2019-20 PPG-MRL Research Assistant Awards

2019-2020 PPG-MRL GRADUATE RESEARCH ASSISTANTSHIPS AWARDED TO FIVE STUDENTS

James Carpenter, Ahyoung Kim, Maggie Potter, Dhawal Thakare, and Chengxi Zhao have been awarded PPG-MRL Graduate Research Assistantships to pursue cutting-edge research broadly related to the areas of interest to PPG.

PPG and the PPG Foundation aim to bring color and brightness to PPG communities around the world. By investing in educational opportunities, the company and foundation help grow today’s skilled workforce and develop tomorrow’s innovators in fields related to coatings and manufacturing. This student program supports the University of Illinois community with new thought leaders at the Materials Research Laboratory (MRL).

James Carpenter (Nenad Miljkovic, advisor)

My research focuses on the rational design of functionalized, micro/nanostructured surfaces. These surfaces have the ability to produced desired outcomes during various phase-change processes. Specifically, the frosting/icing of components can compromise the efficiency and integrity of a multitude of engineering systems. The spacecraft cryogenic system is a great example. Here, water on the spacecraft can deposit and freeze on the cryogenic surfaces. Due to the high infrared absorptivity of ice, the film causes a large parasitic radiative heat load that the cryogenic system must overcome. In this project, I will use MEMS/NEMS fabrication techniques along with a sulfur-based coating deposition technique, which will make the cryogenic surfaces resistant to this type of ice film formation. With a reduced parasitic radiative heat load, cryogenic systems can be made smaller, lighter, and more efficient. More efficient cryogenic systems will bring space agencies like NASA that much closer to exploring Mars and other planets.   

Carpenter’s advisor, Professor Nenad Miljkovic, states that, Carpenter “has made great progress on the project thus far and is now developing a model to quantify the effect that condensing droplets have on the growth rate of nearby droplets, as well as building a vacuum chamber capable of emulating the low pressure/temperature conditions seen in cryogenic systems during frosting. He presented the preliminary results at the 6th Micro and Nano Flows Conference in Atlanta last September and presented additional results at the Gordon Research Conference for Micro and Nanoscale Phase Change Heat Transfer in Italy this past February.”

Ahyoung Kim (Qian Chen, advisor)

My research focuses on developing and employing patchy nanoparticles as functional and reconfigurable “Legos” to assemble meta-materials in an energy-efficient manner. The patchy nano-legos I synthesize have inorganic cores decorated with molecular patterns of different chemistries at nanometer resolution, which can be used as functional additives and targeted delivery systems in coatings and films. Moreover, the patches can serve as glue points, to direct their assembly into unique structures with adaptable optical and mechanical properties upon external stimulus. During the term of PPG-MRL Research Assistantship, I will extend our patchy nano-lego synthesis platform to a variety of core and patch materials combinations. Furthermore, I will visualize and engineer their energy-efficient assembly pathways using the potent imaging tool of liquid-phase transmission electron microscopy at MRL, which can make a liquid sample compatible with the high vacuum conditions of electron microscopy. The understanding from real-time and real-space will guide reverse engineering of meta-materials of desired structures and properties, potentially aiding applications in cloaking coatings, high-gain antennas, and smart power management. Under the PPG-MRL grant, a library of functional nano-legos and in-depth understanding in their assembly rules will provide critical insights to the environmentally adaptive and rich functional structures, from the bottom-up, in an energy-efficient manner.

Kim’s advisor, Professor Qian Chen, states that “the success [Ahyoung] has made and the expanding scope of the project was completely identified by her and was a big and pleasant surprise to me. She has good intuition to make connections between different fields, she has the independence when I couldn't help her much as she forges this new direction, she knows what it takes to go far and deep, and she is never shy to try out of her way to make things work.”

Maggie Potter (Ralph Nuzzo, advisor)

 My research focuses on using Si solar micro-cells to develop and build prototype photovoltaic (PV) window coatings for the built and automotive environment. Si solar micro-cells are small PV devices (no larger than a grain of sand) that can be assembled deterministically in sparse arrays on a variety of substrates, thereby forming an energy-harvesting and effectively transparent window coating. To facilitate light trapping and collection, the micro-cells are embedded in a luminescent solar concentrator (LSC) – a flexible polymeric film containing quantum dots (QDs) with spectrally-matched emission that is directed toward the micro-cells through the total internal reflection modes of the waveguide material. Through careful materials selection and systems modelling, we have determined that our design can achieve module efficiencies of up to 4% with high transparency – a record for this type of technology. Our power-generating “smart coating” allows for implementation of high-performing Si beyond rooftop and “solar-farm” type PV installations, and is important to progress toward large-scale adoption of renewable/sustainable energy and mitigation of the carbon footprint on both the individual and industrial level.

Potter’s advisor, Professor Ralph Nuzzo, states, “Maggie has brought forward a spectacular body of work and engendered leads to new classes of technology (autonomous energy generating/managing windows) that could be transformational.  We have a full paper on an embodiment of this for electrochromic systems that is spectacular.”  

Dhawal Thakare (Nancy Sottos and Randy Ewoldt, advisors)

As a fourth year PhD candidate in the Department of Mechanical Science and Engineering, I work with Prof. Nancy Sottos in the area of Stimuli-Responsive ‘Smart’ Coatings. These coatings provide active, on-demand functionalities to substrate in addition to basic protection. My research specifically involves the development of self-protecting anticorrosion coatings. We use the strategy of encapsulation of anticorrosive actives in microcapsules to achieve this functionality. This strategy allows for a controlled and stimuli-responsive delivery through manipulating the properties of the capsule shell. For instance, if the capsule shell is pH-sensitive, then it can be programmed to release the anticorrosive actives in an acidic media. The pH-release mechanism is ideal for corrosion protection, especially if the corrosion is initiated without a mechanical damage in a coating, by benefiting from a decrease or increase in the pH associated with the anodic or cathodic corrosion half reactions, respectively. Responsive coatings are also ideal for applications encountering acidic/basic operating conditions, like pipelines in oil and gas industry carrying corrosive acidic fluids. This added function enables enhanced service life of coated materials, reduced maintenance costs, and improved energy efficiency in a wide variety of industrial applications including automotive, aerospace, and petrochemical. 

Under the PPG-MRL fellowship, I aim to develop pH responsive microcapsules which can be used to form a self-protecting anticorrosive coating. One of the main challenges is to develop microcapsules which are robust enough to survive a commercial coating environment. Additionally, we focus on developing a ‘green’ coating system having a reduced footprint on the environment.

Thakare’s advisor, Professor Nancy Sottos, states, “Dhawal has extraordinary potential for conducting impactful research, combined with a passion for science and education. I look forward to great things from Dhawal.”

Chengxi Zhao (Daniel Shoemaker, advisor)

My research focuses on developing two-zone chemical vapor transport (CVT) strategies to grow single crystals of complex metallic antiferromagnetic compounds that cannot be simply obtained by solid-state synthesis. For the development of next-generation electronic devices, manipulation of charge and spin at the atomic level is one of the most challenging goals in materials science, and single crystals and oriented thin films are required because the behavior is dependent on the orientation of the crystalline lattice. Currently, I am focusing on growing single crystals of layered tetragonal and hexagonal metallic antiferromagnets, such as Mn₂As, Mn₂Au, and MnPt. Many of those compounds are incongruently melting, which means they cannot be grown as large crystals by cooling them from the melt. Although traditional synthesis via annealing can give us the desired phases, the small grain sizes would fall short of what we need to control and characterize the magnetic response. So, development of the CVT technique is a significant step toward using these complex materials.

Zhao’s advisor, Professor Daniel Shoemaker, states, “Chengxi has generated new routes to magnetic thin films before, when she had to control metal precursor solubility, solvent evaporation behavior, and edge bead formation in order to make large-scale, smooth films of strongly magnetic oxides from an organic solution. She is first author on that paper [C. Zhao, et al. AIP Advances 9035126 (2019)]. Now, she is exploring uncharted territory in the vapor-phase growth of a new class of materials, where crystallinity and grain size are extremely important. Nobody has demonstrated effective growth of these intermetallic compounds, so we are excited to see where the project leads.”