Search Results (193)

Lost circulation during drilling has significantly hindered the safe and efficient development of oil and gas resources. Supramolecular polymer gel–based lost circulation materials have shown significant potential for application due to their unique molecular structures and superior performance. Herein, a high–performance supramolecular polymer gel was developed, and the influence of reservoir conditions on the performance of the supramolecular polymer gel was investigated in detail. The results identified an optimal formulation for the preparation of supramolecular polymer gel comprising 15 wt% acrylamide, 3 wt% 2-acrylamide-2-methylpropanesulfonic acid, 2.6 wt% divinylbenzene, 5 wt% polyvinyl alcohol, 0.30 wt% cellulose nanofibers, and 3 wt% laponite. The performance of the gel-forming suspension and the resulting supramolecular polymer gel was influenced by various factors, including temperature, density, pH, and the intrusion of drilling fluid, saltwater, and crude oil. Nevertheless, the supramolecular polymer gels consistently exhibited high strength under diverse environmental conditions, as confirmed by rheological measurements. Moreover, the gels exhibited strong plugging performance across various fracture widths and in permeable formations, with maximum breakthrough pressures exceeding 6 MPa. These findings establish a theoretical foundation and practical approach for the field application of supramolecular polymer gels in complex geological formations, demonstrating their effectiveness in controlling lost circulation under challenging downhole conditions. Full article

Aiming to obtain insight into the dynamic properties of ionogels, ¹H NMR relaxation experiments were performed for an ionogel composed of 1-butyl-3-methyl-imidazolium chloride [BMIM][Cl] and propylene carbonate. The experiments were conducted in the frequency range of 10 kHz to 20 MHz, spanning the temperature range of 273 K to 338 K. The data were analyzed in term s of a relaxation model including two relaxation contributions—one of them associated with anisotropic (two-dimensional) translation diffusion, the second one representing a power law dependence of spin-lattice relaxation rates on the resonance frequency. The power law relaxation term (characterized by a very low power law factor of about 0.1) was attributed to the collective dynamics of the partially immobilized propylene carbonate matrix, while the relaxation contribution associated with anisotropic translation diffusion was attributed to the movement of BMIM cations in the matrix; the translation diffusion coefficient was estimated as varying in the range of 10⁻¹³ m²/s–10⁻¹² m²/s. Moreover, other parameters were determined as a result of the analysis, such as the residence lifetime on the matrix surfaces. Subsequently, the temperature dependencies of the determined parameters were assessed. Full article

Most existing polymer plastics are nonreusable and also exhibit poor biocompatibility and a poor mechanical strength–tensile strain balance. Herein, using deep eutectic polymers, we prepare reusable hydrophilic supramolecular dry gel plastics with balanced stress–strain characteristics through the hydrogen bonding of poly(vinyl alcohol) (PVA) with betaine (Bta). As PVA exhibits crystalline stiffness and abundant hydrogen-bonding sites, it is employed as a network backbone in the proposed deep eutectic supramolecular polymers. In the prepared PVA/Bta dry gel plastics, PVA and Bta are dynamically and physically crosslinked through high-density hydrogen bonding, resulting in a yield strength of ~109 MPa and toughness of up to ~210.92 MJ m⁻³. In addition, these plastics can be recycled at least five times in an aqueous environment while maintaining a mechanical strength of 100 MPa. Furthermore, the proposed polymers exhibit high transparency (92%) in the visible spectrum. We expect these polymers to be used in synthesizing biodegradable dry gel plastics, as well as to lead to the development of recyclable deep eutectic PVA/Bta polymers with remarkable strength. Full article

Visible-light photoredox catalysis using biacetyl (BA) as a low-cost photosensitizer enables the efficient formation of triarylethylenes (TAEs) via a Mizoroki–Heck-type coupling. The reaction proceeds efficiently in acetonitrile upon blue LED irradiation under anaerobic conditions. Alternatively, supramolecular viscoelastic gels have also been explored as reaction media, allowing the possibility of working under aerobic atmosphere. Mechanistic investigations by means of transient absorption spectroscopy and quenching experiments support a charge-separated intermediate pathway. Reaction quantum yield measurements further validate the efficiency of BA, demonstrating its potential as an alternative to transition-metal catalysts. Overall, this work presents a sustainable and scalable strategy for TAEs synthesis, integrating photoredox catalysis with soft material engineering. These findings pave the way for broader applications in green chemistry and functional materials. Full article

Aiming at the problem that conventional friction reducers used in fracturing cannot simultaneously possess properties such as temperature resistance, salt resistance, shear resistance, rapid dissolution, and low damage. Under the design concept of “medium-low molecular weight, salt-resistant functional monomer, supramolecular physical crosslinking aggregation, and enhanced chain mechanical strength”, acrylamide, sulfonic acid salt-resistant monomer 2-acrylamide-2-methylpropanesulfonic acid, hydrophobic association monomer, and rigid skeleton functional monomer acryloyl morpholine were introduced into the friction reducer molecular chain by free radical polymerization, and combined with the compound suspension technology to develop a new type of multi-functional viscous friction reducer suspension (SAMD), the comprehensive performance of SAMD was investigated. The results indicated that the critical micelle concentration of SAMD was 0.33 wt%, SAMD could be dissolved in 80,000 mg/L brine within 3.0 min, and the viscosity loss of 0.5 wt% SAMD solution was 24.1% after 10 min of dissolution in 80,000 mg/L brine compared with that in deionized water, the drag reduction rate of 0.1 wt% SAMD solution could exceed 70% at 120 °C and still maintained good drag reduction performance in brine with a salinity of 100,000 mg/L. After three cycles of 170 s⁻¹ and 1022 s⁻¹ variable shear, the SAMD solution restored viscosity quickly and exhibited good shear resistance. The Tan δ (a parameter characterizing the viscoelasticity of the system) of 1.0 wt% SAMD solution was 0.52, which showed a good sand-carrying capacity, and the proppant settling velocity in it could be as low as 0.147 mm/s at 120 °C, achieving the function of high drag reduction at low concentrations and strong sand transportation at high concentrations. The viscosity of 1.4 wt% SAMD was 95.5 mPa s after shearing for 120 min at 140 °C and at 170 s⁻¹. After breaking a gel, the SAMD solution system had a core permeability harm rate of less than 15%, while the SAMD solution also possessed the performance of enhancing oil recovery. Compared with common friction reducers, SAMD simultaneously possessed the properties of temperature resistance, salt resistance, shear resistance, rapid dissolution, low damage, and enhanced oil recovery. Therefore, the use of this multi-effect friction reducer is suitable for the development of unconventional oil reservoirs with a temperature lower than 140 °C and a salinity of less than 100,000 mg/L. Full article

A chiral gelator (R)-H₆L with multiple carboxyl groups based on a 1,1′-bi-2,2′-naphthol (BINOL) skeleton was prepared, and it could form a supramolecular gel under the induction of water in DMSO/H₂O and DMF/H₂O (1/1, v/v). In the EtOH/H₂O system, the original partial gel transformed into a stable metal–organic gel (MOG), specifically with Cu²⁺ among 20 metal ions. It is proposed that Cu²⁺ coordinates with the carboxyl groups of (R)-H₆L to form a three-dimensional network structure. With the addition of a variety of α-hydroxy acids and amino acids, the Cu²⁺-MOG collapsed with merely 0.06 equivalents of L-tartaric acid (L-TA), while other acids required much larger amounts to achieve the same effect, realizing the visual chemoselective and enantioselective recognition of tartaric acid. Therefore, the chiral gelator (R)-H₆L achieved the tandem visual recognition of Cu²⁺ and chiral tartaric acid by sequence gel formation and collapse, offering valuable insights for visual sensing applications and serving as a promising model for future chiral sensor design. Full article

Cosmetic formulations are complex mixtures of ingredients that must fulfill several requirements. One of the challenges of the cosmetic industry is to find natural alternatives to replace synthetic polymers, preserving desirable sensory characteristics. The aim of this work is to induce the formation of gels, by replacing synthetic polymers with a low-molecular-weight gelator (LMWG), a small molecule able to self-assemble and form supramolecular networks. The impact of low-molecular-weight gelators on the environment is reduced as they are highly biodegradable. Thus, the behavior of solutions containing Boc-L-Dopa(Bn)₂-OH, an LMWG, together with ten different anionic surfactants, was studied to understand if the LMWG may act as a rheological modifier by increasing the viscosity of the formulation or forming gels with these ingredients. An amphoteric surfactant, cocamidopropyl betaine (CAPB), often used to increase cleansing gentleness, was also added to the solutions to better mimic a cosmetic formulation. In most cases, the addition of the gelator at only a 1% w/v concentration induces the gelification or an increase in the viscosity of the solutions, thus showing that this molecule is also able to self-assemble in complex mixtures. Full article

Spatial control over molecular self-assembly at the nano scale offers great potential for many high-tech applications, yet remains a challenging task. Here, we report a polymer brush-mediated strategy to confine the self-assembly of hydrazone-based hydrogelators exclusively at nanoparticle surfaces. The surfaces of these nanoparticles are grafted with negatively charged polyacrylic acid, which enrich protons that can catalyze the in situ formation and self-assembly of hydrazone-based gelators. We found that, with respect to the polymer lengths, the concentration of the nanoparticles presents more significant effects on the self-assembly process and the properties of the resultant hydrogels, including gelation time, stiffness, and network morphology. More interestingly, the hydrogel fibers are found to be formed specifically around the nanoparticles, demonstrating the directed nanoscale molecular self-assembly. This work demonstrates that triggering molecular self-assembly using catalysis can serve as an effective way to realize directed molecular self-assembly at the nano scale, which may serve as a powerful approach to improve many material properties, such as the mechanical properties of supramolecular materials as we found in this work. Full article

Rapid rehydration is a critical challenge in the production of dry rice noodles. This study investigated the impact of high-temperature short-time treatments (HTSTTs) at temperatures of 120 °C, 130 °C, and 140 °C for 80 s on the rice noodle rehydration time and the underlying mechanisms. HTSTT led to a reduction in the relative crystallinity and molecular weight of starch, along with the disruption of its supramolecular structure. Moreover, significant alterations were observed in the pore properties after HTSTT, characterized by a notable increase in total pore volume and average pore size. The enhanced porosity and disrupted starch multiscale structure resulted in shortened cooking times for the rice noodles. This reduction in cooking time mitigated gel disruption during cooking, thereby reducing amylose leaching and preserving a more intact gas cell wall structure. Consequently, HTSTT markedly enhanced the overall quality of the rice noodles. For instance, noodles treated at 140 °C for 80 s exhibited a 26.55% decrease in cooking time, a 30.37% reduction in cooking loss, a 37.62% increase in hardness, and a 13.24% increase in resilience compared to the control group. In summary, HTSTT emerges as a feasible method for reducing the cooking time of rice noodles. Full article

Stimuli-responsive materials, particularly supramolecular hydrogels, exhibit a dynamic adaptability to external factors such as pH and ultrasound. Among these, phenylalanine (Phe)-derived hydrogels are promising due to their biocompatibility, biodegradability, and tunable properties, making them ideal for biomedical applications. This study explores the effects of pH and ultrasound on the gelation properties of N-substituted Phe derivatives, with a primary focus on the role of ultrasound in optimizing the gelation process. A series of N-substituted Phe derivatives were synthesized via reductive amination and hydrolysis. Hydrogel formation was possible with two of these compounds, namely G1 and G2, using the following two methods: heating–cooling (H–C) and heating–ultrasound–cooling (H–US–C). The critical gelation concentration (CGC), gelation kinetics, thermal stability (T_gel), and viscoelastic properties were assessed. Morphological and cytotoxicity analyses were performed to confirm the suitability of these gels for biomedical applications. Both G1 and G2 derivatives demonstrated enhanced gelation under the H–US–C protocol compared to H–C, with notable reductions in CGC (up to 47%) and gelation time (by over 90%). Ultrasound-induced gels led to an improved network density and stability, while maintaining thermal reversibility and mechanical properties comparable to those of hydrogels formed without ultrasound. Cytotoxicity studies confirmed a high biocompatibility, with cell viability rates above 95% across the tested concentrations. Given the similar rheological and morphological properties of the hydrogels regardless of the preparation method, drug release experiments were performed with representative gel samples and demonstrated the efficient encapsulation and controlled release of 5-fluorouracil and methotrexate from the hydrogels, supporting their potential as pH-responsive drug delivery platforms. This study highlights the role of ultrasound as a powerful tool for accelerating and optimizing the gelation process of supramolecular hydrogels, which is particularly relevant for applications requiring rapid gel formation. The developed Phe-based hydrogels also demonstrate promising characteristics as drug delivery systems. Full article

Gelling agents are critical for food texture and stability; usually, polymeric substances are employed. Low-molecular-weight gelators (LMWG) like phenylalanine (PHE) form supramolecular gels. However, food applications are limited due to amino acid derivatization or gelling solvent. This study characterizes PHE, water, and propylene glycol solutions and their gelling capability when cooled or stirred. Gelation is faster at higher stirring speeds. Gel strength increases if pH is near the PHE isoelectric point or at higher PHE concentrations, which increases gel transition temperature. Solutions develop browning in xylose (XYL) presence via first-order kinetics, accelerated by increasing PHE or xylose concentration. Full article

Nowadays, large amounts of wastewater arise from various industrial applications. The discharge of wastewater into the environment represents a threat to the aquatic ecosystem and human health. Thus, in the present study, innovative double-network (DN) hydrogels with pH-sensitive features and applicability as adsorbents in the treatment of leather dye wastewater were prepared. The polyelectrolyte, poly(N,N-dimethylaminoethyl methacrylate (PDMAEMA), was obtained via the radical polymerization process, while the supramolecular structure was co-assembled through physical interactions. As a novelty, the double network was obtained through the interpenetration of the supramolecular network in the cross-linked polymeric one. The new hydrogels were physico-chemically and morphologically characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and in terms of thermogravimetric analysis (TGA), swelling degree measurements, and dye adsorption studies. The DN hydrogels present interconnected macropores and high thermal stability. The swelling capacity of the dual network gels highlights a superadsorbent behavior at pH 3. Furthermore, the dye adsorption study highlights the effects of several variables (pH, concentration dose of adsorbent) on the ability of the gels to adsorb an anionic dye. The adsorption kinetics of the anionic dyes fitted the pseudo-first-order model (PFO). The estimated maximum adsorption capacities for the anionic dyes was 451 mg g⁻¹ for PDMAEMA and 545 mg g⁻¹ for DN gel. Full article

A series of triphenylene (TP) compounds—denoted 3,6-THTP-DiCnOH—bearing four hexyloxy ancillary chains and two variable-length alkoxy chains terminally functionalized with hydroxyl groups have been synthesized and characterized. The shorter homologs revealed mesogenic characteristics, giving rise to thermotropic mesophases in which π-stacked columns of H-bound dimers self-organize yielding superstructures. Molecular-scale models are proposed to account for their structural features. The three studied compounds yielded supramolecular gels in methanol; their ability to gelify higher alcohols was found to be enhanced by the presence of water. The intermediate homolog also gelled n-hexane. Compared to their isomeric 2,7-THTP-DiCnOH analogs, the 3,6-derivatives showed a higher tendency to give rise to LC phases (wider thermal ranges) and a lower organogelling ability (variety of gelled solvents, lower gels stabilities). The overall results are analyzed in terms of different kinds of competing H-bonds: intramolecular, face-to-face dimeric, lateral polymeric, and solvent–TP interactions. Full article

The development of new convenient tools for the design of multicomponent nucleic acid (NA) complexes is one of the challenges in biomedicine and NA nanotechnology. In this paper, we analyzed the formation of hybrid RNA/DNA concatemers and self-limited complexes by a pair of oligonucleotides using UV melting, circular dichroism spectroscopy, and a gel shift assay. Effects of the size of the linker between duplex-forming segments of the oligonucleotides on complexes’ shape and number of subunits were compared and systematized for RNA/DNA, DNA/DNA, and RNA/RNA assemblies. The data on complex types summarized here as heat maps offer a convenient tool for the design of NA constructs. General rules found for RNA/DNA, DNA/DNA, and RNA/RNA complexes allow not only designing complexes with desired structures but also purposefully transforming their geometry. The A-form of the double helix of the studied RNA/DNA complexes was confirmed by circular dichroism analysis. Moreover, we show for the first time efficient degradation of RNA in hybrid self-limited complexes by RNase H and imidazole. The results open up new prospects for the design of supramolecular complexes as tools for nanotechnology, nanomachinery, and biomedical applications. Full article

In this study, novel anion photo-responsive supramolecular hydrogels based on cysteine–silver sol (CSS) and iodate anions (IO₃⁻) were prepared. The peculiarities of the self-assembly process of gel formation in the dark and under visible-light exposure were studied using a complex of modern physico-chemical methods of analysis, including viscosimetry, UV spectroscopy, dynamic light scattering, electrophoretic light scattering, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. In the dark phase, the formation of weak snot-like gels takes place in a quite narrow IO₃⁻ ion concentration range. The visible-light exposure of these gels leads to an increase in their viscosity and dramatic change in their color. The morphology of gels alters after light irradiation that is reflected in the formation of a huge number of spherical/elliptical particles and the thickening of the fibers of the gel network. The interaction of CSS with IO₃⁻ anions has features of a redox process, which leads to the formation of silver iodide/silver oxide nanoparticles inside and on the surface of CSS particles. CSS possesses selectivity only to IO₃⁻ anions compared to many other inorganic ions relevant for humans and the environment. Thus, the CSS/IO₃⁻ system is non-trivial and can be considered as a novel low-molecular-weight gelator with photosensitive properties, as another way to produce silver iodide nanoparticles, and as a new approach for IO₃⁻ ion detection. Full article