Aerogels are lightweight materials with large microscopic pores, which can be used in thermal insulation, energy devices, aerospace structures, and flexible electronic technologies. However, traditional ceramic-based aerogels are soft, which limits their performance in load-bearing materials. Due to the limitations imposed by their composition, a class of polymeric aerogels developed (Drug-resistant aerogels) recently can achieve high performance by lowering their porosity or their weight characteristics.
A study by Dr. Lizhi Xu and Dr. Yuan Lin from the Department of Mechanical Engineering, Faculty of Engineering, University of Hong Kong (HKU), has developed a new type of polymer aerogel material in a large variety of applications working tools.
In this study, a new type of aerogels was successfully created (Drug-resistant aerogels) using a network of self-assembling nanofibers including aramids, or Kevlar, a polymeric material used in armor and helmets. Instead of using millimeter-sized Kevlar fibers, the research team used a solution processing method to disperse aramids into nanoscale fibrils.
The interaction between nanofibers and polyvinyl alcohol, another soft and “gooey” polymer, created a 3D fibrillar network with high nodal connections and strong connections between nanofibers. “It’s like a microscopic 3D truss network, and we managed to weld the trusses together, resulting in a very strong and resilient material that can withstand significant mechanical loads, out performing other airgel materials,” said Dr. Xu.
The team also used detailed process simulations to describe the fine mechanical properties of the open aerogels. “We built a variety of 3D network models on the computer, which captured the important properties of nanofibrillar aerogels,” said Dr Lin, who led the scientific process for the research. “The nodal mechanics of fibrillar networks is important for all their functional behavior.
Our demonstration shows that the nodal connections and the bond strength between fibers affect the strength of the network by several orders of magnitude even at the same solid content, Dr. Lin said. “The results are very interesting.
“We have not only developed a new type of polymer aerogels with good functional properties, but also provided insight into the production of various nanofiber materials,” said Dr. Xu, adding, “The simple manufacturing process of aerogels these also allow for use in a variety of ways, tools, devices, such as wearable electronics, thermal stealth, filtration membranes and other techniques.
