Chemically and thermally robust fiber mats, capable of carrying “cargo” such as small molecule compounds, hold tremendous potential for applications in which green materials are imperative, such as wound healing, water remediation, catalysis, and food packaging. The catch is that the manufacturing process for such mats traditionally depends on toxic solvents and/or cytotoxic crosslinking agents. In order to produce environmentally friendly fiber mats, Professors Jessica Schiffman and Sarah Perry of our Chemical Engineering Department have received a three-year, $338,180 grant from the National Science Foundation (NSF) Materials Engineering and Processing Program. See NSF award announcement
Schiffman is the principal investigator, while Perry is the co-principal investigator for their new NSF project, titled “Electrospinning Nanofiber Mats from Aqueous Polyelectrolyte Solutions.”
The NSF award supports fundamental research into the development of chemically robust, nanofiber mats produced in a green, environmentally clean way. The new aqueous, precursor, polyelectrolyte solutions employed in the process will use salt to enable the preparation of thermally and chemically robust fibers without the use of toxic solvents, crosslinkers, or post-processing.
This research will coordinate the processing, structure, and properties of aqueous polyelectrolyte solutions “electrospun” into chemically robust fiber mats. Electrospinning is a fiber-production technique that uses electric forces to draw or pull polymer solutions into solid fibers whose diameters are on the order of nanometers.
As Schiffman and Perry write in their NSF abstract, “Electrospinning is a well-established technique used to manufacture non-woven fiber mats comprised of nano- and micro-scale diameter fibers. Due to their high porosity and surface area, the fiber mats are promising materials for medical, environmental, and energy applications.”
The problem, as Schiffman and Perry explain, is that, while mats have been electrospun from more than 100 different polymers, the full application potential of electrospun, non-woven, polyelectrolyte, fiber mats cannot currently be realized because the manufacturing process utilizes toxic solvents in the precursor electrospinning solution and/or poisonous molecules post-production to make the mats chemically robust.
The NSF research of Schiffman and Perry will address this issue by developing a clean new method. “Using green chemistry to manufacture polyelectrolyte nanofiber mats, which can encapsulate cargo such as small molecule compounds, will broadly impact the design of multifunctional fiber scaffolds for a broad range of applications, including wound healing and active food packaging. The U.S. economy and society will benefit from the production of safer materials as enabled by this research.”
The researchers’ proposal explains how Schiffman and Perry will carry out this kind of green chemistry during their NSF project. “Electrospinning precursor solutions will be comprised of complex coacervates, which are dense, polyelectrolyte-rich liquids that result from the electrostatic complexation of oppositely-charged polymers in water.”
The research team will establish parametric design rules for the electrospinning of polyelectrolyte fibers by correlating electrospinning with thermodynamic phase behavior and the rheological properties of a model coacervate system. Additionally, the researchers say, the partitioning and loading of hydrophilic and hydrophobic cargo into the precursor solutions and electrospun fibers will be established as a function of the hydrophobicity of the polyelectrolytes and the cargo.
In addition to accomplishing the above technical achievements, this research will also educate, mentor, and provide research experiences for a diverse workforce at the emerging interface of chemical engineering, fiber science, and polymer physics. In particular, the research will result in numerous new research experiences and an enhanced engineering education for women and underrepresented groups. (July 2017)