Search Results (39)

With the rapid advancement of the IoT society and growing awareness of environmental issues, thermoelectric conversion technology—which directly converts waste heat into electricity—is gaining attention as a self-powered, autonomous power source capable of driving countless devices. While currently mainstream metal-based inorganic thermoelectric materials demonstrate high performance, their high rigidity and brittleness, as well as their frequent inclusion of toxic heavy metals, have limited their application in biological systems and on curved surfaces. As a next-generation alternative, single-walled carbon nanotubes (SWCNTs)—which possess excellent flexibility, electrical conductivity, and mechanical strength while being low in toxicity—are garnering significant attention. However, n-type SWCNT materials, which are essential for thermoelectric module fabrication, have faced two major barriers to practical application: low atmospheric stability (they easily revert to p-type upon exposure to atmospheric oxygen and moisture) and thermoelectric performance that falls short of inorganic materials. This review comprehensively outlines the latest composite approaches designed to overcome these critical challenges and achieve both extreme atmospheric stability and high thermoelectric performance in n-type SWCNT materials, along with the flexibility required to withstand severe deformation. Three main strategies are discussed. The first is the organic/polymer approach, which involves doping with organic small molecules that control the LUMO level or bicyclic organic superbases with strong electron-donating properties, as well as polymer coating, to achieve long-term stable n-type characteristics and high power output even in air or under severe high-temperature conditions. The second is the inorganic hybrid strategy, which involves nanoscale compositing with inorganic materials such as Bi₂Te₃ and Cu₂O; this reduces thermal conductivity through phonon scattering via interface control, while the inorganic layer physically blocks oxygen to ensure long-term atmospheric stability. The third approach involves ultra-long-term stabilization techniques, such as bulk encapsulation using cationic or gemini surfactants, and environmentally friendly aqueous processes utilizing natural amino acids. Furthermore, we discuss the latest developments in imparting practical-level toughness (flexibility) capable of withstanding thousands of bending cycles and high tensile stress through the introduction of dynamic covalent network polymers and elastomers. The conformal flexible thermoelectric power generation modules created through the integration of composite optimization, low-environmental-impact processes, and doping techniques will serve as a crucial foundational technology for realizing a sustainable next-generation electronics society, including future wearable devices, artificial skin, and smart sensor networks. Full article

Wormlike micelles (WLMs) of surfactants are widely used as smart thickeners in various applications, including enhanced oil recovery. However, their thickening ability needs to be improved both at ambient and elevated temperatures. In the present paper, we propose to enhance the viscoelastic properties of surfactant solutions by incorporating carboxymethylated cellulose nanocrystals (CNCs). Upon addition of CNCs, dilute solutions of short WLMs acquire viscoelasticity and then transition into a viscoelastic solid state. This process is accompanied by an increase in the viscosity and storage modulus by up to five and four orders of magnitude, respectively. The observed effect of CNCs on the storage modulus and viscosity is greater than that of any of the previously studied WLM-CNC systems. It is attributed to the formation of a network of fibrillar-like aggregates composed of WLMs and CNCs, which was confirmed by cryo-TEM data. To our knowledge, such kind of aggregates have not been observed before. When CNCs are added to a transient network of long entangled WLMs, the viscoelastic solution transitions into a viscoelastic solid state, which results in an increase in the viscosity and storage modulus by up to two orders of magnitude. CNCs provide the WLM solution with greater resistance to heating, such that the storage modulus remains almost unchanged when the temperature increases from 20 to 70 °C. Moreover, a heat-induced gelation was observed. It was shown that higher concentrations of nanocrystals lower the critical gel temperature, indicating that they promote the gelation of the mixture. SANS data revealed that the local structures of both micelles and nanocrystals are preserved in the mixed system upon heating. According to ITC data, at room temperature, the interaction between surfactant ions and similarly charged nanocrystals is governed by both enthalpy and entropy, which suggests that hydrogen bonding plays a major role in this process, although hydrophobic interactions may also be involved. When the temperature increases to 60 °C, the aggregation becomes entropy-driven, indicating that hydrophobic interactions begin to dominate. The results obtained can expand the range of practical applications of WLMs as thickening agents, in particular, to higher-temperature conditions in deeper oil wells. Full article

Tight oil reservoirs are widely recognized as a critical successor in global unconventional energy development and are generally characterized by distinct geological features, including fine pore throats, pronounced heterogeneity, and a high concentration of clay minerals (e.g., montmorillonite and mixed-layer illite/smectite). Severe hydration, swelling, and fines migration are readily induced during water injection or conventional water-based fluid operations, thereby resulting in irreversible impairment of reservoir permeability. Despite the excellent injectivity and capacity for viscosity reduction associated with CO₂ flooding, sweep efficiency is severely compromised by viscous fingering and gas channeling, which are induced by the inherent low viscosity of the gas. While CO₂ foam technology is widely acknowledged as a pivotal solution for addressing mobility control challenges, its implementation is hindered by a primary technical bottleneck: the incompatibility between traditional water-based foam systems and strongly water-sensitive reservoirs. A dual challenge comprising water injectivity constraints and gas channeling is presented by strongly water-sensitive tight oil reservoirs. To address these impediments, three emerging low-damage CO₂ foam systems are critically evaluated in this review. First, the synergistic mechanisms of novel quaternary ammonium salts and polymers in inhibiting clay hydration and enhancing foam stability within modified water-based systems are elucidated. Next, the physical isolation strategy of substituting the water phase with a non-aqueous phase (oil/organic solvent) in organic emulsion systems is analyzed, highlighting advantages in wettability alteration and the mitigation of water blocking. Finally, the prospect of waterless operations using CO₂-soluble foam systems—wherein supercritical CO₂ is utilized as a surfactant carrier to generate foam or viscosify fluids via in situ formation water—is discussed. It is revealed by comparative analysis that: (1) Modified water-based systems are identified as the most economically viable option for reservoirs with moderate water sensitivity, wherein cationic stabilizers are utilized to inhibit hydration; (2) Superior wettability alteration and the elimination of aqueous phase damage are provided by organic emulsion systems, rendering them ideal for ultra-sensitive, high-value reservoirs, despite higher solvent costs; (3) CO₂-soluble systems are recognized as the future direction for “waterless” flooding, specifically tailored for ultra-tight formations (<0.1 mD) where injectivity is critical. Current challenges, such as surfactant solubility, high-temperature stability, and cost control, are identified through a comparative analysis of these three systems with respect to structure-activity relationships, rheological properties, damage control capabilities, and economic feasibility. What is more, an outlook is provided on the molecular design of future environmentally sustainable, cost-effective CO₂-philic materials and smart injection strategies. Consequently, theoretical foundations and technical support are established for the efficient exploitation of strongly water-sensitive tight oil reservoirs. By bridging the gap between reservoir damage control and mobility enhancement, this study identifies viable strategies for enhanced oil recovery. Crucially, it supports carbon neutrality and sustainable energy targets via CCUS integration. Full article

Niosomes (NIOs), a class of nanovesicular drug delivery system, have garnered significant attention due to their unique architecture, resulting from the self-assembly of non-ionic surfactants (with or without cholesterol) in aqueous media. This bilayered structure enables the encapsulation of both hydrophilic agents in the aqueous core and lipophilic compounds within the lipid bilayer, offering remarkable versatility in therapeutic applications. This article provides an overview of the key principles underlying niosomal formulations, including their composition, preparation methods, formulation conditions and the critical physicochemical parameters influencing vesicle formation and performance. Special emphasis is placed on recent innovations in surface and content modifications that have led to the development of stimuli-responsive niosomal systems, with precise and controlled drug release. These smart carriers are designed to respond to endogenous stimuli (such as pH variations, redox gradients, enzymatic activity, or local temperature changes in pathological sites), as well as to exogenous triggers (including light, ultrasound, magnetic or electric fields, and externally applied hyperthermia), thereby enhancing therapeutic precision. These surface and content modulation strategies effectively transform conventional NIOs into intelligent, stimuli-responsive platforms, reinforcing their innovative role in drug delivery and highlighting their significant potential in the development of smart nanomedicine. Full article

To address issues of traditional coalbed methane (CBM) fracturing fluids (high displacement, weak sand-carrying, poor stability, severe coal seam damage), this study synthesized CO₂-responsive erucamide propyl dimethylamine surfactant (C₂₂ZEA, yield 99%), with molecular structure verified by ¹H NMR (400 MHz, CDCl₃) matching the target. Molecular simulation showed CO₂ protonates C₂₂ZEA into EA⁺: 1 wt% forms a simple micelle network, while 3 wt% enhances entanglement into a dense 3D network. Experiments indicated: 3 wt% solution reaches 160 mPa·s viscosity in 200 s under CO₂ (0.2 L·min⁻¹); 1.5–4.5 wt% solutions are pseudoplastic (n = 0.14–0.18), with G′ > G″ when concentration > 2 wt%; viscosity recovery rate > 95% after alternating shear (170 s⁻¹/10 s⁻¹); viscosity remains > 160 mPa·s after 1 h shear (170 s⁻¹) at 70 °C; gel breaks to 0.01–0.02 Pa·s in 15 min with N₂ at 45 °C; 1.0–3.0 wt% solutions meet non-toxic standards via EC₅₀/96 h LC₅₀. This study supports high-efficiency low-damage smart fracturing fluids, boosting CBM extraction efficiency. Full article

Thermosensitive hydrogel, as a smart polymer material, showed great potential for application in the field of wound repair due to its unique external temperature responsiveness and excellent biocompatibility. Chitosan, a natural macromolecular polysaccharide derived from the deacetylation of chitin, possessed not only strong interactions with biomolecules such as DNA, proteins, and lipids, but also unique biocompatibility and degradability. Chitosan-based thermosensitive hydrogels, prepared by compounding chitosan with surfactants, underwent sol–gel phase transitions at varying external temperatures, which provided an ideal healing environment for wounds. This comprehensive review was initiated by elucidating the sol–gel phase transformation mechanism underlying thermosensitive hydrogels and the intricate process of wound repair. In addition, this review provided a detailed overview of the prevalent types of chitosan-based thermosensitive hydrogels, highlighting their unique characteristics and applications in different types of wound repair. Finally, the challenges and development directions of chitosan-based thermosensitive hydrogels in wound repair were discussed, aiming to provide theoretical support and practical guidance for their future applications in wound healing. Full article

Background/Objectives: With advancements in biomaterial sciences, biofunctional excipients have emerged to focus on solving issues with the drugs’ inherent biopharmaceutical characteristics such as poor solubility, permeability, in vivo dissolution, and effective targeting. These advanced excipients significantly impact drug solubility, dissolution rates, absorption rates, permeation rates, penetration ability, targeting ability, and pharmacokinetic profiles. Methods: A literature review of recently published articles was prepared. Data were collected using scientific search engines. This review provided a detailed discussion of various biofunctional excipients including smart polymers, targeted polymers, bioadhesive polymers, lipids, amino acids, cyclodextrins, and biosurfactants. Each category was discussed in detail concerning its biofunctional applications, the mechanisms underlying these biofunctions, and examples of their effects on drug performance. Results: The data obtained indicated that the rapid advances in the manufacturing of pharmaceutical excipients have resulted in the development of a diverse array of smart or intelligent excipients that play a crucial role in enhancing inherent poor biopharmaceutical characteristics. Conclusions: These advancements have also facilitated the development of various drug delivery systems, including immediate, controlled, sustained, and targeted drug release systems. Also, numerous nano-based delivery systems have emerged utilizing the newly produced excipients. Full article

CO₂-responsive worm-like micelles (WLMs) are considered promising for applications in smart materials, enhanced oil recovery, and drug delivery because of their reversible and tunable properties. This study presents a novel system of CO₂-responsive WLMs, which is constructed using a double-tailed surfactant (DTS). When exposed to CO₂, the DTS molecules undergo protonation, resulting in the formation of ultra-long-chain cationic surfactants that self-assemble into worm-like micelles. The zero-shear viscosity of the DTS–CO₂ solution achieves approximately 300,000 mPa·s, which is 300,000 times higher than that of pure water. In contrast, the DTS–air solution exhibits a viscosity of only 2 mPa·s. The system retains a viscosity above 100,000 mPa·s across a temperature range of 25–120 °C under a CO₂ atmosphere. Moreover, it demonstrates reversible transitions between high- and low-viscosity states without any loss of responsiveness, even after multiple cycles. The critical overlap concentration of the DTS–CO₂ micellar system is determined to be 80 mM. This research offers valuable insights into the development of CO₂-responsive surfactants, highlighting their potential for designing advanced functional materials. Full article

Background/Objectives: Cationic surfactants are potential antimicrobial candidates. Even so, they are the foremost irritative and incompatible group, which limits their usage. The incorporation of surfactants in biopolymer-based nanoparticles is a feasible strategy to improve their efficacy and reduce those drawbacks. Methods: Surfactants with one amino acid on the polar head (lauroyl arginine methyl ester—LAM and phenylalanine dodecyl amide—PNHC₁₂) and surfactants with two amino acids on the polar heads, arginine-phenylalanine (Lauroyl phenylalanine arginine methyl esther—C₁₂PAM and phenylalanine-arginine dodecyl amide—PANHC₁₂) were loaded to zein nanoparticles. Their antimicrobial and antibiofilm activities were evaluated. Also, the inhibitory activities of the surfactants and nanoparticles over skin-related enzymes were accessed in silico and in vitro, while their cytotoxicity was determined comparatively over immortal human keratinocytes (HaCaT) and human fibroblasts (3T3). Finally, the Vibrio fisheri luminescence reduction test was used to detect its ecotoxicity. Results: The nanoparticles were obtained successfully and exhibited good biocide activity against a wide range of pathogenic bacteria and yeasts. The surfactants were found active over the enzymes assayed: elastase > tyrosinase > collagenase > lipoxygenase, while the inhibitory activity was superior when nanoencapsulated over the enzymes tyrosinase and lipoxygenase. The surfactants and their corresponding nanoparticles presented acceptable cytotoxic levels, except for PNHC₁₂ in both forms, while their ecotoxicity was limited and acceptable. Conclusions: Accordingly, the nanoencapsulation of the arginine-phenylalanine surfactants loaded to zein nanoparticles was found to be a smart strategy to enhance the antimicrobial activity and improve their selectivity over representative skin and connective tissues cell lines. These biological properties render the arginine-phenylalanine surfactant nanoparticles as promising candidates for antimicrobial and tissue repairing applications in wound treatments. Full article

Controlling the hierarchical self-assembly of surfactants in aqueous solutions has drawn much attention due to their broad range of applications, from targeted drug release, preparation of smart material, to biocatalysis. However, the synthetic procedures for surfactants with stimuli-responsive hydrophobic chains are complicated, which restricts the development of surfactants. Herein, a novel single-tailed responsive surfactant, 1-methyl-3-(2-(4-((tetradecylimino) methyl) phenoxy) ethyl)-3-imidazolium bromides (C₁₄PMimBr), was facilely fabricated in situ by simply mixing an aldehyde-functionalized imidazolium cation (3-(2-(4-formylphenoxy) ethyl)-1-methyl imidazolium bromide, BAMimBr) and aliphatic amine (tetradecylamine, TDA) through dynamic imine bonding. With increasing concentration, micelles, vesicles, and hydrogels were spontaneously formed by the hierarchical self-assembly of C₁₄PMimBr in aqueous solutions without any additives. The morphologies of vesicles and hydrogels were characterized by cryogenic transmission electron microscopy and scanning electron microscopy. The mechanical properties and microstructure information of hydrogels were demonstrated by rheological measurement, X-ray diffraction, and density functional theory calculation. In addition, the vesicles could be disassembled and reassembled with the breakage and reformation of imine bonds by adding acid/bubbling CO₂ and adding alkali. This work provides a simple method for constructing stimuli-responsive surfactant systems and shows great potential application in targeted drug release, drug delivery, and intelligent materials. Full article

One of the ways to turn concrete into smart concrete involves the incorporation of conductive fillers. These fillers should be evenly distributed in the matrix to enable the charge propagation necessary for sensing. To homogenize the mixture, typical surface-active chemical compounds are routinely employed. Unfortunately, their presence often negatively impacts the characteristics of concrete. In this work, we show that conductive multi-walled carbon nanotubes (MWCNTs) can be included in the concrete matrix by using off-the-shelf lignosulfonate-based plasticizers. These plasticizers showed a much-improved capability to disperse MWCNTs compared to other routinely used surfactants. They also prevented a significant deterioration of the consistency of the mixture and inhibited the acceleration of the hydration process by MWCNTs. In concretes with MWCNTs and lignosulfonate-based plasticizers, the mechanical properties were largely preserved, while the nanocomposite became electrically conductive. Consequently, it enabled evaluation of the condition of the material by electrical impedance measurements. Full article

In the current study, a smart release system responsive to temperature was developed to improve the efficiency of tetracycline (TC) in antibacterial therapy. The nanovesicles designed consist of a non-ionic surfactant, SPAN60, cholesterol and a phase change material (PCM) as a thermoresponsive gating material. Niosomes were prepared using an increasing amount of PCM and characterized in terms of size, zeta potential, colloidal stability and thermoresponsive properties. The vesicles that developed were homogenous in size, had good biocompatibility and stability for up to 3 months and demonstrated thermoresponsive behavior. A low drug leakage was observed at 37 °C, while a rapid release occurred at 42 °C, due to the faster diffusion rate of the drug trough the melted PCM. This controllable drug release capacity allows us to avoid premature drug release, minimizing unwanted and toxic effects and ensuring a long retention time in the nanodevice so that it reaches the infected sites. In addition, TC-loaded niosomes were screened to investigate their antibacterial activity against various Gram-positive and Gram-negative bacteria by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. An interesting temperature-dependent antibacterial activity was observed against some bacterial strains: the niosomes activity against S. epidermis, for example, was improved by the temperature increase, as suggested by a reduction in MIC values from 112.81 to 14.10 μM observed at 37 and 42 °C, respectively. Taken together, the thermoresponsive platform developed allows us to use lower antibiotic amounts while ensuring therapeutic efficacy and, so, will advance the development of a novel antibacterial agent in clinical practice. Full article

Electric potential controlled lubrication, also known as triboelectrochemistry or electrotunable tribology, is an emerging field to regulate the friction, wear, and lubrication performance under charge distribution on the solid–liquid interfaces through an applied electric potential, allowing to achieve superlubrication. Electric potential controlled lubrication is of great significance for smart tunable lubrication, micro-electro-mechanical systems (MEMS), and key components in high-end mechanical equipment such as gears and bearings, etc. However, there needs to be a more theoretical understanding of the electric potential controlled lubrication between micro- and macro-scale conditions. For example, the synergistic contribution of the adsorption/desorption process and the electrochemical reaction process has not been well understood, and there exists a significant gap between the theoretical research and applications of electric potential controlled lubrication. Here, we provide an overview of this emerging field, from introducing its theoretical background to the advantages and characteristics of different experimental configurations (including universal mechanical tribometers, atomic force microscopes, and surface force apparatus/balances) for electric potential controlled lubrication. Next, we review the main experimental achievements in the performance and mechanisms of electrotunable lubrication, especially using ionic lubricants, including electrolyte solutions, ionic liquids, and surfactants. This review aims to survey the literature on electric potential controlled lubrication and provide insights into the design of superlubricants and intelligent lubrication systems for various applications. Full article

In many practical applications involving surfactants, achieving defoaming without affecting interfacial activity is a challenge. In this study, the antifoaming performance of REP-type block polymer nonionic surfactant C12EOmPOn was determined, and molecular dynamics simulation method was employed to investigate the molecular behaviors of surfactants at a gas/water interface, the detailed arrangement information of the different structural segments of the surfactant molecules and the inter-/intra-interactions between all the structural motifs in the interfacial layer were analyzed systematically, by which the antifoaming mechanisms of the surfactants were revealed. The results show that the EO and PO groups of REP-type polyether molecules are located in the aqueous phase near the interface, and the hydrophobic tails distribute separately, lying almost flat on the gas/water interface. The interaction between the same groups of EOs and POs is significantly stronger than with water. REP block polyethers with high polymerization degrees of EO and PO are more inclined to overlap into dense layers, resulting in the formation of aggregates resembling “oil lenses” spreading on the gas/water interface, which exerts a stronger antifoaming effect. This study provides a smart approach to obtaining efficient antifoaming performance at room temperature without adding other antifoam ingredients. Full article

Cleaning is one of the most important, essential, and delicate operation which has to be handled by conservators before applying new materials to any substrates. In past decades, nanotechnology introduced new concepts and materials in the conservation field, which have been providing many advantageous performances, especially higher than older materials. As a result, the conservators have already started to use nanomaterials in the cleaning processes of artifacts. Taking into consideration this new approach, our study has focused on using nano-structured emulsions (NSE) as smart cleaning materials for removing polymer coatings (e.g., acrylic polymers). For this purpose, Paraloid B-72 was applied on three different substrates (glass, Lecce stone, and Arenaria stone) and cleaning was performed by a specific nano-structured emulsion (NSE) based on an eco-friendly surfactant (EcoSurf) and two organic solvents in different proportions. In order to better understand the interaction of surfactant and organic solvents with polymer coating, plain EcoSurf in water was also used for comparison. In this study, the decay process of the considered polymer was also deeply studied, because it directly affects the cleaning effectiveness. Coated specimens of the different substrates were artificially aged and examined by different techniques: chromatic variations and contact angle measurements, optical microscopy, FTIR, and SEM-EDS. This material characterization process is important to understand the colour, morphology, and micro-structural difference, and the changes of hydrophobic behaviour as well as chemical composition of Paraloid B-72 polymer due to different ageing processes. After that, substrates coated with both unaged and aged polymer were cleaned by NSE according to the direct-contact procedure and cellulose pulp method. Preliminary analyses suggested that the direct-contact cleaning performed by nano-emulsion (i.e., NSE) induced a complete removal of the acrylic polymer, despite that this method is not recommended for the artifacts and can be hardly applicable in real cases. On the other hand, experimental results showed that satisfactory cleaning of stone substrates can be obtained by using NSE/the cellulose pulp system. Full article