Atom transfer radical polymerization of an epoxide‐containing monomer, 4‐vinylphenyloxirane, employing low concentration of catalyst: synthesis of linear and star‐shaped macromolecules

J. Polym. Sci. Part A: Polym. Chem.

2015

Polymers containing electrophilic moieties, such as activated esters, epoxides, and alkyl halides, can be readily modified with a variety of nucleophiles to produce useful functional materials. The modification of epoxide-containing polymers with amines and other strong nucleophiles is welldocumented, but there are no reports on the modification of such polymers with alcohols. Using phenyloxirane and glycidyl butyrate as low molecular weight model compounds, it was determined that the acid-catalyzed ring-opening of arylsubstituted epoxides by alcohols to form b-hydroxy ether products was significantly more efficient than that of alkylsubstituted epoxides. An aryl epoxide-type styrenic monomer, 4-vinylphenyloxirane (4VPO), was synthesized in high yield using an improved procedure and then polymerized in a controlled manner under reversible addition-fragmentation chaintransfer (RAFT) polymerization conditions. A successful chain extension with styrene proved the high degree of chain-end functionalization of the poly4VPO-based macro chain transfer agent. Poly4VPO was modified with a library of alcohols and phenols, some of which contained reactive functionalities, e.g., azide, alkyne, allyl, etc., using either CBr 4 (in PhCN at 90 8C for 2-3 days) or BF 3 (in CH 2 Cl 2 at ambient temperature over 30 min) as the catalyst. The resulting b-hydroxy ether-functionalized homopolymers were characterized using size exclusion chromatography, 1 H NMR and IR spectroscopy, and thermal gravimetric analysis.

Section: Methodsmentioning

confidence: 99%

Well-defined epoxide-containing styrenic polymers and their functionalization with alcohols

McLeod

J. Polym. Sci. Part A: Polym. Chem.

2015

“…Epoxides are often utilized as synthetic intermediates in the production of aziridines. A renewed interest in epoxide‐containing styrenic monomers and their applications in macromolecular design has recently resulted in several new high‐yielding methods for their production . One such monomer, 4‐vinylphenyloxirane (4VPO), proved to be especially convenient as a starting material for the synthesis of styrenic monomers containing activated aziridines (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Reversible Deactivation Radical Polymerization of Monomers Containing Activated Aziridine Groups

McLeod

Macromol. Rapid Commun.

2016

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.

“…It was recently demonstrated that epoxides can act as reducing agents in low-catalyst concentration ATRP reactions (Scheme 2) (50,57), and in the chain extension reactions reported here, the epoxides present in the macroinitiator served to regenerate the lower oxidation state metal complex (activator) via reduction of the higher oxidation state deactivator.…”

Section: Chain Extension Of Hb-polygma-br X Via Low-catalyst Concentrmentioning

confidence: 95%

Synthesis of Star Polymers with Epoxide-Containing Highly Branched Cores by Low-Catalyst Concentration Atom Transfer Radical Polymerization and Post-Polymerization Modifications

Woodruff

2015

ACS Symposium Series

Star polymers were synthesized by atom transfer radical polymerization (ATRP) using a "core first" approach. Multibrominated, highly branched functional polymers were first synthesized by copolymerizing an epoxide-containing monomer, glycidyl methacrylate (GMA), with divinyl crosslinkers, ethylene glycol dimethacrylate or the reductively degradable bis(2-methacryloyloxyethyl) disulfide, in the presence of an efficient chain transfer agent, CBr 4 . Multiple alkyl bromide chain end groups were present in the branched polymers, which were successfully used as multifunctional macroinitiators, from which both polyacrylateand polymethacrylate-type arms were grown under low catalyst concentration ATRP conditions. Due to the ability of epoxides to reduce Cu II to Cu I complexes, the low catalyst-concentration ATRP chain extensions were performed in the absence of any externally added reducing agents. The cores of the obtained stars, contained numerous epoxide functionalities, originating from GMA, and were efficiently modified using reactions with a variety of tertiary aliphatic amines to afford star polymers with hydrophilic, cationic cores. Ring-opening of the oxirane rings in polyGMA with a pyridine derivative, nicotinamide, in