Session: Government Agency Student Posters

Paper Number: 173938

How Do We Sled? 

The increasing demand for high-performance materials that balance environmental sustainability and cost-effectiveness makes microscale coatings and thin films relatively desirable. One reliable method of creating these coatings and films is electrospray deposition (ESD). ESD is a manufacturing process in which a high voltage is applied to a flowing solution. Through the interactions between electrostatic forces and surface tension, the solution atomizes at the end of the capillary, dissipating monodisperse, charged microdroplets towards a grounded substrate where the solvent evaporates and the solid payload remains. This process allows for the fabrication of thin surface coatings for various applications.

The process can be modified to a thickness-limited regime known as self-limiting electrospray deposition (SLED). To satisfy the criteria for SLED, the solvent material must be insulating and below its glass transition temperature. Additionally, the substrate must be conductive. Rather than accumulating in a single spot, new droplets are redirected to uncoated regions of the substrate, thus capable of coating a larger surface area and achieving near-uniform thickness. In addition, the repulsion of these charged droplets from one another allows for the coating of 3D objects or other small, intricate geometries. However, despite these advantages, not all materials innately exhibit the ability to be self-limiting. As a result, the aim of this work was to create blends of nonSLED materials such that the material characteristics could be manipulated to achieve the aforementioned criteria for SLED (e.g., increasing the glass transition temperature). First, we identified the reason for the SLED criteria as the presence of a charge mobile phase, and then categorized nonSLED materials into one of several behaviors. This included grouping sprays of particle dispersions and strong crystal formers into a “charged tower” topographic group that arises, we believe, from electrocondensation of spray solvent vapor in the narrow channels formed in these fractal morphologies. This condensed solvent prevents charge buildup in these structures. Armed with this understanding, we identified pathways to compatibilize nonSLED materials with SLED through (1) complexing, (2) confinement, or (3) combinations of both of these effects.

Through this approach, we can incorporate a much wider array of nanoparticulate and small molecule functionality into conformal coatings, including (i) bioactive vaccine or drug, (ii) catalytic, or (iii) electrically conductive coatings. Here we will highlight two examples complexes of DNA and sugar that allow for coated microneedle array vaccination and (ii) toughened mechanical composites created from the addition of nanofillers to two-part epoxy resins. 

Presenting Author: Shubin Xie Rutgers University

Presenting Author Biography: Shubin earned a Bachelor's degree in Mechanical Engineering from Rutgers University and is currently pursuing a Master's degree in Materials Science and Engineering, also at Rutgers. Under the guidance of Dr. Singer, Shubin is conducting research focused on nanomaterials.

Authors:

Shubin Xie Rutgers University
Jouan Yu Rutgers University
Nasir Amiri University at Buffalo
Isha Shah Rutgers University
Jennifer Zarny Rutgers University
Xin Yong University at Buffalo
Jonathan Singer Rutgers University