Alkoxyamine initiators for nitroxide mediated radical polymerization: Synthesis, characterization, and applications

Nitroxide mediated radical polymerization (NMRP) utilizes alkoxyamine initiators to form polymers with well-controlled chain lengths and low polydispersities. This thesis is a study of the synthesis and polymerization kinetics of several novel alkoxyamines and their use in forming new materials.; Inside-out bidirectional alkoxyamine initiator 2.2 was synthesized and used in the polymerization of styrene, n-butyl acrylate, t-butyl acrylate, isoprene, and dimethylacrylamide. Symmetrical amphiphilic ABA triblock copolymers were prepared; addition of 2,2'-(ethylenedioxy)bis(ethylamine) resulted in AFM images of self-assembled structures.; A hybrid double-headed initiator containing an alpha-bromoester moiety and an alkoxyamine moiety was synthesized. Atom-transfer radical polymerization formed a poly(methyl methacrylate) macroinitiator. The polymerization kinetics of this macroinitiator compared to small molecule initiator TIPNO-St showed no significant difference.; Several outside-in bidirectional alkoxyamines with distal nitroxides were synthesized. The polymerization kinetics were identical to those of monodirectional initiator TIPNO-St. In contrast, outside-in bidirectional alkoxyamine 3.1 exhibited much faster polymerization rates. Low temperature EPR studies of the bisnitroxide 4.1 revealed an unusually strong radical-radical interaction, suggesting that the near proximity of the nitroxide moieties is responsible for the faster rate of polymerization. In comparing bisalkoxyamine 3.1 to TIPNO-St near 120°C, EPR measurements showed a dissociation rate constant approximately twice as large, whereas 1H-NMR investigations of the decomposition revealed a faster rate of decomposition. EPR decomposition studies at 120°C showed that bisnitroxide 4.1 decomposes much more quickly than TIPNO. The increased rates of dissociation and decomposition can be attributed to an intramolecular interaction between the proximal nitroxide moieties.; Carboxylic acid-functionalized alkoxyamine 5.17 and alcohol-functionalized alkoxyamine 5.18 were synthesized and used as initiators in NMRP. Post-polymer coupling of the end groups to pyrene dyes verified end group functionalization of greater than 90% by UV absorption. Poly(dimethylacrylamide) formed from initiator 5.17 was covalently linked to lysozyme to form a protein-polymer conjugate.; A 17-membered cyclic alkoxyamine 6.37 was synthesized and used to polymerize styrene. Polymerization with 6.37 resulted in a macropolymer in which multiple polymer chains are linked through NO-C bonds. EPR homolysis experiments showed that alkoxyamine 6.37 dissociates to form nitroxide, but its rate of dissociation is much slower than that of the parent alkoxyamine TIPNO-St.