Synthesis of star-shaped polystyrenes via nitroxide-mediated stable free-radical polymerization

Abstract

High molecular weight star‐shaped polystyrenes were prepared via the coupling of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) terminated polystyrene oligomers with divinylbenzene (DVB) in m‐xylene at 138 °C. The optimum ratio of the coupling solvent (m‐xylene) to divinylbenzene was determined to be 9 to 1 based on volume. Linear polystyrene oligomers (Mn = 19,300 g/mol, Mw/Mn = 1.10) were prepared in bulk styrene using benzoyl peroxide in the presence of TEMPO at approximately 130 °C under an inert atmosphere. Coupling of the TEMPO‐terminated oligomers under optimum conditions resulted in a product with a number average molecular weight exceeding 300,000 g/mol (Mw/Mn = 3.03) after 24 h, suggesting the formation of relatively well‐defined star‐shaped polymers. Additionally, the intrinsic viscosities of the star‐shaped products were lower than calculated values for linear analogs of equivalent molecular weight, which further supported the formation of a star‐shaped architecture. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 216–223, 2001

Nano‐Star‐Shaped Polymers for Drug Delivery Applications

“…The first report on the synthesis of star‐shaped polymers using NMRP can be dated back to 1997 by Solomon and co‐workers . Since then, several research groups have reported the preparation of star polymers by NMRP . For instance, Kuo and co‐workers reported the synthesis of a series of star block copolymers from POSS by core‐first NMRP .…”

Kinetic Studies of Metallocene‐Catalyzed Copolymerization of Propene with 10‐Undecene‐1‐ol Using In‐Line FTIR Spectroscopy

“…[4] The in-line ATR-FTIR investigations of the carbonylation of epoxides and a mechanistic understanding of these processes were demonstrated by Allmendinger et al [5] Lizotte, Long and Pasquale et al presented the real-time monitoring of the radical polymerizations of acrylate systems and styrene and also the synthesis of maleic anhydride-cyclic olefin alternating copolymers. [6,11,12] Moreover, they calculated the monomer conversions and determined the kinetic data.…”

“…That's why the original second-order kinetic law is reduced to the pseudofirst-order kinetic law (1). [3,6,[10][11][12] À d½Conc dt ¼ k app ½Conc…”

Phosphines: Nucleophilic organic catalysts for the controlled ring‐opening polymerization of lactides

“…The field of polymer synthesis has experienced revolutionary advances in the types and complexity of new synthetic techniques being developed for well‐defined macromolecules. These include the design and synthesis of single‐site metal catalysts for olefins;1–3 ring‐opening metathesis4–6 and ring‐opening polymerization (ROP);7–11 a variety of controlled free‐radical polymerization strategies, including atom transfer radical polymerization12–18 and nitroxide‐mediated19–24 and radical addition–fragmentation/transfer procedures;25–27 and dendritic macromolecules 28–35. With the exception of nitroxide‐mediated polymerization and purely organic approaches to dendritic macromolecules, these synthetic advances are based on organometallic catalysts.…”