Researchers from Virginia Tech synthesized porous carbon fibers with well-controlled mesopores and micropores
A team of researchers from Virginia Tech’s College of Science developed a process to synthesize porous carbon fibers with uniform size and spacing. The team designed, synthesized, and layer processed the polymers in the lab that were later developed into porous carbon fibers. The team used a multistep chemical process using two polymers of long, repeating chains of molecules, known as polyacrylonitrile (PAN) and poly(acrylonitrile-block-methyl methacrylate) (PMMA). PAN is used in the polymer chemistry field as a precursor compound to carbon fibers and PMMA is used as a place-holding material that is later removed to create the pores.
The team created new approach to bond PAN and PMMA to create a block copolymer. 50% of the compound polymer is PAN and the rest is PMMA and the bond is covalent. According to Guoliang ‘Greg’ Liu, an assistant professor in the Department of Chemistry, this is a leading example where block copolymers were used to make carbon fibers and block copolymer-based porous carbon fibers were used in energy storage. The team synthesized the block copolymer in the lab and the viscous solution later underwent three chemical processes to achieve porous carbon fibers.
The first process includes electrospinning—a method that relies on electric force to create fibrous strands and harden the solution into a paper-like material. In the second process, the team put the polymer through an oxidation heating process, in which the PAN and PMMA naturally separated and self-assembled into the strands of PAN. The domains of PMMA were also uniformly scattered in the process. The final step is known as pyrolysis, in which the team heated the polymer to an even higher temperature in order to solidified PAN into carbon. The process removed PMMA and offered interconnected mesopores and micropores throughout the fiber. The research was published in the journal Science Advances on February 1, 2019.