This article is a modified version of an article written by Mick Kulikowski, Director of Strategic Communications and Media Relations in University Communications.
Professor Orlin Velev and his research group have developed unique materials with distinct properties akin to those of gecko feet; the ability to stick to just about any surface.
The materials are created by harnessing liquid-driven microfabrication to produce soft polymer microparticles with hierarchical branching on the micro- and nanoscale, as described in an article in Nature Materials, “Soft dendritic microparticles with unusual adhesion and structuring properties”. Former CBE Ph.D. student Dr. Sangchul Roh is a co-inventor of the nanofabrication process and first author of the paper, which is also co-authored by graduate students Austin Williams and Rachel Bang, who are continuing the investigation of the new material’s formation and applications.
The soft dendritic particle materials with unique adhesive and structure-building properties hold the potential for advances in gels, pastes, foods, nonwovens and coatings, among other formulations. They can be created from a variety of polymers precipitated from solutions under special conditions, says Prof. Velev, the S. Frank and Doris Culberson Distinguished Professor of Chemical and Biomolecular Engineering and corresponding author of the paper.
“We use ‘liquid’ nanomanufacturing to convert most polymers into branched particles after dissolving the polymer and mixing the solution rapidly with another liquid,” he said. “This rapid mixing in turbulent flow creates branched particles organized in a hierarchical way.”
The thinnest branches surrounding these particles form a corona of nanofibers, Velev added, that distribute their stickiness by molecular forces of attraction known as van der Waals forces. See a 3-D video of the particles here.
The new material is unique not only in its structure, but also in the way it’s fabricated.
“The use of turbulent flow is ordinarily not known as a way to fabricate organized structures,” Bang said. “Here, we are using this inherently chaotic process to create hierarchical structures.”
The liquid process used to create these materials works with many types of polymers and is generally efficient and inexpensive. Williams added that the fabrication process can be easily scaled up to produce large amounts of the soft nanomaterial, which is often a challenge for making materials at the micro- and nanoscale.
Future research by Williams and Bang will seek to detail the fundamentals behind this surprising finding. Research will also examine the different types of polymer and biopolymer materials that can be created using the process, including coatings and sheets that attract or repel water, for example, or cell scaffolds and 3-D printing pastes. NC State has filed a patent on the new soft dendritic materials and the process for creating them.
“This work is an illustration of how fundamental and applied science can work synergistically,” said Dr. Simeon Stoyanov, a research collaborator and co-author of the paper. “We started with fundamental scientific findings and while investigating them we found many new applications such as super-adhesives and coatings, which in turn brought new fundamental questions regarding their properties.”
The research is funded by the National Science Foundation under grants CMMI-1825476, CBET-1604116 and by NC State’s Chancellor’s Innovation Fund.