Introduction Of Hydrophobic Groups Research Articles

Improving the performance of a polyamine shale inhibitor by introducing a hydrophobic group in oil and gas development

Wellbore instability in complex shale formations is a major technical problem that threatens drilling safety and efficiency. In this paper, a hydrophobic cationic polyamine shale inhibitor (HCPA) was prepared by introducing a hydrophobic group in the molecular structure of an amine-based shale inhibitor having a branched structure. The shale inhibition performance of HCPA and the amine-based shale inhibitor without the hydrophobic group (CPA) was investigated. The hydration inhibition mechanism of HCPA was studied by experiments of zeta potential, particle size, contact angle, thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), etc. The evaluation results show that HCPA had a better performance than CPA in terms of inhibition of hydration swelling, hydration dispersion and mud making, which indicates that the hydrophobic group is beneficial to improve the inhibition ability of the amine-based shale inhibitor. The mechanism study shows that there is no hydrogen bond between HCPA and clay. The adsorption on the clay surface is mainly driven by electrostatic interaction, which reduces the repulsion of the electric double layer and thus inhibits the osmotic swelling of clay. HCPA could increase the water contact angle of the rock from 36.6° to 133° at a concentration 0.5%, beneficial to reduce surface free energy. The bentonite modified by HCPA had a lower weight loss of at 200 °C than bentonite modified by CPA according to TGA test, and the interlayer spacing of HCPA-modified bentonite was reduced compared with that of the unmodified bentonite, indicating that the ability of bentonite to adsorb water molecules is reduced after the introduction of hydrophobic groups, beneficial to inhibit the crystalline swelling of clays. In addition, HCPA can reduce the imbibition capacity of rocks by reducing the surface tension of water. Therefore, the concept of introducing hydrophobic groups in the molecular structure proposed herein could provide an avenue to develop high-performance shale inhibitors.

Microencapsulated phase change material via Pickering emulsion based on xylan nanocrystal for thermoregulating application

Phase change materials (PCM) are promising for thermal regulation and energy storage, but suffer from the deformation and leakage of capsules. Herein, inspired by cellulose nanocrystal (CNC), xylan nanocrystal (XNC) with a dimension of 25–60 nm was successfully prepared through oxalic acid hydrolysis of high-crystalline xylan as raw materials via a top-down approach. With the introduction of hydrophobic groups, compared to XNC, succinylated XNC showed more remarkable emulsifying property over 7 days of storage at room temperature. Microencapsulated PCM composite consisting of sodium alginate (SA) as “matrix” and succinylated xylan nanocrystal (XNC) stabilized paraffin-based Pickering capsule (PCM beads) as “core” was facilely fabricated. PCM composite with the latent heat of 105.59 J·g−1 showed excellent thermoregulating performance. Our work suggests a new pathway toward sustainability of hemicelluloses in the application of food emulsion and thermal energy management.

A potent mechanism for revealing structurally manipulated sweetness inhibitory property of lactisole derivatives

Lactisole is a potent sweetness inhibitor for alleviating the over-sweet problem in food. For investigating the sweetness inhibition mechanism of lactisole, seven derivatives were synthesized and their structure was characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance and mass spectrometry for confirming the modification on aromatic ring and carboxylic acid. An evaluation method for sweetness inhibition was developed using the electronic tongue, and the results revealed that the introduction of hydrophobic groups onto aromatic ring of lactisole did not improve the inhibitory activity. A certain branching and length of carbon chain between the aromatic ring and the carboxylic group were presumably important for inhibitory function. The plausible interpretation is that the structured carbon chain may influence the spatial position of carboxylic group during the interaction between the inhibitors and the receptor. A potent mechanism for regulating sweetness inhibition of the compounds based on their corresponding structural characteristics is proposed.

Novel adhesive for label derived from peanut meal and MDI

Peanut meal (PM) as the raw material was crosslinked modification by different mass fractions of 4,4′-diphenylmethane diisocyanate (MDI), to prepare adhesives for label. The properties of the adhesives, including water resistance, the viscosity and solid content were investigated. The performance of the label adhesive modified using MDI were significantly higher than those of the unmodified adhesive, making it suitable for applications in the labels. The water resistance duration was up form 3 h to 77 h when the modifier was added at 15 wt.% (based on PM). Further, the viscosity of the modified adhesive increased to an appropriate 82.2 Pa·s, and its solid content increased from 16.01% to 18.16%. In addition, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD) were used to characterize the chemical interactions in the cured adhesives, and the thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used to analyze the reason of adhesive performance improvement. It was found that incorporating MDI into the adhesives resulted in the formation of a dense crosslinking network structure because of chemical reactions between MDI and active groups on the protein molecules and the introduction of hydrophobic groups in the adhesives; these factors effectively prevented water penetration, thus improving the water resistance of the cured adhesives.

Effect of commonly used EOR polymers on low concentration surfactant phase behaviors

High molecular weight polymers are required for the purpose of mobility and conformance control during surfactant chemical flooding. However, they are usually not incorporated in the process of phase behavior tests to screen surfactant formulations. Literature review shows some particular polymers have a boosting effect on surfactant solubilization efficiency. To gain more insight into this subject, we performed phase behavior tests in the presence of four commonly used EOR polymers for low concentration surfactant systems (0.3%). They were two partially hydrolyzed polyacrylamides (HPAM) with different molecular weights, one xanthan gum, and one hydrophobically associating polymer (HAP). Their influence on the optimal salinity, solubilization ratio, quickness of phase equilibration, and middle phase rheological behavior was assessed. The results showed: (1) a decrease of surfactant solubilization efficiency and the optimal salinity was observed with HPAM polymers. This trend became more pronounced as increase of polymer concentration and molecular weight; (2) xanthan seemed to slightly increase the optimal salinity without significantly affecting middle phase volume; (3) both HPAM and xanthan did not delay or quicken the equilibration of various phases compared to the zero polymer case. The analysis of the oil/water solubilization ratios showed HPAM tended to drag water out of the middle phase, while the presence of xanthan increased the water solubilization in the middle phase; (4) the viscosity and rheology of the middle phase microemulsions were very similar for systems containing HPAM, xanthan, and zero polymer. This confirmed the partitioning of polymer molecules in the middle phase was negligible; (5) the association of HAP with surfactants thickened the surfactant-rich phase, which made the phase separation dramatically slow. These phenomena could be explained well by the nature of their molecular structures. For both water-soluble HPAM and xanthan gum, unlike the reported diblock copolymers, they lack the amphiphilic features, which prevents them from adsorbing in the surfactant film. Conversely, the introduction of hydrophobic group into the backbone renders associating polymers some surfactant-like attributes, enabling them to associate with surfactant molecules and affect the surfactant-rich phase behaviors.

Introducing planar hydrophobic groups into an alkyl-sulfonated rigid polyimide and how this affects morphology and proton conductivity

Effects on organized structure and proton conductivity by the introduction of hydrophobic groups into the sulfonated polyimide backbone were investigated. A new sulfonated random co-polyimide with ion exchange capacity (IEC) of 2.69 meq. g−1 was synthesized. In our previous reports, we demonstrated that alkyl-sulfonated polyimide (ASPI-2, IEC = 3.11 meq. g−1) thin film consisting of pyromellitic dianhydride and 3,3′-bis(3-sulfopropoxy)benzidine exhibits the organized lamellar structure and high in-plane proton conduction over 10−1 S cm−1 based on a lyotropic liquid crystalline (LC) property. However, the origin of the lyotropic LC property in the sulfonated polyimide thin films was not clear. In this paper, 20% hydrophobic o-tolidine was introduced into the ASPI-2 polymer backbone to suppress the lyotropic LC property. To discuss the effect on the organized structure and proton conductivity by the introduction of the hydrophobic groups, domain size, internal nanostructure, proton conductivity, water uptake, and proton dissociation from sulfonic acid groups were investigated by polarized optical microscopy, grazing incidence small-angle X-ray scattering, impedance measurements, quartz crystal microbalance, and Fourier transform infrared spectroscopy. The random co-polyimide thin film exhibited the birefringence and in-plane oriented lamellar structure. The lamellar distance was expanded up to 3.0 nm by water uptake. The lamellar expansion, molecular ordering, and proton dissociation showed similar behaviors by water uptake compared to the previous ASPI-2 thin film. Proton conductivity and water uptake per sulfonic acid group exhibited relatively high value of 3.2 × 10−2 S cm−1 and 12.5 at relative humidity (RH) = 95% and 298 K. The estimated mobility of proton carriers decreased by 74% at λ = 12.5. Results suggest that the 20% substitution by hydrophobic monomers does not affect the structural difference but leads to the strong mobility decrease of proton carriers rather than the decrease of number of density.

Synthesis of a Cationic Polyacrylamide under UV Initiation and Its Flocculation in Estrone Removal

A ternary cationic polyacrylamide (CPAM) with the hydrophobic characteristic was prepared through ultraviolet- (UV-) initiated polymerization technique for the estrone (E1) environmental estrogen separation and removal. The monomers of acrylamide (AM), acryloyloxyethyl-trimethyl ammonium chloride (DAC), and acryloyloxyethyl dimethylbenzyl ammonium chloride (AODBAC) were used to synthesize the ternary copolymer (PADA). Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance spectroscopy (1H NMR), thermogravimetry/differential scanning calorimetry (TG/DSC), and scanning electron microscopy (SEM) were employed to characterize the structure, thermal decomposition property, and morphology of the polymers, respectively. FT-IR and 1H NMR results indicated the successful formation of the polymers. Besides, with the introduction of hydrophobic groups (phenyl group), an irregular and porous surface morphology and a favorable thermal stability of the PADA were observed by SEM and TG/DSC analyses, respectively. At the optimal condition (pH = 7, flocculant dosage = 4.0 mg/L and E1 concentration = 0.75 mg/L), an excellent E1 flocculation performance (E1 removal rate: 90.1%, floc size: 18.3 μm, and flocculation kinetics: 22.69×10-4 s−1) was acquired by using the efficient flocculant PADA-3 (cationic degree = 40%, and intrinsic viscosity = 6.30 dL·g−1). The zeta potential and floc size analyses were used to analyze the possible flocculation mechanism for the E1 removal. Results indicated that the charge neutralization, adsorption, and birding effects were dominant in the E1 removal progress.

Two competing reactions of tetrabutylammonium alginate in organic solvents: Amidation versus γ-lactone synthesis

Biocompatibility and thickening properties predetermine alginates as ingredients in food, cosmetic and pharmaceutical products. Further chemical modifications are often desired for a product optimization. The introduction of hydrophobic groups can be realized by employing organic tetrabutylammonium alginate (TBA-Alg) solutions. The synthesis of alginic acid alkyl amides from TBA-Alg with 2-chloro-1-methylpyridinium iodide (CMPI) as a coupling agent, however, has so far not resulted in a high degree of amidation. The analysis of the coupling reaction revealed the formation of mannuronic acid γ-lactone structures, which required a conformation change from 1C4 to 4C1. The opening of the γ-lactone required a high excess of butylamine. In the case of CMPI, triethylamine had to be added prior to the coupling agent in order to suppress the assumed alginic acid formation. The degrees of amidation achieved were up to 0.8, and for propylphosphonic anhydride as the coupling agent up to 1. The molecular weights of the alginic acid butyl amide were ≥35kDa.

Hollow hemisphere and microcapsules of nonionic copolymer

Hemispherical colloidal nanowells or microwells with hollow interiors are becoming increasingly important for the encapsulation of functional materials. There has been rapid progress to develop new methods to obtain such structures. In this work, we present emulsification approach to generate hemisphere and microcapsules of biocompatible organic polymer. The precise control over the size is exhibited by applying variable vortex effect. The hemispheres and microcapsules of a copolymer (BPVA-PVA) were characterized by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). These structures were used for loading of hydrophilic molecules and submicron colloidal particles to demonstrate their potential application. The introduction of hydrophobic groups on poly(vinyl alcohol) was crucial to obtain these structures.

Tuning the moisture stability of metal–organic frameworks by incorporating hydrophobic functional groups at different positions of ligands

The introduction of hydrophobic groups (e.g. methyl) at the most adjacent sites of each and every coordinating nitrogen atom of the bipyridine pillar linker in a carboxylate-based bridging MOF could shield the metal ions from attack by water molecules, and thus enhance the water resistance of the MOF structure significantly.

Multifunctional Polymeric Scaffolds for Enhancement of PARACEST Contrast Sensitivity and Performance: Effects of Random Copolymer Variations

A DOTA (1,4,7,10-tetraazacyclododecane-N,N',N",N'"-tetraacetic acid) tetraamide ligand having a single acrylamide side-chain (M1) was copolymerized with either 2-methylacrylic acid (MAA), 2-(acryloylamino)-2-methyl-1-propanesulfonic acid (AMPS) or N-isopropylacrylamide (NIPAM) to create a series of linear random copolymers using classical free radical chain polymerization chemistry. The metal ion binding properties of hydrolyzed M1 were investigated by pH potentiometry and the europium (III) complexes of the resulting heteropolymers were evaluated as PARACEST imaging agents. All polymeric agents were found to possess similar intermediate-to-slow water exchange and CEST characteristics as the parent EuDOTA-tetraamide monomer. Consistent with basic multiplexing principles, the highest molecular weight polymer, Eu-DMAA 3.1, also showed the highest CEST sensitivity with a detection limit of 20 ± 2 μM. The second arylamide component gave polymers with widely different chemical characteristics and CEST properties. In particular, the Eu-DNIPAM 4.0 and Eu-DMAA 4.1 polymers displayed different solubility characteristics as a function of pH or temperature which, in turn, affected the water exchange and CEST properties of the corresponding agents. It was concluded that introduction of hydrophobic groups into the polymer backbone reduces solvent accessibility to the Eu(3+) component, effectively slowing water exchange between the inner-sphere water coordination position at each Eu(3+) center with bulk water. The CEST properties of the heteropolymers when dissolved in plasma suggest that the more hydrophobic characteristics of these polymers could be advantageous for in vivo applications.

Interrogating Confined Proton-Transfer Reaction Dynamics within Mesoporous Nanotubes

We report on steady-state and time (ns to fs regime) resolved studies of H-bonding interactions and proton-transfer reaction dynamics of silica-based mesoporous material MCM-41 with an H-bond donor and acceptor guest aromatic molecule (7-hydroxyquinoline, 7HQ). We observed the ground state reaction which leads to the formation of intermediates and products of the confined molecular probe. We compare this behavior with the observed one for the dye adsorbed on the surface of silica particles, lacking the nanotubes. The result clearly shows that the formation of keto (or zwitterionic) tautomers at the ground state is enhanced by the confinement provided by the channels of MCM-41. Introduction of hydrophobic groups (by silylation of the OH groups in regular MCM-41 host) changes the ground state tautomeric equilibria and the emission behavior. A new lifetime (3.19 ns, suggested being due to a more stabilized anion of the guest) was observed in addition to the ones due to confined bound enol (0.26 ns), anion (1...

Synthesis and Viscoelastic Properties of Hydrophobically Modified Hydrogels

AbstractSummary: We report the synthesis and characterization of a family of hydrophobically modified hydrogels designed to have an improved fracture resistance. A backbone of poly(acrylic acid) (PAA) was functionalized with double bonds and hydrophobic groups. The functionalized PAA was then crosslinked with a dithiol. The chemical structure of the gels was characterized with a combination of NMR, titration methods and rheological techniques. The crosslinked structure of the hydrogel was found to be dependent on the polymer concentration only, while the dissipative properties of the gel increased strongly at all frequencies, with the introduction of hydrophobic groups which formed reversible associations. We expect these viscoelastic hydrogels to display dramatically different properties from the unmodified hydrogels when stretched and fractured.

Synthesis and evaluation of 2-substituted 8-hydroxyadenines as potent interferon inducers with improved oral bioavailabilities

In order to create novel compounds which possess potent interferon (IFN) inducing activities with excellent oral bioavailabilities, a series of 8-hydroxyadenines, which have various alkoxy or alkylthio moieties at the adenine C(2)-position, were synthesized and evaluated. The introduction of hydrophobic groups was not considered to be effective for potentiating the IFN-inducing activity, but several compounds having hydrophilic groups were effective. Among the compounds tested, compound 13f induced IFN from the dosage of 0.03 mg/kg, which was approximately 100-fold more potent than that of Imiquimod, and showed an excellent oral bioavailability (F=40%) which was 10-fold improved over 5, a lead compound (F=4%).

Tuning the acid recovery performance of poly(4-vinylpyridine)-filled membranes by the introduction of hydrophobic groups

Two series of anion-exchange membranes have been produced by photo-initiated copolymerization of 4-vinylpyridine and divinylbenzene (DVB) within the pores of polypropylene microfiltration membranes followed by quaternization of the pyridine nitrogen atoms. The membranes were tested for use in acid recovery applications by performing diffusion dialysis of acid/salt solutions (HCl/NaCl/MgCl 2) and determining dialysis coefficients and acid/salt selectivity. The nature of the water present in the membranes was examined by differential scanning calorimetry (DSC). The first series was comprised of membranes with varying DVB content and all were quaternized with a methyl group. When compared to similar protonated membranes, this series showed a decrease in fixed charge concentration, an increase in dialysis coefficients, an increase in selectivity of HCl over NaCl and a slight decrease in selectivity of HCl over MgCl 2. The second series had different quaternizing groups. It was found for this series that increasing the size of the N-alkyl substituent resulted in an increase in the membrane fixed charge concentration, a decrease in dialysis coefficients and a dramatic increase in selectivity of acid over salts. The results are interpreted in terms of the effects of the hydrophobic alkyl groups on the water structure in the membranes. The acid recovery performance of the N-alkylated membranes was shown to be better than a commercial diffusion dialysis membrane.

キャピラリー電気泳動の最近の成果と展望 糖および糖タンパク質分析へのキャピラリー電気泳動の応用

Carbohydrates are the least inappropriate group of compounds to be analyzed by capillary electrophoresis (CE), because normally they have no electric charge. However, they can be analyzed by this method by adding various devices. There are a number of methods for conversion of carbohydrates to positively or negatively charged derivatives, which can be analyzed directly by zone electrophoresis. In-situ conversion with certain kinds of oxyacid ions, such as the borate ion, and metal ions, such as alkaline earth metal ions, also form ionic complexes from carbohydrates and derivatives. Furthermore, introduction of hydrophobic groups allows separation based on solubilization of the derivatives into ionic micells, thus permitting micellar electrokinetic chromatography. This paper describes not only such theoretical aspect of CE but its application to the analysis of oligosaccharides in glycoproteins. It gives a number of examples of successful application.

Amiloride inhibition of angiogenesis in vitro.

Angiogenesis is important to such processes as normal embryonic development and tissue growth, and is also a central feature of diseases such as diabetic retinopathy and the growth of solid tumors. Understanding the basic events governing angiogenesis has therefore attracted great interest. The ion channel blocking agent, amiloride, has been shown to inhibit angiogenesis in an in vivo model (Lansing et al., '91). This suggested a vital role for Na(+)-coupled transport processes in angiogenesis. A large number of structural analogues of amiloride have been synthesized (Kleyman and Cragoe, '88), and many of these are well characterized with respect to biological activity. These analogues present an opportunity to dissect the process of angiogenesis and identify potentially important physiological events. In this report we describe the effects of amiloride on an in vitro model for angiogenesis employing vascularized tissue explants. Amiloride inhibits capillary morphogenesis completely and reversibly at concentrations as low as 134 microM. It appears to act by blocking endothelial cell proliferation, but not migration. Inhibition is heightened by the introduction of hydrophobic groups on the terminal guanidino nitrogen atom, or on the 5-amino position. An analogue substituted at both of these positions is 30-fold more potent than the parent compound. Of amiloride's known biological activities, these results most closely correlate with the inhibition of Ca2+ transport processes, and thereby suggest an important role for Ca2+ transport in capillary morphogenesis.

Effect of reductive alkylation on thermal stability of ribonuclease A and chymotrypsinogen A

In order to probe changes in the structural stability induced by the introduction of hydrophobic groups into proteins, the amino groups of ribonuclease A and chymotrypsinogen A were reductively alkylated by reaction with various aliphatic aldehydes, formaldehyde, acetaldehyde, n-butylaldehyde and n-hexylaldehyde, and their thermal stabilities were investigated by differential scanning calorimetry (DSC) at different acidic pH values. Ribonuclease A was thermally unstabilized by reductive alkylation, while chymotrypsinogen A was slightly stabilized, depending on both the size of the introduced alkyl groups and the extent of modification. These observations suggest that the effects induced by alkylation involve not only steric hindrance due to the entering bulky groups but also certain other factors such as the participation of the chemically introduced alkyl groups in hydrophobic interactions.

Setting behavior of wool treated with butyl and phenyl isocyanates evaluated by three methods.

Wool fabrics were treated with butyl and phenyl isocyanates (designated as BI and PI, respectively) in N, N-dimethylformamide and the setting properties were studied by the IWS crease angle test with a Hoffman press or by a similar but handy method with a home steam iron. The results obtained by the two set methods agreed well when the fabrics were set without a reducing agent: both BI- and PI- treated fabrics gave temporary set values much higher than those of the control, but only a PI-treated fabric with a high add-on of 14% gave a high permanent set value and other samples were not permanently set. When fabrics were set under reducing conditions, all the fabrics gave high permanent set values with a Hoffman press, while BI- and PI- treated wool samples gave lower permanent set values than that of the control, when set with a home steam iron. Lincoln wool fibers were treated with BI and PI and the extention set with boiling water was also studied with the treated samples. The results of set experiments with the three different methods indicated that the introduction of hydrophobic groups by treatment with isocyanates, especially with PI, gave two different effects on the set values: the treated samples became more resistant to the diffusion of a reducing agent so that mercaptan/disulfide interchange reaction during setting was not enhanced as much as the interchange in the control, while the hydrophobic groups made the set of the samples more stable in hot water. Depending on the setting conditions under reducing conditions, the set values of the treated samples varied with the balance of the two adverse effects.

Modification of transport properties of ion‐exchange membranes VIII. Changes in properties of anion exchange membranes on introduction of hydrophobic groups

AbstractA copolymer membrane composed of 4‐vinylpyridine‐styrene‐divinylbenezene was reacted with long chain alkyl bromides (octyl bromide, dodecyl bromide, and hexadecyl bromide) in order to introduce hydrophobic groups into the anion exchange membrane by the quaternization reaction. The resulting membranes show a marked increased in fixed ion concentration as a result of lowered water content. Although the electrical resistance of the membranes increased slightly, the apparent diffusion coefficient of hydrochloric acid through the membranes decreased markedly. Complete quaternization of the membranes by methyl iodide after reaction with the long‐chain alkyl bromides caused an increase in the water content and in the apparent diffusion coefficient of the acid and a decrease in the current efficiency in electrodialysis of the acid. This is explained by the high water content of the anion exchange membranes quaternized by methyl iodide.