Professor Ali DhinojwalaThe PhysOrg article Nanotube adhesive sticks better than a gecko’s foot said
Mimicking the agile gecko, with its uncanny ability to run up walls and across ceilings, has long been a goal of materials scientists. Researchers at Rensselaer Polytechnic Institute and the University of Akron have taken one sticky step in the right direction, creating synthetic “gecko tape” with four times the sticking power of the real thing.
“Geckos inspired us to develop a synthetic gecko tape unlike any you’ll find in a hardware store,” Ali Dhinojwala says. “Synthetic gecko tape uses ‘van der Waals interactions’ the same interactions that hold liquids and solids together to stick to a variety of surfaces without using sticky glues.”
The material could have a number of applications, including feet for wall-climbing robots; a dry, reversible adhesive in electronic devices; and outer space, where most adhesives don’t work because of the vacuum.
Ali Dhinojwala, Ph.D. is H.A. Morton Professor,
Department of Polymer Science, University of Akron, USA.
His research focus is broadly divided into three main areas.
The first area is focused toward developing a fundamental understanding of the structure and dynamics of molecules at surfaces and interfaces. Although he has several sophisticated tools available (for examples, NMR, IR, and x-ray) to study properties of polymers in the bulk, the techniques to study polymeric surfaces and interfaces are limited.
Surface properties of polymers play an important role in our understanding of friction, adhesion, wetting, and interfacial tension. He has developed infrared-visible sum-frequency-generation spectroscopy (SFG) techniques to study polymeric surfaces and interfaces. The goal of this research is to couple SFG and mechanics to directly relate macroscopic properties such as adhesion and friction with structure and dynamics of interfacial molecules.
Second, his group builds on the fundamental concepts of surfaces and interfaces to design new materials inspired by nature. In the last six years, he made rapid progress in designing synthetic carbon nanotube-based adhesive tapes inspired by geckos (in collaboration with Professor Ajayan group at Rice). These synthetic tapes stick to surfaces using van der Waals interactions (without any viscoelastic glue) with a shear resistance which is almost four times stickier than a gecko’s foot. Due to the hairy structure of carbon nanotubes, these tapes exhibit lotus-like effects and water slides off these surfaces. Also, it keeps them clean from any dust or contamination.
In addition, his research is also part of the integrated bioscience program at the University of Akron. In close collaboration with faculty members in the IB program, he works with live animals such as geckos and spiders to understand how to utilize natural materials. This research helps him in designing and developing more efficient and environment-friendly materials based on natural materials.
Ali coauthored Sticky Gecko Feet The Role of Temperature and Humidity, Comment on How Water Meets a Hydrophobic Surface, Partial Crystallinity in Alkyl Side Chain Polymers Dictates Surface Freezing, Gecko-Inspired Carbon Nanotube-Based Self-Cleaning Adhesives, Carbon Nanotube-Based Synthetic Gecko Tapes, Dynamic Interfacial Tension at the Oil/Surfactant-Water Interface, Origin of Higher Friction for Elastomers Sliding on Glassy Polymers, Coupling of Interfacial Motion at Polystyrene-Alkane Interface, and Surface Segregation Induced by Surface Freezing.
Ali earned his B.Tech in Chemical Engineering at the Indian Institute of Technology, Bombay, India in 1986 and his Ph.D. in Chemical Engineering at Northwestern University in 1994.
Read “Nano skins” show promise as flexible electronic devices and Sticky Nanotape.