Interfacial Properties Research Articles

Interface Structure and Properties of Polypropylene/Wood Flour Composites Reinforced with Grafted Polypropylene Compatibilizer

AbstractIn this work, a new compatibilizer, ternary monomer grafted polypropylene (hereafter shorted as: G‐PP), was successfully synthesized by solid phase grafting of maleic anhydride, methyl methacrylate, and butyl‐acrylate onto polypropylene. For all developed polypropylene matrix composites, the prepared G‐PP evidently showed enhancing mechanical properties on PP/wood flour (WF) composites, which is obviously superior to those from maleic anhydride grafted polypropylene (W‐PP) and virgin polypropylene (C‐PP). In particular, the wettability of G‐PP was greatly improved, while the melting temperature and β crystal phase amounts of the WF composites with G‐PP are much higher when compared to that of W‐PP and C‐PP. This can be reasonably explained by the formation of continuous micropores and filaments in WF composites containing G‐PP, as verified by hot stage polarizing optical microscope (POM). Meanwhile, the G‐PP effectively reduced movement of molecular chains of WPC and formed a better interface layer with WF, which contributed to penetrate more deeply and form micro‐crosslinking in the WF layer. We believe that the results reported in this work will increase the added value of polypropylene based wood plastics composites (WPC) and allow WPC to participate in lightweight and environmentally friendly products.

Characterization of Novel Exopolysaccharides from Weissella cibaria and Lactococcus lactis Strains and Their Potential Application as Bio-Hydrocolloid Agents in Emulsion Stability

The aim of the present study was the isolation of high exopolysaccharide (EPS) producers, Lactic Acid Bacteria (LAB) strains, from three types of milk: goat, sheep, and camel milk. Among 112 LAB isolates tested for their ability to produce EPS on MRS-sucrose agar, only 11 strains were able to produce EPS and only three higher producers’ strains were identified by 16S rRNA gene sequencing as two strains of Lactococcus lactis subsp. lactis (SP255, SP257) isolated from camel milk and one strain of Weissella cibaria (SP213) isolated from goat milk. The physicochemical characterization of the purified EPSs revealed a significant sugar yield, with concentrations ranging from 2.17 to 2.77 g/L, while the protein content remained relatively low (0.03 g/L). The UV-visible spectrum showed high Ultra Violet (UV) absorption at 240–280 nm and the Fourier-Transform Infrared (FTIR) spectra showed the presence of a large number of functional groups, including hydroxyl (-OH), carbonyl (-C=O), and methyl groups (-CH3). The EPS solubility indicated their hydrophilic properties and the investigation of interfacial properties indicated that these EPSs could be used as natural emulsifiers and stabilizers in both acidic and neutral emulsions. Moreover, a new type of emulsion system was developed by the utilization of EPSs in the formation of multilayer interfaces in oil-in-water (O/W) emulsions stabilized by sodium caseinate (CAS). Thus, the impact of an EPS addition on the particle size distribution and electrical charge has been studied. At pH 3, the studied EPSs adhered to the surfaces of caseinate-coated droplets and the stability of O/W emulsions was improved by adding certain concentrations of EPSs. The minimum concentration required to stabilize multilayer emulsions for EPSs SP255, EPS SP257, and EPS SP213 was 1.5, 1.5, and 1.7 g/L, respectively. These findings reveal a new EPS with significant potential for industrial use, particularly as an emulsion stabilizer.

Effect of plasma treatment on LMPAEK/CF tape and composites manufactured by automated tape placement (ATP)

Automated tape placement (ATP) process is widely used in aerospace for its advanced process control and multi-axis capabilities but faces issues like limited choice of materials and suboptimal tape consolidation. This study investigates air plasma treatment on ATP carbon fiber thermoplastic feedstock tape to address these challenges. The effects on low melt Polyaryletherketone/carbon fiber unidirectional tape (LMPAEK/CF UD tape) were analyzed. Treated and untreated tapes were used to fabricate composites and evaluated for physical, thermal, mechanical, and interfacial properties. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) analyses revealed surface roughness changes (on LMPAEK), extent of oxidation, and the presence of hydroxyl/carboxyl groups. Composites from plasma-treated tapes showed a 7.6% increase in tensile strength, 8% in tensile modulus, 18% in flexural strength, and 8.3% in flexural modulus. The interlaminar shear strength improved by 18.7%. Failure analysis showed untreated composites failed via inter-ply and fiber-matrix delamination, while treated composites experienced matrix cracking and fiber breakage. This study highlights atmospheric plasma treatment as a solution to ATP’s limitations, significantly enhancing LMPAEK/CF UD tape composites’ properties.

Evaluation framework for bitumen-aggregate interfacial adhesion incorporating pull-off test and fluorescence tracing method

The interfacial adhesion between bitumen and aggregate is crucial to maintain the mechanical performance of asphalt pavement. Numerous indicators characterize the bonding ability of bitumen to aggregate; however, indicators based on limited conditions are used infrequently to effectively evaluate the interfacial adhesion between bitumen and aggregate. This study introduces a method to assess adhesion and moisture damage resistance at the bitumen-aggregate interface by combining the pull-off test with the fluorescence tracing method. The improved pull-off test considers different bitumen film thicknesses, ambient temperatures, material combinations, and moisture damage conditions, and the fluorescence tracing method and surface energy parameters are utilized to precisely detect the extent of bitumen adherence to the aggregate. The findings of this study are summarized as follows. (1) The bitumen stripping ratio characterizes the influence of ambient temperature and bitumen film thickness, and the pull-off strength/work quantifies the influence of ambient temperature and material combination. (2) The indicators derived from surface free energy theory exhibit lower sensitivity to material combinations compared with the pull-off performance indicators, with a coefficient of variation for both adhesion and stripping work of approximately 6 % compared to 14.29 %–70.13 % for the pull-off performance indicators. (3) The pull-off strength indicator dominates the pull-off performance evaluation, with the bitumen stripping ratio necessary at 0°C and pull-off work significant at 40°C to evaluate adhesive properties. In addition, the bitumen stripping ratio increment should be considered alongside pull-off strength loss ratio when estimating anti-moisture damage performance. (4) The fluorescence tracing method shows great potential in terms of enhancing the accuracy of bitumen stripping ratio detection in the pull-off test, with bitumen stripping ratio discrepancies at 0°C–40°C ranging from 0.98 % to 7.16 % for 70#-Limestone and 2.10–9.21 % for 70#-Granite. The methodology presented in this study represents a promising framework to determine the interfacial adhesive properties of asphalt mixtures with high accuracy.

Construction of “organic–inorganic” hierarchical structure of carbon fibers and the effect on the properties of epoxy composites

AbstractThe demand for epoxy (EP) in semiconductor, aerospace, and other applications is currently on the rise. However, pure epoxy is difficult to meet these requirements, such as low thermal conductivity and poor toughness. Therefore, in this paper, sulfonamides (SAs) and core‐shell silica (SLC‐SiO2) were grafted onto the surface of short carbon fibers (SCF) with sizes of 0.1–6 mm by the chemical grafting method. As a result, the surface activity of SCF was improved and the interfacial properties of the EP composites were enhanced. The interfacial compatibility of SCF grafted with SAs and SLC‐SiO2 in EP is greatly improved, resulting in stronger mechanical interlocking and chemical bonding ability between EP and SCF. The results showed that when the content of SCF@SAs@SLC‐SiO2/EP composites reached 0.3 wt% of SCF@SAs@SLC‐SiO2, the impact and tensile strengths were increased from 12.15 kJ·m−2 and 43.4 MPa to 16.93 kJ·m−2 and 74.97 MPa compared with the pure epoxy, which were improved 39.3% and 72.7%. In addition, the thermal conductivity of SCF@SAs@SLC‐SiO2/EP composites was also improved by 12.5% from 0.205 W·(m·K)−1 to 0.2306 W·(m·K)−1 compared with the pure EP. This is due to improved chemical interactions and mechanical interlocking at the fiber‐epoxy interface. This study provides a new method for the preparation of high‐performance SCF/EP composites.Highlights The amino group of sulfonamides was grafted with short carbon fiber to increase the surface active group of short carbon fiber. Sulfonamides react with carboxyl groups on the surface of core‐shell silica to form an “organic–inorganic” structure. Improve the surface roughness of short carbon fiber, and make it evenly dispersed in epoxy resin, so as to improve the performance of epoxy composite materials.

Mechanistic insights into lipid extraction from wet microalgae using hydrophobic deep eutectic solvents under hydrothermal conditions

Hydrophobic deep eutectic solvents (HDESs) were first employed under hydrothermal conditions to form a two-phase system for instantaneous and efficient lipid extraction from wet microalgae, preventing lipid degradation and avoiding the use of toxic solvents. Ten HDESs were assessed for their efficiency and selectivity in lipid extraction. Among them, OCT-DEC, composed of octanoic acid and decanoic acid, achieved the highest extraction efficiency at 95.42 %, while also preventing the co-extraction of proteins and reducing sugars. Molecular dynamics simulations revealed that lipid extraction efficiency is primarily influenced by lipid-HDES interactions, which drive lipid diffusion, and the interfacial properties of the two-phase hydrothermal system, which resist lipid diffusion. The superior performance of OCT-DEC is attributed to its high hydrogen bond density and short bond lifetimes, which, combined with its structural stability, synergistically reduce resistance to lipid diffusion at the interface. Additionally, OCT-DEC significantly enhances the thermal stability of unsaturated fatty acids, such as C20:5, effectively preventing the degradation of high-value lipids and highlighting its potential for hydrothermal extraction of these valuable compounds.

Effect of pH-Shifting on Sunflower Meal Protein Isolate: Improved Stability and Interfacial Properties of Chitosan-stabilized Pickering Emulsion

Effect of pH-Shifting on Sunflower Meal Protein Isolate: Improved Stability and Interfacial Properties of Chitosan-stabilized Pickering Emulsion

Resin impregnation and interface property improvement of CFRP composite via modulating wettability of carbon fibers

In this work, the effects of different fiber wettability on resin impregnation during vacuum assisted resin transfer molding (VARTM) process and subsequent interface properties were comprehensively investigated. The fabrics with different surface morphology and wettability were successfully obtained via tuning the concentration of epoxy sizing agents. Results indicate that a low void content of less than 1% is achieved with the improvement of fiber wettability. Additionally, the interlayer property of composites is significantly improved by ∼12%. It is attributed to improved impregnation and capillary number, achieved by optimizing the dual-scale flow of resin in the preform via reducing the contact angle. Achieving equilibrium of dual-scale flow is an important factor in minimizing voids within the CFRP laminate. Furthermore, the introduction of epoxy functional groups significantly enhances interfacial bonding, contributing to an increase in the interlaminar shear strength of CFRP composites. This improvement effectively improves stress concentration by dispersing crack propagation. The findings in this work provide significant information for designing CFRP composites with superior mechanical properties via adjusting fiber wettability.

The role of lignin as interfacial compatibilizer in designing lignocellulosic-polyester composite films

Advancing nanocomposites requires a deep understanding and careful design of nanoscale interfaces, as interfacial interactions and adhesion significantly influence the physical and mechanical properties of these materials. This study demonstrates the effectiveness of lignin nanoparticles (LNPs) as interfacial compatibilizer between hydrophilic cellulose nanofibrils (CNF) and a hydrophobic polyester, polycaprolactone (PCL). In this context, we conducted a detailed analysis of surface-to-bulk interactions in both wet and dry conditions using advanced techniques such as quartz crystal microbalance with dissipation (QCM-D), atomic force microscopy (AFM), water contact angle (WCA) measurements, broadband dielectric spectroscopy (BDS), and inverse gas chromatography (IGC).QCM-D was employed to quantify the adsorption behavior of LNPs on CNF and PCL surfaces, demonstrating LNPs’ capability to interact with both hydrophilic and hydrophobic phases, thereby enhancing composite material properties. LNPs showed extensive adsorption on a CNF model film (1186 ± 178 ng.cm−2) and a lower but still significant adsorption on a PCL model film (270 ± 64 ng.cm−2). In contrast, CNF adsorption on a PCL model film was the lowest, with a sensed mass of only 136 ± 35 ng.cm−2. These findings were further supported by comparing the morphology and wettability of the films before and after adsorption, using AFM and WCA analyses. Then, to gain insights into the molecular-level interactions and molecular mobility within the composite in dry state, BDS was employed. The BDS results showed that LNPs improved the dispersion of PCL within the CNF network. To further investigate the impact of LNPs on the composites’ interfacial properties, IGC was employed. This analysis showed that the composite films containing LNPs exhibited lower surface energy compared to those composed of only CNF and PCL. The presence of LNPs likely reduced the availability of surface hydroxyl groups, thus modifying the physicochemical properties of the interface. These changes were particularly evident in the heterogeneity of the surface energy profile, indicating that LNPs significantly altered the interfacial characteristics of the composite materials.Overall, these findings emphasize the necessity to control the interfaces between components for next-generation nanocomposite materials across diverse applications.

Deep Neutral Network Enhanced Mesoscopic Thermodynamic Model for Unlocking the Electrode/Electrolyte Interface

Structure and properties of the electrode/electrolyte interface significantly influence the electrochemical processes of energy storage and conversion, yet the challenge lies in accurate description of both molecular characteristics and external field effects. Here, we develop a mesoscopic thermodynamic model that calculates the thermodynamic properties of electrolytes based on chemical potential, and its efficiency is enhanced by a deep neutral network. The deep neutral network enhanced mesoscopic thermodynamic (DeepMT) model effectively bridges the gap between micro‐level characteristics of ions and macro‐level effects of external field, enabling precise presentation of ion density distributions over complex conditions. Our result indicates that the DeepMT model not only demonstrates a computational efficiency improvement of approximately four orders of magnitude over direct theoretical calculations, but also accurately predicts interface properties including ion adsorption, surface charge, and differential capacitance through the statistical analysis of density distributions.

Deep Neutral Network Enhanced Mesoscopic Thermodynamic Model for Unlocking the Electrode/Electrolyte Interface.

Structure and properties of the electrode/electrolyte interface significantly influence the electrochemical processes of energy storage and conversion, yet the challenge lies in accurate description of both molecular characteristics and external field effects. Here, we develop a mesoscopic thermodynamic model that calculates the thermodynamic properties of electrolytes based on chemical potential, and its efficiency is enhanced by a deep neutral network. The deep neutral network enhanced mesoscopic thermodynamic (DeepMT) model effectively bridges the gap between micro-level characteristics of ions and macro-level effects of external field, enabling precise presentation of ion density distributions over complex conditions. Our result indicates that the DeepMT model not only demonstrates a computational efficiency improvement of approximately four orders of magnitude over direct theoretical calculations, but also accurately predicts interface properties including ion adsorption, surface charge, and differential capacitance through the statistical analysis of density distributions.

Influence of resins, asphaltenes and petroleum acid interactions on water/model oil interfacial properties and emulsion stability

The presence of natural lipophilic emulsifiers, such as asphaltenes (A), resin (R) and petroleum acids (PA) in crude oil, plays a crucial role in stabilizing the W/O emulsions. This study primarily focuses on elucidating the influence of their interactions on the interfacial properties of the water/model oil system, as well as its emulsion stability. First, equilibrium interfacial tension (IFT), interfacial dilational modulus (IDM) and phase angle are measured. Then, emulsion stability experiments are performed. Finally, microscopic images of the emulsions were captured to evaluate droplet size and dispersity. Results show that the addition of petroleum acid to both asphaltene-only and resin-only system reduces IFT and dilational modulus, weakening the strength of the interfacial film. The inhibitory effect of petroleum acid on resins’ adsorption at the interface is more pronounced compared to asphaltenes’. A low proportion of resin and petroleum acid (A/R ≥ 5, A/PA ≥ 7) enhances emulsion stability by co-adsorbing with asphaltenes at the oil–water interface. Conversely, a high proportion of resin and petroleum acid leads to a decrease in IDM and emulsion stability. For asphaltene/petroleum acid–water system, when A/PA ≤ 5, the presence of petroleum acid decreases the droplet size but enhances droplet dispersion while decreasing emulsion stability. It can be inferred that the presence of petroleum acids contributes more to the formation rather than stabilization of emulsions. This work deepens insights into the emulsion behavior of natural surfactants, providing theoretical guidance for the formation of stable emulsions underground and efficient demulsification above ground.

Mechanical characterization of freestanding lipid bilayers with temperature-controlled phase.

Coexistence of lipid domains in cell membranes is associated with vital biological processes. Here, we investigate two such membranes: a multi-component membrane composed of DOPC and DPPC lipids with gel and fluid separated domains, and a single component membrane composed of PMPC lipids forming ripples. We characterize their mechanical properties below their melting point, where ordered and disordered regions coexist, and above their melting point, where they are in fluid phase. To conduct these inquiries, we create lipid bilayers in a microfluidic chip interfaced with a heating system and optical tweezers. The chip features a bubble trap and enables high-throughput formation of planar bilayers. Optical tweezers experiments reveal interfacial hydrodynamics (fluid-slip) and elastic properties (membrane tension and bending rigidity) at various temperatures. For PMPC bilayers, we demonstrate a higher fluid slip at the interface in the fluid-phase compared to the ripple phase, while for the DOPC:DPPC mixture, similar fluid slip is measured below and above the transition point. Membrane tension for both compositions increases after thermal fluidization. Bending rigidity is also measured using the forces required to extend a lipid nanotube pushed out of the freestanding membranes. This novel temperature-controlled microfluidic platform opens numerous possibilities for thermomechanical studies on freestanding planar membranes.

Assessment of a multiphase formulation of one-dimensional turbulence using direct numerical simulation of a decaying turbulent interfacial flow

The interaction between turbulence and surface tension is studied numerically using the one-dimensional-turbulence (ODT) model. ODT is a stochastic model simulating turbulent flow evolution along a notional one-dimensional line of sight by applying instantaneous maps that represent the effects of individual turbulent eddies on property fields. It provides affordable high resolution of interface creation and property gradients within each phase, which are key for capturing the local behavior as well as overall trends, and has been shown to reproduce the main features of an experimentally determined regime diagram for primary jet breakup. Here ODT is used to investigate the interaction of turbulence with an initially planar interface. The notional flat interface is inserted into a periodic box of decaying homogeneous isotropic turbulence, simulated for a variety of turbulent Reynolds and Weber numbers. Unity density and viscosity ratios serve to focus solely on the interaction between fluid inertia and the surface-tension force. Statistical measures of interface surface density and spatial structure along the direction normal to the initial surface are compared to corresponding direct-numerical-simulation (DNS) data. Allowing the origin of the lateral coordinate system to follow the location of the median interface element improves the agreement between ODT and DNS, reflecting the absence of lateral nonvortical displacements in ODT. Beyond the DNS-accessible regime, ODT is shown to obey the predicted parameter dependencies of the Kolmogorov critical scale in both the inertial and dissipative turbulent-cascade subranges. Notably, the probability density function of local fluctuations of the critical scale is found to collapse to a universal curve across both subranges. Published by the American Physical Society 2024

Unveiling Eco-Friendly Reverse Micelle Systems: Dimethyl Carbonate as a Novel Biocompatible Solvent.

In this study, we systematically explored the characteristics of dimethyl carbonate (DMC)/sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles (RMs) in the presence of water using dynamic light scattering (DLS), proton nuclear magnetic resonance (1H NMR), and molecular probes. DMC, a biocompatible solvent, enables the formulation of AOT RMs without the need for a co-surfactant. DLS revealed that as the water content increased, the droplet sizes grew larger. 1H NMR studies indicated that at low water content, water molecules interacted with DMC via hydrogen bonding. This interaction promoted the penetration of DMC toward the interface, affecting the solvation of AOT's sulfonate group. At higher water content, a competition for hydrogen bonding emerged between water-water and water-surfactant molecules, leading to distinct interfacial properties, as evidenced by molecular probes. The critical micellar concentration for DMC/AOT/water RMs was 7x10-3 M, similar to RMs formed with other biocompatible solvents. The presence of water facilitated the solvation of the surfactant's polar regions, promoting the RMs formation. The polarity of this system was measured using the ET(30) value. This novel micellar system holds significant potential in various fields, including catalysis, nanomaterials, and green chemistry.

Effect of electrochemical anodic oxidation modification on the interfacial properties of carbon fiber reinforced polyimide composites

Effect of electrochemical anodic oxidation modification on the interfacial properties of carbon fiber reinforced polyimide composites

Composite Janus film based on the synergistic interactions of π-π stacking and dynamic covalent bond toward direction recognition sensing

Although flexible strain sensors have made important advancements recently, most of them are unable to recognize the direction of motion, which greatly limits their application in fields such as human-machine interaction. This paper presents the fabrication of a bilayer asymmetric composite film that exhibits Janus dual-sided characteristics and interfacial properties. Specifically, the two sides possess different chemical compositions and surface features. The strong π-π stacking interaction between carbon nanotubes (CNTs) and pyrene enables a tight coating on the surface of poly(glycidyl propyl urethane) (PGPU), resulting in excellent sensing capabilities and electromagnetic shielding properties for the composite material. This composite film can effectively monitor the amplitude and direction of motion. Firstly, pyrene-grafted polyurethane (PGPU) was synthesized including on dynamic covalent bonds. The tensile strength of different samples can reach up to 19.69 MPa, and the strain at break is up to 501.95 %. Furthermore, PGPU/CNTs conductive composite films were fabricated by spray-coating carbon nanotubes (CNTs) onto PGPU, and the pyrene units in PGPU can effectively interact with CNTs via π-π stacking, ensuring that stable adhesion of CNTs layer during long-term usage. Due to the dynamic covalent bonds and hydrogen bonds inside PGPU, PGPU and PGPU/CNTs both exhibit well-performed self-healing capability. Notably, the Janus structure of PGPU/CNTs can adjust the positive and negative values of relative resistance based on stretchable and compressive status of CNTs layer. Thus, PGPU/CNTs are directionally sensitive and self-healing flexible wearable sensor, which might apply in human-machine interaction field.

Characterization of the Lithium/Solid Electrolyte Interface in the Presence of Nanometer-thin TiOx Layers for All-Solid-State Batteries.

It is still unclear which role space charge layers (SCLs) play within an all-solid-state battery during operation with high current densities, as well as to which extent they form. Herein, we use a solid electrolyte with a known SCL formation and investigate it in a symmetric cell under non-blocking conditions with Li metal electrodes. Since the used LICGC™ electrolyte is known for its instability against lithium, it is protected from rapid degradation by nanometer-thin layers of TiOx deployed by atomic layer deposition. Close attention is given to the interfacial properties, as now additional Li+ can traverse through the interface depending on the applied bias potential. The interlayer's impedance response shows efficient lithium-ion conduction for low bias potentials and a diffusion-limiting effect towards high positive and negative potentials. SCLs grow up to a thickness of 5.1 μm. Additionally, estimating the apparent rate constant of the charge transfer across the interface indicates that the potentials where kinetics are hindered coincide with the widest SCLs. In conclusion, the investigation under higher steady-state currents was only possible because of the improved stability due to the interlayer. No chemo-physical failure could be observed after 800+ hours of cycling. However, an ex-situ SEM study shows a new phase at the interface, which grows into the electrolyte.

Role of voltage-controlled magnetic anisotropy in the recent development of magnonics and spintronics

With significant recent progress in the thin film deposition and nanofabrication technology, a number of physical phenomena occur at the interfaces of magnetic thin films, and their heterostructures have been discovered. Consequently, the electric field-induced modulation of those interfacial properties mediated through spin–orbit coupling promises to develop magnetic material based smarter, faster, miniaturized, energy efficient spintronic devices. Among them, the electric field-induced modification of interfacial magnetic anisotropy, popularly termed as voltage-controlled magnetic anisotropy (VCMA), has attracted special attention because of its salient features. This article is devoted to reviewing the recent development of magnonics, which deals with collective precessional motion of ordered magnetic spins, i.e., spin waves (SWs), and skyrmions with chiral spin textures, with VCMA, including the perspectives of this research field. Starting with a broad introduction, the key features of VCMA and its advantages over other electric field-induced methods are highlighted. These are followed by describing the state-of-the-art of VCMA, and various other direct and indirect electric field-induced methods for magnetization reversal; controlling skyrmion dynamics; excitation, manipulation, and channeling of SWs; and tailoring magnonic bands. The critical challenges, their possible solutions, and future perspectives of this field are thoroughly discussed throughout the article.

Density Functional Theory Study of Adhesion Mechanism between Epoxy Resins Cured with 4,4'-Diaminodiphenyl Sulfone and 4,4'-Diaminodiphenylmethane and Carboxyl Functionalized Carbon Fiber.

The molecular mechanism of adhesion of two epoxy resins based on diglycidylether of bisphenol A (DGEBA) cured with 4,4'-diaminodiphenyl sulfone (DDS) and 4,4'-diaminodiphenylmethane (DDM) to the carbon fiber (CF) surface is investigated by employing density functional theory (DFT) calculations. The CF surface was modeled by the armchair-edge structure of graphite functionalized with carboxyl (COOH) groups. Two adhesion interfaces were constructed using the CF surface: one with the DGEBA-DDS molecule (CF/DGEBA-DDS interface) and the other with the DGEBA-DDM molecule (CF/DGEBA-DDM interface). The interfacial properties were analyzed by calculating the maximum adhesion stress (Smax) at the interface. The adhesion stress-displacement curve revealed that Smax is 1160.37 MPa, higher for the CF/DGEBA-DDS interface compared to the CF/DGEBA-DDM interface, which is 1060.48 MPa. The energy decomposition analysis showed a similar DFT contribution to adhesion stress for both interfaces, but the dispersion contribution is more significant at the CF/DGEBA-DDS interface. The crystal orbital Hamilton population (COHP) analysis revealed distinct interfacial interactions despite similar DFT contributions. Hydrogen bonding (H-bonding) between the functional groups at both interfaces including feeble OH-π interactions between the benzene rings of epoxy resins and COOH groups on the CF surface were observed. The orbital interaction energies calculated from integrated COHP, i.e., IpCOHP, revealed that the CF/DGEBA-DDS interface has six H-bonding interactions with large absolute IpCOHP values (>1 eV), whereas the CF/DGEBA-DDM interface has five. The interaction between the amine group of the DGEBA-DDM molecule and the CF surface has a large IpCOHP value among all interactions. The sulfone group being at the center of the DDS molecule and its strong surface interaction positioned the DGEBA-DDS molecule closer to the CF surface than the DGEBA-DDM molecule, enhancing dispersion interaction at the CF/DGEBA-DDS interface. Hence, the CF surface exhibits a stronger affinity toward the DGEBA-DDS molecule than the DGEBA-DDM molecule through dispersion interaction.