We perform coarse-grained simulations of model unentangled polymer materials to quantify the range over which interfaces alter structure and dynamics in vicinity interface. study interfacial zone around nanoparticles (NPs) polymer-NP composites with variable NP diameter, as well at solid substrate free surface thin supported films. These both segmental packing mobility an zone. Variable size allows us gain insight into effect boundary curvature, where film is limit zero curvature. find that...

We computationally investigate the good solvent solution properties of knotted ring and star polymers by combining molecular dynamics (MD) simulation path-integral calculations. consider rings having a minimal crossing number mc in range, 0 ≤ 9, range f arms, 2 20, attached to common core monomer particle. After generating configurational ensembles these MD, we use path-integration program ZENO calculate basic properties, i.e., radius gyration, hydrodynamic radius, intrinsic viscosity, as...

We construct nanoparticle dimers linked by DNA. These are basic units in a possible multiscale, hierarchical assembly and serve as model system to understand DNA-mediated interactions, especially the nontrivial regime when DNA comparable their sizes. examine structure of detail combination scattering experiments molecular simulations. find that, for given length, interparticle separation within dimer is controlled primarily number linking summarize our findings simple that captures interplay...

We explore the structural and dynamic properties of bulk materials composed graphene nanosheets using coarse-grained molecular dynamics simulations. Remarkably, our results show clear evidence that exhibit a fluid-like behavior similar to linear polymer melts at elevated temperatures these transform into glassy-like "foam" state below glass-transition temperature (Tg) materials. Distinct from an isolated sheet, which exhibits relatively flat shape with fluctuations, we find sheets in melt...

Enthalpy–entropy compensation is observed in diverse molecular binding processes of importance to living systems and manufacturing applications. We suggest that variations rigidity might provide a common origin this phenomenon the complex molecules such as DNA.

We perform molecular dynamics simulations on a coarse-grained polymer melt to study the of glass-formation in ring melts variable knot complexity. After generating non-concatenated polymeric rings having range minimum crossing number values, mc, we compute coherent intermediate scattering function, segmental α-relaxation time, fragility, and glass transition temperature as function mc. Variation complexity is found have pronounced effect since both rigidity packing are altered, primary...

DNA origami is a powerful platform for assembling gold nanoparticle constructs, an important class of nanostructure with numerous applications. Such constructs are assembled by the association complementary oligomers. These reactions have yields <100%, requiring development methods to purify desired product. We study performance centrifugation as separation approach combining optical and hydrodynamic measurements computations. demonstrate that bench-top microcentrifugation simple efficient...

In composites, carbon nanotubes (CNTs) are rarely perfectly straight and they usually exhibit complex shapes. this paper, we employ the method-of-moments formulation for arbitrary thin wires to study electromagnetic scattering characteristics of CNTs with realistic More than 800 different CNT shapes were simulated in work. These generated using a coarse-grained molecular dynamics model calibrated encountered experimentally. The analysis shows that shape orientation has strong effect on...

The addition of carbon nanotubes (CNTs) and graphene sheets (GSs) into polymeric materials can greatly enhance the conductivity alter electromagnetic response resulting nanocomposite material. extent these property modifications strongly depends on structural parameters describing CNTs GSs, such as their shape size, well degree particle dispersion within matrix. To model in dilute regime, we determine leading transport virial coefficients CNT GS composites using a combination molecular...

The Coulomb energy E

The morphology of commercially available carbon nanotube materials is often much more complex than the term "carbon nanotube" (CNT) would imply. Commercial CNT are typically composed roughly spherical domains having a highly ramified internal structure and size on order microns. Clearly, such structures cannot reasonably be modeled as "rods". To address this problem, we first perform molecular dynamics simulations (MD) to generate similar those measured experimentally, based presumptions...

The formation of gels through the bundling semi-flexible polymer chains into fiber networks is ubiquitous in diverse manufactured and natural materials, and, accordingly, we perform exploratory molecular dynamics simulations a coarse-grained model polymers solution with attractive lateral interchain interactions to understand essential features this type gel formation. After showing that our gives rise fibrous resembling real kind, investigate how extent influences "melting" temperature, T m...

To understand the effect of chemical composition, cross-link density, and microstructure on linear nonlinear viscoelasticity ethylene propylene diene monomer (EPDM) rubber, we carried out high-frequency oscillatory shear molecular dynamics simulations at varying strain rates. Sweeping through different EPDM compositions with ethylene, propylene, ratios, a positive correlation was observed between ratio complex modulus in glassy regime. For small deformations this regime, found that simplest...

Carbon nanotube composites are lightweight, multifunctional materials with readily adjustable mechanical and electrical properties—relevant to the aerospace, automotive, sporting goods industries as high-performance structural materials. Here, we combine well-established newly developed characterization techniques demonstrate that ultraviolet (UV) light exposure provides a controllable means enhance conductivity of surface commercial carbon nanotube–epoxy composite by over 5 orders...

We compare molecular dynamics simulations and experimental measurements of duplex DNA under confinement to nanofluidic slits. Our analysis indicates that dimensional reduction strongly amplifies the excluded volume interaction.

Graphene flakes (GFs) in real composites are rarely perfectly flat, and often exhibit complicated crumpled shapes. Therefore, the goal of this paper was to quantify electromagnetic scattering characteristics individual GFs with shapes resembling those found composites. The extinction cross sections tens GFs, different sizes various levels crumpleness, were calculated using multiple independent solvers. results show that resonances section spectrum decrease amplitude as become more crumpled....

The characterization of many objects involves the determination a basic set particle size measures derived mainly from scattering and transport property measurements. For polymers, these properties include radius gyration Rg, hydrodynamic Rh, intrinsic viscosity [η], sedimentation coefficient S, for conductive particles, electric polarizability tensor αE self-capacity C. It is often found that measurements deviate each other geometric estimates when or polymer shape complex, phenomenon...

The size and conformation of a series poly(α-olefin) homopolymers in good solvent conditions were measured by combination small-angle neutron scattering (SANS), triple detector exclusion chromatography (SEC), MD simulations. bottlebrush samples prepared via organometallic coordinative insertion polymerization 1-alkenes, with carbon numbers ranging from 6 to 18 carbons. A linear polyolefin, that is, polypropylene, is included this study for comparison. SANS data all the solutions are well...

Theoretically estimated change in hydrodynamic radius of a DNA nanoparticle versus the corresponding simulation estimate based on program ZENO, combination with molecular dynamics to generate representative chain configurations.

Carbon nanotubes (CNTs) exhibit highly complicated structures when incorporated in composites and are neither perfectly straight nor aligned any one direction. Recently, the “clumpy” structure of multiple aggregated CNTs has been likened to desert tumbleweeds. The goal this paper is quantify electromagnetic scattering characteristics tumbleweed configuration using classical simulations. simulation results show that first-plasmon resonance, exhibited by an individual CNT, splits into...

We utilize molecular dynamics simulations (MD) and the path-integration program ZENO to quantify hydrodynamic radius (Rh) fluctuations of spherical symmetric gold nanoparticles (NPs) decorated with single-stranded DNA chains (ssDNA). These results are relevant understanding fluctuation-induced interactions among these NPs macromolecules such as proteins. In particular, we explore effect varying ssDNA-grafted structural parameters, chain length (L), persistence (lp), NP core size (R), number...

We investigate the conformational state of a simple, coarse–grained molecular model for single–stranded DNA chains (ssDNA) grafted onto spherical symmetric gold nanoparticles (NPs) and layer as whole by dynamic simulations. In particular, we compare radius gyration (Rg) an individual chain to its value in solution use path–integration estimate change δRh hydrodynamic ssDNA–grafted NPs (Rh) from bare NP core (R = 5.0 nm) range (N), lengths (L), persistence (lp) relevant experimental studies...

We use molecular dynamic simulations on a coarse-grained model for flexible polymers in solution to study how topology affects the intrinsic rigidity of polymeric chains. In particular, we "topological complexity", defined by minimum number crossing knotted polymers, m and polymer functionality, f, or arm regular star chain measured through determination persistence length, lp. find that increasing these topological constraints leads progressive increase These topologically induced changes...