Performance Gel Research Articles

Translating Solid-Phase Conformational Memory in the Prophecy of Multi-stimuli Responsive Low Molecular Weight Gels.

Polymorphismand its screeningto select the best-performing form is in high demand. In low molecular weight organogels (LMWG), gelators are designed as they contain flexible groups, functionalities capable of varied H-bonding,and increasedthe potential to show polymorphism. We synthesized a bis-urea based LMWGG1and isolated three distinct polymorphic phases (Form I,II, andIII).G1polymorphs showednoticeable differences in solubility;precisely, Form I is highly soluble compared to the other two. Gel screening was carried out for all three polymorphs using different stimuli like heat-cool, sonication, shaking, and grinding. Among the polymorphs,Form Iwas found to have better gelling ability which was reflected by the solvent scope, thermal stability (gel-sol transition temperature Tgel), minimum gelator concentration (M.G.C.), stimuli-responsiveness, morphology, and rheological properties. The differences in their gelation performance among the three polymorphs are associated with their solubility parameter. Stimuli like sonication, shaking, and grinding triggeredForm Ito form a gel. Form IIandIIIresponded to heat-cool stimuli only due to poor solubility. Therefore, it is noted crucial to add polymorph screening as an integral part of the gel synthesis to avoid problems associated with reproducibility in the gel prophecy of LMWG systems.

Amelioration of extremely acidic environment of soy protein amyloid fibrils to enhance gelation performance by dialysis strategy: Effects of pH and ions

The application of soy protein amyloid fibrils (SAFs) to food industrialization field has received focused attention because of their advantages such as ordered supramolecular structure and anti-proteolytic properties. However, the comparatively weak gelation properties of SAFs make it difficult to form self-supporting hydrogels, limiting its potential for future applications. Additionally, the extremely acidic environment (pH 2) of SAFs hinders their practical application in the food pH range (4–7). To address this issue, a dialysis strategy was utilized to enhance the gel structure of SAFs in this paper. The SAFs were dialyzed by deionized water and zinc ions solutions with four different pHs (2, 4, 7, and 9), and the impact of various dialysates on rheological properties, water distribution, and microstructure was investigated. The results demonstrated the method significantly improved gelation properties and modified the extremely acidic environment of SAFs. Various samples were continuously deacidified during dialysis in solutions of different pHs (4, 7, and 9), transforming from pH 2 to a higher pH value. Visual images exhibited that self-supporting hydrogels can be formed by SAFs just at a low concentration of 3% (wt). SAFs-Zn2+-9 hydrogel exhibited the highest storage modulus with a 500-fold compared to SAFs-2. Notably, the SAFs-H2O hydrogels were fabricated without any exogenous substances, in which the storage modulus of SAFs-H2O-9 increased by over 300 times. AFM images demonstrated that the shift from long rigid fibrils to short flexible fibrils induced tightly entanglement among fibrils, which improved gelation performance. Moreover, the transform in pH and the incorporation of ions caused the hydrogels to show dense network structure and strong water retention capacity. The ingenious insights were provided for improving the gelation performance of SAFs and modifying the polar acidic environment in the study, fully exploiting the potential of SAFs as edible ingredients for food applications.

Effect and Mechanism of Zirconium Crosslinker on Retarding Degradation of HPAM/PEI Gel System in Medium-Salinity Reservoirs

Summary The objective of this paper is to investigate the effect of the addition of zirconium crosslinker on retarding the degradation of the partially hydrolyzed polyacrylamide/polyethyleneimine (HPAM/PEI) gel system. Dehydration and degradation under salinity conditions pose serious challenges to the effectiveness of the HPAM/PEI system used for water control treatment in heterogeneous reservoirs. In this study, rheological tests, Fourier transform infrared (FTIR) spectroscopy, and 13C nuclear magnetic resonance (NMR) spectroscopy are used to elucidate the characteristics and mechanisms of dehydration and degradation of HPAM/PEI gel in medium-salinity conditions. The effects of three types of zirconium crosslinkers on the gelation performance of the HPAM/PEI system are evaluated. Furthermore, the mechanism by which an organic zirconium complex (ZrOr complex) with triethanolamine (TEA) and lactic acid (LA) as ligands improves the stability of the HPAM/PEI system under medium-salinity conditions is revealed. The results indicate that ZrOr complex notably retards the degradation of the HPAM/PEI system under medium-salinity conditions (50 g/L) for more than 60 days while improving its gel strength. TEA and LA as ligands have a positive effect on crosslinking of HPAM with the organic Zr4+ complex by modulating the availability of Zr4+ and the homogeneity of the crosslinking reaction. Specifically, our data suggest that TEA stabilized Zr4+ and retarded its release through its chelating effect, while LA improved the efficiency and effectiveness of the crosslinking reaction by increasing the solubility of Zr4+ and providing additional carboxyl groups. The synergistic effect of the two ligands significantly improved the properties of the final crosslinked product. Evidence from FTIR, 13C NMR, and microstructural tests supports the conclusion that the retardation of degradation and enhancement of gelation performance in the HPAM/PEI system by ZrOr complex are associated with its crosslinking with carboxyl groups produced by HPAM hydrolysis, leading to the formation of a more uniform and compact network structure. A field trial conducted in the Beiyao Block demonstrated the potential of the ZrOr complex to extend the treatment lifetime of the HPAM/PEI gel system in medium-salinity reservoirs.

Improvement of the gel properties of curdlan gel by hydrogen bonding interaction with trehalose

This study investigated the effect of trehalose addition (0.5–2.0%) on the gelation properties of curdlan gels were investigated. The results demonstrated that the optimal gelation performance of curdlan-trehalose composite gel was determined at trehalose concentration of 1.0% with preferable water holding capacity, water absorption rate, and freeze-thaw stability. The gelation behavior of the curdlan-trehalose composite gel showed a more intense network structure with increasing storage modulus (G′), loss modulus (G″), and deceasing tan δ at the trehalose concentration in the range of 0%–1%. And the highest gel strength was also observed in 1% trehalose addition. Moreover, the structures characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Low field nuclear magnetic resonance (LF-NMR) and scanning electron microscope analysis (SEM) all revealed that the addition of trehalose strengthened the hydrogen bonding interaction with curdlan to create a much denser network of composite gel, which would provide a better mechanistic insight of the curdlan-trehalose gel in practical application potentials in food and medicine.

Effect of chickpea protein modified with combined heating and high-pressure homogenization on enhancing the gelation of reduced phosphate myofibrillar protein

The effects of chickpea protein (CP) modified by heating and/or high-pressure homogenization (HPH) on the gelling properties of myofibrillar protein under reduced phosphate conditions (5 mM sodium triphosphate, STPP) were investigated. The results showed that heating and HPH dual-modified CP could decrease the cooking loss by 29.57 %, elevate the water holding capacity by 17.08 %, and increase the gel strength by 126.88 %, which conferred myofibrillar protein with gelation performance comparable with, or even surpassing, that of the high-phosphate (10 mM STPP) control. This gelation behavior improvement could be attributed to enhanced myosin tail–tail interactions, decreased myosin thermal stability, elevated trans–gauche–trans disulfide conformation, strengthened hydrophobic interactions and hydrogen bonding, the uncoiling of α-helical structures, the formation of well-networked myofibrillar protein gel, and the disulfide linkages between the myosin heavy chain, actin, and CP subunits. Therefore, the dual-modified CP could be a promising phosphate alternative to develop healthier meat products.

Customized Modification of Welan Gum Properties Through Controllable Grafting of Acrylamide.

Welan gum (WG) has a wide range of applications, but it is not yet suitable for applications such as oil recovery profile control that have complex requirements for viscosity, gelation properties, and so forth. Grafting modification is an important strategy for improving the property of WG, but there are few reports on controllable modification of WG to customize it for specific application. Acrylamide (AM) dosage was identified as the key factor affecting the grafting ratio of AM onto WG by a uniform experimental design. The grafting ratio can be directly adjusted between 99% and 378% based on the positive correlation with dosage of AM, and viscosity can be adjusted between 206 and 327 mPa s based on the negative correlation with grafting ratio. The 50% weight loss temperature of W11 with a grafting ratio of 110% raised from 314 to 336°C after grafting. The viscosity of the hydrogel formed with WG11 reached 15,654 mPa s, nearly nine times higher than that of unmodified WG. In addition, the gelation time can be controlled within 5 days, so that it can be injected to the optimal area in oilfield profile, avoiding pipeline blockage. This study enables adjusting viscosity of WG grafted with AM by controlling the grafting rate, and enhances gelation performance and thermal stability of WG, which will expand the application of WG in oil recovery and other fields.

Structure, characterization, and application of a novel thermoreversible emulsion gel fabricated by citrate agar

A novel thermoreversible emulsion gel was successfully prepared with citrate agar (CA) as the sole emulsifier. Compared with native agar gel emulsion, CA gel emulsion (CAGE) formed a stable emulsion gel when the CA concentration was increased to 1.25 % (w/w). Results of time-temperature scanning experiments showed that the emulsion gel rapidly transformed into liquid emulsion when heated to 40–50 °C and then solidified into emulsion gel after cooling to the critical temperature of solidification. The emulsion gel had stable sol–gel transformation ability after seven cycles repeated heating–cooling treatment (HCT) at 85 °C and 4 °C. However, the stability of emulsion gels gradually decreased because of the large-droplet formation during heating, which affected the CA molecular-reconfiguration network structure in cooling. The conjunction analysis of microstructure and properties of the emulsion gel indicated that its stability depended primarily on the spatial repulsion and electrostatic repulsion provided by CA gel, and the main factor driving thermal reversibility was the temperature-responsive gelation performance of CA. The retention of quercetin was >90.23 % after seven HCTs because CAGEG enhanced the homogeneity and stability of the droplets.

The Application Potential of Artificial Intelligence and Numerical Simulation in the Research and Formulation Design of Drilling Fluid Gel Performance.

Drilling fluid is pivotal for efficient drilling. However, the gelation performance of drilling fluids is influenced by various complex factors, and traditional methods are inefficient and costly. Artificial intelligence and numerical simulation technologies have become transformative tools in various disciplines. This work reviews the application of four artificial intelligence techniques-expert systems, artificial neural networks (ANNs), support vector machines (SVMs), and genetic algorithms-and three numerical simulation techniques-computational fluid dynamics (CFD) simulations, molecular dynamics (MD) simulations, and Monte Carlo simulations-in drilling fluid design and performance optimization. It analyzes the current issues in these studies, pointing out that challenges in applying these two technologies to drilling fluid gelation performance research include difficulties in obtaining field data and overly idealized model assumptions. From the literature review, it can be estimated that 52.0% of the papers are related to ANNs. Leakage issues are the primary concern for practitioners studying drilling fluid gelation performance, accounting for over 17% of research in this area. Based on this, and in conjunction with the technical requirements of drilling fluids and the development needs of drilling intelligence theory, three development directions are proposed: (1) Emphasize feature engineering and data preprocessing to explore the application potential of interpretable artificial intelligence. (2) Establish channels for open access to data or large-scale oil and gas field databases. (3) Conduct in-depth numerical simulation research focusing on the microscopic details of the spatial network structure of drilling fluids, reducing or even eliminating data dependence.

Gelation and Plugging Performance of Low-Concentration Partially Hydrolyzed Polyacrylamide/Polyethyleneimine System at Moderate Temperature and in Fractured Low-Permeability Reservoir.

HPAM/PEI gel is a promising material for conformance control in hydrocarbon reservoirs. However, its use in low-permeability reservoirs is limited by the high polymer concentrations present. In this study, the gelation performance of an HPAM/PEI system with HPAM < 2.0 wt.% was systematically investigated. The gelation time for HPAM concentrations ranging from 0.4 to 2.0 wt.% varied from less than 1 h to 23 days, with the highest gel strength identified as grade H. The hydrodynamic radius manifested the primary effect of HPAM on the gelation performance. Branched PEI provided superior gelation performance over linear PEI, and the gelation performance was only affected when the molecular weight of the PEI varied significantly. The optimal number ratio of the PEI-provided imine groups and the HPAM-provided carboxylic acid functional groups was approximately 1.6:1~5:1. Regarding the reservoir conditions, the temperature had a crucial effect on the hydrodynamic radius of HPAM. Salts delayed the gelation process, and the order of ionic influence was Ca2+ > Na+ > K+. The pH controlled the crosslinking reaction, primarily due to the protonation degree of PEI and the hydrolysis degree of HPAM, and the most suitable pH was approximately 10.5. Plugging experiments based on a through-type fracture showed that multi-slug plugging could significantly improve the plugging performance of the system, being favorable for its application in fractured low-permeability reservoirs.

Moderation-excess interactions of epigallocatechin gallate and CaCl2 modulate the gelation performance of egg white transparent gels

In this study, the moderation–excess interaction of epigallocatechin gallate (EGCG) and calcium ions (Ca2+) to the gelation performance of transparent egg white protein (EWP) gel (EWG) was explored. The oxidation of EGCG introduced a yellowish-brown EWG, whereas the weakening of Ca2+ ionic bonds caused a notable reduction in the hardness of EWG, from 120.67 g to 73.57 g. Achieving the optimal EGCG-to-Ca2+ ratio in EWG conferred enhanced water-holding capacity to 86.98%, while an excess of EGCG attributed to the creation of a three-dimensional structure within the void “walls”. The elevated presence of EGCG influenced the ionic bonds and hydrophobic interactions, thereby presenting a moderate–excess relationship with sulfhydryl and disulfide bonds, β-sheet, and α-helical structures. Notably, EGCG reduced the digestibility of EWG to 50.06%, while concurrently fostering the creation of smaller particle sizes. This study provides a scientific basis for the controllable preparation and quality regulation of transparent EWG.

Applying colloidal silica suspensions injection and sequential gelation to block vertical water flow in well annulus: laboratory testing on rheology, gelation, and injection

We evaluated the application of silica suspension injection and sequential gelation to block vertical water flow in the annuli of long-screened wells. First, we studied the viscosity, rheological behavior, and gelation performance of colloidal silica suspensions in batch tests. Then, we tested the injection of silica suspensions and the water flow blocking efficiency of the later formed silica gel in column and bench-scale sandbox experiments. Micron-sized fumed powder silica suspensions and nanosized silica suspensions recovered from geothermal fluids were tested in this work. Fumed silica suspensions showed shear thinning, while nanosized silica suspensions exhibited Newtonian flow behavior. During the gelation process, the nanosized silica suspension changed from a Newtonian fluid to a shear thinning fluid while increasing its overall viscosity. At comparable concentrations, the nanosized silica suspensions have much lower viscosity than that of the fumed silica suspensions. Increases in the Na+ concentration and silica particle concentration in these suspensions shortened the gelation time. Silica suspension gelation in sand columns completely blocked the water flow and sustained the injection pressure up to 50 psig (344.7 kPa). A silica suspension was successfully injected into the target zone in the annulus of a bench-scale sandbox mimicking long-screened wells in the field. The silica gel formed in the annulus effectively blocked chemical transport through the gelled zone. Our research reveals that a process using silica suspension injection and sequential gelation technology is promising for blocking the vertical water flow and chemical transport through the filter pack in targeted zones within the annulus of long-screened well systems.

A combinatorial library of two-component gelators based on acid-base complexes of pivalic acid and tert-butylacetic acid

Multi-component self-assembled systems can form highly ordered, complex architectures with diverse morphologies which can be utilized for various high-tech applications. Moreover, a combinatorial library approach can allow us to screen various backbones at the same time for tailoring the functionalities as desired. We report two series of multi-component salt-based gelators based on pivalic acid and tert-butylacetic acid (TBAA) using same set of amines. The two sets of compounds were scrutinized for their gelation performance in a variety of solvents and compared, in order to assess and validate the basic principles behind gelation behavior. The role of acid and effect of increasing a methylene group on the gelation behavior, rheological properties and morphology has been probed.

Comparative analysis of soluble and insoluble dietary fiber on improving the gelation performance and fishy odors of silver carp surimi

This work investigated the effects and mechanisms of soluble and insoluble dietary fiber (SDF and IDF) on the gelation performance and fishy odors of silver carp surimi. The results showed that the gel properties of surimi increased and then decreased with increasing SDF content, and the best gel properties were achieved at 1 wt% SDF. The gel strength, elasticity and deformation resistance of surimi increased in a dose-dependent manner as affected by IDF, but its effect on viscosity and recovery ratio was similar to SDF. Moreover, 2 wt% SDF and 1 wt% IDF reduced the content and odor activity value (OAV) of most fishy compounds in surimi, and the latter was superior to the former. The rheological characteristics indicated that SDF affected the thermal gelation properties of surimi mainly through filling, concentration and volume exclusion, and IDF mainly through filling, concentration and intermolecular interactions between IDF and myofibrillar protein. Additionally, SDF and IDF inhibited the release of fishy odors by improving the gel network structure and their adsorption, but more SDF (2 wt%) promoted the formation of escape channels for odors release. In summary, 1 wt% IDF could simultaneously improve the gelation performance and fishy odors of silver carp surimi.

A dual-crosslinked injectable hydrogel derived from muscular decellularized matrix promoting myoblasts proliferation and myogenic differentiation

To investigate the feasibility of a dual-crosslinked injectable hydrogel derived from acellular musclar matrix (AMM) for promoting myoblasts proliferation and myogenic differentiation. Firstly, hyaluronic acid was oxidized with NaIO 4 and methylated to prepare methacrylamidated oxidized hyaluronic acid (MOHA). Then, AMM obtained by washing enzymatically treated muscle tissue was aminolyzed to prepare aminated AMM (AAMM). MOHA hydrogel and AAMM were crosslinked using Schiff based reaction and UV radiation to prepare a dual-crosslinked MOHA/AAMM injectable hydrogel. Fourier transform infrared spectroscopy (FTIR) was used to characterize MOHA, AAMM, and MOHA/AAMM hydrogels. The injectability of MOHA/AAMM hydrogel were evaluated by manual injection, and the gelation performance was assessed by UV crosslinking. The rheological properties and Young's modulus of the hydrogel were examined through mechanical tests. The degradation rate of the hydrogel was assessed by immersing it in PBS. The active components of the hydrogel were verified using immunofluorescence staining and ELISA assay kits. The promotion of cell proliferation by the hydrogel was tested using live/dead staining and cell counting kit 8 (CCK-8) assays after co-culturing with C2C12 myoblasts for 9 days. The effect of the hydrogel on myogenic differentiation was evaluated by immunofluorescence staining and real time quantitative polymerase chain reaction (RT-qPCR). FTIR spectra confirmed the successful preparation of MOHA/AAMM hydrogel. The hydrogel exhibited good injectability and gelation ability. Compared to MOHA hydrogel, MOHA/AAMM hydrogel exhibited higher viscosity and Young's modulus, a reduced degradation rate, and contained a higher amount of collagen (including collagen type Ⅰ and collagen type Ⅲ) as well as bioactive factors (including epidermal growth factor, fibroblast growth factor 2, vascular endothelial growth factor, and insulin-like growth factor 1). The live/dead cell staining and CCK-8 assay indicated that with prolonged incubation time, there was a significant increase in viable cells and a decrease in dead cells in the C2C12 myoblasts within the MOHA/AAMM hydrogel. Compared with MOHA hydrogel, the difference was significant at each time point ( P<0.05). Immunofluorescence staining and RT-qPCR analysis demonstrated that the deposition of IGF-1 and expression levels of myogenic-related genes (including Myogenin, Troponin T, and myosin heavy chain) in the MOHA/AAMM group were significantly higher than those in the MOHA group ( P<0.05). The MOHA/AAMM hydrogel prepared based on AMM can promote myoblasts proliferation and myogenic differentiation, providing a novel dual-crosslinked injectable hydrogel for muscle tissue engineering.

Evaluation on pH-dependent thermal gelation performance of chickpea, pea protein, and casein micelles

Concerns about health, the environment, and sustainable food supply have inspired researchers into searching new alternative plant proteins to dairy proteins. This study investigated thermal treatment coupled with pH manipulation (3.0, 5.0, 7.0, and 9.0) on the structural and gelation performance of pea, chickpea protein, and casein. Gel electrophoresis suggested that only specific fractions contributed to disulfide bond-mediated aggregates formation: bovine κ-casein and αs2-casein in casein micelles, acidic and basic legumin subunits in pea and chickpea protein. No protein formed self-standing gels but precipitated in macroscopic flocs at pH 5.0. Casein displayed optimum gel performance at pH 3.0 (storage modulus (G′) of 2596.00 Pa, hardness of 603.47 g, water holding capacity of 94.92%), and transitioned into fluid-like viscous state (G′ < 1, loss tangent >1) under neutral or higher pH conditions. Pea protein did not form self-holding gels but aggregates with globular particles over all test pH. Nevertheless, chickpea protein formed self-standing gels regardless of pH (except 5.0) and peaked gel performance at pH 9.0. Hence, this study indicated considerable potential of casein in acidic thermal gel-based food products and confirmed the promising applications of chickpea protein as an alternative to pea protein across diverse pH conditions, and to casein in neutral and alkaline food gel formulations. In addition to providing scientific insight understanding the effects of thermal treatment coupled with pH manipulation on the performance of plant-based protein and dairy protein, this research sheds light on the promising prospects of incorporating chickpea protein into gel-based food formulations.

Comparative studies of structural and thermal gelation behaviours of soy, lentil and whey protein: A pH-dependency evaluation

A growing global concern about human health, environment, and sustainable food supplies has motivated researchers to find new alternatives to dairy proteins. To investigate the effects of pH and protein varieties on the thermal gelation behaviors, plant protein (soy and lentil) and dairy protein (whey) were subjected to a variety of pH treatments. SDS-PAGE showed that only partial subunits of soy and lentil protein were involved in disulphide bonded aggregate formation regardless of pH, and that of whey protein was inhibited at acidic conditions and facilitated at higher pH. Both soy and lentil protein did not form self-standing gels at pH 5.0, while whey protein did, and all proteins displayed different morphologies as pH moved away from 5.0, from white, opaque, and heterogeneous to relatively transparent and homogeneous. Soy protein exhibited its optimal gel performance at pH 9.0 (storage modulus of 946.05 Pa) with the highest content of α-helix, intramolecular β-sheet, and intermolecular/aggregated β-sheet, while whey protein demonstrated its peak gel performance at pH 7.0 (storage modulus of 26271.90 Pa). Lentil protein displayed the best gel performance at pH 3.0 and was comparable to that of whey protein (storage modulus of 5366.00 and 4965.00 Pa, respectively). These findings confirmed that lentil protein has the potential to substitute whey and soy protein in formulations of diversified food products in some specific pH systems. This work highlighted the importance of pH control to achieve desired gelation performance and offered valuable insights for selecting suitable protein alternatives in formulating plant-based food products.

Polyacrylamide and polyethylenimine mixed hydrogels tailored with crude glycerol for conformance fluids: Gelation performance and thermal stability

Minimization of water output is key to prolong oil field production. Although hydrogels are an effective alternative to sealing preferable water pathways in highly permeable reservoirs, their thermal and viscoelastic properties must be tuned to withstand harsh reservoir conditions and avoid damage to the formation. To that end, herein we tested a novel solid-free gel system containing crude glycerol (CG) to control fluid loss in overbalanced operations. Analytical grade glycerol (AGG) was also studied for comparison. Polyacrylamide (PAM) crosslinked with polyethyleneimine (PEI) embedded with CG produced hydrogels thermically resistant and capable to prevent filtration in reservoir conditions (65 °C/90 °C and 300 psi). CG significantly lengthened the gelation time and stability of hydrogels in comparison to AGG, a behavior related to the presence of chloride ions in CG. Noteworthy, glycerol-based hydrogels displayed robust viscoelastic properties, similar to those of systems with solid particles and nanomaterials. Glycerol also enhanced PAM-PEI hydrogels thermal stability, retaining most of gel fraction up to 250 °C. The composition of CG associated with PAM-PEI resulted in a complex combination of ionic and hydrogen bonds that boosted hydrogel network conferring greater stability. The possibility of incorporating CG in conformance fluids is quite advantageous to mitigate the ecological shortcoming posed by the accumulation of biodiesel-derived glycerol.

Effect of nano TiO2 and SiO2 on gelation performance of HPAM/PEI gels for high-temperature reservoir conformance improvement

Nanoparticles have been widely used in polymer gel systems in recent years to improve gelation performance under high-temperature reservoir conditions. However, different types of nanoparticles have different effects on their gelation performance, which has been little researched. In this study, the high-temperature gelation performance, chemical structure, and microstructure of polymer gels prepared from two nanomaterials (i.e., nano-SiO2 and nano-TiO2) were measured. The conventional HPAM/PEI polymer gel system was employed as the control sample. Results showed that the addition of nano-TiO2 could significantly enhance the gel strength of HPAM/PEI gel at 80 °C. The gel strength of the enhanced HPAM/PEI gel with 0.1 wt% nano-TiO2 could reach grade I. The system also had excellent high-temperature stability at 150 °C. The enhanced HPAM/PEI gel with 0.02 wt% nano-TiO2 reached the maximum gel strength at 150 °C with a storage modulus (G′) of 15 Pa, which can meet the need for efficient plugging. However, the nano-SiO2 enhanced HPAM/PEI polymer gel system showed weaker gel strength than that with nano-TiO2 at both 80 and 150 °C with G′ lower than 5 Pa. Microstructures showed that the nano-TiO2 enhanced HPAM/PEI gel had denser three-dimensional (3D) mesh structures, which makes the nano-TiO2 enhanced HPAM/PEI gel more firmly bound to water. The FT-IR results also confirmed that the chemical structure of the nano-TiO2 enhanced HPAM/PEI gel was more thermally stable than nano-SiO2 since there was a large amount of –OH groups on the structure surface. Therefore, nano-TiO2 was more suitable as the reinforcing material for HPAM/PEI gels for high-temperature petroleum reservoir conformance improvement.

Molecular Assembly and Gelating Behavior of (l)-Alanine Derivatives.

In this study, a low-molecular-weight organogelator derived from (l)-amino acids was designed and synthesized. Gelation assays using (l)-amino acid derivatives were performed to confirm the gelation ability, which was found to be high in several compounds. The (l)-alanine derivatives were determined to be excellent gelators, forming good gels even when smaller amounts were added. These results led to a library of amino acid-derived organogelators. In addition, the thermal properties of the (l)-alanine derivatives with high gelation performance were measured. Differential scanning calorimetry measurements revealed that the thermal stability of the gels could be controlled by changing the gelator concentration. The surface states of the obtained gels were observed by field-emission scanning electron microscopy and atomic force microscopy measurements, which confirmed the structure of the self-molecular aggregates. Self-molecular aggregates were observed to be helical or sheet-like, and the gels were constructed by forming aggregates by self-molecular recognition.

Acquisition of insoluble soybean fiber with high gelation performance based on structural modifications through pH-shifting during steam-cooking treatment

Utilization of by-products remains a critical technical challenge in the food industry. This work aimed to improve the gelation performance of insoluble soybean fiber (ISF) from okara based on structural modifications via pH-shifting during steam-cooking treatment. Okara was intrinsically compact and tightly aggregated. Its amorphous region was degraded by steam-cooking at pH 3 and inter-molecular H-bonds were reduced, resulting in increased content of cellulose from 37.86 wt% to 43.32 wt% and crystallinity degree from 7.79% to 40.10%. The compact structure of okara was dissociated into flexible fibers by steam-cooking at pH 11, allowing for higher porosity with a specific surface area reaching 1.4428 m2/g. However, there were no significant changes in microstructure except for a decreased particle size as pH approached neutral. The outstanding structure and adsorption capacity of ISF supported the higher gelatin performance. The hydrogels with a self-supporting and dense network structure were observed after continuous stirring from ISF steam-cooked at pH 3, 4, and 11, which was attributed to H-bonds between ISFs, while okara and other ISF suspensions exhibited good fluidity. These findings provide a new method for ISF treated by steam-cooking to enable hydrogel formation for potential applications in reconstituted foods and low-calorie gel systems.