Women in Nanoscience

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Women in Nano Blog

Transporting nanoparticles via tiny water droplets to make smooth thin films (Hua-Li Nie)

Posted on August 29, 2015 at 3:10 PM

Langmuir-Blodgett (LB) assembly is a widely used thin-film processing technique, that was discovered by Irving Langmuir and Katharine Blodgett at a GE Research laboratory in the 1930s. In LB assembly, floating thin-films are formed by spreading material in a volatile, water-immiscible solvent onto a water surface, which can be transferred to solid substrates for coating applications. This robust technique has been used for over 80 years largely unaltered, but there remains room for improvement in the large-scale production of thin films for new applications. For instance, there are challenges when using LB assembly to form thin-films of nanoparticles. Highly monodispersed systems of nanoparticles are required, and some organic solvents can damage the nanoparticles, leading to thin-films with poor quality. Some of these organic solvents are toxic and harmful to the environment.


 

Dr. Hua-Li Nie, an associate professor of chemistry, chemical engineering, and biotechnology at Donghua University (China) recently demonstrated a new technique that addresses these issues. While working as a visiting scientist at the Huang Group at Northwestern University, she used a water-miscible solvent with an electrospray to produce high-quality thin films of nanoparticles. In conventional LB techniques, a water-miscible solvent cannot be used because its mixing with water will sink the nanoparticles. Using an electrospray solved this problem by breaking the solvent into millions of smaller droplets that contain nanoparticles. Just like tiny micron water droplets suspended in the atmosphere, these small droplets gently hit the water surface and quickly evaporate, only leaving a thin-film of nanoparticles on the water surface. This improved LB assembly technique seems to promise significant economic benefit for large-scale production of thin films, not to mention a reduced need for using toxic organic solvents.


 

Dr. Nie's research focuses on studying self-assembly and applications of peptide-based nanostructures and biomedical materials, and utilizing electrospinning and electrospraying for synthesizing new materials. She received 2015 Technological Leading Talent in Jiangsu Province in China, and 2010 Outstanding Young Teacher in Shanghai, China.


- Written by Eugene Choi, Edited by Paulette Clancy


(Photo credit: Provided by and used with permission from Dr. Nie).

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