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ME researchers develop ultra-strong aerogels with materials used in bullet-proof vests

Aerogels are lightweight materials with extensive microscale pores, which could be used in thermal insulation, energy devices, aerospace structures, as well as emerging technologies of flexible electronics. However, traditional aerogels based on ceramics tend to be brittle, which limits their performance in load-bearing structures. Due to restrictions posed by their building blocks, recently developed classes of polymeric aerogels can only achieve high mechanical strength by sacrificing their structural porosity or lightweight characteristics.

A research team led by Dr Lizhi Xu and Dr Yuan Lin from the Department of Mechanical Engineering of the Faculty of Engineering of the University of Hong Kong (HKU), has developed a new type of polymer aerogel materials with vast applicational values for diverse functional devices.

In this study, a new type of aerogels was successfully created using a self-assembled nanofiber network involving aramids, or Kevlar, a polymer material used in bullet-proof vests and helmets. Instead of using millimetre-scale Kevlar fibres, the research team used a solution-processing method to disperse the aramids into nanoscale fibrils. The interactions between the nanofibers and polyvinyl alcohol, another soft and “gluey” polymer, generated a 3D fibrillar network with high nodal connectivity and strong bonding between the nanofibers. “It’s like a microscopic 3D truss network, and we managed to weld the trusses firmly together, resulting in a very strong and tough material that can withstand extensive mechanical loads, outperforming other aerogel materials,” said Dr Xu.

The team has also used theoretical simulations to explain the outstanding mechanical performance of the developed aerogels. “We constructed a variety of 3D network models in computer, which captured the essential characteristics of nanofibrillar aerogels,” said Dr Lin, who led the theoretical simulations of the research. “The nodal mechanics of fibrillar networks are essential to their overall mechanical behaviours. Our simulations revealed that the nodal connectivity and the bonding strength between the fibres influenced the mechanical strength of the network by many orders of magnitudes even with the same solid content,” said Dr Lin.

“The results are very exciting. We not only developed a new type of polymer aerogels with excellent mechanical properties but also provided insights for the design of various nanofibrous materials,” said Dr Xu, adding, “the simple fabrication processes for these aerogels also allow them to be used in various functional devices, such as wearable electronics, thermal stealth, filtration membranes, and other systems,”

The research was published in Nature Communications, in an article entitled “Ultrastrong and multifunctional aerogels with hyperconnective network of composite polymeric nanofibers”.

Link of the paper:




該新型氣凝膠材料製備方法簡易,具潛力開發應用於可穿戴器件、熱學隱身、濾膜結構以及其他多種新型功能器件中。研究結果已在《自然-通訊》刊登,文章題爲 ”Ultrastrong and multifunctional aerogels with hyperconnective network of composite polymeric nanofibers”。






Figure 1. a – Schematics of the assembly process of our composite nanofiber aerogels. 複合納米纖維氣凝膠的製造過程示意圖。

Figure 1. b - Scanning electron microscope image showing the micro-structure of the developed aerogel materials. 掃描電子顯微鏡所顯示氣凝膠的微觀結構。

Figure 1. c - The aerogel possesses desirable features such as lightweight, semi-transparent and high load bearing capability. 開發的氣凝膠具有輕質、半透明和高承載能力等理想特性。

Figure 1. d - Both high toughness and tensile modulus are achieved by our composite nanofiber aerogels, when compared to other polymeric aerogels. 與其他聚合物氣凝膠相比,我們的複合納米纖維氣凝膠具有高韌性和高拉伸模量。

Dr Lizhi Xu (Right) and Dr Yuan Lin (Left). 徐立之博士(右)和林原博士(左)。

Dr Lizhi Xu (Right) and Dr Yuan Lin (Left). 徐立之博士(右)和林原博士(左)。

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