A team of Florida State University researchers has discovered a way to use low-energy light to manipulate photopolymer or plastic film – a discovery that has implications for a range of technologies that use light as an energy source to create shape-changing structures.
Researchers have discovered a way to use low-energy light to manipulate photopolymers or plastic films. Image credit: FSU
The study was published in the journal Applied polymeric materials ACS and is the joint work of Associate Professors of Chemistry and Biochemistry Ken Hanson and Justin Kennemur and Professor William Oates of FAMU-FSU College of Engineering.
“The idea was that we wanted to harness low-energy light and generate mechanical force as efficiently as possible,” says Hanson.
Researchers worldwide have been studying materials that respond to external stimuli such as light, temperature, magnetic fields or electricity. These stimuli can cause a material to change its shape, molecular arrangement or mechanical properties and have been used in robotics research, aerospace engineering, drug delivery and Moreover.
The FSU research team is particularly interested in lighting response systems for mechanical work, an area that is less well studied.
From L: FAMU-FSU, William Oates College of Engineering Professor, graduate student Grace McLeod, graduate student Gina Guillory, Associate Professor of Chemistry Ken Hanson and Associate Professor of Chemistry Justin Kennemur. Image credit: FSU
To date, research in that area has shown that converting light for this purpose is generally not energy efficient and requires high-energy light to have significant results. Hanson, Kennemur and Oates felt that their combined expertise – Hanson as an expert in solar cells, Kennemur in polymer synthesis and Oates in characterization and modeling of materials – could be help them develop a new approach.
Finally, their research team collaborated on a new process that effectively captures low-energy light and uses it to bend plastic films the thickness of Scotch™ tape.
“Many polymers have stability limitations that lead to slow decomposition when exposed to high-energy ultraviolet light,” Kennemur said. “Using lower-energy visible light is a great way to solve this problem.”
The FSU team experimented with a photopolymer based on the chemical compound stilbene. Stilbene itself has limited applications, but it can be used to produce dyes, optical brighteners or dye lasers. Hanson, Kennemur, and Oates applied a mechanism called a tripartite sensitizer to the polymer that allows it to absorb low-energy light and convert it into high-energy mechanics.
When the team shined low light on plastic films made of stilbene, they found the films were bent in response to the energy transfer.
“It is remarkable that for the first time, low-energy photons can manipulate stilbene to precisely control the shape of a polymer using polarized light,” says Oates.
With this proof of concept, the researchers plan to improve this process further in the future using a variety of polymeric structures, light-absorbing nanostructures, and advanced modeling tools.
Source: Florida State University
