Polymer Chemistry: Uniform chiral polymers by IEG: synthesis and assembly
Abstract
Nature makes use of macromolecules with precise structure, i.e., length, sequence, and stereochemistry, to accomplish an astonishing array of complex functions such as catalysis (e.g., enzymes), information storage (e.g., DNA and RNA), and selective recognition (e.g., antibodies). Similarly, the function of synthetic polymers is intimately related to their structure at the molecular level. The past century has witnessed numerous advances in polymer synthesis, with outstanding control over tacticity (stereochemistry), sequence, and mass in certain cases. For example, catalyst controlled polymerizations such as Ziegler-Natta polymerization led to the plastics revolution. ÒLivingÓ polymerization methods led to novel block architectures and birthed the field of polymer self-assembly. Solid-phase synthesis revolutionized the synthesis of macromolecules with absolute control over structure. Despite these advances, there still exists an inverse relationship between scalability and structural control in polymer synthesis; solid-phase methods offer complete control but general are not atom economical while living polymerization is scalable but lacks complete structural control. The Johnson group has recently focused on the development of ÒIterative Exponential GrowthÓ (IEG) methods for polymer synthesis that offer a unique balance of absolute structure control and potential scalability. For example, the Johnson group showed that through IEG plus sidechain functionalization (IEG+) that it is possible to achieve gram-scale syntheses of linear macromolecules with masses greater than 6.5 kDa and dispersity of 1.00. Furthermore, through development of continuous flow IEG these macromolecules could be prepared on tens of grams scale in one day. The proposed research seeks to establish novel synthetic methods for IEG polymers, and also to use IEG polymers as building blocks for the synthesis of more complex higher-order structured materials. Three new IEG methods are proposed: Òallyl-IEGÓ will produce macromolecules with allyl functionality at any position for late-stage functionalization; a new mixture of amino acids and IEG will produce ÒIEG-peptide-peptoidÓ (IPP) polymers with diverse possibilities for folding and assembly; lastly, a molecular tripling strategy, ÒIEGX3Ó, is proposed that will utilize orthogonal IEG methods to produce complex stereo- and sequence-defined polymers. Then methods and strategies for the controlled assembly of these polymers into higher-order tertiary structures are proposed. Specifically, we seek to establish design principle for IEG polymer structure and properties in the bulk and solution states. Our results will establish efficient syntheses for next-generation IEG polymers that will represent new benchmarks in the field of precision synthetic polymers.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 16, 2018
- Source ID
- W911NF1710521
Entities
People
- Jeremiah A Johnson
Organizations
- Army Contracting Command
- Massachusetts Institute of Technology
- United States Army