Research |
The Barnes research group works at the interface of chemistry, engineering, materials science, biology, and medicine. The overarching goal of our research is to develop next-generation polymeric materials that we as synthetic chemists can program at the (macro)molecular level with precise functions, resulting in advanced materials that have enhanced properties for a broad range of applications. Specifically, we design functional polymers and crosslinkers with non-covalent bonding capabilities – i.e., supramolecular polymers – that adopt unique pathways of self-assembly and/or activation. Thus, we create functional materials from the nanometer to the macroscopic scale and are inspired by Nature’s forms of molecular recognition and function, but possess the robustness and enhanced durability of synthetic materials.
New (Photo)Redox-Responsive Polymers and Mechanisms for Actuating Soft Materials
The Barnes group is interested in the design, synthesis, and function of redox-responsive sequence-defined macromolecules and macrocrosslinkers, where the primary functional component is based on viologens (4,4'-bipyridinium). We discovered that by integrating oligo- and polyviologens into hydrogel polymer networks, it is possible to reversibly contract macroscopic materials through a concerted mechanism that involves reduction of a dicationic viologen (V(2+)) to its radical cation (V(•+)), which induces viologen radical-based self-assembly (i.e., chain folding), while also decreasing the number of positive charges by half and losing a corresponding number of counteranions. We have also shown that it is possible to reverse this contraction mechanism simply by oxidizing the viologen subunits back to their dicationic oxidation state in the presence of ambient O2 and re-swelling the hydrogels in water. We also demonstrated that a photoredox catalytic cycle could be implemented to reduce the polyviologens in situ, which affords spatiotemporal control over the actuation using visible light. We are now exploring these materials to improve actuator properties and performance for a variety of applications.
New (Photo)Redox-Responsive Polymers and Mechanisms for Actuating Soft Materials
The Barnes group is interested in the design, synthesis, and function of redox-responsive sequence-defined macromolecules and macrocrosslinkers, where the primary functional component is based on viologens (4,4'-bipyridinium). We discovered that by integrating oligo- and polyviologens into hydrogel polymer networks, it is possible to reversibly contract macroscopic materials through a concerted mechanism that involves reduction of a dicationic viologen (V(2+)) to its radical cation (V(•+)), which induces viologen radical-based self-assembly (i.e., chain folding), while also decreasing the number of positive charges by half and losing a corresponding number of counteranions. We have also shown that it is possible to reverse this contraction mechanism simply by oxidizing the viologen subunits back to their dicationic oxidation state in the presence of ambient O2 and re-swelling the hydrogels in water. We also demonstrated that a photoredox catalytic cycle could be implemented to reduce the polyviologens in situ, which affords spatiotemporal control over the actuation using visible light. We are now exploring these materials to improve actuator properties and performance for a variety of applications.
Ring-Opening Metathesis Polymerization to Construct Nanomaterials from Self-Assembled Polymer Architectures
Combination drug cocktails administered in the clinic have proven to be effective at treating aggressive forms of cancer or multidrug resistant bacterial infections. However, these combinations are known to be incredibly toxic due to off target effects from the drugs. We are interested in using non-toxic 'universal' drug-loaded polymeric nanoparticles that can encapsulate a wide range of drug combinations and are prepared through polymerization of macrocyclic monomers and novel crosslinkers. This bionanotechnology platform is currently being investigated for the treatment of cancer and multidrug resistant bacteria, as well as chronic kidney diseases.
Topologically Complex Molecules, Polymers, and Materials
As the worldwide demand for better performing materials continues to rise, novel polymers and bulk materials are needed to meet this call. We are interested in developing new polymers and polymer networks comprising topologically elastic linkers that may provide unforeseen properties at the bulk level. Template-directed syntheses are a critical aspect of this research, with a focus on creating modular building blocks and scalable methodologies.
Combination drug cocktails administered in the clinic have proven to be effective at treating aggressive forms of cancer or multidrug resistant bacterial infections. However, these combinations are known to be incredibly toxic due to off target effects from the drugs. We are interested in using non-toxic 'universal' drug-loaded polymeric nanoparticles that can encapsulate a wide range of drug combinations and are prepared through polymerization of macrocyclic monomers and novel crosslinkers. This bionanotechnology platform is currently being investigated for the treatment of cancer and multidrug resistant bacteria, as well as chronic kidney diseases.
Topologically Complex Molecules, Polymers, and Materials
As the worldwide demand for better performing materials continues to rise, novel polymers and bulk materials are needed to meet this call. We are interested in developing new polymers and polymer networks comprising topologically elastic linkers that may provide unforeseen properties at the bulk level. Template-directed syntheses are a critical aspect of this research, with a focus on creating modular building blocks and scalable methodologies.
