Star polymer synthesis using trithiocarbonate functional β‐cyclodextrin cores (reversible addition–fragmentation chain‐transfer polymerization)

Polystyrene stars were synthesized with reversible addition-fragmentation chain-transfer (RAFT) polymerization. The core of the stars comprised a trithiocarbonate heptafunctional beta-cyclodextrin ring. Polymerizations were performed at 100 and 120 degreesC in the absence of an extraneous initiator and at 60 degreesC in the presence of a radical initiator. Monofunctional trithiocarbonate was also synthesized and used to make linear polystyrene to allow direct a comparison with the star synthesis. In all cases, the polymerization kinetics conformed to pseudo-first-order behavior. The measured molecular weights of the stars were found to deviate from those predicted on the basis of the monomer/trithiocarbonate group ratio. The extent of this deviation was dependent on the polymerization temperature, RAFT agent concentration, and conversion. Despite the low radical concentrations, termination reactions are suggested to play a significant role in the seven-arm polystyrene star syntheses. The synthetic method was found to be suitable for generating star block structures. (C) 2002 Wiley Periodicals, Inc.

[1]  C. Barner‐Kowollik,et al.  Kinetic Investigations of Reversible Addition Fragmentation Chain Transfer Polymerizations: Cumyl Phenyldithioacetate Mediated Homopolymerizations of Styrene and Methyl Methacrylate , 2001 .

[2]  William J. Brittain,et al.  Synthesis of Polymer Brushes on Silicate Substrates via Reversible Addition Fragmentation Chain Transfer Technique , 2002 .

[3]  Leonie Barner,et al.  Living free‐radical polymerization of styrene under a constant source of γ radiation , 2002 .

[4]  C. Hawker,et al.  High-throughput synthesis of nanoscale materials: structural optimization of functionalized one-step star polymers. , 2001, Journal of the American Chemical Society.

[5]  H. Fischer.  The Persistent Radical Effect In “Living” Radical Polymerization , 1997 .

[6]  C. Barner‐Kowollik,et al.  Origin of Inhibition Effects in the Reversible Addition Fragmentation Chain Transfer (RAFT) Polymerization of Methyl Acrylate , 2002 .

[7]  C. Barner‐Kowollik,et al.  The Kinetics of Free‐Radical Polymerization , 2003 .

[8]  A. Fane,et al.  Synthesis of Poly(styrene) Star Polymers Grown from Sucrose, Glucose, and Cyclodextrin Cores via Living Radical Polymerization Mediated by a Half-Metallocene Iron Carbonyl Complex , 2001 .

[9]  O. Guerret,et al.  Synthesis of Stars and Starlike Block Copolymers from a Trialkoxyamine Used as Initiator , 2002 .

[10]  T. Fukuda,et al.  Mechanism and kinetics of RAFT-mediated graft polymerization of styrene on a solid surface. 1. Experimental evidence of surface radical migration , 2001 .

[11]  J. Voß,et al.  ESR‐Untersuchungen an Carbonsäureestern, 10. Bildung persistenter Benzylradikale durch Protonierung der Radikalanionen sterisch gehinderter Dithiobenzoesäureester , 1989 .

[12]  Leonie Barner,et al.  Reversible Addition−Fragmentation Chain Transfer Polymerization Initiated with Ultraviolet Radiation , 2002 .

[13]  D. Haddleton,et al.  Amphiphilic diblock, triblock, and star block copolymers by living radical polymerization: Synthesis and aggregation behavior , 2002 .

[14]  G. Moad,et al.  Living polymerization: Rationale for uniform terminology , 2000 .

[15]  E. Harth,et al.  New polymer synthesis by nitroxide mediated living radical polymerizations. , 2001, Chemical reviews.

[16]  G. Moad,et al.  Living Radical Polymerization with Reversible Addition−Fragmentation Chain Transfer (RAFT): Direct ESR Observation of Intermediate Radicals , 1999 .

[17]  C. McCormick,et al.  Water-Soluble Polymers. 81. Direct Synthesis of Hydrophilic Styrenic-Based Homopolymers and Block Copolymers in Aqueous Solution via RAFT , 2001 .

[18]  J. Quinn,et al.  Facile synthesis of comb, star, and graft polymers via reversible addition–fragmentation chain transfer (RAFT) polymerization , 2002 .

[19]  M. Sawamoto,et al.  Living radical polymerization of para-substituted styrenes and synthesis of styrene-based copolymers with rhenium and iron complex catalysts , 2000 .

[20]  T. Long,et al.  Synthesis of star-shaped polystyrenes via nitroxide-mediated stable free-radical polymerization , 2000 .

[21]  H. Fischer.  Unusual selectivities of radical reactions by internal suppression of fast modes , 1986 .

[22]  K. Matyjaszewski,et al.  End-Functional Poly(tert-butyl acrylate) Star Polymers by Controlled Radical Polymerization , 2000 .

[23]  E. Rizzardo,et al.  Ambient temperature reversible addition–fragmentation chain transfer polymerisation , 2001 .

[24]  D. Haddleton,et al.  Synthesis of well-defined cyclodextrin-core star polymers , 2001 .

[25]  M. Monteiro,et al.  Intermediate radical termination as the mechanism for retardation in reversible addition-fragmentation chain transfer polymerization , 2001 .

[26]  A. K. Chatterjee,et al.  LIVING FREE-RADICAL POLYMERIZATION—A REVIEW , 2001 .

[27]  Graeme Moad,et al.  A more versatile route to block copolymers and other polymers of complex architecture by living radical polymerization : The RAFT process , 1999 .

[28]  C. Hawker.  Architectural Control in “Living” Free Radical Polymerizations: Preparation of Star and Graft Polymers , 1995 .

[29]  B. Sumerlin,et al.  Water-soluble Polymers. 84. Controlled Polymerization in Aqueous Media of Anionic Acrylamido Monomers via RAFT , 2001 .

[30]  Y. Aoyama,et al.  Ternary Complexation Involving Protein. Molecular Transport to Saccharide-Binding Proteins Using Macrocyclic Saccharide Cluster as Specific Transporter , 1998 .

[31]  J. Chiefari,et al.  Tailored polymer architectures by reversible addition‐frasmentation chain transfer , 2001 .

[32]  Graeme Moad,et al.  Living Polymers by the Use of Trithiocarbonates as Reversible Addition−Fragmentation Chain Transfer (RAFT) Agents: ABA Triblock Copolymers by Radical Polymerization in Two Steps , 2000 .

[33]  M. Sawamoto,et al.  FeCp(CO)2I: A Phosphine-Free Half-Metallocene-Type Iron(II) Catalyst for Living Radical Polymerization of Styrene1 , 1999 .

[34]  C. Barner‐Kowollik,et al.  Long‐lived intermediates in reversible addition–fragmentation chain‐transfer (RAFT) polymerization generated by γ radiation , 2002 .

[35]  K. Matyjaszewski,et al.  Atom transfer radical polymerization. , 2001, Chemical reviews.

[36]  C. Barner‐Kowollik,et al.  Modeling the reversible addition–fragmentation chain transfer process in cumyl dithiobenzoate‐mediated styrene homopolymerizations: Assessing rate coefficients for the addition–fragmentation equilibrium , 2001 .

[37]  S. Pispas,et al.  Star‐branched polystyrenes by nitroxide living free‐radical polymerization , 2001 .

[38]  K. Matyjaszewski,et al.  Improving the Structural Control of Graft Copolymers. Copolymerization of Poly(dimethylsiloxane) Macromonomer with Methyl Methacrylate Using RAFT Polymerization , 2001 .

[39]  S. Pispas,et al.  Multifunctional ATRP initiators : Synthesis of four-arm star homopolymers of methyl methacrylate and graft copolymers of polystyrene and poly(t-butyl methacrylate) , 2001 .

[40]  B. Sumerlin,et al.  RAFT Polymerization of N,N-Dimethylacrylamide in Water† , 2002 .

[41]  A. Fane,et al.  Star-polymer synthesis via radical reversible addition-fragmentation chain-transfer polymerization , 2001 .

[42]  Y. Murata,et al.  A Kinetic Study on the Rate Retardation in Radical Polymerization of Styrene with Addition−Fragmentation Chain Transfer , 2002 .

[43]  M. Sawamoto,et al.  Living Radical Polymerization of Styrene by Half-Metallocene Iron Carbonyl Complexes1 , 2000 .

[44]  A. Fane,et al.  Porous Polymer Films and Honeycomb Structures Made by the Self‐Organization of Well‐Defined Macromolecular Structures Created by Living Radical Polymerization Techniques , 2001 .

[45]  J. Hedrick,et al.  Investigation of the Initiation Behavior of a Dendritic 12-Arm Initiator in Atom Transfer Radical Polymerization , 2001 .

[46]  Steven C. Farmer,et al.  (Thiocarbonyl‐α‐thio)carboxylic acid derivatives as transfer agents in reversible addition–fragmentation chain‐transfer polymerizations , 2002 .