By marrying the inorganic with the organic and the rigid with the stretchable, UNL chemist Stephen Morin has begun crafting hybrid materials that could find use in technologies ranging from soft electronics to soft robotics.
Morin will expand his efforts to seamlessly combine hard and soft materials with the help of a five-year, $649,474 Faculty Early Career Development Program Award from the National Science Foundation. Known as CAREER awards, these prestigious grants support pre-tenure faculty who exemplify the role of teacher-scholar through outstanding research, excellent education and an integration of the two.
“If you look at a lot of emerging technologies, there’s this big push to combine the functionality of hard, inorganic structures with soft, organic structures,” said Morin, assistant professor of chemistry. “It’s that combination that gives (the resulting materials) a diversity of properties applicable to many technologies.”
To achieve this, Morin will continue exploring how best to deposit rigid films atop the surfaces of elastic polymers. The greatest challenge lies in the fact that the two classes of material have vastly different thermal and mechanical properties, he said.
Whereas inorganic materials are often synthesized at extremely high temperatures, organics have a much lower temperature threshold. Even more difficult: melding a material that has the brittleness of glass with one that has the elasticity of a rubber band. So far, Morin’s approaches have included applying droplets of chemical compounds that crystallize on soft polymers and bathing silicone rubbers in inorganic salts.
Morin is especially interested in how stretching a polymer can affect the formation and structure of the harder material that resides on its surface. In doing so, Morin has already managed to build adaptable patterns of microscopic crystals on rubber films and create elastic materials that become highly reflective when stretched.
“You can use mechanical deformation as a unique way of controlling processes on these soft surfaces,” he said. “If you’re talking about integrating hard materials with soft materials, it’d be powerful if we could get the hard material to nucleate directly on the soft material, yielding the most seamless and efficient synthetic process possible.
“There’s a lot of benefit from understanding how these materials can come together into one final structure or device. Really, that motivates a good amount of the research that this project is focused on.”
Morin’s lab further plans to study how soft, microscopic channels filled with flowing liquid solutions might be used to grow hybrid materials and structures. The flexibility of the channels, combined with the ability to control liquid transport within them, should allow the team to systematically identify which conditions are best suited for the task.
“So we’re synthesizing inorganic structures inside of these flowing liquids that are confined by these microchannels,” Morin said. “The hypothesis – and there’s a lot of evidence that it’s a good hypothesis – is that you can tune a lot of the parameters to control how an inorganic structure grows.”
Morin and his team will also use the NSF funding to develop an annual workshop for Nebraska’s Native youth, an underrepresented demographic in the fields of science, technology, engineering and mathematics.
The workshop will give students the opportunity to design soft robotic components – a gripper shaped like a starfish, for instance – that they build on site with a 3-D printer provided by the team. The students can then test their designs by using the grippers to pick up eggs or build towers from paper cups, Morin said.
“The basic idea is that a lot of the kinds of things that we do in my group are pretty accessible for middle school- and high school-aged students who are interested in science,” he said. “That’s sort of the vision: learning about the concepts, being able to actually implement them, and then, in the end, having a little bit of fun in testing the devices and seeing what happens. Kids love it. It’s very engaging.”