Synthesis of block, graft and star polymers from inorganic macroinitiators

Abstract

Recent advances in the synthesis of block, graft and star polymers containing inorganic macromolecular species are described. Anionic copolymerization techniques were used in the formation of diblock copolymers of poly(styreneblock-methylphenylsilylene) and poly(isopreneblock-methylphenylsilylene) by the ring-opening polymerization of 1,2,3,4-tetramethyl-1,2,3,4tetraphenylcyclotetrasilane initiated by living anionic polystyrene and isoprene respectively. Hydrosilation of an attachable initiator onto telechelic vinyl-or hydrosilyl-terminal or-pendant poly(dimethylsiloxane) (PDMS) yielded a PDMS macroinitiator. This macroinitiator was used in atom transfer radical polymerization (ATRP) of styrene and isobornyl acrylate to produce ABA triblock copolymers. As a model for graft copolymers from a polyphosphazene backbone, chemical transformation of hexachlorocyclotriphosphazene resulted in hexafunctional molecules containing either benzyl bromide or bromopropionyl moieties. The initiator 1,1,3,3,5,5-hexakis[4-(2bromopropionyloxymethyl)phenoxy]cyclotriphosphazene was used in the ATRP of styrene to yield a polymer with a narrow, monomodal molecular weight distribution. Chain extension of this star polymer with isobornyl acrylate is also described.

Synthesis of Polymer Brushes Using Atom Transfer Radical Polymerization

“…Due to the high local concentration of tethered chains, grafted chains extend away from the polymeric backbone, to mitigate steric crowding effects. Star and graft copolymers [125][126][127][128][129][130] have not been included in this discussion and the reader is directed to more comprehensive reviews. [1,2,16,17,131] Initial attention to molecular brushes has been largely driven by their ''aesthetic value'' since these well-defined copolymers can be visualized by AFM.…”

Synthesis and self-assembly behavior of six-armed block copolymers with pH- and thermo-responsive properties

“…Fortunately, cyclotriphosphazene is a kind of inorganic heterocyclic compound which can be easily introduced to organic materials. Since Chang 14 and Matyjaszewski 15 et al prepared star polymers with cyclotriphosphazene, its unique properties have been recognized and a great number of relevant researches have been carried out. Several groups like Tang, 9,[16][17][18][19][20] Luo, 19 and Kwon 10 have synthesized a series of star-shaped aliphatic polyesters with cyclotriphosphazene.…”

Configurational sequence determination of poly(isobornyl acrylate) by NMR spectroscopy

“…PiBA has extensive range of applications as in cosmetics [5], coatings [6], bio-applications [7], drug delivery systems [8] and as construction material [4]. Various coworkers have reported controlled radical polymerization of isobornyl acrylate by atom transfer radical polymerization (ATRP) [9][10][11][12] and Nitroxide Mediated Polymerization (NMP) [13]. ATRP is a useful method of controlled/living radical polymerization to form polymers having control molecular weights and low polydispersity, which attracted a great deal of attention of polymer chemists world wide [8,14,9,15].…”