Interfacial Thermal Conductance Between a Polyethylene Glycol Polymer Chain and Water: A Molecular Dynamics Study

TL;DR

This study uses molecular dynamics simulations to quantify how temperature and interfacial interactions affect heat transfer between polyethylene glycol chains and water, revealing structural and dynamical factors influencing interfacial thermal conductance.

Contribution

It provides the first detailed atomistic analysis of interfacial thermal conductance between PEG and water, emphasizing the roles of temperature, conformation, and vibrational dynamics.

Findings

Temperature significantly influences thermal conductance.

Chain conformation affects interfacial heat transfer.

Vibrational coupling has minimal impact on conductance.

Abstract

Understanding interfacial heat transfer between polymers and water is crucial for the design of biomaterials, drug delivery platforms, and nanofluidic systems. In this study, we employed all atom molecular dynamics (MD) simulations to quantify the interfacial thermal conductance between a polyethylene glycol (PEG) 36mer chain and explicit water over the temperature range of 280-350 K. To compare the conformational behavior of the PEG chain, we examined its radius of gyration and observed a temperature dependent chain collapse consistent with previous coarse grained models. By employing a transient non equilibrium MD approach, we imposed temperature difference across the interface and analyzed the energy relaxation behavior to compute heat transfer across the polymer water interfaces. Our results demonstrate that both temperature and interfacial interaction strength influence interfacial thermal conductance, with temperature playing the dominant role. Structural factors such as chain conformation and interfacial area were found to mediate the effect of interfacial interaction. Additional analysis of the vibrational density of states (VDOS) and the mean square displacement (MSD) reveal that vibrational coupling has minimal impact on thermal conductance across interfaces, whereas increased water thermal motion enhances energy transfer. These findings highlight the structural and dynamical origins of interfacial thermal conductance and provide atomistic insights into the tuning of interfacial heat transport in molecular systems through temperature and solvent interactions.