[Paper Review] Click Metamaterials: Fast Acquisition of Thermal Conductivity and Functionality Diversities

Chengmeng Wang, Peng Jin+3 more|arXiv (Cornell University)|Aug 30, 2023

Thermal properties of materialsMaterials Science3 citations

TL;DR

This paper introduces 'click metamaterials'—a universal design paradigm that enables fast, reconfigurable thermal conductivity and adaptive functionalities using tunable hollow-filled unit cells (THFCs). By structuring these THFCs to mimic click chemistry's modular building blocks, the authors achieve isotropic-to-anisotropic thermal conductivity conversion without refabrication, demonstrated experimentally via an adaptive thermal cloak that maintains performance across varying environmental backgrounds.

ABSTRACT

Material science is an important foundation of modern society development, covering significant areas like chemosynthesis and metamaterials. Click chemistry provides a simple and efficient paradigm for achieving molecular diversity by incorporating modified building blocks into compounds. In contrast, most metamaterial designs are still case by case due to lacking a fundamental mechanism for achieving reconfigurable thermal conductivities, largely hindering design flexibility and functional diversity. Here, we propose a universal concept of click metamaterials for fast realizing various thermal conductivities and functionalities. Tunable hollow-filled unit cells are constructed to mimic the modified building blocks in click chemistry. Different hollow-filled arrays can generate convertible thermal conductivities from isotropy to anisotropy, allowing click metamaterials to exhibit adaptive thermal functionalities. The straightforward structures enable full-parameter regulation and simplify engineering preparation, making click metamaterials a promising candidate for practical use in other diffusion and wave systems.

Motivation & Objective

• Address the lack of a general design mechanism for reconfigurable thermal conductivities in metamaterials.
• Overcome the case-by-case fabrication limitation of traditional thermal metamaterials.
• Enable functional diversity and design flexibility through a modular, scalable approach inspired by click chemistry.
• Develop a platform for fast acquisition of thermal conductivity and functionality variations using natural materials.
• Demonstrate practical adaptability through experimental validation of an adaptive thermal cloak.

Proposed method

• Propose tunable hollow-filled cells (THFCs) as structural analogs to modified building blocks in click chemistry.
• Design a click metashell composed of THFCs to enable full-parameter regulation of thermal conductivity.
• Use finite-element simulations and experimental validation to test thermal performance under varying background conditions.
• Implement a modular arrangement of THFCs (e.g., 2×2 arrays) to achieve adjustable anisotropic thermal conductivity without refabrication.
• Apply the method to fabricate an adaptive thermal cloak that maintains isothermal behavior regardless of background component changes.
• Employ infrared thermography and temperature measurements to validate experimental results against simulations.

Experimental results

Research questions

• RQ1 Can a universal design paradigm be established to enable fast, reconfigurable thermal conductivity in metamaterials?
• RQ2 How can a limited set of structural units generate diverse thermal functionalities without full device re-fabrication?
• RQ3 To what extent can thermal anisotropy be tuned using modular, reconfigurable unit cells?
• RQ4 Can a thermal cloak maintain its functionality across different environmental thermal backgrounds using this approach?
• RQ5 What is the role of interfacial thermal resistance in the performance of such modular metamaterials?

Key findings

• The click metamaterial platform enables conversion of thermal conductivity from isotropic to anisotropic through structural tuning of THFCs, without requiring new fabrication.
• An adaptive thermal cloak composed of the click metashell successfully maintains isothermal behavior in the center region under three different background components, with measured temperatures of 24.2 °C, 24.6 °C, and 22 °C, respectively.
• Experimental temperature distributions closely match finite-element simulations, validating the design’s effectiveness and adaptability.
• The interfacial thermal resistance between concentric annuli is negligible due to optimized mechanical contact and material compatibility, allowing reliable performance at macro-scale.
• The method supports switchable functionalities by modifying the structure of expanded THFCs, demonstrating design flexibility and reconfigurability.
• The approach is generalizable to other diffusion and wave systems, including optics, acoustics, and electromagnetism, due to its modular and tunable nature.