Initiating Systems for Nitroxide-Mediated “Living” Free Radical Polymerizations:  Synthesis and Evaluation

Abstract

A variety of initiating systems for the preparation of macromolecules by nitroxide-mediated "living" free radical procedures have been prepared and evaluated. The systems can be divided into two classes, unimolecular initiators in which alkylated TEMPO (2,2,6,6-tetramethylpiperidinyloxy) derivatives dissociate to provide both the initiating radical and the stable radical, and bimolecular systems in which a traditional free radical initiator, such as BPO or AIBN, is used in conjunction with TEMPO. For the unimolecular initiators it was found that an R-methyl group is essential for "living" character, while a variety of substituents could be placed on the phenyl ring or the β-carbon atom without affecting the efficiency of the unimolecular initiator. It was also found that the rate of polymerization is approximately the same for both the unimolecular and corresponding bimolecular systems; however, the unimolecular initiators afforded better control over molecular weight and polydispersity.

Catalytic polymeric nanoreactors: more than a solid supported catalyst

“…The dynamic equilibrium can be achieved by two general mechanistic approaches: the first one involves the reversible deactivation of propagating chains that subsequently can be reactivated, either catalytically as in atom transfer radical polymerization (ATRP) [18] or spontaneously like in nitroxide-mediated polymerization (NMP). [19] The second approach relies on the degenerative transfer between propagating chains and dormant species with a typical example of this being reversible addition-fragmentation chain transfer (RAFT) polymerization. [20] One of the main advantages of CRPs is that they can tolerate a wide range of functionalities while retaining excellent control over the molecular characteristics of the products and hence allowing the synthesis of precisely engineered BCP macromolecular architectures.…”

Thermal Degradation Behavior of Polystyrene/Magadiite Nanocomposites Prepared by Surface-initiated Nitroxide-Mediated Radical Polymerization

“…4-Methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl was provided from ADEKA Co., Ltd. and a hydroxy functionalized alkoxyamine 2 shown in Scheme 1 was synthesized with reference to the literature. 22 Cyclopentadienyl platinum (II) dichloride (Cp 2 PtCl 2 ) used as a catalyst for hydrosilylation was prepared according to the literature. 23 Magadiite was prepared by means of hydrothermal synthesis according to the literature.…”

Exploring the Full Potential of Reversible Deactivation Radical Polymerization Using Pareto-Optimal Fronts

“…This brings the synthesis of well-defined macromolecular architectures, such as block and star copolymers, within reach. Two important RDRP techniques, which are studied in this work, are activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) [10][11][12][13][14][15][16] and nitroxide mediated polymerization (NMP) [17][18][19][20][21].…”