Search Results (281)

Background/Objectives: Electrospun polyvinylpyrrolidone (PVP) fibers are highly promising for fast-dissolving drug delivery. Methods: In this study, five PVP grades with molecular weights ranging from 4000 to 1,300,000 Da were investigated over a broad concentration range (10–60 w/w%) to evaluate their electrospinnability and dissolution behavior. Results: A well-defined viscosity window of approximately 150–680 mPa·s was identified for the formation of continuous, bead-free fibers. Deviations from this optimal window resulted in electrospraying or jet instability. Continuous fibers were successfully prepared from all investigated PVP grades, including low-molecular-weight PVP K-12 (Mw 4000), demonstrating that appropriate solution viscoelasticity can compensate for limited chain entanglement. Remarkably, in vitro testing revealed that all fibrous formulations exhibited ultrafast disintegration (0.29–1.33 s) and dissolution (0.39–2.32 s). Statistical analysis confirmed no significant differences attributable to polymer molecular weight or fiber diameter, effectively challenging the common assumption that higher-molecular-weight PVP delays disintegration. Instead, the immediate dissolution originates from rapid wetting and capillary-driven fluid uptake, facilitated by the highly porous nano- and microfibrous network. Conclusions: By highlighting the dominant role of macroscopic structural properties over polymer chain length, these findings provide a practical framework for the development of fast-dissolving electrospun PVP-based drug delivery systems. Full article

Environmental stress cracking (ESC) severely limits the long-term reliability and engineering application of polycarbonate (PC)-based materials. In this work, a universal strategy is proposed to enhance the ESC resistance of PC by introducing crack-termination sites, enabling efficient suppression of crack propagation without compromising the intrinsic mechanical properties of PC. A quantitative evaluation framework based on a constant-strain method is established, and the critical strain rate (η) is defined as a key parameter for assessing ESC behavior under chemo-mechanical coupling. Systematic experiments reveal that chain entanglements, rubbery phases, and crystalline region can effectively increase η value of PC-based materials, demonstrating their superior crack-termination efficiency. Notably, the β-crystalline phase in PBT and microcrystalline domains induced by ethylene–acrylate copolymer tougheners are identified as the most efficient crack-termination structures, providing continuous energy-dissipation pathways and effectively halting crack propagation. This work not only establishes a practical and quantitative approach for evaluating ESC performance but also provides an integrated material-modification strategy. The proposed concept of crack-termination sites offers new insight into the development of high mechanical performance and ESC resistance PC-based polymer systems for advanced industrial applications. Full article

This paper addresses the problem of formulating generalized, non-extensive information-theoretic measures on finite non-distributive algebraic structures equipped with Riečan states, with particular emphasis on product Sheffer stroke basic algebras. Our approach formalizes finite summations, admissible partitions, refinement relations, and Sheffer stroke joint refinement candidates by using the primitive Sheffer stroke operation, with partition and marginalization properties imposed under the stated product and admissibility assumptions. By leveraging the state-theoretic properties of Riečan states, we construct baseline Shannon and logical entropies alongside algorithmic procedures for their computational evaluation. As the main result, we introduce and analytically characterize a parametric Tsallis entropy functional over these basic algebras. We prove its fundamental properties, including bounding inequalities, state concavity, monotonicity under refinement, subadditivity (for $\alpha >1$), conditional chain-type identities under the relevant joint refinement marginalization assumptions, and exact analytical convergence to the classical Shannon limit as the entropic index $\alpha \to 1$. Furthermore, under a state-dependent statistical independence condition, we show that the joint Tsallis entropy satisfies a pseudo-additive relation. By defining the Tsallis mutual information and the associated pseudo-additive residual, we isolate the deviation of a joint Sheffer stroke refinement from the factorized model determined by its marginal Riečan-state distributions. This residual is intended as a state-dependent algebraic indicator of deviations from the factorized Tsallis pseudo-additive model; it is not claimed to be an operational contextuality witness, a contextuality inequality, an entanglement measure, or a physical implementation criterion. Full article

Maintaining the rheological performance of wormlike micellar fluids at elevated temperatures remains challenging. Conventional viscoelastic surfactant (VES) systems may undergo thermally induced micellar scission and loss of gel-like viscoelasticity at elevated temperatures. In this study, we investigate the size-dependent reinforcement of long-chain C22⁺ wormlike micellar systems by silica nanoparticles under a temperature-ramp protocol reaching 160 °C. Under the applied temperature-ramp protocol, the formulation containing 0.10 wt% of 15 nm SiO₂ nanoparticles exhibited the highest measured rheological response among the tested formulations, retaining an apparent viscosity of approximately 210 mPa·s and a plateau storage modulus of approximately 18.5 Pa during the 20 min isothermal holding period at 160 °C, compared with a plateau storage modulus of approximately 11 Pa for the corresponding VES system. At equal nanoparticle mass loading, the 15 nm particles produced approximately 18% and 6% higher G′ and G″, respectively, than the 500 nm particles. The rheological results, together with qualitative electrokinetic measurements after dilution, are consistent with nanoparticle-surfactant association that may promote micellar entanglement and network reinforcement. The nanoparticle-enhanced viscoelastic surfactant (N-EVES) formulation reduced the acid-rock reaction rate to approximately 25% of that measured for conventional HCl while showing an apparent effective H⁺ diffusion coefficient of the same order. Scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDS) detected Si- and N-containing species on the treated carbonate surface, suggesting that surface adsorption or deposition may contribute to reaction retardation. Parallel dual-core flooding under a permeability contrast of approximately 13 showed fluid redistribution toward the low-permeability core. Based on the axial wormhole penetration length obtained from the CT reconstruction, the normalized axial wormhole penetration fraction of the low-permeability core was approximately 70% for the 0.10 wt% formulation. These results provide experimental evidence of nanoparticle-size-dependent rheological reinforcement, acid-rock reaction retardation, and core-scale flow redistribution under strongly acidic and high-temperature conditions. Full article

Lost circulation is a major technical bottleneck restricting safe and efficient while-drilling plugging operations. Polyacrylamide gel has become a widely used plugging material in drilling engineering. Unlike rigid, cement-like plugging materials, the gel system formed in this study does not develop a hardened, consolidated structure capable of anchoring or binding the drill bit during subsequent drilling operations, thereby eliminating the risk of bit-sticking. Nevertheless, the gel possesses sufficient elastic (viscoelastic) structural strength—reflected in its storage modulus (G′)—to effectively resist deformation and displacement under differential pressure, thereby providing reliable fracture-sealing performance, which effectively prevents pipe-sticking risks. However, high-concentration PAM molecular chains easily stretch and entangle in aqueous solution, triggering an abnormal increase in initial viscosity and poor pumpability. Although Ca²⁺ can inhibit the premature water absorption and thickening of PAM to maintain system fluidity, an excessively high Ca²⁺ concentration will suppress the hydrolysis of Al³⁺ and hinder the formation of hydroxyaluminum—the key crosslinking component of the gel system. To solve the above contradiction, a CaCl₂-tolerant delayed-release crosslinker was synthesized. ZnO was selected as a carrier to adsorb and immobilize polynuclear hydroxyaluminum complexes hydrolyzed from an inorganic aluminum crosslinker at 70 °C, realizing the controlled delayed release of the crosslinker. The microstructures and chemical bonding were characterized by SEM elemental mapping, FT-IR and ²⁷Al MAS NMR. The results confirm that abundant aluminum species are uniformly loaded on the ZnO surface to form stable Zn–O–Al covalent bonds, and the loaded aluminum exists mainly in the form of hydroxyaluminum. With increasing temperature, the Zn–O–Al bonds gradually break and slowly release hydroxyaluminum species. A novel delayed crosslinking gel system was ultimately optimized, composed of 6% CaCl₂, 10.4% PAM and 3% ZnO loaded with polynuclear hydroxyaluminum. The system exhibits excellent delayed gelation behavior, with a fluidity loss time longer than 120 min and a gelation time over 200 min. It maintains favorable fluidity within 30–90 °C, and the formed gel shows a stable elastic modulus (G′) and viscous modulus (G″). Moreover, the system achieves a plugging rate of more than 90% and a breakthrough pressure above 5 MPa, demonstrating superior comprehensive plugging performance for while-drilling plugging applications. Full article

This study presents targeted contributions to the development of macromolecular silane coupling agents (MSCAs) and high-performance fiber-reinforced polyimide (PI) composites. Three novel MSCAs were synthesized via chemical imidation and transamidation reactions, using hexafluoroisopropylidene diphthalic anhydride and 2,3,3′,4′-diphenyl ether tetracarboxylic acid as dianhydride monomers, 4,4′-diaminodiphenyl ether and 1,3-bis(4′-aminophenoxy)benzene as diamine monomers, and aminopropyltriethoxysilane (KH550) as the capping agent. Structural characterization by FTIR, ¹H NMR, and XPS confirmed the successful synthesis of the target products, with silicon contents of 3.29%, 3.37%, and 3.66%, respectively. The MSCAs exhibited excellent thermal stability, with 10% weight loss temperatures ranging from 462 °C to 543.3 °C, and good solubility in most polar organic solvents, addressing the poor processability of conventional macromolecular coupling agents. Compared with small-molecule KH550, the MSCAs significantly enhanced interfacial properties: the average tensile and flexural strengths of the composites increased by 11.0% and 9.8%, respectively, compared to 3.9% and 4.0% for KH550. SEM analysis demonstrated that MSCAs improved resin adhesion to fibers and fiber–resin compatibility. Additionally, the T5, T10, and glass transition temperatures of the composites were further optimized due to polymer chain diffusion and entanglement. This work provides a feasible strategy for interfacial design in high-performance polyimide composites. Full article

Liquid water in hydrogels exhibits an adsorption-desorption dynamic equilibrium with the surrounding environment, which leads to the instability of mechanical properties. To address this limitation, we propose an innovative design of conductive composite organogels by incorporating compatible linear lauryl alcohol (LA) and multi-walled carbon nanotubes (CNTs) into a poly(butyl methacrylate) (PBMA) network. Carbon chains of LAform physical crosslinks with PBMA side chains, effectively replacing inherent polymer chain entanglements. This structural innovation facilitates rapid chain rotation and sliding during stretching, so that the gel has a super stretching property of up to 2460%. At elevated temperatures, weakened interactions between LA–PBMA and PBMA–PBMA chains reduce physical confinement of CNTs within the PBMA network. Simultaneously applying a directional electric field, CNTs undergo rotation and translation to reconstruct an optimized conductive pathway, granting the composite distinctive temperature-sensitive electrical conductivity. Critically, all components in the PBMA/LA/CNTs (PLCs) exhibit low volatility and hydrophobicity. These characteristics enable the organogel to retain excellent flexibility and stable electrical performance after prolonged immersion in deionized water, exposure to vacuum, and even under extreme conditions at 120 °C. Such comprehensive stability suggests promising applications in deep-sea exploration and aerospace engineering. Full article

The study aimed to enhance the interchain entanglement between tapioca starch (TS) and hydrocolloids by partially weakening starch structure and promoting chain reassociation, using critical melting combined with freeze-thawing treatment (CMFT). Compared to simple blends (SBL), CMFT induced partial structural disruption and facilitated soluble starch release, likely promoting chain entanglement with hydrocolloids to form large reorganized clusters with a rough granular surface. The observed structural and functional changes support this interpretation. CMFT reduced relative crystallinity from 25.88% (TS) to ~20%, while preserving granular integrity, and increased gelatinization temperatures by ~3 °C. The CMFT-prepared composite showed significantly improved pasting properties, with PV and FV rising from 2526.50 and 2087.00 (TS) to ~2700 and ~2400 mPa·s, respectively. CMFT transformed the weak, elongated TS paste into a cohesive, structurally integrated network with ~3-fold higher gel hardness and substantially reduced digestibility (RS content increased from 43.3% to approximately 60%). The study provides an effective strategy to enhance TS-hydrocolloid interaction by partially weakening starch structure and chain reassociation for designing starch-based ingredients with tailored functional properties. Full article

Maintaining effective fluid-loss control in water-based drilling fluids under coupled high-salinity, high-temperature, and high-density conditions remains a critical challenge in deep and ultra-deep drilling operations. In this study, a low-molecular-weight polymer fluid-loss additive (LM-ASQF) was synthesized via redox-initiated copolymerization of acrylamide, dimethyldiallylammonium chloride, and sodium allyl sulfonate. The synthesis route and proposed polymer structure were further illustrated to clarify the incorporation of amide, quaternary ammonium, and sulfonate functional units within the LM-ASQF molecular architecture. The polymer exhibited a controllable number-average molecular weight of 18.2–29.4 kDa with a unimodal distribution. Thermal analysis confirmed that no main-chain-dominated degradation occurred below 220 °C, indicating structural stability under high-temperature conditions. In drilling-fluid systems containing NaCl, CaCl₂, and mixed salts (0–20%), LM-ASQF maintained stable rheological properties, with apparent viscosity ranging from 26.1 to 41.6 mPa·s, while the API fluid loss was controlled within 5.8–11.2 mL. After thermal aging at 220 °C for 16 h, the API fluid loss remained below 13 mL in both freshwater and mixed-salt systems. In high-density systems (1.80–2.40 g/cm³), the drilling fluids preserved continuous rheological structures and showed no abrupt increase in filtration. Mechanistically, fluid-loss control was primarily attributed to synergistic interfacial adsorption of amide groups, hydration stabilization induced by sulfonate functionalities, and particle rearrangement-driven filter-cake densification, rather than viscosity enhancement through long-chain entanglement. This mechanism enables effective filtration control without excessive viscosity increase, thereby maintaining rheological compatibility under complex conditions. These results demonstrate that the low-molecular-weight design strategy provides a reliable approach for achieving stable fluid-loss control in water-based drilling fluids under high salinity, elevated temperature, and high-density conditions. Full article

Conductive hydrogel strain sensors using poly(3,4-ethylenedioxythiophene) (PEDOT) as fillers are rapidly advancing and are emerging as candidates for monitoring devices such as wearable electronic skin. However, due to limitations such as low elongation and high hysteresis, it is difficult to fully leverage its promising sensor properties in practical applications. In this study, we synthesized flake-like PEDOT particles (FP particles) and used Polyacrylamide (PAM) as the hydrogel matrix to fabricate a conductive hydrogel strain sensor. These particles were obtained by grinding PEDOT particles prepared via a template-free method. After swelling with ethylene glycol (EG) and assembly with polyvinyl alcohol (PVA), the FP particles become porous and contain many hydroxyl groups. This design enables the adsorption of acrylamide (AM) monomers within FP particles, facilitating the in situ polymerization of PAM onto the PEDOT/PVA chains, thereby yielding a dual-network structure with strong entanglements. This gives the sensor high elongation and very low hysteresis. In addition, it offers favorable sensor performance, including high sensitivity, high repeatability, and reliability. This strain sensor can be used in wearable electronic skin applications for facial monitoring and motion detection. Full article

Mucoadhesive drug delivery systems have emerged as a promising strategy to enhance the therapeutic efficacy of pharmaceuticals by improving drug residence time, bioavailability, and site-specific targeting. Among various materials investigated, biopolysaccharides have gained significant attention due to their biocompatibility, biodegradability, non-toxicity, and inherent mucoadhesive properties. Natural polymers such as chitosan, alginate, pectin, hyaluronic acid, and cellulose derivatives exhibit strong interactions with mucosal surfaces through hydrogen bonding, electrostatic interactions, and polymer chain entanglement. These properties enable prolonged drug retention at mucosal sites, controlled drug release, and enhanced permeation across biological barriers. Mucoadhesive biopolysaccharides have been explored for diverse routes of administration, including oral, buccal, nasal, ocular, vaginal, and pulmonary delivery. Furthermore, chemical modification and nanostructuring of these polymers have expanded their functionality, enabling targeted delivery of small molecules, proteins, peptides, and nucleic acids. This review highlights the mechanisms of mucoadhesion, key biopolysaccharides used in drug delivery, formulation approaches, and recent advances in their application as versatile platforms for novel therapeutic delivery systems. The continued development of mucoadhesive biopolysaccharide-based carriers holds substantial potential for improving treatment outcomes and patient compliance. Full article

Water-soluble viscosity-modifying admixtures (VMAs) were initially introduced into cementitious materials to enhance cohesion, stability and resistance to bleeding and segregation. With the development of self-compacting concrete, underwater concrete, grouting materials and 3D-printed cementitious materials, VMAs have become increasingly important for regulating rheological behavior, workability retention, shape retention and construction processability. Recent studies further indicate that VMAs can affect not only fresh-state properties, but also hydration kinetics, early-age microstructure evolution, mechanical performance, transport behavior and long-term durability. This review systematically summarizes the types, action mechanisms, and performance effects of water-soluble VMAs in cementitious materials. Particular emphasis is placed on the relationships among the molecular structure, liquid phase viscosity enhancement, particle adsorption and bridging, polymer-chain entanglement, ion-responsiveness, admixture compatibility, and microstructure evolution. The review shows that the effects of VMAs are not governed solely by admixture type or dosage, but depend strongly on molecular mass, functional groups, substituent composition, charge characteristics, binder chemistry, and the pore solution environment. Finally, current research gaps and future directions are discussed, including quantitative structure–mechanism–performance relationships, applicability in low-carbon binders, service-life prediction, and application-oriented VMA design. Full article

Bacteria-infected wounds remain a major global biomedical challenge, with persistent inflammation and the lack of real-time monitoring significantly impairing wound healing. To address the limitations of conventional dressings, which often provide single-function and static treatment, we developed a multifunctional HP@CGA hydrogel based on methacrylated hyaluronic acid (HA-MA) and polyvinyl alcohol (PVA), incorporating chlorogenic acid (CGA) and bromothymol blue (BTB). In the presence of a photoinitiator, the methacryloyl groups of HA-MA undergo UV-induced free-radical polymerization to form a covalently crosslinked network, while PVA chains interact with the HA-MA backbone through hydrogen bonding and physical entanglement, resulting in a stable interpenetrating double-network structure. This integrated “treatment + monitoring” design offers a low-cost and convenient alternative to conventional wound dressings and separate sensing systems. Material characterization and preliminary experiments demonstrated that the hydrogel enabled visual pH detection within the range of 6.0–8.0 through distinct color changes. In addition, it exhibited excellent antibacterial activity, achieving antibacterial rates of 99.9% ± 0.08% against both S. aureus and E. coli. These results demonstrate the multifunctional performance of the HP@CGA hydrogel, including bacterial inhibition, inflammation alleviation, and real-time wound pH feedback, thereby providing a favorable microenvironment for infected wound healing. This work highlights the potential of HP@CGA hydrogel for precise and intelligent wound care. Full article

The Successive Self-Nucleation and Annealing (SSA) technique is a thermal fractionation method that involves subjecting a polymer sample to sequential self-nucleation and annealing steps at progressively decreasing temperatures, using differential scanning calorimetry (DSC). Since its introduction in the late 1990s, SSA has been widely applied to study the molecular structure of polymers with structural irregularities, including highly branched or crosslinked polyethylenes and random copolymers. However, the use of SSA for medical-grade ultra-high-molecular-weight polyethylene (UHMWPE), a highly linear homopolymer with minimal defects, has not yet been explored. This study aims to evaluate both its applicability to biomedical UHMWPE and its ability to reveal morphological differences among commercially available formulations. Several biomedical UHMWPE formulations, including conventional, highly cross-linked, and α-tocopherol-stabilized materials, were characterized by micro-FTIR, gel fraction and cross-link density measurements and subsequently subjected to SSA thermal fractionation. The results show that ram extrusion induces entanglements that act as interruptions in the otherwise linear chain structure, thereby enabling thermal fractionation: more than 80% of the crystalline fraction of ram-extruded UHMWPE is composed of three crystal populations melting at approximately 135, 132, and 126 °C, accompanied by four additional minor fractions at progressively lower melting temperatures. Gamma irradiation followed by thermal treatments significantly modifies the fractionation behavior, leading to the formation of an additional population of high-melting crystallites as evidenced by an increase in the number of melting peaks from 7 to 8. Oxidative degradation of highly crosslinked and annealed UHMWPE increases crystallinity by approximately 11% relative to its unoxidized counterpart but reduces the ability of the material to undergo thermal fractionation, decreasing the number of melting peaks. In contrast, the addition of low concentrations of α-tocopherol does not significantly influence the fractionation behavior. These findings demonstrate that thermal fractionation of medical-grade UHMWPE is feasible and that SSA is an effective tool for detecting morphological differences among formulations. Full article

To meet the requirements of forest fire prevention, a water glass-based composite gel foam was developed by introducing hydroxypropyl methylcellulose (HPMC) and nanosilica sol into a sodium silicate/sodium bicarbonate matrix. The resulting water glass/HPMC/silica sol ternary system (SGF-HPMC-SOL) was designed to improve water retention, foam stability, substrate adhesion, and fire-barrier durability. The results indicate that HPMC and silica sol contributed to network reinforcement through hydrogen bonding, polymer-chain entanglement, nanoscale filling, and possible interfacial condensation. The optimized SGF-HPMC-SOL retained 20.4% of its initial mass after heating at 100 °C for 5 h, compared with 4.65% for SGF and 9.54% for SGF-HPMC; reached a carbonization time of 164 s under direct-flame exposure, versus 100 s for SGF and 137 s for SGF-HPMC; and maintained a residual mass of 76% at 800 °C in TGA, compared with 58.3% for SGF and 55.1% for SGF-HPMC. These improvements were associated with the formation of a denser silica-rich protective layer after combustion, which delayed heat transfer to the wood substrate. Under the adopted direct-flame screening conditions, SGF-HPMC-SOL exhibited enhanced flame-retardant performance compared with the reference gel foams, indicating its potential for enhanced flame-retardant performance under laboratory screening conditions for forest fire prevention. Full article