Meet the Lab: Renato Maraula

Friction is a familiar force.

We all have a general understanding what friction is-- whether is be the metaphorical friction we feel when a coworker is being difficult or the literal kinetic friction we feel when trying to push said coworker out of our office (or at least we can imagine...)

But what exactly is friction?

Despite his warm and friendly disposition, Renato Maraula is someone who is actually very familiar with friction. He places his palms atop one another and slides them back and forth as he explains, "the science of friction is everything that is between two bodies that move against each other". 

Thankfully Renato's familiarity with friction comes from a scientific perspective because here at CPI he is researching friction-- or to be a bit more exact-- how to reduce it.

Why reduce friction?

Friction is a naturally occurring phenomena, "if we want to move something, then we need to spend energy and this energy, of course, has a cost. Spending energy also means the releasing of carbon dioxide  into the atmosphere. So basically we want to reduce friction because if we reduce friction we also reduce costs and energy".    

Scientists have already figured out a solution for this query by using oil lubricants to reduce friction. While effective, it is not the most environmentally friendly material. Water however, has a low environmental impact and better yet, we already have a great example which proves that water can serve as an effective lubricant. 

"If we think about our bones in our knee, we have two bones- one below and one above- between these two bones there is a cavity and this cavity is filled with a liquid called synovial fluid which is basically water and other biomolecules. This fluid is the reason we have low friction between these two bones". 

Taking the knee as partial inspiration, Renato works to create and optimize hydrogels, which are materials that can incorporate water. These hydrogels then act as water-based lubricants to reduce friction. 

Renato presents his AFM cantilevers which he uses to test the properties of the hydrogel. 

While the logic of 'it works in our body, so it can work outside our body' is intoxicatingly simple, the reality is that this presents quite a challenge. 

"These materials, hydrogels, are very, very soft, so if you want to use one in a high pressure application, they can break easily. So the challenge is to produce a material with low friction, which means high lubrication, but also to understand which pressure is critical for these materials and prevent any rupture...". 

Hitting the breaks on surface topography 

What makes this venture even more challenging is that besides working with surface chemistry of the material (which is basically the water-based lubricants) this material has other parameters to work with: surface topography and microstructure.  

The structure of the surface of the material can affect how and when a hydrogel will exhibit high or low friction. To better understand this concept, Renato presents an everyday example of a situation where we might need a material to perform both high and low friction: a car tire.

 "If you want to stop the car because you see something dangerous, you have to immediately increase the friction. But, of course, when you want to run your car easily, and not spend too much energy or oil, you also need low friction between the wheels and the street. So, basically this rubber has to have an optimum value of friction". 

A car must have this optimal value of friction to allow for stopping and gliding, however Renato's aim is to create a material with a bit of a different functionality. Rather he wants to develop a hydrogel that depending on the application, can exhibit either high or low friction.

Renato takes to paper and pen to visually show the surface topography which allows his hydrogel to exhibit both high and low friction depending on the application. 

While Renato busies himself daily at work with friction, thankfully it is only in the scientific sense. In terms of working at CPI, Renato relishes in the opportunity to work with people from all over the world. 

"In Napoli (Renato's home city) you just talk to Neapolitan people and it's boring after a while. Here you can find a little bit of everything and this is really nice". 

To learn more about Renato's research, read more here: Synovial joint as a model for the development of super-lubricated surface-attached hydrogels