Cyclic Polymers: Molecular Knots Robert M. Waymouth, Stanford University, DMR 1001903

1. Cyclic Polymers: Molecular KnotsRobert M. Waymouth, Stanford University, DMR 1001903 Cyclic Polymers, a class of molecular knots, have fascinated chemists, biologists and material scientists for decades. Constraining a large macromolecule into a ring influences its properties in ways that remain poorly understood. We have developed novel synthetic strategies to generate cyclic poly(esters) and have shown that cyclic poly(ε-caprolactone) (PCL) crystallizes faster than its linear analogue. We have also expanded our synthetic strategies to develop new families of cyclic polymers, such as cyclic gradient polymers. The copolymerization of δ-valerolactone and ε-caprolactone (VL and CL) using a stable N-heterocyclic carbene catalyst affords a cyclic gradient copolymer comprised of VL-rich sequences that transition to CL-rich sequences in a cyclic macromolecule. monomer faster crystallization Angew. Chem. Int. Ed. 2007, 46, 2627-2630; J. Am. Chem. Soc. 2007, 129, 8414-8415; J. Am. Chem. Soc. 2009, 131, 4884-4891; Macromolecules,2011, 44, 2773; Angew. Chem. Int. Ed.,2011, 50, 6388

2. Cyclic Polymers: Molecular KnotsRobert M. Waymouth, Stanford University, DMR 1001903 Three graduate students (Eun Ji Shin, Hayley Brown, and Tyler Stukenbroeker) are currently supported on the project. Additionally, a summer undergraduate student affiliated with the Center on Polymer Interfaces and Macromolecular Assembly (Jolene Mork, Carlton College) has participated as well. An interdisciplinary collaboration with the research group of Prof. Gerald Fuller (Stanford University, Department of Chemical Engineering) is also a component of the project.