Crystalline polymer nanofibers with ultra-high strength and thermal conductivity

Abstract

Polymers are widely used in daily life, but exhibit low strength and low thermal conductivity as compared to most structural materials. In this work, we develop crystalline polymer nanofibers that exhibit a superb combination of ultra-high strength (11 GPa) and thermal conductivity, exceeding any existing soft materials. Specifically, we demonstrate unique low-dimensionality phonon physics for thermal transport in the nanofibers by measuring their thermal conductivity in a broad temperature range from 20 to 320 K, where the thermal conductivity increases with increasing temperature following an unusual ~T1 trend below 100 K and eventually peaks around 130–150 K reaching a metal-like value of 90 W m−1 K−1, and then decays as 1/T. The polymer nanofibers are purely electrically insulating and bio-compatible. Combined with their remarkable lightweight-thermal-mechanical concurrent functionality, unique applications in electronics and biology emerge.

Light-triggered thermal conductivity switching in azobenzene polymers

“…The thermal conductivity reversibly switches between 0.35 ± 0.05 W m −1 K −1 in transazopolymer to 0.10 ± 0.02 W m −1 K −1 in cis-azopolymer. These values are within the values expected for polymers: for example, the thermal conductivity of polyethylene varies from 0.1 W m −1 K −1 , when randomly oriented to 90 W m −1 K −1 along the draw direction of a highly oriented crystalline fiber (26,27). , which is the rate to achieve 90% of the total thermal conductivity change, increases from 0.016 to 0.126 s −1 as the UV light intensity increases from 38 to 630 mW cm −2 (Fig.…”

Nanocelluloses and Related Materials Applicable in Thermal Management of Electronic Devices: A Review

“…Recent experiments show that polymers can be eminent thermal conductors when the polymer chains are straight and aligned in crystalline fiber forms. Ultra-drawn polyethylene nanofibers were found to have thermal conductivity up to 100 W·m −1 ·K −1 [33][34][35][36] and the value is three orders of magnitude greater than that of their amorphous counterpart. Organic polymer chains exhibit another unique property.…”

A Multidirectional Superelastic Organic Crystal by Versatile Ferroelastical Manipulation

“…Relationships between functions and structures can be studied at the atomic/molecular level by X‐ray crystallographic studies as a result of their highly ordered three‐dimensional structures. An increase in the crystallinity and anisotropy improves the functions of solids, as demonstrated in crystalline polymers . Functions and anisotropic characters are further enhanced in single crystals, even though they have a specific morphology and a low ability to undergo reshaping.…”