Entropically Constrained Self-Limiting Supramolecular Polymerization

With the support of the Macromolecular and Nanochemistry Program in the Division of Chemistry, Honggang Cui and Thi Vo of Johns Hopkins University will combine experimental and computational modeling techniques to explore how small molecular units can be assembled into designed supramolecular polymers. These innovative polymers blend the strength and flexibility of traditional plastics with useful features like self-healing, recyclability, and responsiveness to environmental stimuli, but controlling their structure and properties remains challenging. This research aims to uncover the fundamental factors that influence how these materials are synthesized, paving the way for advanced applications in energy storage, medical implants, and drug delivery. In addition to publications and conferences, results of this research will be disseminated via educational and outreach programs designed to reach diverse students from K12 to graduate levels. Both faculty leads play active roles in supporting undergraduate research, and women in engineering initiatives, as well as outreach programs in Baltimore's inner-city schools to foster diversity in science, technology, engineering and mathematics (STEM). This project will employ the parallel use of experimental and computational methods to explore the essential self-assembly characteristics of multi-armed aromatic amphiphiles. By harnessing the adjustable features of entropy constraints in supramolecular design, the research aims to limit supramolecular propagation below a predefined threshold. To achieve these objectives, three key questions will be addressed. (i) Can the contour length of a supramolecular polymer be fine-tuned through strategic molecular design and/or control of its polymerization kinetics? (ii) What are the crucial factors (e.g. nucleation mechanism and growth kinetics) that regulate supramolecular polymerization? (iii) Can theoretical and computational results be utilized to define molecular principles and create blueprints for achieving self-limiting supramolecular polymerization? These studies seek to reveal the entropic parameters that govern supramolecular growth, ultimately to establish a self-limiting polymerization mechanism that would enable precise control over supramolecular polymer length and length distribution. Correlations between molecular features and thermodynamics and kinetics associated with supramolecular polymerization will be sought throughout the project. A successful outcome will enhance foundational understanding of molecular design, chemical structure, and supramolecular dimension relationships in supramolecular polymeric systems, with potentially far-reaching implications for the development of advanced supramolecular materials. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.