Abstract

Research within the Scherman group focuses on the design and development of well-defined molecular and supramolecular assemblies at interfaces. We exploit various assembly strategies to form controlled polymer architectures for integration into complex dynamic networks and to achieve assembly at hybrid inorganic-organic interfaces. The materials we develop are of great interest for applications in a wide range of areas including catalysis, sensing, diagnostics, biomaterials, drug-delivery as well as energy harvesting and conversion.

Over the last decade, supramolecular polymer networks (SPNs) have emerged as an exciting new area within the fields of supramolecular and polymer chemistry, materials science as well as biomedical engineering. We have pioneered the use of cucurbit[8]uril (CB[8])-mediated interactions as dynamic crosslinks for the design and preparation of new classes of SPNs with tuneable viscoelasticity and stimuli-responsivity (JACS, 2010 & 2012). 

Although significant advances have been made, a major challenge remains endowing SPNs with robust and controllable material properties. To address this, we reported the introduction of crosslinks formed through CB[8]-mediated π-π interactions between guest moieties with a high binding affinity (Ka > 1012 M-2). This resulted in dynamic, yet strong crosslinks and the fabrication of rubber-like SPNs with remarkable stretchability (> 100x), high toughness (>2000 J/m2), rapid self-healing and self-recovery. This provided a facile strategy for the development of SPNs with robust mechanical properties and promising applications as strain sensors and in electronic devices (Adv. Mater., 2017 & 2017). 

We recently developed a new class of CB[8]-mediated polar-π interactions (JACS, 2020), which enables slow, tuneable dissociation kinetics (kd < 1 s−1) within non-covalent crosslinks. Slowing the dissociation kinetics allows access to a new class of glass-like SPNs, which display ultra-high compressive strengths up to 100 MPa with no fracture, even when compressed at 93% strain over 12 cycles of compression and relaxation. Notably, these networks also demonstrate fast, room-temperature self-recovery (< 120 s), key for the design of high-performance soft materials. Retarding the dissociation kinetics of non-covalent crosslinks through structural control enables access to such glass-like supramolecular materials, holding substantial promise in applications including soft robotics, tissue engineering and wearable bioelectronics (Nat. Mater., 2022). 

In addition, we have developed a new SPN that simultaneously exhibits both high electronic and ionic conductivity while maintaining tissue-like mechanical properties, providing an ideal electronic interface with the human body. These new materials possess high stretchability (> 500%), low Young’s modulus (< 5 kPa), self-recovery and high electronic conductivity (> 50 S/m). These material properties enabled the fabrication of an intrinsically stretchable stand-alone bioelectrode to accurately and comfortably monitor electromyography signals, free from any rigid materials (Adv. Mater. 2023). In parallel, multi-layer hydrogel devices for soft robotics and bioelectronics have been developed through the integration of supramolecular poly(ionic) networks. The introduction of dynamic crosslinks gives rise to superior inter-layer adhesion, enabling the fabrication of intrinsically stretchable hydrogel power sources (Sci. Adv. 2024). 

To probe host-guest complexation dynamics on a molecular level we have developed a library of optically-active guests based on bispyridinium moieties. Structural augmentation enables access to a diverse library of molecules that have wide-reaching applications beyond optically-responsive crosslinkers within materials including electrolytes for energy storage technologies (Nature 2023) and in catalysis (Nat. Nanotechnol. 2021). 

We postulate that gaining molecular level understanding of dynamics within materials will enable us to connect material properties such as homogeneity to performance (stretchability, compressibility, conductivity etc.) for the first time. We anticipate that these advances will inspire interest into structure-property relationships and controlled mechanical properties of supramolecular materials.

Biography

Professor Oren A. Scherman (h-index 81, >26,000 cites, >2500 citations/yr) is the Director of the Melville Laboratory for Polymer Synthesis and Professor of supramolecular and polymer chemistry in the Department of Chemistry at the University of Cambridge. He completed his PhD in the group of Professor Robert H. Grubbs (Caltech, USA) focused on the use of controlled-polymer architectures for materials science via Ring-Opening Metathesis Polymerization (ROMP). He then moved to Europe for a post-doctoral stay in the group of Professor E.W. (Bert) Meijer (TU/e, Netherlands) where he worked on the recognition and engineering of supramolecular polymers, exploiting multiple hydrogen bonding motifs. 

Following this he began his academic career in 2006 at the University of Cambridge where he set out to address one of the fundamental issues limiting the widespread application of supramolecular polymers in materials, their recognition and self-assembly in aqueous environments. He pioneered the use of cucurbit[n]uril (CB[n]) macrocycles as molecular “handcuffs” for assembling macromolecular architectures in water. In 2013 he was appointed Director of the Melville and in 2015 he became a full professor. 

Currently his research group utilizes the powerful recognition properties of CB[n]s to direct and control interfacial assembly, harness interactions at interfaces and bring together a variety of chemical motifs. 

He has won several awards of note, the 2018 Corday-Morgan Prize, 2014 Cram Lehn Pedersen International Prize in Supramolecular Chemistry, 2014 Bob Hay Lectureship, 2013 Hickinbottom Award and 2013 McBain Medal, 2010 Macro Group UK Young Researchers Medal, and 2009 Harrison-Meldola Prize and Medal. Additionally, he sits on the advisory board for several European funding agencies, the ICCB conference series and is on the scientific advisory boards for SABIC IP and the spin-out Aqdot of which he is a co-founder. 

In 2013, Professor Scherman was named the Xuetang Visiting Professor of Chemistry at Tsinghua University (Beijing, China) where he spent a year sabbatical. To date, he has supervised 50 PhD students, 40 Postdocs, 18 MPhil students, his current group comprises 15—20 researchers.