Diverse Spreading Behavior of Binary Polymer Nanodroplets

David R. Heine; Gary S. Grest; Edmund B. Webb III

Home/Archive/arXiv

arXiv · cond-mat/0501457

Diverse Spreading Behavior of Binary Polymer Nanodroplets

David R. Heine·Gary S. Grest·Edmund B. Webb III

View original source ↗Read source document ↗Export metadata ↓

Abstract

Molecular dynamics simulations are used to study the spreading of binary polymer nanodroplets in a cylindrical geometry. The polymers, described by the bead-spring model, spread on a flat surface with a surface-coupled Langevin thermostat to mimic the effects of a corrugated surface. Each droplet consists of chains of length 10 or 100 monomers with ~350,000 monomers total. The qualitative features of the spreading dynamics are presented for differences in chain length, surface interaction strength, and composition. When the components of the droplet differ only in surface interaction strength, the more strongly wetting component forms a monolayer film on the surface even when both materials are above or below the wetting transition. In the case where the only difference is the polymer chain length, the monolayer film beneath the droplet is composed of an equal amount of short chain and long chain monomers even when one component (the shorter chain length) is above the wetting transition and the other is not. The fraction of short and long chains in the precursor foot depends on whether or not both the short and long chains are in the wetting regime. Diluting the concentration of the strongly wetting component in a mixture with a weakly wetting component decreases the rate of diffusion of the wetting material to the surface and limits the spreading rate of the precursor foot, but the bulk spreading rate is not affected until the more strongly wetting component is removed completely.

Explore related subjects

cond-mat.soft cond-mat.mtrl-sci

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

David R. Heine, Gary S. Grest, Edmund B. Webb III. 2005-01-19. Diverse Spreading Behavior of Binary Polymer Nanodroplets. https://arxiv.org/abs/cond-mat/0501457

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Control of filament network rigidity by the condensation of crowding molecules

Understanding how liquid-liquid phase separation impacts the mechanics of filament networks is a fundamental physical problem at the heart of biological cellular processes and soft material design. While a few theoretical mechanisms have been proposed, a clear demonstration of the direct coupling of phase separation to the overall network stiffness is missing. We report experiments that reveal a universal mechanism by which the condensation of macromolecular crowders induces a rigidity transition in a model filament network. We reconstituted stiff sterically interacting helical filaments and polymeric crowders. Initially, the macromolecules were uniformly dissolved and the filaments formed bundles that assembled a rigid entangled network. Once the crowders condensed into droplets, the network structure lost its rigidity and its mechanical response weakened by an order-of-magnitude. The subsequent dissolution of the condensates was accompanied by the re-establishment of rigidity. Our results show that crowder phase separation modulates the mechanics of filament networks by tuning the osmotic pressure holding the network together. This principle may serve as a paradigm for devising dynamically tunable filamentous materials.

cond-mat.soft↗

arXiv2026

Speed up of passive tracers in mixtures with active chemical reactions

Diffusivity of passive tracers in complex mixtures is widely relevant for industrial applications and for probing biological systems. Interactions with the surrounding medium typically generate a drag force that suppresses tracer diffusion, although self-propulsion can accelerate tracers via active fluctuations. Similar effects are not understood in mixtures with particle conversion and exchange, although these are particularly relevant in biological contexts, where actively driven reactions prevail. By studying a thermodynamically consistent model of chemical reactions in mixtures, we show that reactions provide an additional relaxation pathway that suppresses interaction-induced memory, reducing the drag on tracers and restoring their diffusivity toward the value expected in the absence of solutes. Moreover, active reactions generate nonequilibrium fluctuations that can push tracer diffusivity beyond this limit, an effect we confirm with particle-based simulations. Our results identify chemical activity as a distinct route to controlling mass transport and offer a framework for interpreting microrheology experiments in chemically active mixtures.

cond-mat.soft↗

arXiv2026

Diffusion of charged rods across 3D varying section channels

We analyze the transport of rod-like particles by diffusion and drift in a three-dimensional channel with varying circular or elliptic cross section. Applying the Fick-Jacobs approximation to the transport equation of the particles' probability distribution, we derive an effective one-dimensional substitute model and the associated free energy profile. Our results show that the data for the mean first passage time of rods, once expressed as a function of the effective free energy barrier, collapse onto the same master curve as obtained for point or spherical particles. The observed universality provides a simple framework for predicting transport times of anisotropic particles in confined geometries without resolving the full multidimensional dynamics.

cond-mat.soft↗