Preparation and solubility of a partial ladder copolymer from p-phenylenediamine and o-phenetidine

A series of copolymers were synthesized by chemically oxidative polymerization of p-phenylenediamine (PPD) and o-phenetidine (PHT) in acidic aqueous media. The polymerization yield, intrinsic viscosity, and solubility of the copolymers were comprehensively studied by changing the comonomer ratio, polymerization time and temperature, oxidant, monomer/oxidant ratio, and acidic medium. As-prepared fine powder of the PPD/PHT copolymers was characterized by FT-IR, UV-vis, high-resolution ¹H-NMR, and DSC techniques. A circular dichroism technique was firstly used to characterize the macromolecular structure of the copolymers. The results showed that the oxidative copolymerization from PPD and PHT is exothermic and the resulting copolymers exhibit an enhanced solubility in most of the organic solvents as compared with poly(p-phenylenediamine), sometimes also with poly(o-phenetidine). The polymer obtained is a real copolymer containing PPD and PHT units, and the actual PPD/PHT ratio calculated by ¹H-NMR spectra of the polymers is very close to the feed ratio. The DSC measurement indicates that the copolymers are amorphous and chemically instable at elevated temperature.     

Electrochemical copolymerization of m-toluidine and o-phenylenediamine

Electroactive copolymers of m-toluidine (MT) and o-phenylenediamine (OPD) were prepared electrochemically in aqueous sulfuric acid by potential cycling and characterized with cyclic voltametry, in situ conductivity measurements and FT-IR spectroscopy. The voltammograms of the copolymers exhibit different behavior for different concentrations of OPD in the comonomer feed. At optimum conditions the resulting poly(OPD-co-MT) shows an extended useful potential range of the redox activity as compared to the corresponding homopolymers. The effect of scan rate and pH on the electrochemical activity was studied. The copolymer was electrochemically active even at pH 8.0. The stability of the copolymer film was also tested. The copolymer has a potential region of maximum conductivity different from that of PMT and POPD. The conductivity of the copolymer is between the conductivity of the homopolymers. The vibrational bands at 3122/3450 and 2922/875 cm⁻¹ in the FT-IR spectra of the copolymer indicate the presence of both OPD and MT units, respectively, in the copolymer backbone.     

A promising copolymer of aniline and m-aminophenol: Chemical preparation, novel electric properties and characterization

A copolymer, poly(aniline-co-m-aminophenol), was synthesized chemically. The monomer concentration ratio strongly affects the copolymerization rate and the properties of the copolymer. A solution consisting 0.34 M aniline, 0.012 M m-aminophenol, 0.47 M ammonium peroxydisulfate and 2 M H₂SO₄ was found to be an optimum mixture for the chemical copolymerization. The visible spectra show that a high concentration ratio of m-aminophenol/aniline in the mixture inhibits the chain growth of the copolymer. The spectra of IR and ¹H NMR demonstrate that m-aminophenol units are included in the copolymer chain, which play a key role in extending usable pH region of the copolymer. The result of cyclic voltammograms in a wide potential region of −0.20-0.80 V (vs. SCE) indicates that the copolymer prepared under the optimum condition still held 52.7% of the electrochemical activity when the copolymer electrode was transferred from a solution of pH 4.0 to a solution of pH 11.0, which is much better than that of polyaniline. The X-ray diffraction spectra and images of the copolymers reveal a fact that the changes in the crystal structure and morphology of the copolymers are as a function of the monomer ratio in the mixture. The conductivity of the copolymer prepared under the optimum condition is 2.3 S cm⁻¹ and slightly depends on the pH value.     

Electrode passivation by reaction products of the electrochemical and enzymatic oxidation of p-phenylenediamine

The electrochemical and enzymatic oxidation of p-phenylenediamine (PPD) was studied under various conditions to evaluate its reversibility and stability when used as a laccase redox mediator. In accordance with published results, PPD oxidation during cyclic voltammetry showed that a passivation occurred with cycling in static systems without laccase. Such passivation was observed both in McIlvaine and acetate buffers on glassy carbon and platinum electrodes. Our results suggest that the oxidised form of PPD reacts with other PPD molecules in their reduced state to form a polymer on the surface of the electrode. When laccase is present in solution, PPD is only found in its oxidised state and another behaviour is observed at the electrode, with the appearance of a redox couple with an E’ centered at about −25 mV vs. Ag/AgCl in 0.1 M acetate buffer. These redox waves are attributed to the formation of soluble PPD oligomers. RRDE experiments showed no passivation, meaning that in order to form a film, the reaction products from the first oxidation of PPD must be further oxidised in a slow, homogeneous reaction. Results from these experiments have a significant importance in the design of efficient enzyme-modified electrodes since PPD diffusion in the thick polymer layers used to immobilise enzymes is a much slower process than in free solution, which allows enough time for the oxidation products to further react at the electrode and to polymerise on its surface. Passivation can therefore be observed with modified electrodes, even under hydrodynamic conditions, while similar conditions will provide a reversible system on bare electrodes. An example of this consequence of the reactivity of PPD oxidation products on the mediator's reversibility is given through experiments with a modified glassy carbon RDE functionalised with a thick layer of poly(ethyleneimine) microcapsules. In such case, the cyclic voltammograms showed that the oxidation and reduction processes are broader than at a bare electrode and that higher scan rates or rotation rates must be used to avoid passivation.     

Preparation and identification of a soluble copolymer from pyrrole and o-toluidine

A series of copolymers were prepared by chemically oxidative polymerization of pyrrole (PY) and ortho-toluidine (OT) in HCl aqueous medium. The yield, intrinsic viscosity, and solubility of the copolymers were studied by changing the monomer molar ratio. The resulting PY/OT copolymers were identified by FTIR, ¹H–NMR, DSC, and WAXD techniques. The experimental results showed that the oxidative polymerization of pyrrole and o-toluidine is exothermic and the resulting polymers exhibit an enhanced solubility in most organic solvents compared with that of pyrrole homopolymer. The polymer obtained is a real and amorphous copolymer containing pyrrole and o-toluidine units. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 510–518, 2001     

BA／VAc／AN／AA共聚乳液胶粘剂的研制

介绍了一种丙烯酸丁酯／醋酸乙烯酯／丙烯腈／丙烯酸四元共聚乳液胶粘剂的制备方法,该胶具有良好的耐黄变性,可替代天然橡胶胶乳应用于EVA低发泡体与腈纶绒面布的复合。     

A water‐soluble self‐doped conducting polypyrrole‐based copolymer

A water‐soluble self‐doped conducting polypyrrole‐based copolymer was synthesized via the grafting of pyrrole onto the p‐aminodiphenylamine moieties of a water‐soluble copolymer. The conductive copolymer exhibited a conductivity as large as 3.4 S/cm. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 86–89, 2001     

Nano-phase structures and mechanical properties of epoxy/acryl triblock copolymer alloys

Phase structures and mechanical properties of epoxy/acryl triblock copolymer alloys using several curing agents were studied. PMMA-b-PnBA-b-PMMA triblock copolymers synthesized by living anionic polymerization were applied as the toughening modifiers for the epoxy resins. An aromatic amine, an acid anhydride and an anionic polymerization catalyst as curing agents resulted in macro-phase separation in the epoxy/triblock copolymer blends during the cure process. However, a phenol novolac as the curing agent created nano-phase structures in the epoxy blends. The size of the spherical phases or cylindrical phases was about 40 nm in diameter, and the main component in the nano-phases was the PnBA of the triblock copolymer. The fracture toughness of the epoxy/triblock copolymer alloys with the nano-cylindrical phases reached 2530 J/m². The fracture toughness was more than twenty fold relative to the unmodified epoxy resin, and was equivalent to the toughness of polycarbonates.     

茂金属乙烯-辛烯共聚物用作树脂改性剂的进展

概述了茂金属乙烯－辛烯共聚物在聚丙烯,聚乙烯,聚酯,聚酰胺,苯乙烯基树脂等中的应用进展。     

Effect of polymerization conditions on o‐phenylenediamine and o‐phenetidine oxidative copolymers

A series of new o‐phenylenediamine (OPD)/o‐phenetidine (PHT) copolymers with partly phenazine‐like structures has been successfully synthesized at three polymerization temperatures by chemically oxidative polymerization in four different polymerization media. The molecular structures and properties of the resulting OPD/PHT polymers were investigated by IR, UV–vis and high‐resolution ¹H NMR spectroscopies, and DSC, in order to ascertain the effect of reaction temperature, comonomer ratio and acid medium. The copolymerization mechanism of OPD with PHT monomers has been proposed. It is found that the statistical OPD/PHT copolymer obtained at a temperature of 118 °C has a higher degree of polymerization than that obtained at 12–17 °C. The OPD content in the copolymers calculated from NMR spectroscopic analysis is higher than that in the feed OPD content, whereas the OPD content calculated from element analysis is slightly lower than the feed OPD content. It can be predicted that denitrogenation takes place in the OPD units during the polymerization process at OPD/PHT molar ratios of 90/10 and 100/0. These OPD/PHT copolymers exhibit a much better solubility than the OPD homopolymer, hence suggesting an incorporation of PHT units into the phenazine structure of the homopolymer. The thermal behavior of the copolymers was also studied. Copyright © 2004 Society of Chemical Industry     

茂金属乙烯－辛烯共聚物弹性体的应用

综述了茂金属乙烯－辛烯共聚物作为弹性体系材料的最新应用进展,采用藏属催化剂合成的乙烯－辛烯共聚物是一咎新型热塑性弹性体,可用注射,挤出,吹塑等常用加工方法成型,又可用过氧化物进行化学交联,用橡胶加工方法制成弹性体材料。     

Crystal structure analysis of cylindrical phase of polystyrene-b-polyethylenebutylene-b-polystyrene triblock copolymer

Crystal structure analysis of cylindrical phase of polystyrene-b-polyethylenebutylene-b-polystyrene triblock polymer was carried out. One cylinder with radius 74.20 Å passes through a hexagonal unit cell with c=∞, β=120°. The temperature factor which reflects the disorder of the cylinder is 14,525 and 〈Δr²〉^1/2 is estimated as 13.56 Å. This suggests that the cylinder is distorted and the surface of the cylinder is disordered.     

Synthesis and characterization of photochromic homopolymer/copolymer

Photochromic spiropyran homopolymer/copolymers have been prepared by radical polymerization of 5-acrylamino-1,3,3-trimethylindolino-6′-nitro-8′-methoxy spiropyran using different vinyl monomers such as methylmethacrylate, methylacrylate, and styrene. The polymerization was carried out at 80°C in dimethylformamide using α,α′-azobisisobutyronitrile as initiator. The polymers have been characterized by viscometry, gel permeation chromatography, thermogravimetric analysis, and infrared spectroscopy. The kinetics of photochromic behavior have been investigated by preparing a film of one copolymer blended with polymethylmethacrylate. This film, on exposure to sunlight or suitable wavelength, showed a very strong photochromic effect. The decoloration reaction kinetics follow a first-order relationship. The duration for return of the color depends upon the intensity of incident light, ambient temperature, moisture content, and thermal treatment of the film. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 841–848, 1997     

Asymmetric morphology from an organic/organometallic block copolymer

Block copolymer self-assembly is a burgeoning subject in polymer and materials science driven by both fundamental and applied inspirations. Whereas the vast majority of block copolymer studies have focused on highly symmetric morphologies, here we report the first observation of an unusual asymmetric cylindrical phase in thick films of an organic/organometallic block copolymer, poly(styrene-block-ferrocenyldimethylsilane) (PS-b-PFS). Microscopy and X-ray scattering data establish the lack of symmetry in this structure and reveal an unusual 3-D network organization. Following selective removal of the PS matrix, the remaining nanoporous film has characteristics of potential value in separation applications such as substantial interconnection (mechanical strength), uniform pore size, and chemical and physical stability.     

丙烯/1-丁烯无规共聚物与丙烯/乙烯抗冲共聚物的对比研究

对丙烯/1-丁烯无规共聚物(PPB)与丙烯/乙烯抗冲共聚物(PPE)的结晶行为进行对比,在等温结晶时,通过相对结晶度随时间的变化关系、等温结晶曲线等研究,表明丙烯/1-丁烯无规共聚物结晶速率明显低于丙烯/乙烯抗冲共聚物,同时丙烯/乙烯抗冲共聚物的等温结晶速率随乙烯单元含量增加没有明显降低。根据Avrami方程计算了共聚物的结晶活化能,证明丙烯/1-丁烯无规共聚物的结晶能力较丙烯/乙烯抗冲共聚物低。扫描电镜分析丙烯/1-丁烯无规共聚物在丁烯单元摩尔分数2.39%时没有韧性拉伸,而丙烯/乙烯抗冲共聚物在乙烯单元摩尔分数3%时出现韧性拉伸。     

Solution properties and self-association of multi-blocks like copolymer P(AM/AA) prepared by template copolymerization

The association and properties of multi-block like copolymers (TP) of acrylamide(AM) and acrylic acid (AA) prepared by template copolymerization in aqueous solution were studied. The results showed that the copolymers of this type exhibited a significant structure effect compared with that of similar random copolymers (CP) obtained by copolymerization in the absence of template. Decreasing the value of pH or adding Ca²⁺ ion to the copolymer solution will make phase separation occur. The TEM images demonstrated that the phase separation caused by Ca²⁺ ion was due to the formation of extensively intermolecular cross-linking. With the increase of the pH value of copolymer solution, the changes of the solution viscosity was similar with that of homopolyacrylic acid, which originally increased and then decreased. But the increase range of template copolymer was higher than that of homopolyacrylic acid. TEM images indicated that at the maximal viscosity the copolymer obtained in the presence of template formed coiled aggregates. Translated from Acta Polymerica Sinica, 2006, 5(8): 666–670 [译自: 高分子学报]     

Relating microhardness to morphology in styrene/butadiene block copolymer/polystyrene blends

The microhardness behaviour of binary blends comprising a styrene/butadiene star block copolymer and polystyrene homopolymer (hPS) over a wide composition range is investigated. In particular, the interrelation between the morphology, tensile properties (such as yield stress σ_Y and the Young's modulus, E) and the microhardness H is explored. As in the case of microphase separated block copolymers and binary block copolymer blends, as reported in preceding publications, a clear deviation in the microhardness behaviour from the additivity law is observed. The lamellar block copolymer system is compared with the nanostructure of semicrystalline polymers having a lamellar morphology. A dependence of H upon PS lamellar thickness is found. For the samples with lamellar morphology the hardness value was found to correlate with the mechanical parameters obtained by uni-axial tensile testing according to: H/σ_Y∼2.2 and E/H∼22.     

Super‐toughed polymer blends derived from polypropylene random copolymer and ethylene/styrene interpolymer

In this article, blends of polypropylene random copolymer (PP‐R) with a novel impact modifier, namely ethylene/styrene interpolymer (ESI), were prepared to evaluate the effectiveness of ESI in toughening PP‐R and the influence of ESI content on the mechanical, thermal, and rheological properties of polymer blends. Results showed that super‐toughened PP‐R/ESI blends (ca. Izod impact strength ≥ 500 J/m) were readily achieved with only 5 wt % ESI. The blends exhibited significant improvement in both impact strength and elongation, while small loss in tensile strength and elastic modulus when increasing ESI content. ESI had a nucleating effect that caused PP matrix to crystallize at higher temperatures, whereas PP‐R/ESI blends presented lower melting temperatures (T_m) than PP‐R matrix and T_m decreased with the increment of ESI content. Rheology study indicated that both PP‐R matrix and PP‐R/ESI blends presented shear thinning behaviors during melt processing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of diblock copolymers on morphology and mechanical properties for syndiotactic polystyrene/ethylene‐propylene copolymer blends

Interfacial agents are often used to compatibilize immiscible polymer blends. They are known to reduce the interfacial tension, homogenize the morphology, and improve adhesion between phases. In this study, two diblock copolymers of styrene/ethylene‐propylene (SEP), which have different molecular weights, were used to compatibilize a blend of syndiotactic polystyrene (sPS) 75% and ethylene‐propylene rubber (EPR) 25% so as to extend the applications of sPS as incoming thermoplastics. The morphological analysis and emulsification curve, which relates the average size of the dispersion particles to the concentration of diblock copolymers added, was used to investigate the efficiency of the interfacial agents on the blend morphology. A notched izod impact test and a tensile test were also performed to determine the compatibilization effect of different molecular weight copolymers on the mechanical properties of the blends and to establish links between morphology and mechanical properties. Results suggest that the lower molecular weight diblock copolymer showed an effective emulsifying capacity for sPS/ERP immiscible blend in morphology and mechanical properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3618–3626, 2004     

苯乙烯和甲基丙烯酸甲酯梯度共聚物的应用

将用原子转移自由基聚合及连续补加甲基丙烯酸甲酯（MMA）的方法制备的苯乙烯（St）/MMA梯度聚合物P（Pt-t-MMA）作为增容剂应用于聚氯乙烯/苯乙烯-丁二烯-苯乙烯嵌段共聚物（PVC/SBS）和PS/PMMA聚合物合金的增容和改性。扫描电镜结果表明,P（St-t-MMA）可以改善PVC/SBS和PMMA/PS合金的相容性。PVC/SBS合金中加入少量P（St-t-MMA)后,冲击强度从6.0kJ/m^2提高到12.1kJ/m^2,加工流变性能得到了改善。SBS用量也影响PVC/SBS合金的冲击强度。