Chemical and Biomolecular Engineering at Illinois

New insights from Schroeder group will guide solution-based processing for next-gen functional materials

New research from Chemical and Biomolecular Engineering at the University of Illinois offers new insight into the self-assembly of electrically-active biohybrid materials, which consist of natural peptides linked to synthetic conductive polymers. The results, published recently in ACS Central Science, promise to aid solution-based processing of next-generation optoelectronic materials such as flexible organic semiconductors.

The sol−gel transition of π-conjugated oligopeptides is studied using a combined microrheology-spectroscopy approach. These results will be used to inform the solution-based processing of soft organic electronic materials.

Thanks to recent advances in materials chemistry, researchers have been able to design and create new materials for advanced energy storage and capture applications. Supramolecular assembly of molecular-scale building blocks is a powerful method that can be used to generate materials with exceptional structural and functional diversity for these applications. However, there’s still a need to understand the mechanisms underlying the assembly of biohybrid/synthetic molecular building blocks, which ultimately control the emergent properties of hierarchical assemblies, according to Charles Schroeder, Professor and Ray and Beverly Mentzer Faculty Scholar.

Professor Charles Schroeder

Using cutting-edge techniques in microrheology, optical spectroscopy, and electron microscopy, Schroeder and his research team studied the concentration-driven self-assembly and sol-gel transition of synthetic pi-conjugated oligopeptides with different chemistries.

“Using this combined approach based on optical and mechanical analysis, we monitored the self-assembly process of synthetic oligopeptides in situ through the sol-gel transition, which reveals fundamentally new insight for how these materials form gels and how they can be processed,” Schroeder said.

Graduate student Peter Zhou

Yuecheng (Peter) Zhou, a graduate student in Schroeder’s group, was first author on the study. “For the first time, we measured the critical fiber concentration, critical gel concentration, and diffusive exponent for pi-conjugated oligopeptides. Our results show that the assembled gel microstructures remain homogeneous throughout the sol-gel transition by concentration-driven assembly under neutral pH. These findings will effectively guide the bottom-up design in solution processing for next-generation functional materials,” Zhou said.

The article, “Concentration-Driven Assembly and Sol-Gel Transition of π-Conjugated Oligopeptides” is available online.­ In addition to Schroeder and Zhou, the authors are University of Illinois postdoc Dr. Bo Li and graduate student Songsong Li; along with Herdeline Ann Ardoa, graduate student at Johns Hopkins University, John Tovar, Professor at Johns Hopkins University; and William Wilson, Professor at Harvard University and Adjunct Research Professor at the Frederick Seitz Materials Research Laboratory at the U of I.