Congratulations to Chris on his successful PhD defense “Tribological properties of gradient-density hydrogel surfaces”

Hydrated gels are very slippery, and we now know it’s partly due to their surfaces! Chris made composite hydrogels with a soft surface skin, then fully characterized the effective stiffness of that layer, contact mechanics, and how it contributes to good lubrication (or not!) He did an impressively-large number of experiments involving materials synthesis, careful […]

New paper out: “Cartilage-like tribological performance of charged double network hydrogels”

While we normally work with single-polymer hydrogels, we had the opportunity to work with the Grunlan group at Texas A&M to study their charged double-network hydrogels. These hydrogels are tough! Looking more like cartilage all the time. In this paper we present evidence that their lubrication behavior matches or exceeds that of native cartilage. Higher […]

New paper out: “Compositional Dependence of Polyacrylamide Hydrogel Abrasive Wear Resistance”

Many researchers are aware that hydrogels, even a single kind of hydrogel (polyacrylamide) can be designed to have properties that range from brittle to viscoelastic. It’s truly a versatile material! As hydrogels are being considered as replacements for cartilage in the body, they need to be able to take a beating: they can’t break under […]

Congratulations to Shab on her successful PhD defense on Friday! “Wear mechanisms of chemically crosslinked hydrogels under mild abrasion”

Hydrogels are the next “engineering material” that we need new textbooks for, to teach the next generation of engineers to design with them. Shabnam’s work contributes directly to that, and over the past 4 years she has discovered that the material nature of the hydrogel determines how it wears away — sometimes it acts brittle, […]

New paper: “Similarity of internal and external friction: Soft matter frictional instabilities obey mean field dissipation through slip avalanches”

We usually think of hydrogels as slippery and wet — that’s their definition! But if a probe pushes on them to a higher pressure before applying lateral slip, that high pressure causes unstable friction, or stick-slip (just like the elastomer in our prior post!). So even inherently low-friction materials relieve interfacial strain in extreme ways. […]

New Paper: “Precise Correlation of Contact Area and Forces in the Unstable Friction between a Rough Fluoroelastomer Surface and Borosilicate Glass”

Last year I had the privilege of hosting the now Dr. Chao Wang in my lab to use our optical in situ microtribometer to study the stick-slip behavior of seal elastomers. He obtained a supporting fellowship from the Austrian Marshall Plan Foundation, and used this work toward his PhD in Polymer Tribology from Montanuniversit√§t Leoben. […]