ChE Undergrad Yaozu Chen Wins Prestigious AIChE Poster Contest

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Undergraduate research assistant Yaozu Chen, a Chemical Engineering (ChE) major who works in the lab of ChE Professor Sarah Perry, presented the winning poster in the student poster contest at the 2024 Annual Meeting of the American Institute of Chemical Engineers (AIChE), held from October 27 to 31 in San Diego. Chen’s first-place poster depicts his fundamental research on so-called “polyelectrolyte complexes” (PECs), which form a type of polymer plastic that can be used in everything from biomedical and food applications to energy and electronics. His research on PECs is designed to provide a more environmentally friendly option for these applications compared to current plastics.

Drug Delivery Today describes a polyelectrolyte as a type of polymer plastic that has multitudinous ionizable functional groups. “Ionized polyelectrolytes in solution can form a complex with oppositely charged polyelectrolytes — a polyelectrolyte complex.” 

In addition, the Chemical Engineering Journal explains that “polyelectrolyte complexes from synthetic origins are largely utilized in energy and electronic applications due to their excellent conductivity, stretchability, and self-healing properties, whilst those from natural sources are employed in pharmaceutical, biomedical, and food applications owing to their non-toxicity and biocompatibility.” 

As Chen explains the backstory to his research, “PECs benefit from aqueous processing and avoid high temperatures or organic solvents. Additionally, their properties can be tuned by modulating the length, charge density, and hydrophobicity of the polyelectrolyte. Furthermore, it is well understood that salt concentration strongly affects the mechanics of the PEC. Salt ions disrupt the electrostatic interactions between polyelectrolytes, which typically causes the complex to soften and swell.” 

The problem, says Chen, is that, while such electrostatic interactions are known to be important, “the effect of the identity of the ionizable group of the polyelectrolytes on the mechanics of the material is not well-understood.” Chen’s fundamental research aims to make these mechanics much more understandable.

As Chen explains, “To bridge this knowledge gap, we are studying the effect of changing the identity of the ionizable group and its relationship with salt concentration on the linear viscoelasticity and phase behavior of these materials.”

In that context, as Chen says in his poster, “Rheology provides insight on PEC material properties from viscosity to solid-liquid transitions and how these properties change with salt concentration and polymer chemistry.”

As Chen concludes, “By understanding how salt concentration and polymer chemistry affect PEC mechanics, we can design and aqueously process PECs for specific applications, presenting a more environmentally friendly option compared to current plastics.” 

Research in the Perry laboratory, where Chen works, “utilizes self-assembly, molecular design, and microfluidic technologies to generate biomimetic microenvironments to study and enable the implementation of biomolecules to address real-world challenges.” Chen’s current projects in the Perry lab include developing an electrically actuated microfluidic device for protein crystallography and studying the rheology of polyelectrolyte complexes, as depicted in his winning poster. 

Chen is a senior in Chemical Engineering with a concentration in Biochemical Engineering and a minor in Chemistry. In the summer of 2023 Chen participated in an internship at MacDermid Alpha Electronics Solutions in Waterbury, Connecticut, and in the summer of 2024 he did a prestigious internship at the Advanced Photon Source at Argonne National Laboratory in Lemont, Illinois. He has also played the violin in the UMass All-University Orchestra. (November 2024)