By Kwok Fan Chow
The Kennedy College of Science, Department of Chemistry, invites you to attend a Ph.D. Dissertation defense by Sevil Kaynar Turkoglu entitled “Extreme Wetting Surfaces: The Effect of Surface Topography and Composition.”
Date: Thursday, April 6, 2023
Location: ETIC, Room 445, North Campus
Or via Zoom: Meeting ID: 343 056 7846; Passcode: 629248
Prof. Joey Mead, Department of Plastics Engineering, University of Massachusetts Lowell
- Prof. Jinde Zhang, Department of Plastics Engineering, University of Massachusetts Lowell
- Prof. Hanna Dodiuk, Department of Polymer Materials Engineering, Shenkar College
- Prof. Samuel Kenig, Department of Polymer Materials Engineering, Shenkar College
- Jo Ann Ratto, U.S. Army Combat Capabilities Development Command Soldier Center
- Prof. Marina Ruths, Department of Chemistry, University of Massachusetts Lowell
- Prof. James Whitten, Department of Chemistry, University of Massachusetts Lowell
In chapter 1, the effect of particle loading on the wetting properties of coatings was investigated by modifying a coating formulation based on hydrophilic silica nanoparticles and poly (acrylic acid) (PAA). Water contact angle (WCA) measurements were conducted for all coatings to characterize the surface wetting properties. Wettability was improved with an increase in particle loading. The resulting coatings showed superhydrophilic (SH) behavior when the particle loading was above 53 vol. %. No new peaks were detected by attenuated total reflection (ATR-FTIR). The surface topography of the coatings was studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The presence of hydrophilic functional groups and nano-scale roughness were found to be responsible for superhydrophilic behavior. The surface chemistry was found to be a primary factor determining the wetting properties of the coatings. Adhesion of the coatings to the substrate was tested by tape test and found to be durable. The antifogging properties of the coatings were evaluated by exposing the films under different environmental conditions. The SH coatings showed anti-fogging behavior. The transparency of the coatings was significantly improved with the increase in particle loading. The coatings showed good transparency (>85% transmission) when the particle loading was above 84 vol. %.
In Chapter 2, superhydrophilic coatings based on a hydrophilic silica nanoparticle suspension and Poly (acrylic acid) (PAA) were prepared by dip coating. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were used to examine the morphology of the coating. The effect of surface morphology on the dynamic wetting behavior of the superhydrophilic coatings was studied by changing the silica suspension concentration from 0.5% wt. to 3.2% wt. while keeping the silica concentration in the dry coating constant. The droplet base diameter and dynamic contact angle with respect to time were measured using a high-speed camera. A power law was found to describe the relationship between the droplet diameter and time. A significantly low experimental power law index was obtained for all the coatings. Both roughness and volume loss during spreading were suggested to be responsible for the low index values. The water adsorption of the coatings was found to be the reason for the volume loss during spreading. The coatings exhibited good adherence to the substrates and retention of hydrophilic properties under mild abrasion.
Chapter 3 involves two sections. Section 1 describes the formulation and process optimization to develop environmentally friendly crack free superhydrophobic coatings using non-hazardous solvents and non-Polyfluorinated Alkyl Substances (PFAS or FAS) materials on a glass and steel substrates by spray coating method. The formulations were developed with the hydrophobic silica, epoxy, and non-fluorinated hydrophobic silane components. The coatings with FAS were also used with the same silica and epoxy system to compare FAS and non-FAS coatings. Anti-icing, anti-corrosion and drag reduction performances of the coatings were evaluated and compared. Section 2 focuses on the effect of FAS content on the chemistry, topography and wetting properties of the silica and epoxy coatings. The effect of particle loading on the topography and wetting properties of the prepared coatings were also investigated.
All interested students and faculty members are invited to attend.