Extreme Thermal Insulation in Nano-Bubble Wrap Materials

TL;DR

This paper introduces nano-bubble wrap architectures that significantly reduce thermal conductivity by combining nanoscale gas confinement with atomically thin materials, achieving near-zero heat transfer at room temperature.

Contribution

The study presents a scalable method to create ultra-low thermal conductivity nano-bubble materials using 2D monolayers and nano-patterning, surpassing existing thermal insulators.

Findings

Thermal conductivity below 0.001 W·m$^{-1}$·K$^{-1}$ at room temperature.

Out-of-plane thermal resistance nearly ten times lower than air and aerogels.

Suppression of gas conduction, phonon transport, and interfacial coupling.

Abstract

Achieving ultra-low thermal conductivity under ambient conditions is a fundamental challenge constrained by classical heat transport limits and material design trade-offs. Here, we introduce a new class of nano-bubble wrap architectures that achieve exceptionally low thermal conductivity by integrating nanoscale gas confinement with atomically thin, weakly coupled van der Waals solids. Using scalable patterning of 2D monolayers into periodic nano-bubbles and nano-wrinkles, we construct materials with structural analogies to macroscopic bubble wrap but engineered at length scales much shorter than the mean free path of air and the mean free path of phonons in the atomically thin monolayers. Time-domain thermoreflectance measurements reveal out-of-plane thermal conductivities nearly an order of magnitude lower than that of air and commercial aerogels, reaching critical values below 0.001 W $\cdot$ M$^{-1}$K$^{-1}$ under room temperature and atmospheric pressure. This extreme thermal resistance arises from the combined suppression of gas-phase conduction, phonon transport, and interfacial coupling. Our findings establish nano-bubble wraps as a versatile platform for tuning heat flow in ultrathin materials and open new pathways for designing thermal metamaterials and energy-efficient technologies.