Enhanced premelting at the ice-rubber interface using all-atom molecular dynamics simulation

TL;DR

This study uses all-atom molecular dynamics to resolve the molecular-scale behavior of the ice–rubber interface, focusing on premelting layers at the basal ice surface in contact with styrene-butadiene rubber over 254–269 K. The authors demonstrate that hydrophobic rubber increases structural disorder within premelting layers while confining water motion, yielding glassy-like dynamics; near the melting point, rubber chains penetrate the premelting region and form a mixed rubber–water interfacial layer with coupled dynamics. The work reveals that nanoscale roughness and polymer morphology disrupt ice hydrogen-bond networks, enhancing premelting and potentially reducing ice adhesion, while the interfacial coupling suggests new design strategies for polymer materials to control ice friction and slipperiness. Overall, the findings provide molecular-level mechanisms for ice–rubber tribology and guide the development of hydrophobic polymers with tunable ice adhesion and friction properties, grounded in explicit atomistic interactions and layer-resolved dynamics.

Abstract

The ice-rubber interface is critical in applications such as tires and shoe outsoles, yet its molecular tribology remains unclear. Using all-atom molecular dynamics simulations, we studied premelting layers at the basal face of ice in contact with styrene-butadiene rubber from 254 to 269 K. Despite its hydrophobicity, rubber enhances structural disorder of interfacial water, promoting premelting. In contrast, water mobility is suppressed by confinement from polymer chains, leading to glassy dynamics distinct from the ice-vapor interface. Near the melting point, rubber chains become more flexible and penetrate the premelting layer, forming a mixed rubber-water region that couples the dynamics of both components. These results suggest that nanoscale roughness and morphology of hydrophobic polymers disrupt ice hydrogen-bond networks, thereby enhancing premelting. Our findings provide molecular-level insight into ice slipperiness and inform the design of polymer materials with controlled ice adhesion and friction.

Figures (13)

• Figure 1: Simulation system. (A) Chemical structure of styrene-butadiene rubber used in this work. We generated a single chain by randomly shuffling the monomers, using the indicated number of monomer units. (B) Representative zoomed-in snapshot of the interface, with the full simulation system shown in Fig. \ref{['fig:snapshot_full_simulation_box']}. The top side is the ice--rubber interface, while the lower is the ice--vapor interface.
• Figure 2: Molecular structure of ice--rubber and ice--vapor interfaces. (A) Representative snapshots at 264 and 269 K for the ice--rubber and ice--vapor interfaces. Labels (1st, 2nd, and 3rd) indicate the layer positions (Layer 1--3). (B) Density profile of water oxygen atoms and rubber atoms in the ice--rubber interface at 264 and 269 K. (C) The density profile of water oxygen atoms, comparing the ice--rubber and ice--vapor interfaces, at 264 and 269 K.
• Figure 3: Comparison of the dynamical properties of ice--rubber and ice--vapor interfaces. (A) Mean squared displacement (MSD) of premelting layers (combined Layer 1 and Layer 2) in the ice–rubber interface. $\alpha$ is the scaling exponent of MSD. (B) Parallel diffusion coefficient as a function of temperature. Bulk liquid values at 0 MPa were taken from Baran et al. baran2023self. Values of the parallel diffusion coefficients are listed in Tab. \ref{['tab:tabS1_combined']}. (C) Distribution of the score, $g(\bm{x})$, which quantifies deviation from bulk solid behavior in single-molecule short-term dynamics. Layer 1--4 represent the distributions from the ice–rubber interface at 269 K, while "Ice" and "Water" correspond to bulk solid and liquid systems, respectively. The black dashed line indicates the threshold used to classify molecules as solid-like or liquid-like. (D–F) Ratio of liquid-like molecules in Layers 1--3 at different temperatures. Error bars represent the standard error of the mean calculated using time block averaging (5 ns per block) in (B) and (C--F).
• Figure 4: Analysis of the atomistic structure of the ice–rubber interface. (A) Snapshot of Layer 1 at 269 K, showing water molecules as Van der Waals spheres and rubber atoms as a surface representation. (B) Root-mean-square fluctuation (RMSF) of surface rubber atoms in Layer 1. Error bars represent the standard error of the mean calculated using time block averaging (5 ns per block). (C) Representative snapshot of a region within Layer 1, where the densities of water and rubber are comparable, at 254 and 267 K. Water molecules are shown as oxygen atom positions and are colored by the score $g(\bm{x})$, which quantifies deviation from bulk ice. Higher values (yellow) indicate greater mobility. Rubber atoms are shown as green spheres.
• Figure S1: Snapshot showing the full simulation box.