10/26/2026
By Marley O'Neil

The Francis College of Engineering, Department of Plastics Engineering, invites you to attend a doctoral dissertation proposal defense by Florence Nkemamaka Acha titled "PFAS-free liquid-repellent textile finishes through chemistry and topography."

Details

  • Date: Friday, Nov. 6, 2026
  • Time: 9 – 11 a.m.
  • Location: Southwick 240

Committee members

  • Advisor: Joey Mead, Ph.D., professor, Plastics Engineering Department, UMass Lowell
  • Co-advisor: Jinde Zhang, Ph.D., assistant research professor, Plastics Engineering Department, UMass Lowell
  • Jay Park, Ph.D., associate professor, Plastics Engineering Department, UMass Lowell
  • Hanna Dodiuk, professor, Polymer Materials Engineering Department, Shenkar College of Engineering and Design
  • Samuel Kenig, professor, Polymer Materials Engineering Department, Shenkar College of Engineering and Design

Abstract

PFAS have typically been used as the standard for water- and oil-repellent finishes on textiles, including military uniforms. Because they persist in the environment and pose serious health risks, fluorine-free alternatives are needed that can repel both water and low-surface-tension liquids such as oils. This proposal investigates PFAS-free liquid-repellent surfaces by studying the amount of treatment required for fabric repellency, how the chemistry of the liquid controls wetting, and the effect of surface geometry. The work focuses on how these factors govern the creation of fluorine-free treatments that repel both water and low-surface-tension liquids without compromising fabric comfort.

First, the study evaluated how a fluorine-free epoxy/silica superhydrophobic treatment, first developed for rigid substrates, can be applied to a nylon/cotton (NYCO) military fabric. The effect of solids content on water repellency (AATCC 22), weight gain, air permeability and color change was evaluated. Water repellency was dependent on surface texture rather than on how much material was deposited. A spray rating of 100 held down to 2.0 wt.% solids and dropped below that as Cassie–Baxter wetting weakened. The 2.0 wt.% formulation was able to meet the target metrics.

Next, a fluorine-free siloxane finish is used to study the difference in wetting of polar and nonpolar liquids with similar surface tension. Seven polar liquids (water/isopropanol mixtures) and seven nonpolar liquids (hydrocarbons), matched in surface tension from 21 to 32 mN/m, were tested on siloxane-treated glass and fabric. Using Wu's harmonic-mean model, the siloxane surface was found to be fully nonpolar (~21.4 mN/m), and the solid–liquid interfacial tension (γSL) was calculated for each liquid. Hansen solubility analysis is used to study the interaction between different liquids and surfaces, which can be used to predict the repellency of PFAS-free surface finishes.

Last, the effect of topography on the repellency of low-surface-tension liquids will be investigated with the goal of creating fluorine-free surfaces designed and evaluated for their ability to repel oils and other low-surface-tension liquids. The aim is to find the structural features needed for fluorine-free omniphobic surfaces.