Unique adhesive formed from liquid-driven chaos

Materials with properties like those found in gecko feet have been created by harnessing so-called liquid-driven chaos to produce soft polymer microparticles.

liquid chaos
Branched, sticky particles are the result of harnessing liquid chaos (Image: Orlin Velev, NC State University)

The findings from North Carolina State University could lead to advances in gels, pastes, foods, or non-woven sheets and coatings. Their results are described in Nature Materials.

Adhesive material mimics the way geckos stick to surfaces

Gecko footpad inspires adhesive materials

The soft dendritic particle materials with unique adhesive and structure-building properties can be created from a variety of polymers precipitated from solutions under special conditions, said Orlin Velev, S. Frank and Doris Culberson Distinguished Professor of Chemical and Biomolecular Engineering at NC State 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 in a statement. “This rapid mixing in turbulent flow creates branched particles organised in a hierarchical way.”

Velez said the thinnest branches surrounding these particles form a corona of nanofibres that distribute their stickiness via van der Waals forces.

The university added that fabrication of the new material is as unique as its structure.

“The use of turbulent flow is ordinarily not known as a way to fabricate organised structures,” Velev said. “Here, we are using this inherently chaotic process to create hierarchical structures.”

The liquid process used to create these materials is said to work with many polymers and is generally efficient and inexpensive. Velev 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 in Velev’s lab 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, or cell scaffolds and 3D 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 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.”