Abstract Graphene oxide (GO) is a promising building block for nanocomposites due to its excellent mechanical properties and tunable interfacial interactions with polymers. While experiments have shown that GO sheets consist of graphitic regions clustering into patches and oxidized regions constituting the remaining areas, the role that these heterogeneous patches play on interfacial and mechanical properties of GO reinforced nanocomposites have not yet been investigated. To address this issue at spatiotemporal scales beyond atomistic simulations, we employ recently developed coarse-grained models of GO sheet and polybutadiene to model patchy GO sheets and a representative GO/polybutadiene nanocomposite with GO sheets serving as fillers. We quantify how interfacial adhesion energy and polymer conformations depend on the size of patches and corroborate these findings with the viscoelastic behaviors of the nanocomposite determined via oscillatory shear simulations conducted at multiple temperatures. We find that heterogeneous patchy structures on GO sheets are responsible for variations in interfacial and viscoelastic properties. Specifically, larger patches result in stronger filler-matrix adhesion or enhanced material stiffness with strong or weak oxidized region-polymer interactions, respectively. Our study provides fundamental insights into the interfacial mechanisms of GO-polymer nanocomposites and the influence of heterogeneous functionalized surfaces on the mechanical properties of polymer nanocomposites.
Last. Jack F. Douglas(NIST: National Institute of Standards and Technology)H-Index: 91
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Multiscale coarse-grained (CG) modeling of soft materials, such as polymers, is currently an art form because CG models normally have significantly altered dynamics and thermodynamic properties compared to their atomistic counterparts. We address this problem by exploiting concepts derived from the generalized entropy theory (GET), emphasizing the central role of configurational entropy s c in the dynamics of complex fluids. Our energy renormalization (ER) method involves varying the cohesive in...
Understanding and designing nanoscale interfaces are essential to advancing the thermomechanical performance of polymer nanocomposites reinforced by nanocellulose. In this context, it remains to be understood how disorder introduced on the surfaces of crystals as filler materials during extraction and processing influences interfacial adhesion with glassy polymers. Using atomistic molecular dynamics (MD) simulations, here we systematically explore the interfacial adhesion between nanocellulose a...
#2David D. Hsu(Wheaton College (Illinois))H-Index: 10
Last. Sinan Keten(NU: Northwestern University)H-Index: 34
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Developing temperature transferable coarse-grained (CG) models is essential for the computational prediction of polymeric glass-forming (GF) material behavior, but their dynamics are often greatly altered from those of all-atom (AA) models mainly because of the reduced fluid configurational entropy under coarse-graining. To address this issue, we have recently introduced an energy renormalization (ER) strategy that corrects the activation free energy of the CG polymer model by renormalizing the ...
Due to their exceptional properties, graphene and hexagonal boron nitride (h-BN) nanofillers are emerging as potential candidates for reinforcing the polymer-based nanocomposites. Graphene and h-BN have comparable mechanical and thermal properties, whereas due to high band gap in h-BN (~5 eV), have contrasting electrical conductivities. Atomistic modeling techniques are viable alternatives to the costly and time-consuming experimental techniques, and are accurate enough to predict the mechanical...
In the inertial limit, the resonance frequency of the quartz crystal microbalance (QCM) is related to the coupled mass on the quartz sensor through the Sauerbrey expression that relates the mass to the change in resonance frequency. However, when the thickness of the film is sufficiently large, the relationship becomes more complicated and both the frequency and damping of the crystal resonance must be considered. In this regime, a rheological model of the material must be used to accurately ext...
Last. Binbin Yuan(Civil Aviation Administration of China)H-Index: 1
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In this work by adopting coarse-grained molecular dynamics simulation, we focus our attention on investigating the effect of the chemical coupling between polymer and nanoparticles (NPs) on the viscoelastic properties of polymer nanocomposites (PNCs). Firstly we examine the effect of the interfacial chemical coupling on the non-linear behavior, such as the change of the storage moduli, the loss moduli and the loss factor as a function of the strain amplitude. Besides the reinforcing effect contr...
Last. Sinan Keten(NU: Northwestern University)H-Index: 34
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The bottom-up prediction of the properties of polymeric materials based on molecular dynamics simulation is a major challenge in soft matter physics. Coarse-grained (CG) models are often employed to access greater spatiotemporal scales required for many applications, but these models normally experience significantly altered thermodynamics and highly accelerated dynamics due to the reduced number of degrees of freedom upon coarse-graining. While CG models can be calibrated to meet certain proper...
#2Peng Wang(University of Texas at Austin)H-Index: 8
Last. Pradeep Sharma(UH: University of Houston)H-Index: 37
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Abstract The study of statistical mechanics of thermal fluctuations of graphene—the prototypical two-dimensional material—is rendered rather complicated due to the necessity of accounting for geometric deformation nonlinearity. Unlike fluid membranes such as lipid bilayers, coupling of stretching and flexural modes in solid membranes like graphene leads to a highly anharmonic elastic Hamiltonian. Existing treatments draw heavily on analogies in the high-energy physics literature and are hard to ...
#1Mohannad Naeem(UniSA: University of South Australia)H-Index: 1
#2Hsu-Chiang Kuan(Communist University of the Toilers of the East)H-Index: 42
Last. Jun Ma(UniSA: University of South Australia)H-Index: 110
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Abstract Many preparation methods reported for polymer/graphene nanocomposites are associated with graphene surface modification and consumption of organic solvents. A facile, green and novel approach has been developed in this study for preparation of epoxy/graphene nanocomposites. The approach involves microwaving a commercial graphene precursor and mechanically stirring to produce graphene platelets in a hot, liquid-state epoxy resin, eliminating the need for organic solvents and external sur...
Molecular dynamics simulations are used to obtain mode I and mode II fracture energies and cohesive laws for bulk epoxy and interfaces formed between epoxy and single-layer graphene (SLG), multilayer graphene (MLG), and multilayer graphene oxide (MLGO). The elastic moduli and ultimate tensile and shear strengths of epoxy–graphene interfaces are calculated from uniaxial tension and simple shear loadings. The results show that Young’s modulus and the ultimate tensile strength increase relative to ...
Abstract Multilayer graphene sheets (MLGSs) are promising nano-reinforcements that can effectively enhance the properties of polymer matrices. Despite many studies on MLGSs-reinforced polymer nanocomposites, the effect of wrinkles formed in MLGSs on the reinforcement effect and the viscoelastic properties of polymer nanocomposites has remained unknown. In this study, building upon previously developed coarse-grained models of MLGSs and poly(methyl methacrylate) coupled with molecular dynamics si...
Last. Xiaohu Yao(SCUT: South China University of Technology)H-Index: 14
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Abstract Incorporating graphene nanosheets into a polymer matrix is a promising way to utilize the remarkable electronic, thermal, and mechanical properties of graphene. However, the underlying mechanisms near the graphene-polymer interface remain poorly understood. In this study, we employ coarse-grained molecular dynamics (MD) simulations to investigate the nanoscale mechanisms present in graphene-reinforced polycarbonate (GRPC) nanocomposites and the effect of those mechanisms on GRPC’s mecha...
Polyamide-based nanocomposites containing graphene platelets decorated with poly(acrylamide) brushes were prepared and characterized. The brushes were grafted from the surface of graphene oxide (GO), a thermally conductive additive, using atom transfer radical polymerization, which led to the formation of the platelets coated with covalently tethered polymer layers (GO_PAAM), accounting for ca. 31% of the total mass. Polyamide-6 (PA6) nanocomposites containing 1% of GO_PAAM were formed by extrus...
Abstract Carbon fiber-reinforced polymer (CFRP) composite is subject to external loads during service life, suffering the interfacial creep between the fiber and the matrix and eventually the interfacial slippage. CFRP composite loses the interfacial integrity due to the interfacial creep and the long-term durability is weakened. In order to understand the degradation, microscopic details of interfacial structural changes during the creep are essential. This study aims to investigate microscopic...
Abstract A bottom-up multi-scale modeling approach is used to develop an Integrated Computational Materials Engineering (ICME) framework for carbon fiber reinforced polymer (CFRP) composites, which has the potential to reduce development to deployment lead time for structural applications in lightweight vehicles. In this work, we develop and integrate computational models comprising of four size scales to fully describe and characterize three types of CFRP composites. In detail, the properties o...
Materials chemistry is at the forefront of the global "Fourth Industrial Revolution", in part by establishing a "Materials 4.0" paradigm. A key aspect of this paradigm is developing methods to effectively integrate hardware, software, and biological systems. Towards this end, we must have intimate knowledge of the virtual space in materials design: materials omics (materiomics), materials informatics, computational modelling and simulations, artificial intelligence (AI), and big data. We focus o...