近红外光谱法快速检测单基发射药中的二苯胺含量

采用近红外光谱法快速测定了单基发射药中二苯胺(DPA)的含量。评价了多个光谱预处理方法的优化效果,采用反向偏最小二乘法(biPLS)优选了建模波段(4 698~4 991、6 464~6 761和9 414~9 708cm-1),并根据光谱分析结果和回归系数图解释了波段的选择。基于建模参数优化结果建立了二苯胺定量模型,并对模型进行了重复性验证。研究了环境温度对模型预测结果的影响。结果表明,确定的最佳光谱预处理方法是标准正态变换(SNV)、一阶导数和平滑的组合;模型校正相关系数(Rc)和验证相关系数(Rp)分别为0.995 3和0.988 5,预测均方根误差RMSEP为0.163 5;重复性极差和标准偏差均低于0.1%;环境温度的变化对模型预测的影响不显著。该方法可用于快速检测单基发射药中的二苯胺含量。     

Reactions in Stabilizer and Between Stabilizer and Nitrocellulose in Propellants

HPLC analysis of the stabilizer is one of the major methods in use for surveillance testing of diphenylamine (DPA) stabilized propellants. Often 0.2% DPA is used as a minimum content for safe propellants. In most cases the propellant can be stored much longer after this limit has been reached without any risk for self‐ignition. We report here about a reaction where DPA bonds to nitrocellulose, leaving a non extractable aromatic stabilizing compound left in the propellant, resulting in a longer time to autocatalysis than predicted. Diphenylnitramine is discussed as a possible intermediary compound occurring from the reaction between DPA and nitrocellulose. This should add to a better understanding of the degradation processes in propellants.     

Determination of epigallocatechin‐3‐gallate with a high‐efficiency electrochemical sensor based on a molecularly imprinted poly(o‐phenylenediamine) film

An electrochemical molecularly imprinted polymer (MIP) sensor for detecting the existence of epigallocatechin‐3‐gallate (EGCG) in tea and its products was successfully developed on the basis of a glassy carbon electrode modified with an electropolymerized nonconducting poly(o‐phenylenediamine) film. The properties of the electrode were characterized by cyclic voltammetry, differential pulse voltammetry, and infrared spectroscopy. The template molecules could be rapidly and thoroughly removed by methanol/acetic acid. The linear response range for EGCG was 5.0 × 10^?7–1.0 × 10^?4 mol/L, and the limit of detection was as low as 1.6 × 10^?7 mol/L. The prepared MIP sensor could discriminate between EGCG and its analogs. In addition, satisfactory results were obtained in the detection of real tea samples. The results of our investigation indicate that the MIP sensor was useful for the determination of EGCG with excellent selectivity, high sensitivity, repeatability, and reproducibility. This MIP sensor provides the potential for monitoring the variation of EGCG content during the industrial processes and for predicting the quality of tea and its products. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

一种评估库存发射药安全贮存寿命的方法

为了科学评估库存发射药的安全贮存寿命,通过对库存弹药(发射药)长期贮存试验研究,得到了在库存环境下贮存30多年部分发射药的DPA含量试验数据,建立了相应的数据处理数学模型和安全贮存寿命预测方法。依据试验结果和该数据处理方法,计算出该发射药在置信水平为90％的条件下,安全贮存寿命不低于56年。经试验验证,该评估结果与实际情况基本相符,表明提出的估算库存发射药安全寿命的方法是可以接受的。     

Development of a voltammetric sensor based on a molecularly imprinted polymer (MIP) for caffeine measurement

A new voltammetric sensor for caffeine measurement is introduced. A caffeine-selective molecularly imprinted polymer (MIP) and a non-imprinted polymer (NIP) were synthesized and then used for carbon paste (CP) electrode preparation. The MIP, embedded in the carbon paste electrode, functioned as a selective recognition element and a pre-concentrator agent for caffeine determination. The prepared electrode was used for caffeine measurement via a three-step procedure including analyte extraction in the electrode, electrode washing and electrochemical measurement of caffeine. The MIP-CP electrode showed very high recognition ability in comparison to NIP-CP. It was shown that electrode washing after caffeine extraction led to enhanced selectivity. Differential pulse voltammetry for caffeine determination was more effective than square wave voltammetry. Some parameters affecting sensor response were optimized, and a calibration curve was then plotted. A linear range of 6 × 10⁻⁸ to 2.5 × 10⁻⁵ mol L⁻¹ was obtained. The detection limit of the sensor was calculated to be equal to 1.5 × 10⁻⁸ mol L⁻¹. This sensor was used successfully for caffeine determination in spiked beverage and tea samples.     

On the Chemical Reactions of Diphenylamine and its Derivatives with Nitrogen Dioxide at Normal Storage Temperature Conditions

The chemical reactions between nitrogen dioxide vapour and diphenylamine (DPA), some of its nitro/nitroso derivatives and between their consecutive products have been studied at temperatures of about 23 °C, whereby cellulose was used as substrate material. The following stabilizer compounds were used as starting components: DPA, N‐NO‐DPA, 2‐NO₂‐DPA and 4‐NO₂‐DPA. Concentration profiles as function of added nitrogen dioxide have been measured by HPLC. These profiles are similar to the ones obtained by accelerated aging, and the typical consecutive stabilizer products have been formed. The profiles are interpreted in terms of possible reactions. Furthermore, the influences of time and light on the decomposition of the mono‐nitro‐N‐nitroso compounds have been investigated. The consequences of these reactions are discussed to explain differences between the storage aging at ambient temperatures and the higher temperature induced accelerated aging. The reactivity towards nitrogen dioxide for each stabilizer compound was obtained by a kinetic model for the decrease of the starting component.     

Electrochemical sensor based on a poly(para-aminobenzoic acid) film modified glassy carbon electrode for the determination of melamine in milk

A novel and simple sensor is developed in this paper for melamine detection, which is based on an electropolymerized molecularly imprinted polymer (MIP) of para-aminobenzoic acid (pABA). The poly(para-aminobenzoic acid) (P-pABA) film was deposited in a pABA solution by potentiodynamic cycling of potential with and without the template (melamine) on a glassy carbon electrode. The surface feature of the modified electrode was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The molecular imprinted sensor was tested by differential pulse voltammetry (DPV) to verify the changes in redox peak currents of hexacyanoferrate. Several important parameters controlling the performance of the P-pABA were investigated and optimized. In the optimal conditions, the relative redox peak currents of hexacyanoferrate were linear. The concentration of melamine ranged from 4.0 μM to 0.45 mM, with a linear correlation coefficient of 0.9992. The detection limit was 0.36 μM (S/N = 3). The MIP sensor was successfully applied to the determination of melamine in milk products and showed high selectivity, sensitivity, and reproducibility. The results of this research demonstrate that it is feasible to use the molecular imprinting methodology when preparing sensing devices for analytes that are electrochemically inactive.     

Deposition of poly(diphenylamine‐co‐o‐chloroaniline) by pulse potentiostatic method: Growth equation and characterization

Electrochemical copolymerization of diphenylamine (DPA) with o‐chloroaniline (OCA) was performed in aqueous 4M sulfuric acid using the pulse potentiostatic method (PPSM). By employing the tunable parameters in PPSM, polymeric films were deposited under different conditions. Cyclic voltammetry was used for evaluating the characteristics of the deposited polymeric films. A suitable growth equation for the deposition of polymer, relating the charge associated for the film deposition and the pulse parameters in PPSM, was deduced. Various surface parameters are evaluated. The formation of copolymer during PPSM deposition was revealed through critical analysis of the results. The characteristic differences between the individual homopolymers, poly(diphenylamine) and poly(o‐chloroaniline) and the copolymer, poly(diphenylamine‐co‐o‐chloroaniline), were brought out. The copolymer was also synthesized through a chemical method and characterized through infrared and ultraviolet‐visible spectroscopic analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 389–397, 2003     

Electrochemical quartz crystal microbalance study of formation and redox transformations of poly(diphenylamine)

The electropolymerization of diphenylamine (DPA) dissolved in 2 mol dm⁻³ H₂SO₄ has been studied on a gold electrode by cyclic electrochemical quartz crystal microbalance measurements. Similar experiments have been accomplished with DPA microcrystals attached to a gold electrode, in the presence of aqueous acidic media. In both cases the redox transformations of the poly(diphenylamine) films formed on Au have been investigated in solutions of different pHs. The cyclic voltammograms and the mass changes refer to two closely spaced redox reactions resulting in the formation of cation radicals and dications, respectively. The irregular, broad shape of the voltammetric waves may be explained by presence of other electrochemically active sites beside the linear diphenylbenzidine structure. The results indicate a pH and potential-dependent relative contribution of anions and hydrogen ions to the overall ion exchange process. The expulsion of protons is the predominant ion transport process at the beginning of the oxidation and the incorporation of anions occurs at a later stage of oxidation. The sorption/desorption of solvent molecules also contributes to the mass change observed during the redox transformations of the polymer.     

Development of a new two‐enzyme biosensor based on poly(pyrrole‐co‐3,4‐ethylenedioxythiophene) for lactose determination in milk

A new lactose biosensor was developed by preparing a suitable copolymer of polypyrrole and poly(3,4‐ethylenedioxythiophene) synthesized using the electropolymerization method. Pyrrole and 3,4‐ethylenedioxythiophene monomers were deposited in the presence of sodium dodecylbenzene sulphonic acid on a platinum disc electrode, which was used as the working electrode. The sensor is based on the serial reactions of β‐galactosidase and galactose oxidase immobilized on a copolymer‐modified platinum disc electrode. Successful synthesis of the enzyme‐immobilized copolymer was confirmed by FT‐IR spectrometry, SEM, and electrochemical analysis. The response of the enzyme electrode to lactose was determined by cyclic voltammetry at + 0.40 V. The response time of the biosensor was found to be from 8 to 10 s, and the upper limit of the linear working portion was found to be at a lactose concentration of 2.30 mM with a detection limit of 1.4 × 10^?5 M. The apparent Michaelis–Menten constant was found to be 0.65 mM of lactose. The effects of interferents were also investigated. Lactose concentrations determined by the biosensor were in good agreement with those measured by the reference methods. Our results show that the developed biosensor has a significant potential to the determination of lactose concentration in milk. POLYM. ENG. SCI., 58:839–848, 2018. © 2017 Society of Plastics Engineers     

Synthetic Procedures Yielding Targeted Nitro and Nitroso Derivatives of the Propellant Stabilisers Diphenylamine,N‐Methyl‐4‐nitroaniline,and N,N′‐Diethyl‐N,N′‐diphenylurea

Synthetic methodologies have been developed which yield a variety of diphenylamine (DPA) and 1,3‐diethyl‐l,3‐diphenylurea (ethylcentralite or EC) propellant stabiliser degradation derivatives in high yield. The N‐alkyl nitroanilines (N‐methyl‐2,4,6‐trinitroaniline; N‐methyl‐2,4‐dinitroaniline; N‐ethyl‐2,4,6‐trinitroaniline; N‐ethyl‐2,4‐dinitroaniline; N‐ethyl‐4‐nitroaniline; N‐ethyl‐2‐nitroaniline) have been obtained either by reaction of the parent aniline with the required alkyl halide under mild conditions or via Ullmann type chemistry. A robust and high yielding approach for the synthesis of di, tri and tetranitrodiphenylamines (2,2′,4,4′‐tetranitrodiphenylamine; 2,4,4′‐trinitrodiphenylamine; 2,2′,4‐trinitrodiphenylamine; 2,4,6‐trinitrodiphenyl‐amine; 2,4‐dinitrodiphenylamine) is reported which involves passing the nitroanilines and chloronitrobenzenes down a base activated alumina column. The N‐nitroso‐N‐alkyl compounds (N‐nitroso‐N‐ethyl‐4‐nitroaniline; N‐nitroso‐N‐ethyl‐2‐nitroaniline; N‐nitroso‐N‐Methyl‐4‐nitroaniline; N‐ethyl‐N‐nitrosoaniline; N‐nitroso‐2‐nitrodiphenylamine) have been synthesised using nitrosyl acetate in acetic acid as the N‐nitrosating agent.     

A novel self-assembly approach to form tubular poly(diphenylamine) inside the mesoporous silica

MCM-41 materials were synthesized using alkyl(decosane, dodecyl)trimethyl ammonium bromide as structure directing surfactants. X-ray diffraction (XRD) analysis and nitrogen adsorption measurements reveal that the pores are hexagonal with tunable textural properties through the choice of surfactant and experimental condition. Poly(diphenylamine), PDPA was entrapped into the pores of MCM-41 by initial sorption of diphenylamine (DPA, monomer) in a medium (napthalein sulfonic acid) that provides self-assembling of DPA inside the pores and subsequent oxidative of polymerization with peroxydisulphate. Clear presence of an additional peak (around 9-10°) in XRD pattern for the DPA loaded MCM-41 provides evidence for self-assembled structure. Upon polymerization the self-assembly of DPA molecules resulted tubular PDPA inside the pores of MCM-41. PDPA thus formed shows different electronic property than the PDPA prepared by conventional method. XRD and FTIR spectroscopic analysis of PDPA loaded MCM-41 clearly informs that PDPA are entrapped in channels of MCM-41.     

Characterization of Gun Propellants by Long‐Term Mass Loss Measurements

Three different gun propellants (A5020, JA‐2 or L5460, NK1074) have been investigated up to 35 years by mass loss at isothermal temperatures between 30 °C and 90 °C. From these data, activation energies for the different reactions of zero order (mass loss increase up to stabilizer consumption) and first order (solvent evaporation at begin) are derived. The mass loss data are described very well by a combination of these two reactions. Stabilizer consumption has been determined by HPLC. In case of diphenylamine (DPA), several consecutive products (mononitro‐DPA up to tetranitro‐DPA) have been regarded also. Activation energies are in the range of energies obtained by other methods: 84 kJ/mol [A5020], 150 kJ/mol [JA‐2], 100 kJ/mol [NK 1074]). Long term measurements show seasonal influence in the mass loss data. Respective graphs are shown in this work. At least four years of measurement are recommended to compensate for the signal drift caused by seasonal changes.     

The Effects of Conventional Stabilizers and Phenol Compounds Used as Antioxidants on the Stabilization of Nitrocellulose

The thermal behavior of nitrocellulose (NC) containing diphenylamine (DPA), 2‐nitrodiphenylamine (2‐NO₂‐DPA), N‐nitrosodiphenylamine (N‐NO‐DPA), ethyl centralite (EC), akardite II (AKII), 1,1,3‐tri‐(2‐methyl‐4‐hydroxy‐5‐tert‐butyl‐phenyl)‐butane (BP_less), 3‐(3,5‐di‐tert‐butyl‐4‐hydroxy‐phenyl)‐propionic acid octadecyl ester (BP_hin), and 3‐(3‐tert‐butyl‐4‐hydroxy‐5‐methyl‐phenyl)‐propionic acid 2‐(9‐{2‐[3‐(3‐tert‐butyl‐4‐hydroxy‐5‐methyl‐phenyl)‐propionyloxy]‐1,1‐dimethyl‐ethyl}‐2,4,8,10‐tetraoxa‐spiro [5.5] undec‐3‐yl)‐2‐methyl‐propyl ester (BP_semi) was observed during isothermal storage at 393 K using a C80 microcalorimeter. The results indicate that each stabilizer decreased NC's maximum heat release rate and increased the induction period of heat release. We also observed that the maximum heat release rate and the induction period were dependent on the amount of stabilizer. DPA decreased the maximum heat release rate to the greatest extent, with the other stabilizers having similar effects on the decrease of maximum heat release rate. AKII prolonged the induction period of heat release most. The order of prolongation of the induction period was AKII>2‐NO₂‐DPA≈DPA>N‐NO‐DPA≈EC>BP_less≈BP_semi≈BP_hin.     

A novel potentiometric sensor for promethazine based on a molecularly imprinted polymer (MIP): The role of MIP structure on the sensor performance

A novel potentiometric sensor based on a molecularly imprinted polymer (MIP) for determination of promethazine (PMZ) was prepared. Promethazine MIP particles were prepared and dispersed in 2-nitrophenyloctyl ether and then embedded in a polyvinyl chloride matrix. The effect of the monomers type on the sensor performance was investigated, and an important role for this parameter was shown. It was shown that the membrane electrode with a MIP prepared by vinylbenzene and divinylbenzene had a better performance in comparison to membrane electrodes containing MIPs prepared with methacrylic acid-ethylene glycol dimethacrylate or vinylbenzene-ethylene glycol dimethacrylate. After optimization, the membrane electrode constructed with a MIP of vinylbenzene-divinylbenzene exhibited a Nernstian response (31.2 ± 1.0 mV decade⁻¹) over a wide concentration range, from 5.0 × 10⁻⁷ to 1.0 × 10⁻¹ M, with a low detection limit of 1.0 × 10⁻⁷ M and a response time of ∼50 s. The method has the requisite accuracy, sensitivity and precision to assay PMZ in syrup samples and biological fluids.     

Preparation and evaluation of a molecularly imprinted polymer for tolazoline

A uniformly sized molecularly imprinted polymer for the peripheral vasodilator drug tolazoline (T‐MIP) was prepared, and a nonimprinted polymer (NIP) was also synthesized in the same way but in the absence of the template. The T‐MIP was prepared with methylacrylic acid as functional monomer and ethylene glycol dimethacrylate as crosslinker by a multistep swelling and polymerization method. These imprinted materials were characterized by scanning electron microscopy, nitrogen adsorption, and static adsorption experiments. Binding studies were also performed to evaluate the uptake of T‐MIP and NIP with the results that T‐MIP had a significantly higher binding capacity for tolazoline (T) than did NIP. The maximum static adsorption capacities of T‐MIP and NIP for T were 78.9 and 38.8 μmol/g, respectively. The T‐MIPs and NIPs were used as stationary phases of solid‐phase extraction (SPE), and a relative selectivity coefficient (k′) value of 5.21 was obtained, which showed that the T‐MIP sorbent had higher selectivity than the NIP sorbent. The method was applied to the determination of T in urine samples. The prepared polymer sorbent showed promise for SPE for gas chromatography determination of T in urine samples. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

三种烷基二苯胺类抗氧剂的合成与性能

以二苯胺为原料,在无水氯化铝的催化作用下,分别和正己烯、正十二烯、苯乙烯反应,合成了3种不同结构的烷基二苯胺类(ADPA)抗氧剂。用红外光谱和气质联用对其分子结构进行了表征,分别采用热重和旋转氧弹法对比考察了自制抗氧剂与国外产品L57的热稳定性和抗氧化性能,并进一步研究了其与2,6-二叔丁基对甲酚(T501)、二烷基二硫代磷酸锌(ZDDP)的复配抗氧化性能。结果表明,所研制抗氧剂中对位单取代质量分数达80%以上;添加质量分数为1%时可将基础油的氧化诱导时间最高提至77倍,其与传统抗氧剂之间的复配效应则主要受烷基二苯胺分子结构的影响。     

A highly selective electrochemical sensor for l‐tryptophan based on a screen‐printed carbon electrode modified with poly‐p‐phenylenediamine and CdS quantum dots

A new highly selective electrochemical sensor for the determination of l ‐tryptophan was proposed by modifying the surface of screen‐printed carbon electrodes (SPCEs). The surface of SPCE was firstly modified by electropolymerization of p‐phenylenediamine (PPD). The polymer film was then covalently linked with cysteamine capped cadmium sulfide quantum dots (Cys‐CdS QDs) by using glutaraldehyde (GA) as a cross‐linker resulted in an organic–inorganic hybrid composite film (QDs/GA/PPD/SPCE). The modified electrode was applied as a working electrode for detecting various amino acids. It was found that the modified electrode gave an electrochemical response selectively to l ‐tryptophan over other amino acids. The experimental parameters, including pH of solution, buffer types, electropolymerization cycles, scan rate, and accumulation time, were studied and optimized. The proposed sensor can be used to detect l ‐tryptophan with a low detection limit of 14.74 µmol L^?1 with good precision and the relative standard deviation less than 3.7%. The modified electrode was used to detect l ‐tryptophan in beverage samples and gave satisfactory recoveries from 91.9 to 104.9%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40356.     

Promethazine determination in plasma samples by using carbon paste electrode modified with molecularly imprinted polymer (MIP): Coupling of extraction, preconcentration and electrochemical determination

A promethazine (PMZ) molecularly imprinted polymer (MIP) and a non-imprinted polymer (NIP) were synthesized by two different formulations of methacrylic acid-ethylene glycol dimethacrylate (MAA-EGDMA) and vinyl benzene-divinyl benzene (VB-DVB). Then, the MIPs were used to modify the carbon paste electrode (CP). The response difference between MIP-CP and NIP-CP electrodes, containing VB-DVB polymer, was higher than that for MIP-CP and NIP-CP modified with polymer of MAA-EGDMA, indicating the lower nonselective surface adsorption property of the VB-DVB based MIP. The MIP, incorporated in the carbon paste electrode, functioned as selectively recognition element and pre-concentrator agent for PMZ determination. The prepared electrode was used for PMZ measurement by the three steps procedure including analyte extraction in the electrode, electrode washing and electrochemical measurement of PMZ. It was shown that the electrode washing, after PMZ extraction, led to enhanced selectivity. Square wave voltammetry (SWV) for PMZ determination by proposed electrode was proved to be better than that of differential pulse voltammetry. Some parameters, effective on the electrode response, were optimized and then a calibration curve was plotted. Two dynamic linear range of 7 × 10⁻⁹ to 4 × 10⁻⁷ and 4 × 10⁻⁷ to 7 × 10⁻⁶ mol L⁻¹ were obtained. The detection limit of the method was calculated equal to 3.2 × 10⁻⁹ mol L⁻¹. This method was used successful for PMZ determination in blood serum sample.     

Preparation and characterization of conducting poly(diphenylamine) entrapped polyurethane network electrolyte

Composites of thermoplastic polyurethane (TPU) with poly(diphenylamine) (PDPA) were prepared by entrapping diphenylamine (DPA) molecules into the matrix of TPU and polymerizing DPA within the TPU matrix. Swelling rate of the parent TPU and the composites in 1M LiClO₄ in propylene carbonate solution were compared to understand the influence of the presence of PDPA in the composite in altering the morphology, conductivity, and electrolyte behavior. The nitrogen atoms in the PDPA interact and are likely to form hydrogen bonding with the carbonyl and ether groups in TPU. As a result, different morphology, thermal, and impedance behavior were witnessed for the composites in comparison to TPU. Results from differential scanning calorimetry, scanning electron microscopy (SEM), thermogravimetric analysis, and ac impedance measurements were obtained as supporting evidences. An increase in glass transition temperature for the composite in comparison to TPU infers the increase in phase mixing of soft and hard segment of TPU. The SEM micrograph shows the presence of fibrillar morphology of PDPA molecules in the composite. The ionic conductivity of the swelled composite was 1‐fold higher than that of pure TPU. A schematic representation showing the interaction of PDPA molecules with TPU is presented. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 611–617, 2006