title: Reversible Deactivation Radical Polymerization of Monomers Containing Activated Aziridine Groups.
abstract: Polymers bearing activated aziridine groups are attractive precursors to α-substituted-β-amino-functionalized materials due to the enhanced reactivity of the pendant aziridine functionalities toward ring-opening by nucleophiles. Two aziridine-containing styrenic monomers, 2-(4-vinylphenyl)aziridine (VPA) and N-mesyl-2-(4-vinylphenyl)aziridine (NMVPA), were polymerized under a variety of reversible deactivation radical polymerization conditions. Low-catalyst-concentration atom transfer radical polymerization (LCC-ATRP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization were ineffective at producing well-defined polymers from VPA due to side reactions between the aziridine functionalities and the agents controlling the polymerizations (catalysts or chain transfer agents). PolyVPA produced under nitroxide-mediated polymerization (NMP) conditions had narrow molecular weight distribution at low to moderate conversions of monomer, but branched and eventually cross-linked polymers were formed at higher conversions due to ring-opening reactions of the aziridine groups. Most of these undesirable side reactions were eliminated by attaching a methanesulfonyl (mesyl) group to the aziridine nitrogen atom, and well-defined linear homopolymers with targeted molecular weights were realized from NMVPA under RAFT and NMP conditions; however, side reactions between the aziridine groups and the catalyst in LCC-ATRP still occured and the polymerization was uncontrolled using this technique.
authors.affiliation: Department of Chemistry and Center for Drug Discovery, Design, and Delivery at Dedman College, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX, 75275, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: McLeod
authors.affiliation: Department of Chemistry and Center for Drug Discovery, Design, and Delivery at Dedman College, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX, 75275, USA. nvt@smu.edu.
authors.forename: Nicolay V
authors.initials: NV
authors.lastname: Tsarevsky
mesh_terms: D001388:Aziridines / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry; D015394:Molecular Structure; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry*; D013343:Styrenes / Q000737:chemistry*
chemical_list: D001388:Aziridines; D005609:Free Radicals; D011108:Polymers; D013343:Styrenes
keywords: aziridines; controlled/living radical polymerization; functional polymers; reversible-deactivation radical polymerization