Dispersion Stability Research Articles

Effect of silver nanoparticles modified by depolymerized monomer from waste PET on the thermo‐induced shape memory properties of PVA

AbstractDepolymerization of waste polyethylene terephthalate (PET) into monomers for high‐value reuse serves as an effective recycling strategy. Polyvinyl alcohol (PVA) is an important water‐soluble polymer, which can be improved by the addition of silver nanoparticles modified with depolymerized monomer terephthalic acid (rTPA) to further improve the shape memory performance of PVA. Silver nanoparticles are notably responsive to thermal changes due to their distinctive chemical and physical properties. Nonetheless, their tendency to aggregate and high surface energy present difficulties in achieving stable dispersions in aqueous environments. In this research, silver nitrate solution was reduced to prepare silver nanoparticles under the action of the reducing agent ascorbic acid. Modified silver nanoparticles p‐rTPA@Ag were prepared by co‐precipitation of the nanoparticles with rTPA. A mixture of PVA and p‐rTPA@Ag was prepared to form a composite PVA/p‐rTPA@Ag. Modified silver nanoparticles, p‐rTPA@Ag, exhibited enhanced dispersion in aqueous solution. The elongation at break of the composite rose markedly from 169.8% to 315.3%, an increase of 86.7%. Additionally, the shape recovery rate improved from 53.51% to 83.86%, reflecting a 56.7% enhancement.Highlights Silver nanoparticles were modified by depolymerized terephthalic acid (rTPA) Monomer rTPA improves the compatibility between PVA and Ag nanoparticles p‐rTPA@Ag enhances temperature sensitivity of PVA p‐rTPA@Ag enhances thermo‐induced shape memory properties of PVA

Development of Potato Nano Carbon as Electrode for Supercapacitors Achieves Green-Sustainable Development Goals

The development of potato nanocarbon as an electrode from potatoes for supercapacitors will answer the energy needs that are needed and are continuously researched. This research was conducted in the laboratory by giving marinade treatment to potatoes and measured repeatedly and testing was carried out to determine the extent of the carbon content so that potatoes are very good to be used as electrodes with electroplating method. The results obtained were 0.8 grams of potatoes with a very high conductivity increase to 0.97 m S. The result TEM 160 nm after treatment an average size of 100 nm successfully coated on the surface of the particles. FTIR shows a wavelength of 3282.48 cm due to the width of potato absorption and overlapping with the C-H-O group. AAS shows the adsorption capacity of modified potato on metals occurs in the pH range 4.5-5.5. Analysis of potatoes to be made as electrodes with two positive and negative pieces showed better dispersion stability. The electrodes are made and have been tested using a smartphone. The acid in the potato forms a chemical reaction with zinc and copper and when electrons flow from one material to another energy is released.

Fast Solid-Phase Exfoliation of Layered Double Hydroxides with Tunable Functionalization.

Two-dimensional (2D) layered double hydroxides (LDHs) with adjustable compositions and structure have been promising candidates for various domains, including catalysis, water treatment, and energy storage. To unlock their full potential, there is a strong demand for versatile and effective exfoliation techniques capable of generating diverse types of 2D LDHs. However, the conventional liquid-phase exfoliation methods typically rely on toxic solvents and face challenges with agglomeration and restacking. Herein, a series of LDHs, including CoAl-LDH, MgAl-LDH, ZnAl-LDH, and NiFe-LDH, have been successfully exfoliated into nanosheets using a solid-phase exfoliation technique. Meanwhile, surface functional groups and defects are introduced into the exfoliated LDHs. The incorporation of surface functional groups improves the homogeneity and aqueous dispersion stability of LDH nanosheets, enabling them to be stably stored for over six months while remaining redispersible and processable even after freeze-drying. Furthermore, the induced defects alter the electronic structure of the LDH nanosheets, generating more active sites that enhance their electrocatalytic performance. These advantages contribute to the superior OER activity of the exfoliated NiFe-LDH nanosheets with an ultralow overpotential of 258 mV at 10 mA cm-2. This work highlights the potential of solid-phase exfoliation as an efficient, environmentally friendly, and scalable method for the preparation and functionalization of 2D LDHs.

Dispersion Stability Mechanism of Asphaltene in Deep Eutectic Solvents through Multiresolution Simulation Approaches

Dispersion Stability Mechanism of Asphaltene in Deep Eutectic Solvents through Multiresolution Simulation Approaches

Quantitative Analysis of Physical Stability Mechanisms of Amorphous Solid Dispersions by Molecular Dynamic Simulation.

Amorphous solid dispersions (ASDs) represent a promising strategy for enhancing the solubility of poorly soluble drugs. However, the mechanisms underlying the physical stability of ASDs remain insufficiently understood. This study aims to investigate these mechanisms and propose quantitative thresholds to predict the maximum stable drug loading using molecular dynamics simulations. Poly(vinylpyrrolidone) (PVP) and poly (vinylpyrrolidone-co-vinyl acetate) (PVPVA64) are selected as polymeric carriers, while naproxen and acetaminophen serve as model drugs, resulting in the formulation of 18 distinct ASDs across four types for comparison with experimental results. Our findings indicate that the molecular mobility of active pharmaceutical ingredients (APIs) is the primary determinant of solid dispersion stability. High polymer concentrations limit drug molecular mobility through spatial structural constraints and ASD viscosity. As drug loading increases, the polymer concentration reaches a critical threshold (C*), beyond which drug-rich regions form, leading to potential aggregation, rearrangement, and recrystallization of drug molecules into more energetically stable forms. Notably, both the interaction energy and diffusion coefficient show sharp fluctuations at the maximum stable drug loading, which can serve as predictive indicators for ASD stability. Additionally, a search strategy is used to identify potential pre-crystalline sites. By integrating kinetic, thermodynamic, and pre-crystalline analyses through molecular dynamics simulations, this study provides a foundation for more accurate predictions of ASD stability, significantly aiding future formulation development.

Fundamental Thermodynamic Aspects for the Effective Dispersion of Carbon Nanotubes and Improve Performance Grade of Bitumen

The application of carbon nanotubes to enhance bitumen properties is relevant due to the need to increase the durability of asphalt concrete pavements and reduce maintenance costs. Key areas requiring further study include the processes during ultrasonic dispersion, the selection of the optimal medium, and the stability of the resulting dispersions. This study examines dispersions containing multi-walled carbon nanotubes (MWCNTs) Taunit M (from 5·10−4 to 5·10−2%) and various hydrocarbon plasticizers. For the first time, the change in Gibbs free energy, enthalpy (interaction energy), and mixing and disordering entropy was calculated based on experimental data (surface tension, average cubic diameter of MWCNTs, molecular mass, etc.). The data were compared with the storage stability of polymer-modified binders (PMBs). It was found that mixing entropy plays a key role in forming thermodynamically stable dispersions, while the contribution of disordering entropy is minimal. High dispersion enthalpy of MWCNTs can reduce dispersion stability at high concentrations despite entropy growth. Systems with selective purification extracts showed the best PMB stability despite thermodynamic instability. The property changes after 3 days at 180 °C were no more than 5%. This suggests structural changes from component interactions are critical, highlighting the need for an integrated approach considering both thermodynamic and macroscopic properties.

Optimization of preparation parameters and testing verification of carbon nanotube suspensions used in concrete

Abstract Carbon nanotubes (CNTs) have received extensive attention due to their exceptional properties and wide range of applications. However, the agglomeration of CNTs in aqueous solutions and organic solvents significantly limits their large-scale application. In this study, the microscopic morphology and dispersion stability of the CNT suspensions were analyzed, and the most suitable surfactant in this study was selected. The preparation parameters of the CNT suspensions were optimized, and uniaxial compression tests were conducted on carbon nanotube concrete (CNTC) prepared using the optimized parameters. Scanning electron microscope analysis was used to investigate the improvement in the microstructure of the concrete by CNTs. Transmission electron microscope micrographs of the polyvinyl pyrrolidone (PVP)-CNT suspensions exhibited a uniformly distributed CNT cross-linked network. The absorbance reduction ratio of PVP-CNT suspensions after standing for 90 days was 13.75 and 22.41%, respectively. The absorbance reduction ratio of the suspensions first increased and then decreased with increasing dispersant ratio and ultrasonic dispersion time and increased with increasing ultrasonic power ratio. Compared with that of plain concrete, the uniaxial compressive strength of CNTC significantly improved, with a maximum increase of 18.15% when the content was 0.10%, and the failure mode exhibited typical shear failure characteristics. The optimized preparation parameters for the CNT suspensions were a PVP-to-multiwalled carbon nanotube mass ratio of 4:1, an ultrasonic dispersion time of 20 min, and an ultrasonic power of 60%. These optimized parameters are ideal choices for preparing CNT cement-based composite suspensions.

A simple strategy to significantly improve the anticorrosion and aging resistance of epoxy coatings by adding polyaniline modified multi-walled carbon nanotubes

Epoxy coatings are widely used for corrosion protection of metals, but under extremely harsh environments, the epoxy polymer chains such as the C-O bonds of epoxy ether and aromatic ether, and the -OH in the epoxy chain structure can also undergo aging and degradation, leading to the failure of the coating in service. How to extend the anti-aging capability of epoxy resins while maintaining their other properties unchanged has become a major challenge in the practical application of epoxy coatings. In this study, the polyaniline (PANI) modified multi-walled carbon nanotubes (MWCNT@PANI) were synthesized by polymerization in-situ and added to epoxy resin as an anti-aging filler. The various measurements have been adopted to characterize the composition and structure of MWCNT@PANI, and the anticorrosive performance of the composite coating for carbon steel were evaluated via salt spray, chemical aging and UV light aging. Results showed that the impedance value of the blank epoxy coating decreases by at least two orders of magnitude after the salt spray tests, and the contact angle decreases by about 30° and gradually changes from hydrophobic to hydrophilic, indicating a significant decline in corrosion resistance. In contrast, the composite coating confirmed the excellent anti-aging performance, while the impedance values increased by approximately 2-5 orders of magnitude compared to that in blank epoxy coatings, and remained around 1010 Ω·cm2. Given the dense encapsulation of MWCNT@PANI, the dispersion stability between the filler and EP can be improved, and the effective corrosion resistance performance was also supported by molecular dynamic simulation. Besides that, the ability of free radical quenching along with the labyrinth effect and hydrophobic interaction have also been investigated to explain the anticorrosion and anti-aging mechanism.

Corrosion of nickel foam electrodes during hydrothermal reactions: The influence of a simple protective carbon black coating

Nickel foam (NF) substrates are widely used to support electrocatalysts, and this is frequently achieved using hydrothermal reactions, where the NF is immersed in the hydrothermal reactor together with the electrocatalyst precursors. However, other reactions including the corrosion of the NF and changes to the pH occur simultaneously, and these can affect the quality of the final electrocatalyst. Herein, a simple approach is devised to minimise these unwanted reactions. Carbon black (CB) was non-covalently functionalised at room temperature using tannic acid to give very stable and good dispersions of fCB in deionised water. Using a simple sonication step, the NF was coated with a uniform layer of the dispersed fCB. This layer served to minimise the corrosion of the underlying NF during the hydrothermal reactions with very good protection observed up to a temperature of 160 °C in deionised water at a pH of 2.0. The corrosion currents of the NF and fCB@NF were estimated at 8.7 µA and 3.9 µA, respectively, at room temperature in this acidic solution. Using a model reaction, the successful nucleation and growth of MnCo2O4 cubes was observed at fCB@NF, but not at the corroding NF.

Osteogenic potential of esculetin-loaded chitosan nanoparticles in microporous alginate/polyvinyl alcohol scaffolds for bone tissue engineering.

Bone tissue engineering (BTE) is an emerging strategy for the treatment of critical bone defects using biomaterials and cells. Esculetin (ES), a coumarin phytocompound, has demonstrated therapeutic potential, although its osteogenic effects remain insufficiently explored. Owing to its hydrophobic nature, which limits its bioavailability, this study developed a drug delivery system using chitosan nanoparticles (nCS) to achieve sustained release of ES. These ES-loaded nCS nanoparticles were incorporated into biocomposite scaffolds composed of alginate (Alg) and polyvinyl alcohol (PVA) using freeze-drying. The synthesized nCS-ES nanoparticles exhibited spherical morphology with a uniform size distribution, ranging from 105 to 117 nm, and demonstrated excellent entrapment efficiencies (94.07 to 97.61 %). The nanoparticles displayed high zeta potential values (+27.8 to +33.2 mV), ensuring stable dispersion. The biocomposite scaffolds exhibited a uniform distribution of pores, with pore diameters ranging from 106 ± 14 μm to 112 ± 14 μm. The biocomposite scaffolds exhibited excellent swelling, protein adsorption, biodegradation, and biomineralization properties. The ES-loaded scaffolds showed sustained ES release, promoting osteogenesis in vitro, with the activation of the Wnt/β-catenin signaling pathway. In vivo studies using a rat tibial bone defect model further confirmed that these scaffolds stimulated new bone formation, highlighting the ES's potential for BTE applications.

Unraveling the modulation art of ordered nanomesh-like hydration product on fiber-cement interfaces: Insights from fishing net inspiration

The morphology of interface hydration products is crucial as it directly determines the interface mechanics. Inspired by the fishing nets, we employed photo-grafted active copolymer Poly(vinylpyrrolidone-co-acrylic acid) on the inert glass fibers. Providing a template for PVP-co-PAA maintains its regulatory capability in cement paste. For the first time, ordered nanomesh-like hydrated calcium silicate (CSH) with average pore diameter of 30 nm are developed in cement paste. The interface strength and energy absorption increased by 90 % and 253 %, respectively. XPS and SEM revealed that the multi-scale regulation mechanisms originated from the preferential adsorption and stable dispersion of Ca2+ result from the strong electronegativity and steric hindrance of pyrrolidone rings. CSH nuclei (60 nm) dispersed well on fiber templates, stacked along fiber surfaces, without collapse or tilt, intertwined into nanomesh. Nanomesh-like CSH in cement paste holds significant potentials for the improvement of mechanical properties of fiber-cement interfaces, contributing to construction sustainability.

Ethylene glycol-mediated dispersion enhancement of oxidized MWCNTs for improved electrochemical performance in flexible, free-standing OCNT/LMO electrode

The rapid advancement of flexible electronics and wearables necessitates high-capacity flexible batteries that adapt to various shapes and movements. Carbon nanotubes (CNTs), with their exceptional electrical conductivity, mechanical flexibility, and structural stability, are promising candidates. However, achieving a well-dispersed and uniform distribution of CNTs and heavy active materials like lithium manganese oxide (LMO) particles in different matrices is challenging due to issues with agglomeration and quick sedimentation. This study uses ethylene glycol (EG) as a dispersing solvent to form strong hydrogen bonds with oxidized CNTs, enhancing dispersion stability and preventing re-aggregation. Its higher viscosity compared to water helps in better stabilizing and dispersing LMO particles within the oxidized CNT suspension by reducing sedimentation. The OCNT/LMO-EG electrode shows a higher discharge capacity of 128 mAh/g with Coulombic efficiency of 99.6% after 200 cycles, compared to the OCNT/LMO-W2 electrode, which uses water for dispersion and achieves 108 mAh/g with 99.6% efficiency. These results highlight ethylene glycol's potential to improve CNT and LMO dispersion, resulting in a homogeneous electrode structure with enhanced conductivity and higher capacity.

Hydrotalcite-derived well-dispersed and thermally stable cobalt nanoparticle catalyst for ammonia decomposition

Ammonia is a carbon-free hydrogen carrier, and development of non-noble metal catalyst to decompose ammonia into hydrogen is desirable for practical applications. However, the metal catalyst is challenged by the sintering of metal particles under high-temperature reaction conditions. In this study, a series of Li-, Al-, and Co-containing hydrotalcite-like compounds (HTlc) were synthesized by co-precipitation and used as precursors to prepare well-dispersed and thermally stable Co nanoparticle catalysts for ammonia decomposition. The obtained precursors and catalysts were characterized by means of X-ray powder diffraction (XRD), temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and so on. All of the precursors formed hydrotalcite-like phase, which consisted of Li–Al–(Co) HTlc and/or Co–Al HTlc dependent on the Co content. Upon calcination at 500 °C, HTlc decomposed into an Al-substituted Co3O4 spinel oxide, as confirmed by two distinctly separated reduction steps in H2-TPR. Following reduction at 700 °C, well-dispersed Co metal nanoparticles with an average particle size of ∼9.2–12.4 nm were obtained. It was suggested that the incorporation of Al3+ into Co3O4 led to a strong interaction between cobalt and aluminum, which suppressed the crystal growth of Co3O4 and the sintering of Co metal during the thermal treatments, resulting in good Co dispersion. The optimal LiAlCo(1.5) catalyst showed superior activity than that prepared by impregnation method, giving almost complete conversion of ammonia at 575 °C under a space velocity of 5,000 mL gcat–1 h–1. More importantly, this catalyst maintained stable activity at 625 °C for 100 h, exhibiting high stability and sintering resistance. The good catalytic performance was attributed to the high Co metal dispersion and strong metal–support interaction benefiting from the uniform distribution of cobalt in the HTlc precursor. These results demonstrate the applicability of HTlc to the preparation of metal catalysts with improved dispersion and thermal stability.

Thermodynamics of Polyethylene Glycol Intrusion in Microporous Water.

Polymers can be used to augment the properties of microporous materials, affording enhanced processability, stability, and compatibility. Manipulating polymers to target specific properties, however, requires detailed knowledge of how different polymers and microporous materials interact. Here, we report a study of the thermodynamics of polyethylene glycol (PEG) intrusion into a representative hydrophobic zeolite (silicalite-1) and metal-organic framework [ZIF-67; Co(2-methylimidazolate)2] in water, both of which can be formed into colloidally stable aqueous dispersions─termed "microporous water"─with dry, guest-accessible pore networks. Through a combination of O2 capacity measurements and isothermal titration calorimetry (ITC), we establish relationships between PEG intrusion behavior, polymer length, polymer end groups, and the structure of the microporous framework. In particular, we find that PEG intrusion is exothermic for silicalite-1 but endothermic for ZIF-67. Our results provide fundamental insights into polymer intrusion in microporous materials that should inform efforts to design composite solids and fluids with enhanced functionality.

Insights into the Solution Processing of Non-van der Waals Boron Carbide.

Exfoliation of non-layered materials is crucial to unleash their enormous potential in wide range of applications. However, the presence of strong non-van der Waals interactions in all three dimensions makes exfoliation challenging. Boron carbide (B4C), known for its high hardness, holds great potential for diverse applications. In this work, B4C is exfoliated in 29 solvents to determine its Hansen solubility parameters (HSP) and understand the dispersion stability. The experimentally determined HSP values are 19.6, 15.3 and 15.1 MPa1/2 for dispersive interactions (δD), polar interactions (δP) and hydrogen bonding interactions (δH), respectively. Subsequently, in situ dispersion stability is analyzed qualitatively and quantitatively from the space-time resolved extinction profiles employing an analytical centrifuge. The sedimentation kinetics of B4C dispersions are analyzed using instability index, integral extinction and sedimentation velocity. B4C dispersions in solvents like ε-caprolactone, isopropyl alcohol, propylene carbonate and formamide exhibited excellent stability. Additionally, B4C nanosheets are utilized to investigate their field emission properties. These nanosheets exhibit a turn-on electric field of 3.35 V/μm at an emission current density of 1 μA cm-2, and it delivered a large emission current density of ~ 375 μA cm-2 at an applied electric field of 5.7 V/μm.

Ionic Character and Alkyl Chain Length of Surfactants Affect Titanium Dioxide Dispersion and Its UV-Blocking Efficacy

The dispersion of titanium dioxide (TiO2) determines the performance of TiO2-based formulations in cosmetic and coating applications. In particular, the chemical and structural characteristics of the surfactants used to prepare TiO2 dispersions are significant. However, the influence of surfactants on TiO2 dispersion quality has not been systematically investigated. In this study, we observed the effects of the ionic character of commercial surfactants on the dispersion stability and UV-blocking efficacy of TiO2. Among the experimental surfactant groups, anionic sodium dodecyl sulfate was efficient in stabilizing TiO2 as a water-in-oil formulation and enhancing its UV-blocking efficacy. Furthermore, an anionic fatty acid as a surfactant with a longer alkyl chain length was sufficient to stabilize the TiO2 formulation, which also displayed the highest UV-blocking efficacy, comparable to the values of commercial TiO2-based cosmetic products.

Simulation of Scalar Wave Propagation with High-Order Temporal and Spatial Accuracy by a New Multi-Axial Staggered-Grid Finite-Difference Scheme

ABSTRACT Staggered-grid finite-difference (SFD) stencils are extensively applied for scalar wavefield simulations and inversions in seismology because of their easy implementation and effectiveness of propagating the wave in heterogeneous media. The conventional SFD (CSFD) stencil adopts second-order temporal and high-order spatial finite-difference operators to approximate the partial derivatives inside the wave equation. The spatial SFD operator only adopts grid points along one orthogonally axial direction to approximate the spatial partial derivative along that direction. Therefore, increasing the number of grid points along the axis will not improve the temporal accuracy. To simultaneously enhance the temporal and spatial accuracy, we propose a new multi-axial SFD (MASFD) stencil, which consists of grid points along three directions for each partial derivative in space. The MASFD weightings (coefficients) are derived by preserving the dispersion relation of the scalar wave in the frequency–wavenumber domain. We prove that increasing the number of the grid points of the new stencil can simultaneously reach high-order accuracy in time and space. The performance of the new MASFD scheme is compared with the CSFD schemes by quantitative dispersion analyses, stability analyses, and numerical examples. Our comprehensive comparisons demonstrate that the MASFD scheme can be more accurate than the CSFD ones because of improved temporal accuracy. Under comparable accuracy, the MASFD scheme can be more efficient than the CSFD ones because the MASFD scheme can adopt larger time steps to perform stable wave extrapolation.

Fabrication of Ionic Supramolecular Oleogel Lubricants Enhanced with Liquid Metal Nanodroplets for Superior Tribological Performance.

Supramolecular Oleogel lubricants provide a versatile and reliable strategy for optimizing the long-term dispersion stability of nanoadditives in the base oils. In this work, GLM-based ionic gelators constructing supramolecular oleogels were prepared by adding ultrasonically treated gallium-based liquid metal (GLM) nanodroplets carrying free radicals and vinyl-containing ionic liquids (ILs) directly to a free radical polymerization system of polymer gelators. The electrostatic interactions between the ionic liquids and GLM nanodroplets enhanced the cross-linking degree of supramolecular gels and formed denser self-assembled structures. The as-prepared GLM-based ionic oleogels as thermoreversible gels exhibit exceptional thixotropic properties. Compared to the base oil PAO10, the coefficient of friction (COF) for both GLM@IGel-1 and GLM@IGel-2 decreased significantly from 0.192 to 0.097, while the wear volume dropped from 100.10 × 104 μm3 to 13.28 × 104 μm3 for GLM@IGel-1, and to 9.69 × 104 μm3 for GLM@IGel-2. In addition, GLM@IGel-2 demonstrates a higher load-bearing capacity of 550 N due to further chemical cross-linking by ionic liquids. The outstanding lubrication performance of GLM-based ionic oleogels is achieved by the synergy of GLM nanodroplets and gel lubricants, promoting the formation of a stable tribo-chemical reaction film.

Stability and thermo-physical characteristics of EG/H2O-based nanofluid with graphene nanoplatelets for secondary coolant applications

In the present article, the thermophysical properties of an EG-H2O dispersed with GNP nanofluid are studied. The graphene nanoplatelets were dispersed in a 50:50 volume ratio (1113.2:1000 by mass in g per litre) of EG and H2O along with Gum Arabic surfactant to create the stable nanofluid dispersions by varying vol% of GNP from 0.1% to 0.5% in steps of 0.1%. The stability of proposed GNP-EG/H2O nanofluid was found using the zeta potential distribution method. A thermal properties analyzer, densitometer and rheometer were used to measure the thermal conductivity (k) (heat conduction), specific heat capacity (Cp), density (ρ) and viscosity (µ) of the nanofluid. All the properties were measured with various temperatures ranging from −15 °C to 15 °C with interval of 5 °C. The outcomes of steadiness test performed and reveal that the GNP-EG/H2O nanofluid was stable and exhibits a zeta potential distribution of −33.7 mV at 0.5 vol% of GNP. The thermal conductivity and thermal diffusivity of nanofluid enhanced by about 8.6% and 10.43% respectively when compared to the base fluid while the specific capacity decreased by 8.96% at 15 °C for 0.5 vol%. The proposed nanofluid favorable for all volume concentration under laminar flow regime while it was favorable up to 0.1% under turbulent regime which observed from the predicted effectiveness.

Pre-stack wave-equation time migration

In conventional time migration, the Green’s function is commonly calculated using ray tracing which may produce inaccurate images for complex structures with strongly lateral velocity variations. To mitigate this issue, we develop an accurate prestack wave-equation time migration method, borrowing from reverse time migration (RTM). First, a two-way acoustic wave equation is derived in the image-ray coordinate system. Then, we directly solve this equation using the finite-difference method to extrapolate source- and receiver-side wavefields, which does not require any approximation as in conventional ray-based time migration. Finally, a zero-lag crosscorrelation imaging condition is applied to generate the time migration image. In addition, we derive the dispersion relation and stability condition for the finite-difference method in the image-ray coordinate system, which provides guidance for temporal and spatial grid discretization. The perfectly matched layer (PML) boundary condition is utilized in the image-ray coordinate system to attenuate boundary reflections. Numerical examples of synthetic and field data verify the feasibility and adaptability of the proposed approach for low signal-to-noise land data. In addition, after mapping the images from the time domain to the depth domain, the image results are even better than RTM results.