http://hdl.handle.net/2374.MIA/6241 Dr. Scott Hartley - Professor, Chemistry & Biochemistry Wed, 08 Apr 2026 15:52:23 GMT 2026-04-08T15:52:23Z http://hdl.handle.net/2374.MIA/7022 Data archive for "Mechanisms of Chiral Induction in Foldamers" Devkota, Govinda Prasad; Lama, Roshan; Hartley, C. Scott Foldamers, oligomers that adopt well-defined conformations, represent an efficient strategy toward nanoscale structural complexity. While most foldamers fold into (chiral) helices, many abiotic foldamers are built from achiral repeat units. They therefore do not have a preferred twist sense. The handedness can, however, be controlled by attaching groups with chirality centers to the foldamer backbone. This process allows the chiral information from readily available feedstocks to be amplified into larger-scale structural asymmetry and, ultimately, translated into functional behavior. This review describes mechanisms whereby the point chirality of chiral “controller” groups direct the helicity of the foldamer to which they are attached in illustrative examples of aromatic oligoamides, oligohydrazides, oligoindoles, oligo(ortho-phenylenes), and oligo(aminoisobutyric acids). We consider cases where the controller groups are attached at either the oligomers’ termini or side-chains. Our emphasis is on applying intuitive concepts from conformational analysis and, where appropriate, computational models of small substructures. In each case, we consider first short-range interactions that orient the controller group in space relative to its direct point of attachment to the foldamer. We then consider long-range interactions between the controller group and more-distant parts of the oligomer, typically one turn farther along the helix. Together, these interactions allow the twist sense to be predicted (or rationalized). Understanding these mechanisms should facilitate the design of systems with dynamic control over helicity. http://hdl.handle.net/2374.MIA/7022 http://hdl.handle.net/2374.MIA/6979 Data archive for "Controlling Carbodiimide-Driven Reaction Networks Through the Reversible Formation of Pyridine Adducts" Salvia, William S.; Mantel, Georgia; Saha, Nirob K.; Rajawasam, Chamoni W. H.; Konkolewicz, Dominik; Hartley, C. Scott Carbodiimide-driven anhydride formation from carboxylic acids is useful in a variety of non-equilibrium systems. While multiple strategies to control deactivation rates (anhydride hydrolysis) have been reported, control over activation rates (anhydride formation) is currently limited. We show that pyridines reversibly form adducts with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide methiodide in water. These adducts are unreactive with carboxylic acids and thus reduce the anhydride formation rate while prolonging carbodiimide lifetime. The best results are obtained with 4-methoxypyridine. This strategy can be used to control the formation of transient polymer network hydrogels, in one example increasing the time to reach peak modulus by 86% and the lifetime by 43%. http://hdl.handle.net/2374.MIA/6979 http://hdl.handle.net/2374.MIA/6956 Data archive for "Transient Polymers through Carbodiimide-driven Assembly" Saha, Nirob K.; Salvia, William S.; Konkolewicz, Dominik; Hartley, C. Scott Biochemical systems make use of out-of-equilibrium polymers generated under kinetic control. Inspired by these systems, abiotic supramolecular polymers driven by chemical fuel reactions have recently been reported. Conversely, polymers based on transient covalent bonds have received little attention, although they have the potential to complement supramolecular systems by generating transient structures based on stronger bonds and offering a straightforward approach to tuning the reaction kinetics. In this study, we show that simple aqueous dicarboxylic acids give poly(anhydrides) when treated with the carbodiimide EDC. Transient covalent polymers with molecular weights exceeding 15,000 are generated which decompose over the course of days. Disassembly kinetics can be controlled using simple substituent effects in the monomer design. The impact of solvent polarity, carbodiimide concentration, and monomer concentration on polymer properties and lifetimes has been investigated. The results reveal substantial control over polymer assembly and disassembly kinetics, highlighting the potential for fine-tuned kinetic control in nonequilibrium polymerization systems. http://hdl.handle.net/2374.MIA/6956 http://hdl.handle.net/2374.MIA/6918 Data archive for "Carbodiimide-driven toughening of interpenetrated polymer networks" Rajawasam, Chamoni W. H.; Tran, Corvo; Sparks, Jessica L.; Krueger, William; Hartley, C. Scott; Konkolewicz, Dominik Recent work has demonstrated that temporary crosslinks in polymer networks generated by chemical “fuels” afford materials with large, transient changes in their mechanical properties. This can be accomplished in carboxylic-acid-functionalized polymer hydrogels using carbodiimides, which generate anhydrides with lifetimes on the order of minutes to hours. Here, the impact of the polymer architecture on the mechanical properties of materials was explored. Single networks (SNs) were compared to interpenetrated networks (IPNs). Notably, semi-IPN precursors that give IPNs on treatment with the carbodiimide gave much higher fracture energies (i.e., resistance to fracture) and superior resistance to compressive strain compared to other network structures. A precursor semi-IPN material featuring acrylic acid in only the free polymer chains yields, on treatment with carbodiimide, an IPN with a fracture energy of 2400 J/m2, a fourfold increase compared to an analogous semi-IPN precursor that yields a SN. This resistance to fracture enables the formation of macroscopic complex cut patterns, even at high strain, underscoring the pivotal role of polymer architecture in mechanical performance. http://hdl.handle.net/2374.MIA/6918