Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 99464

99464 - Advanced In-Situ Fabrication of Nanofibers via a Modified Wet Electrospinning Method to Yield Polymer-Ceramic Nanocomposites 

Nanofiber-reinforced composites have provided tremendous opportunities in advanced engineering material design. However, the manufacturing of nanofiber-reinforced composites commonly features sequential synthesis steps and poor control over the fiber morphology. Our research focuses on developing an innovative fabrication approach for nanofiber-reinforced composites with the capability of in-situ generation and integration of nanofibers, as well as the potential for controlling the morphology and distribution of the nanofibers.

This project develops a highly efficient and low-cost manufacturing method for producing nanofiber-reinforced polymer ceramic composites based on a modified wet electrospinning process. This process uses high voltage to draw a charged jet of polymer solution or polymer melt into fibers with diameters ranging from nanometer scale to micrometer scale and the fibers are directly infused into a liquid bath collector consisting of a reactive ceramic precursor gel. The liquid gel and fiber mixture is then combined with other reactive phases in the synthesis of ceramic matrix and results in an nanofiber-reinforced ceramic composite upon curing. Consequently, the adoption of a liquid gel as the collector during electrospinning enables the direct integration of nanofibers in an inorganic ceramic matrix at the same time when they are generated. Meanwhile, it facilitates the uniform distribution of nanofibers within the ceramic composite. The proposed method will significantly reduce the time and effort required in the conventional composite manufacturing process.

We demonstrated the viability of our method by fabricating a 0.5 wt% electrospun Polyethylene oxide (PEO) fiber-reinforced geopolymer composite. We performed microstructural and mechanical characterization of the geopolymer nanocomposite through scanning electron microscopy and micro-indentation tests, respectively. The fabricated fiber-reinforced polymer ceramic composite exhibited a random distribution of the PEO fibers with individual fibers well blended in the matrix, suggesting great bonding between the electrospun fiber and the ceramic matrix. The micro-indentation tests revealed that 0.5 wt% electrospun PEO fibers are sufficient to yield a substantial increase of 29% and 22% in the indentation modulus and indentation hardness, respectively. This enhancement can be attributed to the fact that electrospun PEO fibers served as both a catalyst during the ceramic precursor gel reaction due to their high surface area and a toughening phase of the ceramic composite through fracture micro-mechanisms such as crack-bridging.

Our proposed approach allows in-situ fabrication of nanofibers and incorporates nanofiber production in the process of ceramic synthesis. It will lead to a potentially scalable manufacturing approach for nanofiber-reinforced organic-inorganic composites. This method also grants larger control of the morphology and distribution of nanofibers through tuning the process parameters of electrospinning, therefore, providing significant potential in multifunctional and architected nanocomposite design.

Presenting Author: Yunzhi Xu Northwestern University

Presenting Author Biography: Yunzhi Xu is in her third year of Ph.D. studies in the lab of Dr. Akono at Northwestern University in Evanston, Illinois, where the main research focus is investigation of fracture at the nanoscale in complex material systems. Yunzhi's research focuses on the design and manufacturing of nanofiber-reinforced ceramic composites based on the electrospinning method, from controlling the distribution of nanofibers through characterization of material behavior at the nanoscale, to accelerate the discovery of organic-inorganic nanocomposites with enhanced physical and mechanical properties.

Authors:

Yunzhi Xu Northwestern University
Ping Guo Northwestern University
Ange-Therese Akono Northwestern University