a LB technique, and then the nickel ultra‐thin films were deposited by chemical reduction. The interfacial reactions, the metal transformations and the non‐metal bond types during the film formation were detected by the X‐ray photoelectron spectroscopy, atomic force microscope and attenuated total reflection infrared spectroscopy. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis,characterization, and proton‐conducting properties of organic–inorganic hybrid membranes based on polysiloxane zwitterionomer

The synthesis and characterization of a series of zwitterionic hybrid membranes based on a zwitterionic siloxane precursor (ZS) are described. Flexible, transparent, optically homogeneous films were prepared. With the further incorporation of poly(ethylene glycol) (PEG), the hybrid films became more flexible but translucent. The structure of the inorganic sides was probed with solid‐state ²⁹Si NMR spectroscopy, and the organic sides and the chemical process involved were characterized with solid‐state ¹³C cross‐polarization/magic‐angle spinning NMR. A higher content of ZS led to higher proton conductivity of the hybrid electrolytes. Moreover, the proton conductivity was enhanced by the addition of the plasticizing component of PEG to the hybrid matrix; this was ascribed to the increased water uptake and free volume of the hybrid matrix and the dissociation of sulfonic acid groups. The proton conductivity of these hybrid membranes could be increased up to 3.5 × 10^?2 S/cm by the temperature and relative humidity being increased to 85 °C and 95%, respectively. The proton‐conduction behavior of these hybrid membranes is also briefly discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3444–3453, 2006     

XPS studies of Ni deposition on polymethyl methacrylate and poly(styrene‐co‐acrylonitrile)

Thin Ni layers were deposited onto clean polymethyl methacrylate (PMMA) and poly(styrene‐co‐acrylonitrile) (SAN) surfaces by a high vacuum thermal evaporation process. The resulting interfaces were studied by X‐ray photoelectron spectroscopy. The Ni deposition on PMMA changes the relative intensity of the C1s spectra associated with the O CO and C O carbon species, and modifies the shape of the O1s peak, while the Ni evaporation on SAN alters the C1s band intensity assigned to the CN moiety and gives a second N1s band at low binding energies. These observations suggest the formation of new chemical species at the interface between Ni and the PMMA ester group, and between Ni and the SAN nitrile group, which are the most reactive sites on these two polymers. Copyright © 2000 John Wiley & Sons, Ltd.     

Spectroscopic studies of interactions in poly(N‐acryloyl‐N′‐methylpiperazine)/acidic polymer complexes

Poly(N‐acryloyl‐N′‐methylpiperazine) (PAMP) forms complexes with four strong acidic polymers, namely, poly(styrenesulfonic acid), poly(vinylphosphonic acid), poly(acrylic acid) and poly(methacrylic acid) in ethanol/water (1:1) solution. The nature of interpolymer interactions in various complexes was studied by Fourier transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS). Both the carbonyl oxygen and the amide nitrogen of PAMP are involved in hydrogen‐bonding interactions. Some of the amine nitrogens of PAMP are protonated and therefore PAMP also interacts with the acidic polymers through ionic interactions. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 501–508, 2000     

Thermotropic liquid‐crystalline polymers containing five‐membered heterocyclic groups. X. Relationships between structures of semirigid polyesters based on three disubstituted 2,5‐diphenyl‐1,3,4‐thiadiazoles and thermotropic liquid‐crystalline and optical properties

Thermotropic liquid‐crystalline (LC) semirigid polyesters based on three terphenyl analogues of 1,3,4‐thiadiazole (2,5‐diphenyl‐1,3,4‐thiadiazole)s (DPTD) linking undecamethyleneoxy chain at different substituted positions were synthesized from three disubstituted (4,4′‐, 3,4′‐, and 3,3′‐) dioxydiundecanols of DPTD and four diesters, and the relationships between polymer structures and LC and optical properties were investigated. DSC measurements, texture observations, and wide‐angle X‐ray analyses revealed that the polymers composed of DPTD moiety having a more linear molecular structure and 1,4‐phenylene unit or short aliphatic chain tend to exhibit LC smectic C and/or A phases. The following observations were made: (1) the emergence of smectic C and/or A phases in all the polymers on the basis of 4,4′‐disubstituted DPTD, (2) formation of enantiotropic smectic C and/or A phases in the polymers containing a 1,4‐phenylene unit in the main chain, (3) formation of a more stable smectic C phase in the polymers having a short aliphatic [(CH₂)₄] chain, and (4) a decrease of the mesomorphic property of the polyesters in the order of 4,4′‐DPTD > 3,4′‐DPTD > 3,3′‐DPTD. Solution and solid‐state ultraviolet–visible and photoluminescent spectra indicated that all the polyesters display maximum absorbances and blue emissions arising from the DPTD moiety, whose peak maxima were shifted to lower wavelengths in the order of 4,4′‐DPTD > 3,4′‐DPTD > 3,3′‐DPTD as well as the aforementioned LC property. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2676–2687, 2003     

Synthesis of networked polymer based on ring‐opening addition reaction of 1,3‐benzoxazine with resorcinol

A highly efficient ring‐opening addition reaction of benzoxazine at ambient temperature has been developed with 2‐methylresorcinol as a nucleophilic reagent. In this reaction, 2‐methylresorcinol reacted with two equivalent amount of benzoxazine to give the corresponding 1:2 adduct, demonstrating its potential as a bifunctional nucleophile. Based on this reaction, a new crosslinking system consisting of a polymer bearing benzoxazine moieties in the side chains and 2‐methylresorcinol as a crosslinker has been performed to obtain the corresponding networked polymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and characterization of epoxy‐based semi‐interpenetrating polymer networks sulfonated polyimides proton‐exchange membranes for direct methanol fuel cell applications

Novel epoxy‐based semi‐interpenetrating polymer networks (semi‐IPNs) of aromatic polyimide, derived from 2,2‐benzidinedisulfonic acid (BDSA), were prepared through a thermal imidization reaction. Dynamic scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were utilized to verify the synchronization of the imidization of sulfonated poly(amic acid) (SPAA) and the crosslinking reactions of epoxy. The semi‐IPNs of epoxy/sulfonated polyimides (SPI‐EPX) exhibit excellent film‐forming characteristics and mechanical integrity at room temperature. Conductivities at 100 °C of 0.0243 S cm^?1 (SPI‐EP30) and 0.0141 S cm^?1 (SPI‐EP50) were obtained, which are similar to that of the Nafion 117 (0.0287 S cm^?1). The increase in the conductivity of SPI‐EP(30,40) with temperature is more rapid than that of Nafion 117. The SPI‐EPX exhibited lower methanol permeability than did Nafion117. The hydrolytic stability of the SPI‐EPX was followed by FTIR spectroscopy at regular intervals. SPI‐EPX prepared using epoxy‐based semi‐IPNs of sulfonated polyimide, SPI‐EP(40,50), exhibited higher hydrolytic stability than the phthalic polyimides (five‐membered ring polyimides).The microstructure was analyzed using atomic force microscopy (AFM) in the tapping mode, which demonstrated that SPI‐EP50 exhibited a nanophase that was separated into an essentially reticulated and venous hydrophobic and hydrophilic domains. Transmission electron microscopy (TEM) confirmed widespread and well‐connected hydrophilic domains, proving the higher hydrolytic stability and strong proton‐transporting properties of the SPI‐EPX membrane. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2262–2276, 2008     

XPS and resistive studies on thin films of a copper(II)‐based coordination polymer deposited on functionalized interdigital electrodes

A symmetrical 2‐thiopyrimidine based molecule with an expanded π‐electron system is synthesized and used to form a self‐assembled monolayer (SAM) on gold surfaces. Utilizing chemical vapor deposition a monolayer of (3‐mercaptopropyl)triethoxysilane is formed on silicon dioxide substrates. Both of these SAM coated substrates are characterized by X‐ray photoelectron spectroscopy and the growth of a coordination polymer built up from 5,5′‐(ethyne‐1,2‐diyl)bis(2‐hydroxyacetophenone) and copper(II) on dual SAM coated transducers is studied. After the deposition procedure on interdigital electrodes the electrical properties of the polymer are investigated performing resistive measurements. A significant change of the resistance, which depends on the surrounding atmosphere, proves the sensing behavior of the synthesized coordination polymer. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 335–344     

Synthesis and optical and electrochemical properties of thermotropic,liquid‐crystalline,semirigid copolyesters based on 2,5‐diphenyl‐1,3,4‐thiadiazole units

Novel thermotropic liquid‐crystalline (LC) copolyesters were prepared with three disubstituted (4,4′‐, 3,4′‐, and 3,3′‐) dioxydiundecanol derivatives of terphenyl analogues of 1,3,4‐thiadiazole [2,5‐diphenyl‐1,3,4‐thiadiazole (DPTD)], and their optical and electrochemical properties were examined. Their structures were characterized with Fourier transform infrared, ¹H NMR spectroscopy, and elemental analyses. The thermal and mesomorphic properties of the copolyesters were investigated with differential scanning calorimetry measurements, polarized microscopy observations, and X‐ray analyses; the data suggested that these copolymers formed LC smectic or nematic phases. The mesomorphic tendency decreased in the following order: 4,4′‐DPTD and 3,4′‐DPTD copolyesters > 4,4′‐DPTD and 3,3′‐DPTD copolyesters > 3,4′‐DPTD and 3,3′‐DPTD copolyesters. Solution and solid‐state ultraviolet–visible (UV–vis) and photoluminescence spectra indicated that the copolyesters displayed maximum absorbances and blue emissions according to the DPTD unit; the peak maxima of absorption and emission spectra of the copolyesters shifted to lower wavelengths in the aforementioned order for the LC properties. Cyclic voltammetry measurements indicated that the electrochemical band gaps of the polyesters estimated from the onset of reduction and oxidation processes were almost the same as the optical band gaps determined from the solid‐state UV–vis spectral data. The DPTD unit enhanced the hole‐injection barrier and improved the charge‐injection balance in these polyesters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1511–1525, 2005     

Analysis of the complex thermal behavior of poly(L‐lactic acid) film. I. Samples crystallized from the glassy state

The melting behavior of poly(L ‐lactic acid) film crystallized from the glassy state, either isothermally or nonisothermally, was studied by wide angle X‐ray diffraction (WAXD), small angle X‐ray scattering (SAXS), differential scanning calorimetry (DSC), and temperature‐modulated differential scanning calorimetry (TMDSC). Up to three crystallization and two melting peaks were observed. It was concluded that these effects could largely be accounted for on the basis of a “melt‐recrystallization” mechanism. When molecular weight is low, two melting endotherms are readily observed. But, without TMDSC, the double melting phenomena of high molecular weight PLLA is often masked by an exotherm just prior to the final melting, as metastable crystals undergo melt‐recrystallization during heating in the DSC. The appearance of a double cold‐crystallization peak during the DSC heating scan of amorphous PLLA film is the net effect of cold crystallization and melt‐recrystallization of metastable crystals formed during the initial cold crystallization. Samples cold‐crystallized at 80 and 90 °C did not exhibit a long period, although substantial crystallinity developed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3200–3214, 2006     

Report on the 47th IUVSTA Workshop ‘Angle‐Resolved XPS: the current status and future prospects for angle‐resolved XPS of nano and subnano films’

A summary of the workshop entitled ‘Angle‐Resolved XPS: The Current Status and Future Prospects for Angle‐resolved XPS of Nano and Subnano Films’ is given, which was held at the Riviera Maya, Mexico, 26–30 March 2007, under the main sponsorship of the International Union for Vacuum Science, Technique and Applications (IUVSTA). Angle‐resolved X‐ray photoelectron spectroscopy (ARXPS) can provide detailed chemical as well as depth profile information about the near‐surface composition of materials and thin films. This workshop was held to review the present status and level of understanding of Angle‐resolved XPS, and to stimulate discussions leading to a deeper understanding of current problems and new solutions. The main goal of the workshop was to find better ways to perform experiments and, very importantly, better ways to extract information from the experimental data. This report contains summaries of presentations and discussions that were held in sessions entitled ‘Basics and Present Limits of ARXPS’, the Analysis of ARXPS Data, Applications of ARXPS, Equipment for ARXPS, and Future Developments in ARXPS'. There were 33 participants at the workshop. Copyright © 2009 John Wiley & Sons, Ltd.     

Polymer crystalline structure and morphology changes in nylon‐6/ZnO nanocomposites

The influence of ZnO nanoparticles on the crystalline structures of nylon‐6 under different crystallization conditions (annealing at different temperatures from the amorphous solid, isothermal crystallization from the melt at different temperatures, and crystallization from the solution) has been examined with differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared. ZnO nanoparticles can induce the γ‐crystalline form in nylon‐6 when it is cooled from the melted state and annealed from the amorphous solid. This effect of ZnO nanoparticles increases with decreasing particle size and changes under different crystallization conditions. The effects of ZnO nanoparticles on the crystallization kinetics of nylon‐6 have also been studied with DSC. The results show that ZnO nanoparticles have two competing effects on the crystallization of nylon‐6: inducing the nucleation but retarding the mobility of polymer chains. Finally, the melting behavior of the composites has been investigated with DSC, and the multiple melting peaks of composites containing ZnO nanoparticles and pure nylon‐6 are ascribed to the reorganization of imperfect crystals. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1033–1050, 2003     

Preparation and properties of novel thermotropic liquid crystalline hyperbranched polyesters composed of five‐membered heterocyclic mesogen by A2 + B3 approach

New thermotropic liquid crystalline (LC) hyperbranched (HB) polyesters containing 2,5‐diphenyl‐1,3,4‐thiadiazole (DTD) unit as mesogen in the interiors were prepared at various mole ratios (A₂/B₃) by melt and solution polycondensations of a dioxydiundecanol of DTD (A₂) and 1,2,3‐propanetricarboxylic acid (B₃) via the A₂ + B₃ approach and their LC and optical properties were investigated. FTIR and ¹H‐NMR spectroscopies indicated that all the expected HB polyesters, which show good solubilities in organic solvents, are produced without gelation during the polymerization. Among them, the HB polymer prepared in the mole ratio of A₂/B₃ = 3/2 by the solution polycondensation had the highest inherent viscositiy. DSC measurents, polarizing microscope observations of optical textures, and X‐ray analyses suggested that the LC properties of HB polymers depend on the polymerization methods and the feed mole ratios. In the HB polymers prepared using the melt polycondensation, only the polymer prepared in the mole ratio of A₂/B₃ = 3/1 formed a highly‐ordered, tilted, crystal‐like smectic phase, but all the polymers prepared by the solution polycondensation formed highly‐ordered, tilted, smectic phases. Solution and solid‐state UV‐vis and photoluminescent (PL) spectra indicated that the HB polymers show maximum absorbances and blue‐light emission on the basis of the DTD unit, where the Stokes‐shifts were observed, probably because of intermolecular aggregation effects © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2998–3008, 2007