Tailoring Strength and Toughness of Ternary Adhesives by Relating their Structure and Properties: Insights from Reactive Coarse-Grained MD - dataset

Abstract:from [1] Structural adhesive joints are essential for bonding dissimilar materials, offering a superior strength-to-weight ratio over conventional fastening methods. Despite their widespread industrial use, a comprehensive understanding necessary to unlock their full potential is lacking. This gap stems from the high complexity of commercial adhesives and the adherends’ intricate influence on the adhesive's curing process, which alters nanostructure and mechanical properties. Notably, the specific effects of compositional complexity are seldom addressed in the literature. We present a molecular dynamics model for a ternary adhesive (DGEBA resin with PACM and Jeffamine hardeners) capturing key aspects of real adhesives. We show how resin/hardener ratios and hardener composition affect joint structure, dynamics, and mechanical properties, focusing on the interphase region. Thermodynamically driven segregation occurs: Jeffamine agglomerates at the adherend surface, followed by a DGEBA-rich region. This segregation produces an interphase with locally varying curing, controlled by the resin-to-hardener ratio. \RevII{Segregation} alters local molecular dynamics, with the Debye-Waller factor indicating increased stiffness in the interphase. Tuning constituent proportions enables a wide range of stiffness, strength, and toughness, correlating mechanical properties with structural and dynamic features. Crucially, the interphase is the joint’s weak point, limiting its load-bearing capacity. A slight excess of hardener mitigates adverse interphase effects and enhances the joint’s overall performance, providing a clear molecular design rule. The structure–property relationships established here are a key step toward next-generation adhesives with enhanced performance. The openly available simulation framework invites researchers to utilize it or collaborate, as our methodology is applicable to other interfacial systems. Contact: Maximilian RiesInstitute of Applied MechanicsFriedrich-Alexander-Universität Erlangen-NürnbergEgerlandstr. 591058 Erlangen Software: All MD simulations were performed with LAMMPS [2,3], version: 10 Sep 2025 with REACT package [4,5] Compiled withCompiler: GNU C++ 11.2.0 with OpenMP not enabledC++ standard: C++11 Installed packages:MOLECULE KSPACE BPM CLASS2 DPD-BASIC EXTRA-DUMP EXTRA-FIX EXTRA-MOLECULE EXTRA-PAIR INTEL MANYBODY MC MISC OPT REACTION RIGID Post-processing Matlab R2023b License: Creative Commons Attribution 4.0 International Context: Data set supplementing journal paper:[1] M. Ries, A. Giuntoli, "Tailoring Strength and Toughness of Ternary Adhesives by Relating their Structure and Properties: Insights from Reactive Coarse-Grained MD." submitted. Content: data of equilibration and uniaxial deformation of all adhesive compositions naming convention for simulation folders - Lambda resin/hardener mixing ratio - Mu hardener composition - trailing number replica ID (0-4) Each simulation directory contains: lammps input files (*.in) all scripts executed by LAMMPS, starting with main.in data files (*.data) containing the sample configuration in LAMMPS data format dat files (*.dat) containing simulation output, format explained below info files (*.info) containing progress information of the simulation and meta data parameters.prm parameter file governing the simulation Standard_Input: simulation input files including - starting configurations, - reaction files for REACT package, - DGEBA, Jeffamine, PACM molecule files LAMMPS_out: simulation results - data files, documenting the simulation progress (steps 1 and 2 omitted to save space) 3_afterGrafting.data 4_afterCuring.data 5_afterCooldown.data 6_afterSampling.data 7_afterDeformation.data - thermoEQU.dat thermodynamic quantities during sample preparation - thermoUT.dat thermodynamic quantities during deformation - CuringSummary.dat summary of final curing state - GraftingSummary.dat summary of final grafting state - result quantities in thermoEQU.dat TimeStep timestep c_thermo_temp temperature in K c_thermo_press isobaric pressure in atm v_Ly joint length in y direction in A v_Density mass density in g/cm^3 v_CurDeg curing degree v_MaxCurDegEpoxy maximum epoxy-limited curing degree v_MaxCurDegAmine maximum amine-limited curing degree v_CrossDeg cross-linking degree v_MaxCrossDeg maximum cross-linking degree v_NormMixing normalized resin/hardener mixing ratio v_NormMixingEff normalized effective resin/hardener mixing ratio (corrected by grafting) v_GraftDeg grafting degree (averaged over left and right substrate) v_Etot total energy in kcal/mol v_Epair pair energy in kcal/mol v_Ebond bond energy in kcal/mol v_Eangle angle energy in kcal/mol v_Epot potential energy in kcal/mol v_Ekin kinetic energy in kcal/mol v_Stress_xx_MPa normal stress in x direction in MPa v_Stress_yy_MPa normal stress in x direction in MPa v_Stress_zz_MPa normal stress in x direction in MPa v_Stress_xy_MPa shear stress in xy direction in MPa v_Stress_xz_MPa shear stress in xz direction in MPa v_Stress_yz_MPa shear stress in yz direction in MPa c_MSD ensemble average mean-squared displacement in A^2 - result quantities in thermoUT.dat TimeStep timestep c_thermo_temp temperature in K v_Ly joint length in y direction in A v_Density mass density in g/cm^3 v_Strain_xx engineering tensile strain in x direction v_Strain_yy engineering tensile strain in y direction v_Strain_zz engineering tensile strain in z direction v_Strain_xy engineering shear strain in xy direction v_Strain_xz engineering shear strain in xz direction v_Strain_yz engineering shear strain in yz direction v_Etot total energy in kcal/mol v_Epair pair energy in kcal/mol v_Ebond bond energy in kcal/mol v_Eangle angle energy in kcal/mol v_Epot potential energy in kcal/mol v_Ekin kinetic energy in kcal/mol v_Stress_xx_MPa normal stress in x direction in MPa v_Stress_yy_MPa normal stress in x direction in MPa v_Stress_zz_MPa normal stress in x direction in MPa v_Stress_xy_MPa shear stress in xy direction in MPa v_Stress_xz_MPa shear stress in xz direction in MPa v_Stress_yz_MPa shear stress in yz direction in MPa v_NumBondsBroken number of broken bonds (cumulative) c_PEcrosslink potential energy of cross-link atoms (type 10) in kcal/mol c_PElinlink potential energy of linear-link atoms (type 9) in kcal/mol c_PairSubstrate pair potential of substrate in kcal/mol c_GraftingEnergy bond energy in grafting bonds in kcal/mol v_DGEBAStressMPa tensile stress contribution of DGEBA in y direction in MPa v_PACMStressMPa tensile stress contribution of PACM in y direction in MPa v_JEFFStressMPa tensile stress contribution of Jeffamine in y direction in MPa v_TOTStressMPa tensile stress in y direction computed via contributions of DGEBA, PACM, Jeffamine in MPa v_SUBStressMPa tensile stress contribution of Al2O3 substrates in y direction in MSD v_AdhVolume volume of adhesive in A^3 v_AdhDens density of adhesive in g/(mol A^3) References: [1] M. Ries, A. Giuntoli, "Tailoring Strength and Toughness of Ternary Adhesives by Relating their Structure and Properties: Insights from Reactive Coarse-Grained MD." submitted. [2] S. Plimpton, “Fast parallel algorithms for short-range molecular dynamics,” Journal of computational physics, 1995, 117, 1-19. [3] A. P. Thompson et al., “LAMMPS - a flexible simulation tool for particle-based materials modeling at the atomic, meso, and continuum scales,” Computer Physics Communications, vol. 271, p. 108171, 2022. [4] J. R. Gissinger, B. D. Jensen, and K. E. Wise, “Modeling chemical reactions in classical molecular dynamics simulations,” Polymer, vol. 128, pp. 211–217, 2017. [5] J. R. Gissinger, B. D. Jensen, and K. E. Wise, “Reacter: A heuristic method for reactive molecular dynamics,” Macromolecules, vol. 53, no. 22, pp. 9953–9961, 2020.