Microemulsion polymerization of styrene stabilized by sodium dodecyl sulfate and diethylene glycol monoalkyl ether

The effects of the cosurfactants diethylene glycol monoalkyl ether [C _i H_{2 i +1}O(CH₂CH₂O) _j OH (C _i E _j ; i=4, 6 and j=1, 2)] on the formation of an oil-in-water styrene (ST) microemulsion and the subsequent free radical polymerization were studied. For comparison, the data for the C _i H_{2 i +1}OH (C _i OH; i=4, 6) systems obtained from the literature were also included in this work. Sodium dodecyl sulfate was used as the surfactant. The pseudo three-component phase diagram (macroemulsion, microemulsion and lamellar gel phases) was constructed for each cosurfactant. The primary parameters selected for the polymerization study are the concentrations of cosurfactant and styrene. The number of latex particles nucleated is much smaller than that of the microemulsion droplets initially present in the reaction system. Limited flocculation of the latex particles occurs to some extent during polymerization. Among the cosurfactants investigated, the C₄OH-containing polymerization system is the least stable. By contrast, the diethylene glycol monoalkyl ether group of C _i E _j tends to enhance the latex stability. C _i E _j is more effective in stabilizing the ST microemulsion and the subsequent polymerization in comparison with the C _i OH counterpart. Received: 24 December 1999 Accepted: 9 February 2000     

Catalysis of heteropoly acidic salts for synthesis of diethylene glycol ethyl ether with diethylene glycol and ethanol

Ag₃PW₁₂O₄₀ and Ag₄SiW₁₂O₄₀ showed high activity and stability in the synthesis of diethylene glycol ethyl ether with diethylene glycol and ethanol, on which the conversion is 80.2% and 78.4%, respectively, and the selectivity of diethylene glycol ether is 75.4% and 80.6%, respectively. After the third reaction cycle, Ag₃PW₁₂O₄₀ and Ag₄SiW₁₂O₄₀) still showed higher activity and selectivity, on which the conversion is 72. 6% and 77.5% respectively. But the activity of Ag₃PMo₁₂O₄₀ is lower, the conversion is only 21.0%. IR, XRD, TG and n‐butylamine titrimetry showed that the catalysis may be connected with two kinds of acidic centers owned by heteropoly acidic salt.     

气相色谱-质谱法快速测定牙膏中的二甘醇

建立了气相色谱-质谱法（GC-MS）快速测定牙膏中的二甘醇的方法。牙膏样品经三氯甲烷提取后,应用气相色谱-质谱联用仪,以选择离子监测（SIM）模式对其中的二甘醇进行分析。二甘醇的线性范围为21.24-1062 mg/L,线性相关系数（r）为0.9995;检出限和定量限分别为2.0、5.0 mg/L;高、中、低3种浓度下的回收率在88.51%-101.6%之间,相对标准偏差（RSD）在1.6%-8.11%之间;仪器对二甘醇的响应在24 h内保持稳定。     

Identification and quantification of polyethylene glycol types in polyethylene glycol methyl ether and polyethylene glycol vinyl ether

Quantitative determination of polyethylene glycol (PEG) impurities in two monofunctional polyglycol types, PEG methyl ether (M-PEG) and PEG vinyl ether (V-PEG), has been carried out by reversed-phase liquid chromatography with evaporative light scattering detection (ELSD). In addition to optimizing the resolution between PEG and monofunctional PEG peaks, the major focus has been to determine the molecular weights of PEG impurities in M-PEG and V-PEG of diverse molecular weights. The latter is achieved by examining liquid chromatography–mass spectrometry (LC–MS) mass spectra of both monofunctional PEG and PEG in several cases, and matching peak retention times with those of available PEG standards for all M-PEG and V-PEG sample types. This information is helpful in selecting the appropriate PEG standard to determine PEG content in each sample type. ELSD response factors for various PEG standards have also been compared. It has been found that PEG standards with molecular weights from 1000 Da to 8000 Da show responses that are within 10% of each other. However, a low molecular weight PEG such as PEG 400, provides approximately 30% less response compared to its higher molecular weight counterparts.     

Simultaneous determination of diethylene glycol and propylene glycol in pharmaceutical products by HPLC after precolumn derivatization with p-toluenesulfonyl isocyanate

A simple and reliable HPLC method was developed for the simultaneous quantitative analysis of diethylene glycol (DEG) and propylene glycol (PG) in pharmaceutical products by precolumn derivatization. The derivatization reagent p-toluenesulfonyl isocyanate (TSIC, 10 microL, 20% in ACN v/v) was added to 100 microL of the sample, and then 10 muL of water was added. The resulting derivatives were separated using a C(18)analytical column and a mobile phase composed of 0.01 M KH(2)PO(4)buffer (adjusted to pH 2.5 with phosphoric acid) and ACN (47:53 v/v) at 1 mL/min and 25 degrees C. For detection, UV light at 227 nm was used. The derivatization conditions including reaction time, temperature, and concentration of TSIC were optimized. The calibration curves were linear from 0.062 to 18.6 microg/mL (r(2)= 0.9999) and from 0.071 to 21.3 microg/mL (r(2) = 0.9999) for DEG and PG, respectively. The RSD values of intra- and interday assays were all below 4% for DEG and PG. The proposed method was then successfully applied to analyze two Armillarisin A injection samples and two spiked syrup samples.     

Ternary diffusion coefficients of diethylene glycol and lithium chloride in aqueous solutions containing diethylene glycol and lithium chloride

In this work, ternary diffusion coefficients of diethylene glycol and lithium chloride in aqueous solutions containing diethylene glycol and lithium chloride were reported for temperatures (303.2, 308.2, and 313.2 K) using the Taylor dispersion method. The investigated ternaries contained total glycol–salt concentrations of 10, 15, and 20 wt%. The main diffusion coefficients (D₁₁ and D₂₂) and the cross-diffusion coefficients (D₁₂ and D₂₁) were discussed as function of temperature and concentration. A modified equation originally proposed by Batchelor [1] for mixture of hard spheres in a continuum solvent was used to correlate the present diffusion coefficient data and the results are satisfactory.     

Kinetics of poly(ethylene terephthalate) glycolysis by diethylene glycol. I. Evolution of liquid and solid phases

The kinetics of uncatalysed glycolysis, at 220 °C, of poly(ethylene terephthalate) (PET) by diethylene glycol (DEG) in high excess has been studied. An experimental device allowing good separation, at reaction temperature, of the solid and liquid phases was set up.The results suggest that PET is initially depolymerized in the slightly swollen solid phase, by glycolysis of the amorphous interlamellar chains. This mechanism continues until a solid phase of highly crystallized polyester is obtained.The internal tensions engendered by this chemical modification cause cracks, delamination and mechanical disintegration of the polymer. The transfer towards the liquid phase is then strongly accelerated and the solvolysis of the depolymerization products continues in the liquid phase, up to equilibrium.     

丁二酸二(二乙二醇单甲醚)酯的制备及其应用

以二乙二醇单甲醚和丁二酸酐为原料,对甲苯磺酸为催化剂,在二甲苯中经开环反应合成了丁二酸二(二乙二醇单甲醚)酯(1),其结构经1H NMR和IR确证。采用恒电流充电法、循环伏安扫描和充放电性能测试了电解质溶液[1.2 mol·L-1双三氟甲基磺酰亚胺锂(LiTFSI)/V(1)∶V(EC)∶V(DEC)=3∶3∶4]在锂离子电池中的电化学性能。结果表明:1与石墨负极有较好的相容性,在0 V~2 V,0.1 C下充放电20次后放电比容量为346.2 mAh·g-1,容量保持率为111.10%。     

Kinetics of poly(ethylene terephthalate) glycolysis by diethylene glycol. Part II: Effect of temperature, catalyst and polymer morphology

The influence of various parameters on the kinetics of poly(ethylene terephthalate) (PET) glycolysis by diethylene glycol (DEG), namely temperature (from 190 to 220 °C), temperature profile, catalysis and PET morphology has been studied.The results showed a strong influence of some experimental conditions (temperature and catalysis) on the mixture evolution during depolymerisation. The temperature study showed a critical temperature between 210 and 220 °C which seems to be the consequence of a better diffusion of DEG in PET, allowing easier reactions in solid phase. The initial morphology of PET scraps does not affect the rates of reactions much, in contrast to the temperature profile which has a great importance: time of PET dissolution at 220 °C is considerably shorter by heating PET and DEG separately at 220 °C before mixing, than by heating a cold mixture of the two reagents to 220 °C.     

Synthesis of highly cross-linked poly(diethylene glycol dimethacrylate) microparticles in supercritical carbon dioxide

Herein we report the synthesis of poly(diethylene glycol dimethacrylate), poly(DEGDMA), by free-radical heterogeneous polymerization in supercritical carbon dioxide (scCO₂), using a commercially available carboxylic acid end-capped perfluoropolyether oil (Krytox 157FSL) as stabiliser. The effect of initial concentration of stabiliser, monomer and initiator on the yield and morphology of the resulting polymer has been investigated. Krytox worked effectively as a stabiliser and discrete poly(DEGDMA) particles with diameters ranging from 1.28 to 2.08 μm and narrow particle size distribution were produced in supercritical carbon dioxide, in high yield and in short reaction times, without making use of harmful organic solvents.     

A means of analysing glycols,especially ethylene glycol and diethylene glycol,by a method used for the determination of carbohydrates in alcoholic beverages

Summary This paper describes the separation of carbohydrates/glycerol/ethylene glycol/diethylene glycol in alcoholic liquids by TLC. An in situ reaction already proven in carbohydrate analysis is used for the detection among other things, of diethylene glycol in low, unpermitted concentrations and is compared with vanadium pentoxide derivatisation also described in the literature. Only the vanadium pentoxide reaction yields satisfactory results for diethylene glycol. The information capacity of HPTLC chromatograms is also demonstrated by the simultaneous analysis of 19 samples. Chromatogram filing is an important consideration, since the lifespans of chromatograms derivatised by the two methods vary considerably. Plates or sheets treated with dichlorofluorescein can still be evaluated over a period of years, whereas plates treated with vanadium pentoxide are unusable after only a few weeks. An advantage of the latter procedure, however, is the amenability of the chromatograms to normal photocopying.     

Assessment of dentifrice adulteration with diethylene glycol by means of ATR-FTIR spectroscopy and chemometrics

A direct and fast method for determination of the adulterant diethylene glycol (DEG) in toothpaste and gel dentifrices combining attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy with partial least squares (PLS) regression has been proposed. Considering the high heterogeneity of dentifrices available in the market, the possibility of reducing the number of calibration samples for PLS was evaluated. Similar prediction performance was achieved by both employing a large calibration set of 20 dentifrices spiked with different amounts of DEG and a reduced calibration set of seven ones selected by means of hierarchical cluster analysis (HCA). The feasibility of using the simple calibration model to predict DEG adulteration in a wide variety of unknown dentifrice samples increases the applicability of the proposed method. With this approach, DEG was quantified with a root mean squared error of prediction value of 1.1% for a validation set of 40 different dentifrices containing DEG in the range 0–16% (w:w).     

LC-ESI-MS determination of diethylene glycol pollution in sea water samples collected around gas extraction platform plants

Produced formation waters (PFWs) represent the largest aqueous wastes that are normally discharged into the marine environment during the offshore gas production processes. The chemical additive diethylene glycol (DEG) is widely used in the gas production line and therefore can be found in the PFW, becoming of environmental concern. In this study, a new method has been developed for trace determination of DEG in sea water samples collected around offshore gas platforms. The method is based on liquid chromatography coupled to electrospray ionization mass spectrometry (LC-ESI-MS). Prior to analysis, water samples were derivatized using the Schotten-Baumann method for the benzoylation of glycols. The derivatization procedure allowed us to maximize the ESI-MS response of DEG and minimize the influence of interfering compounds. The method was validated and allowed a quantification of DEG in sea water samples with a method LOD of 0.4 ng/mL. The applicability of the procedure was demonstrated by analyzing sea water samples collected around eight gas platforms located in the Adriatic Sea (Italy).     

Densities and relative permittivities of binary mixtures containing dipropylene glycol monomethyl ether

Relative permittivities () and densities () of numerous binary mixtures of dipropylene glycol monomethyl ether (1)+propylene glycol mono n-butyl ether (2) and dipropylene glycol monomethyl ether (1)+dipropylene glycol mono n-butyl ether (2) at five temperatures, between (293.15 and 313.15) K, are reported. The excess molar volumes (V ^E) and the relative permittivity deviations () were calculated from these experimental data. The results are discussed in terms of intermolecular interactions in the bulk of studied the binary mixtures.     

Synthesis of nano-TiO2 assisted by diethylene glycol for use in high efficiency dye-sensitized solar cells

The performance of dye-sensitized solar cells(DSSCs) consisting of anatase TiO_2 nanoparticles that were synthesized via a hydrothermal method was studied.The synthesized TiO_2 nanoparticles were characterized by X-ray diffraction(XRD),nitrogen sorption analysis,scanning electron microscopy(SEM),high resolution transmission electron microscopy(HRTEM),and UV-vis spectroscopy.Then the J-Vcurve,electrochemical impedance spectroscopy(EIS),and open-circuit voltage decay(OCVD) measurement were applied to evaluate the photovoltaic performance of DSSCs.Compared with the commercial TiO_2nanoparticles(P25),the synthesized-TiO_2 nanoparticles showed better performance.By adding diethylene glycol(DEG) before the hydrothermal process,the synthesized TiO_2 nanoparticles(hereafter referred to as TiO_2-DEG particles) shows narrower size distribution,larger specific surface area,higher crystallinity,and less surface defects than TiO_2(DEG free) particles.The analysis of photovoltaic properties of DSSCs based on TiO_2-DEG particles showed that the recombination of electron-hole pairs was decreased and the trapping of carries in grain boundaries restrained.It was believed that the photoelectrode fabricated with the as-prepared TiO_2 nanoparticles improved the loading amount of dye sensitizers(N719).and enhanced the photocurrent of the DSSCs.As a result,the TiO_2-DEG particle based cells achieved a photo-to-electricity conversion efficiency(η) of 7.90%,which is higher than 7.53%for the cell based on TiO2(DEG free) and 6.59%for the one fabricated with P25.     

硅胶负载硫酸锆催化合成乙二醇乙醚乙酸酯

以乙酸和乙二醇单乙醚为原料,硅胶负载筛选得到的硫酸锆为催化剂,环己烷为带水剂,合成了乙酸乙二醇单乙醚酯。考察了乙二醇单乙醚与乙酸的摩尔比、催化剂、带水剂用量、反应温度、时间等因素对反应的影响。在120℃反应2.5h,乙酸乙二醇单乙醚酯收率达到98%以上,产物经IR,1H NMR等方法确证。     

New derivatizing reagent for analysis of diethylene glycol by HPLC with fluorescence detection

N‐(2‐Phenyl‐indolyl)‐acetic acid (PIAA), a new fluorescent derivatizing reagent, was used for the determination of diethylene glycol (DEG) by high‐performance liquid chromatography with fluorescence detection. DEG was derivatized to ester by using PIAA in the presence of 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodimide hydrochloride (as dehydrating agent) and 4‐(dimethylamino)pyridine (as base catalyst) in acetonitrile at 60°C for 75 min. The influence of solvent, temperature, catalyst base, concentration of labeling reagent, and couple reagent on the derivatization was investigated. The fluorescence detection was performed with excitation at 340 nm and emission at 377 nm. Baseline separation was obtained on an Ultimate XB‐C18 analytical column with water/acetonitrile gradient elution, good linearity was obtained within 0.5–50 μg/mL with a correlation coefficient of 0.9997. The limit of detection was 0.01 μg/mL (signal‐to‐noise ratio = 3). The method has been successfully applied to determine DEG in toothpaste samples with satisfactory recoveries ranging from 89.0 to 94.9%. The proposed method was shown to be a promising technique for the determination of DEG with high sensitivity.