“We determined this unique nanostructure sample is suitable for optical applications, such as eyeglasses, as it has high transparency and anti-reflective properties”Nguyen Ba Duc
Research by scientists in Vietnam has demonstrated an effective approach to de-icing. They showed a new nanostructure surface that displays greatly improved anti-icing performance that benefits from combining both water repellency and its heat-delaying structure. In exploring the potential of using unique nanostructures covered with a paraffin layer that was modeled on moth eyes, Nguyen Ba Duc from Tan Trao University and Nguyen Thanh Binh from Thai Nguyen University of Education were able to demonstrate anti-icing and anti-reflective properties that could lead to solutions for the problem of ice accumulation on aircraft wings and energy transmission systems, vehicles, and ships in harsh environments, helping prevent serious accidents.
As reported in the paper ‘Investigate on structure for transparent anti-icing surfaces’, which appeared in the journal AIP Advances [Ba Duc, N. and Thanh Binh, N. AIP Advances (2020) DOI: 10.1063/5.0019119], the pair produced the moth eye nanostructure from a substrate of quartz covered with a flat paraffin layer that isolates it from the surrounding environment, regardless of whether it is cold and humid. Moth eyes have a distinct ice-phobic and transparent surface. They used paraffin wax for their coating material because of its low thermal conductivity and ease of coating, as well as it water repellency.
As ice accumulation on aircraft wings works to reduce lifting force and constrain moving parts, while ice accretion on energy transmission systems and vehicles can lead to major problems, much research has gone into improving the anti-icing performance on functional surfaces. To that effect, the team were able to assess the anti-icing properties of their paraffin-covered nanostructure in terms of adhesion strength, freezing time and mimicking rain sustainability.
The paraffin was shown to successfully interfere in the icing process in both water droplets and freezing rain experiments, while the amount of air blocks trapped in the nanostructure also managed to delay heat transfer, leading to an increase in freezing time of the attached water droplets.
Their findings were compared with bare quartz coated paraffin, superhydrophobic nanostructure surfaces, demonstrating outstanding anti-icing performance. The contribution of the paraffin layer and air block combined with the nanostructure was explained as the important criteria for maintaining stable adhesion strength and extending freezing time.
In addition, the high transparency and anti-reflective effects shown also indicate potential for use in practical optical applications. As Ba Duc said, “We also determined this unique nanostructure sample is suitable for optical applications, such as eyeglasses, as it has high transparency and anti-reflective properties”.
Ice accumulation on a bare coated, nanostructure (NS) and nanostructure covered in paraffin (NSP) samples after a freezing test (Credit: Nguyen Ba Duc)