Gas-hydrate formation, agglomeration and inhibition in oil-based drilling fluids for deep-water drilling

One of the main challenges in deep-water drilling is gas-hydrate plugs, which make the drilling unsafe. Some oil-based drilling fluids (OBDF) that would be used for deep-water drilling in the South China Sea were tested to investigate the characteristics of gas-hydrate formation, agglomeration and inhibition by an experimental system under the temperature of 4 ℃ and pressure of 20 MPa, which would be similar to the case of 2000 m water depth. The results validate the hydrate shell formation model and show that the water cut can greatly influence hydrate formation and agglomeration behaviors in the OBDF. The oleophobic effect enhanced by hydrate shell formation which weakens or destroys the interfacial films effect and the hydrophilic effect are the dominant agglomeration mechanism of hydrate particles. The formation of gas hydrates in OBDF is easier and quicker than in water-based drilling fluids in deep-water conditions of low temperature and high pressure because the former is a W/O dispersive emulsion which means much more gas-water interfaces and nucleation sites than the later. Higher ethylene glycol concentrations can inhibit the formation of gas hydrates and to some extent also act as an anti-agglomerant to inhibit hydrates agglomeration in the OBDF.     

Predicting hydrate forming pressure of pure alkanes in the presence of inhibitors

An inherent problem with natural gas production or transmission is the formation of gas hydrates, which can lead to safety hazards for production/transportation systems, and substantial economic risks. Hydrate inhibition with different inhibitors such as, methanol, ethylene glycol （EG）, triethylene glycol （TEG）, and sodium chloride solution continues to play a critical role in many operations. An understanding of when the hydrates form in the presence of these hydrate inhibitors, is therefore necessary to overcome hydrate problems. Several thermodynamic models have been proposed for predicting the hydrate formation conditions in aqueous solutions containing methanol/glycols and electrolytes. However, available models have limitations that include the types of liquid, compositions of fluids, and inhibitors used. The aim of this study is to develop a simple-to-use correlation for accurate prediction of hydrate-forming pressures of pure alkanes in the presence of different hydrate inhibitors, where the obtained results illustrate good agreement with the reported experimental data.     

气相色谱法检测工业用乙二醇纯度及杂质

以Rtx-624色谱柱（30 m×0.32 mm×1.8 μm）为分析柱进行分析，采用校正面积归一化法，建立了检测工业用乙二醇纯度及其中有机杂质的气相色谱分析法。该法可检测传统乙烯法制得的乙二醇中固有杂质二乙二醇、三乙二醇和1，3-二氧杂烷-2-甲醇，同时也适用于检测草酸酯加氢法制得的乙二醇中的新杂质（1，2-丁二醇、1，4-丁二醇、1，2-己二醇、碳酸乙烯酯等）。结果表明，该法具有良好的重复性和较高的检测灵敏度，检出限最低可达0.0002%（质量分数），回收率在91.2%~105.4%之间。该法在乙二醇生产控制、产品检测、市场贸易等过程中具有良好的应用前景。     

Synthesis of novel poly(ethylene glycol)‐containing imidazolium‐functionalized phosphine ligands and their application in the hydrosilylation of olefins

A series of polyethylene glycol‐containing imidazolium‐functionalized phosphine ligands (mPEG‐im‐PPh₂) were successfully synthesized and used in the rhodium‐catalyzed hydrosilylation of olefins. The results indicate that the RhCl₃/mPEG‐im‐PPh₂ catalytic system exhibits both excellent activity and selectivity for the β‐adduct. In addition, the catalytic system may be recycled at least six times.     

聚苯乙烯负载聚乙二醇在合成碳酸亚丙酯上的应用

用金属钾、金属钠以及氢氧化钠水溶液等方法制备聚苯乙烯负载聚乙二醇，结果表明，采用金属钾比金属钢具有更好的接枝效果，并能使反应在较低的温度下较快进行。在氢氧化钠溶液中添加少量相转移剂，如Bu4NBr，接枝效果也有所提高。以聚苯乙烯负载聚乙二醇和KI一起为催化剂，研究了溶剂、温度等因素对CO2与环氧丙烷合成碳酸亚丙酯催化活性的影响。结果表明，以甲醇为溶剂催化活性较高。研究还表明，聚苯乙烯负载聚乙二醇具有较好的热稳定性，可以在150℃下重复使用至少5次。     

Pharmaceutical performance of solid dispersions containing poly(ethylene glycol) 6000 and diazepam or temazepam

Differential scanning calorimetry (DSC) data showed that the crystallinity of poly(ethylene glycol) 6000 in solid dispersions containing and diazepam or temazepam only slightly increased upon aging and that the twice folded modification of the polymer unfolded into the once folded modification during aging, while the once folded modification did not unfold. This unfolding was found to be time and temperature dependent. X-ray powder diffraction data revealed that the drug crystallinity in the solid dispersions slightly increased upon aging. The dissolution profiles of aged and non-aged solid dispersions were comparable. It was concluded that polymer unfolding did not have an impact on the pharmaceutical performance of the investigated dispersions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and plugging effect of inverse emulsion polymerization microspheres (OPME) for oil-based drilling fluids

It is difficult to seal oil-based drilling fluids in the large pore and micro-fracture formation, and there are few suitable materials for the oil phase with good sealing ability at present. In order to solve the problem of the lack of sealing ability of oil-based drilling fluids, acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and acryloyl morpholine were used as monomers, N'N-methylenebisacrylamide was used as a cross-linking agent, Span-80 and Tween-60 were used as emulsifiers, and 2,2′-azobis(2-methylpropionamidine) dihydrochloride was used as an initiator. Polymer microsphere emulsion OPME was synthesized by inverse emulsion polymerization. The structure of polymer microspheres was characterized by infrared spectroscopy, scanning electron microscopy, electron microscopy, H NMR, laser particle size analysis and thermogravimetric analysis. The optimal synthesis conditions were determined by the control variable method: the monomer ratio of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and acryloyl morpholine was 45:20:15, the amount of emulsifier was 8%, and the reaction temperature was 55℃. The synthetic polymer microspheres were added to the oil-based drilling fluids to perform filtration and loss plugging at atmospheric pressure and high-temperature and high-pressure, as well as pore and artificial fracture core plugging evaluation. The evaluation results show that the permeability reduction rate of pore core can reach 82%, and that of fracture core can reach 100% by adding polymer microspheres with 3% dosage. Finally, the pressure transmission experiment proves that the addition of polymer microspheres can slow the pressure transmission and filtrate intrusion, and enhance the stability of wellbore. Therefore, polymer microspheres are a micron-level plugging agent with good compatibility and high performance with oil-based drilling fluids, and the 3% dosage can better seal the formation of large pores and micro-fractures, which has a good potential for field application.     

Synthesis and characterization of poly(ethylene glycol) diacrylate copolymers containing azobenzene groups prepared by frontal polymerization

A novel polymer matrix containing amino–nitro substituted azobenzene groups was obtained by frontal polymerization. (E)‐2‐(Ethyl(4‐((4‐nitrophenyl)diazenyl)phenyl)amino)ethyl methacrylate (MDR‐1) was copolymerized with poly(ethylene glycol) diacrylate (PEGDA) using this easy and fast polymerization technique. The effect of the amount of the incorporated azo‐monomer into the polymer matrix was studied in detail and correlated to front velocity, maximum temperature, initiator concentration, and monomer conversion. The obtained materials were characterized by infrared spectroscopy (Fourier transform infrared), and their thermal properties were studied by thermogravimetric analysis and differential scanning calorimetry. Moreover, the optical properties of the polymers were studied by absorption spectroscopy in the UV–Vis region. Absorption spectra of the copolymers exhibit a significant blue shift of the absorption bands with respect to the azo‐monomer, due to the presence of H‐aggregates. Cubic nonlinear optical (NLO) characterizations of the PEGDA/MDR‐1 copolymers were performed according to the Z‐Scan technique. It has been proven that samples with higher MDR‐1 content (0.75 mol %) exhibited outstandingly high NLO‐activity with negative NLO‐refractive coefficients in the promising range of n₂ = ?8.057 × 10^?4 esu. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Regioselective grafting of poly(ethylene glycol) onto chitosan and the properties of the resulting copolymers

PEG was grafted onto chitosan regioselectively at the hydroxyl groups with phthaloylchitosan as an intermediate. After the graft reaction, the phthaloyl groups were deprotected to give chitosan-g-PEG copolymers with free amino groups. The chemical structure of the graft copolymers was confirmed by FT-IR, (1)H and (13)C NMR spectroscopy. The resulting graft copolymers showed improved thermal stability compared to the original chitosan, and showed a lower thermal transition temperature at around 185 degrees C. Chitosan-g-PEG exhibited a high affinity not only for aqueous acid but also for some organic solvents because of the presence of abundant free amino groups and PEG branches, and it exhibited higher hygroscopicity and moisture retention ability than chitosan. [structure: see text]     

Pharmaceutical performance of solid dispersions containing poly(ethylene) glycol 6000 and diazepam or temazepamInfluence of grinding

The effect of grinding on the physical properties and pharmaceutical performance of solid dispersions made of poly(ethylene) glycol 6000 (PEG6000) and temazepam or diazepam was studied using differential scanning calorimetry (DSC), X-ray powder diffraction and dissolution experiments. DSC-analysis of flash-cooled dispersions revealed that amorphous PEG present immediately after grinding crystallised upon aging mainly into the twice folded modification and to a small extent into the extended form. DSC-analysis of dispersions kept in the slab form for 1 month and subsequently ground, revealed that in the abscence of the grinding impulse crystallisation of PEG6000 takes place in the same way as in dispersions ground immediately after preparation and then aged for 1 month. Grinding solid dispersions immediately after preparation resulted in superior dissolution properties compared with solid dispersions kept in the monolith-slab form and subsequently ground. This difference in dissolution properties was found to be attributed to the drug and not to the polymer, more precisely, it was suggested that the drug particle size in ground dispersions was smaller than in dispersions kept in the slab form and subsequently ground. These findings suggest that grinding of solid dispersions immediately after preparation is the preparation method of choice instead of liquid filling of hard gelatin capsules resulting in monoliths. This revised version was published online in July 2006 with corrections to the Cover Date.     

The structure and chromatographic properties of poly(ethylene glycol) 20M layer on the surface of a diatomaceous earth type support

Summary The properties of poly(ethylene glycol) 20M (PEG 20M) coated on the hydroxylated surface of Chromaton N AW were investigated by inverse gas chromatography. It was found that the solid form of PEG 20M exhibits partition as the retention mechanism even below its melting range. The contribution of adsorption to the specific retention volume was also determined. It was demonstrated that inverse gas chromatography establishes the existence of a polymer surface layer but precise determination of its thickness is difficult. The limitation of the applicability of inverse gas chromatography results from the structure of the investigated surface layer which is thin and not coherent so that solute molecules can penetrate it.     

Suspension polymerization of poly(ethylene glycol) methacrylate: a route for swellable spherical gel beads with controlled hydrophilicity and functionality

 Spherical and swellable gel beads were obtained by the suspension polymerization of poly(ethylene glycol) methacrylate macromonomer (PEG-MA). The average size and size distribution properties, the equilibrium swelling behaviour and the protein adsorption characteristics of PEG-MA-based gel beads were determined. In the suspension polymerization system, the organic phase including monomer, cross-linker and diluent solution was dispersed in an aqueous medium by using poly(vinylpyrrolidone) as the stabilizer. The diluent solution was prepared by mixing cyclohexanol and octanol at different volume ratios. The suspension polymerization experiments were designed in two separate parts. In the first part, ethylene glycol dimethacrylate was selected as the cross-linker and swellable PEG-MA-based gel beads were obtained by changing the cross-linker concentration, the monomer/diluent ratio and the stirring rate. In the second part, a more hydrophobic structure, divinylbenzene (DVB) was tried as a cross-linker. In this part, PEG-MA-DVB copolymer beads were obtained by changing the DVB/PEG-MA feed ratio. Then, the hydrophicility of the resulting gel beads could be controlled by changing the feed ratio of hydrophilic macromonomer to hydrophobic cross-linker. This property was also used to control the extent of nonspecific protein adsorption onto the surface of the gel beads. The non specific albumin adsorption onto the gel beads decreased with increasing PEG-MA content. No significant nonspecific adsorption at the isoelectric point of albumin was detected onto the gel beads produced with the higher PEG-MA/DVB feed ratios. For specific albumin adsorption, a triazinyl dye (i.e., cibacron blue, CB F3G-A) was covalently attached onto the surface of the copolymer beads via terminal hydroxyl groups of PEG-MA. The results of albumin adsorption experiments with the CB F3G-A carrying beads indicated that an appreciable specific albumin adsorption capacity could be obtained with the gel beads produced with a PEG-MA/DVB feed ratio of 1.5/4.0. Received: 16 August 1999/Revised: 27 December 1999     

聚苯乙烯-g-聚乙二醇的制备及其表面改性作用

通过沉淀聚合方法,利用自由基共聚制备了苯乙烯-顺丁烯二酸酐共聚物(SMA),利用SOCl2的酰氯反应,在SMA大分子链上接枝聚乙二醇侧链,制备了聚苯乙烯-g-聚乙二醇(PEG-g-PS)的大分子表面改性剂。利用大分子表面改性剂在聚苯乙烯基体中具有选择性迁移扩散的特性,实现了对聚苯乙烯薄膜表面极性的改善作用。采用衰减全反射傅立叶变换红外光谱仪和表面静态接触角法检测了聚苯乙烯的表面极性。结果发现,PEG-g-PS上的聚醚链段可以有效的富集在聚合物表面,明显改善PS的表面极性和亲水性,表面极性可提高3倍,达到11.6mN/m。同时,大分子表面改性剂和聚苯乙烯基体间有一定的相容性,有效地克服了小分子表面改性剂容易流失,改性寿命较短的重要缺陷,使表面改性的持久性充分增加,实现对聚合物表面改性效果终生化的目的。而且大分子表面改性剂在极性溶剂的诱导作用下,可以实现进一步的迁移扩散,充分提高了聚苯乙烯的表面极性。     

Terpolymerization of methyl methacrylate, poly(ethylene glycol) methyl ether methacrylate or poly(ethylene glycol) ethyl ether methacrylate with methacrylic acid and sodium styrene sulfonate: determination of the reactivity ratios

Materials bearing ionic monomers were obtained through free radical terpolymerization of methyl methacrylate (MMA), poly(ethylene glycol) methyl ether methacrylate (PMEM) or poly(ethylene glycol) ethyl ether methacrylate (PEEM) with methacrylic acid (MA) and sodium styrene sulfonate (NaSS). The reactions were carried out in dimethyl sulfoxide using azobis(isobutyronitrile) as initiator. The reactivity ratios of the different couple of monomers were calculated according to the general copolymerization equation using the Finnemann-Ross, Kelen-Tüdos and Tidwell-Mortimer methods. The values of the reactivity ratios indicate that the different monomer units can be considered as randomly distributed along the chains for terpolymerizations of MMA, PMEM or PEEM with MA and NaSS. The average composition of the comonomers in the different terpolymers were calculated, showing a good agreement between the experimental and theoretical compositions. The instantaneous compositions are constant until about 70% of conversion. For higher conversions, the insertion of ionic monomers increases or decreases according to the system studied.     

The behavior of poly(amino acids) containing l‐cysteine and their block copolymers with poly(ethylene glycol) on gold surfaces

Poly(ethylene glycol) (PEG) is often used to biocompatibilize surfaces of implantable biomedical devices. Here, block copolymers consisting of PEG and l ‐cysteine‐containing poly(amino acid)s (PAA's) were synthesized as polymeric multianchor systems for the covalent attachment to gold surfaces or surfaces decorated with gold nanoparticles. Amino‐terminated PEG was used as macroinitiator in the ring‐opening polymerization, (ROP), of respective amino acid N‐carboxyanhydrides (NCA's) of l ‐cysteine (l ‐Cys), l ‐glutamate (l ‐Glu), and l ‐lysine (l ‐Lys). The resulting block copolymers formed either diblock copolymers, PEG‐b‐p(l ‐Glu_x‐co‐l ‐Cys_y) or triblock copolymers, PEG‐b‐p(l ‐Glu)_x‐b‐p(l ‐Cys)_y. The monomer feed ratio matches the actual copolymer composition, which, together with high yields and a low polydispersity, indicates that the NCA ROP follows a living mechanism. The l ‐Cys repeat units act as anchors to the gold surface or the gold nanoparticles and the l ‐Glu repeat units act as spacers for the reactive l ‐Cys units. Surface analysis by atomic force microscopy revealed that all block copolymers formed homogenous and pin‐hole free surface coatings and the phase separation of mutually immiscible PEG and PAA blocks was observed. A different concept for the biocompatibilization of surfaces was followed when thiol‐terminated p(l ‐Lys) homopolymer was first grafted to the surface and then covalently decorated with HOOC‐CH₂‐PEG‐b‐p(Bz‐l ‐Glu) polymeric micelles. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 248–257     

Heterobifunctional Poly(ethylene glycol) Derivatives for the Surface Modification of Gold Nanoparticles Toward Bone Mineral Targeting

Heterobifunctional poly(ethylene glycol)s can be used for many biomedical applications ranging from solubility enhancement of hardly soluble compounds to surface modification of medical devices. In order to modify gold nanoparticles as model particles for drug targeting applications, PEG derivatives are synthesized that possess a high affinity for gold surfaces, namely a thioalkyl function, known to form stable monolayers on gold. Additionally a bisphosphonate function is introduced in the PEG molecule to allow targeting of hydroxyapatite rich tissues, like bone. Gold nanoparticles are modified using the synthesized bifunctional PEG and investigated for their stability in biological fluids and their ability to bind to hydroxyapatite granules in these fluids.

     

Surface modification of polydimethylsiloxane with photo-grafted poly(ethylene glycol) for micropatterned protein adsorption and cell adhesion

In this study, we applied photo-induced graft polymerization to micropatterned surface modification of polydimethylsiloxane (PDMS) with poly(ethylene glycol). Two types of monomers, polyethylene glycol monoacrylate (PEGMA) and polyethylene glycol diacrylate (PEGDA), were tested for surface modification of PDMS. Changes in the surface hydrophilicity and surface element composition were characterized by contact angle measurement and electron spectroscopy for chemical analysis. The PEGMA-grafted PDMS surfaces gradually lost their hydrophilicity within two weeks. In contrast, the PEGDA-grafted PDMS surface maintained stable hydrophilic characteristics for more than two months. Micropatterned protein adsorption and micropatterned cell adhesion were successfully demonstrated using PEGDA-micropatterned PDMS surfaces, which were prepared by photo-induced graft polymerization using photomasks. The PEGDA-grafted PDMS exhibited useful characteristics for microfluidic devices (e.g. hydrophilicity, low protein adsorption, and low cell attachment). The technique presented in this study will be useful for surface modification of various research tools and devices.     

Poly(ethylene glycol) diacrylate based monolithic capillary columns for the analysis of polar small solutes by capillary electrochromatography

Monolithic stationary phases based on poly(ethylene glycol) diacrylates for capillary electrochromatography were developed. Several poly(ethylene glycol) diacrylates (M_n 250, 575, and 700) were used as single monomers and the resulting columns were carefully compared. Methanol and ethyl ether were selected as porogenic solvents, and in all cases ultraviolet radiation was selected as initiation method to prepare polymeric monoliths. The influence of the monomer chain length and ratio monomer/porogen on the morphological and electrochromatographic properties of the resulting monoliths was investigated. Several families of compounds with different polarity (alkyl benzenes, organophosphorous pesticides, benzoic acid derivatives, and sulfonamides) were selected to evaluate the performance of the fabricated monolithic columns. The best results were obtained for poly(ethylene glycol) diacrylate 700 monoliths affording efficiencies of 144 000 plates/m for retained polar aromatic small molecules and excellent reproducibility in column preparation (RSD values below 2.5%).     

Experimental and thermodynamic modelling of systems containing water and ethylene glycol: Application to flow assurance and gas processing

Accurate knowledge of hydrate phase equilibrium in the presence of inhibitors is crucial to avoid gas hydrate formation problems and to design/optimize production, transportation and processing facilities. In this communication, we report new experimental dissociation data for various systems consisting of methane/water/ethylene glycol and natural gas/water/ethylene glycol. A statistical thermodynamic approach, with the Cubic-Plus-Association equation of state, is employed to model the phase equilibria. The hydrate-forming conditions are modelled by the solid solution theory of van der Waals and Platteeuw. The thermodynamic model was used to predict the hydrate dissociation conditions of methane and natural gases in the presence of distilled water or ethylene glycol aqueous solutions. Predictions of the developed model are validated against independent experimental data and the data generated in this work. A good agreement between predictions and experimental data is observed, supporting the reliability of the developed model.     

Preparation of polyzirconoxane from zirconium oxychloride octahydrate and ethylene glycol as a precursor for zirconia ceramics

An Erratum has been published for this article in Applied Organometallic Chemistry 2001; 15(4):317. The preparation of polyzirconoxanes (EG‐PZO) was investigated by a one‐pot reaction of zirconium oxychloride octahydrate with ethylene glycol. Triethylamine was added dropwise into a mixture of zirconium oxychloride octahydrate, ethylene glycol and methanol to give EG‐PZO with a good spinnability and stability to self‐condensation. The ¹H NMR spectrum, IR spectrum, analytical data and expanded X‐ray absorption fine‐structure analysis indicated that EG‐PZO consisted of Zr < (OH)₂ > Zr linkages as a main chain with pendant 2‐hydroxyethoxy groups, chloro groups and water. The 3Y₂O₃–97ZrO₂ ceramic fibers were prepared by sintering the precursor fibers after the addition of <?tw=97%>Y(acac)₃ (acac = acetoacetate) to EG‐PZO. Copy‐<?tw>­right © 2000 John Wiley & Sons, Ltd.