Research in my laboratory uses organic synthesis, physical organic chemistry, spectroscopic methods, and computation to design, prepare, and study novel organic molecules that show unique and useful behavior. In this context we are particularly interested in predicting and controlling properties that emerge when individual molecules aggregate, by weak noncovalent interactions, in solution. The phenomenon is called “self-assembly,” and it is a process borrowed from nature to achieve complexity rapidly and reversibly (e.g., assembly of the DNA duplex or binding of a receptor to its enzymatic target). It is also the central theme of supramolecular chemistry, an established field that studies chemistry “beyond the molecule.” Our specific areas of interest and expertise include: stereoelectronic effects in supramolecular chemistry, construction of novel donor-acceptor molecules with useful electronic or optical properties, functional molecules (for materials and/or sensing applications) from biorelevant building blocks, and molecular-based strategies to novel therapeutics.

We are interested in materials composed of well-defined polymers with selected functionality, composition, and molecular architecture. Particular focus is on water-soluble polymers that are stimuli-responsive. Such “smart” polymers have the ability to self-assemble or dissociate in solution in response to changes in their surroundings. Potential target applications include controlled and targeted drug delivery, surface modification, and self-healing materials. Our interests are at the interface of bio-, organic, nano-, and polymer chemistry, with particular focus on fusing the fields to prepare materials with synergistic properties.

1.Functional polymer synthesis and efficient polymer modification via specific and orthogonal methodologies. A significant effort is dedicated to devising new synthetic routes to functional macromolecules. In addition to relying on living/controlled radical polymerization techniques to prepare polymers of controlled molecular weight and retained end group functionality, highly efficient postpolymerization modification is required to incorporate functionality not easily included in monomer, initiator, or chain transfer agents. Many chemical transformations employed in organic synthesis do not demonstrate the same degree of efficiency and orthogonality when used for functionalization of high molecular weight macromolecules. Therefore, a significant effort in our group has involved the extension of “click chemistry” methodologies for functional polymer synthesis.

2.Stimuli-responsive water-soluble block copolymers. The solution behavior of polymers that exhibit “smart” behavior in aqueous media is being investigated. Responsive block copolymers can be induced to form micelles, vesicles, or gels, and may ultimately lead to new applications in controlled drug delivery, tissue engineering, and surface biocompatibilization.

3.Dynamic-covalent macromolecular materials. By constructing macromolecular assemblies with linkages that are reversibly covalent, we prepare new materials with the ability to adapt their structure, constitution, and reactivity depending on the nature of the surrounding environment. Reversibility being a key attribute, these systems offer versatility typically associated with supramolecular materials (dynamic rearrangement, self-assembly, self-repair, etc.), while maintaining the integrity and robust nature of covalently formed polymers. Materials constructed via covalent bonds that can be triggered to dissociate in response to specific chemical stimuli include smart nanoparticles, organogels, and self-healing coatings.

4.Smart polymer-protein bioconjugates. Modifying biological molecules with “smart” polymers provides a means to externally control the solubility and activity of proteins, peptides, and nucleic acids. Examples of such hybrid materials include polymer-protein conjugates in which the activity, stability, or solubility of the protein can be tuned by capitalizing on the responsive nature of the immobilized synthetic polymer.