Poly(ethylene oxide)‐block‐polystyrene copolymers obtained by radical polymerization involving chain‐transfer processes

Abstract

Poly(ethylene oxide)‐block‐polystyrene (PEO–PSt) block copolymers were prepared by radical polymerization of styrene in the presence of iodoacetate—terminated PEO (PEO‐I) as a macromolecular chain‐transfer agent. PEO‐I was synthesized by successively converting the OH end‐group of α‐methoxy ω‐hydroxy PEO to chloroacetate and then to the iodoacetate. The chain‐transfer constant of PEO‐I was estimated from the rate of consumption of the transfer agent versus the rate of consumption of the monomer (Ctr, PEO‐I = 0.23). Due to the involvement of degenerative transfer, styrene polymerization in the presence of PEO‐I displayed some of the characteristics of a controlled/‘living’ process, namely an increase in the molecular weight and decrease of polydispersity with monomer conversion. However, because of the slow consumption of PEO‐I due to its low chain‐transfer constant, this process was not a fully controlled one, as indicated by the polydispersity being higher than in a controlled polymerization process (1.65 versus < 1.5). The formation of PEO–PSt block copolymers was confirmed by the use of size‐exclusion chromatography and 1H NMR spectroscopy. Copyright © 2004 Society of Chemical Industry

Radical Terpolymerization of 1,1,2-Trifluoro-2-pentafluorosulfanylethylene and Pentafluorosulfanylethylene in the Presence of Vinylidene Fluoride and Hexafluoropropylene by Iodine Transfer Polymerization

“…Ideally, in ITP, to obtain polymer with a narrow molar mass-distribution the rate of exchange should be higher than that of the propagation. ITP allows one to control a great variety of hydrogenated monomers, such as acrylates, styrenics, , methacrylates (by reverse iodine transfer polymerization), and vinyl acetate, − and also fluorinated monomers, , such as VDF , or a mixture of fluoroolefins (VDF/HFP, , VDF/HFP/TFE, , VDF/MAF (where MAF represents α-trifluoromethacrylic acid 44 ).... Finally, ITP allows the synthesis of well-defined architectures such as monofunctional and telechelic polymers, ,, PVDF- b -poly(styrene) diblock copolymer, and PVDF- g -PS graft copolymer …”

Use of Iodocompounds in Radical Polymerization

“…Unlike fluorinated CTAs, most nonfluorinated transfer agents 15,18,19,[30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] are rather easy to synthesize and their chemical structure enables an easy transfer of the iodine atom to the propagating polymer chain while the resulting radical is stabilized by either inductive/polar or resonance effects. Such reasons, their low price, their solubility in organic solvents, and the good control results make them an obvious choice for many different applications (Table 1).…”

Synthesis and characterization of copolymers with the same proportions of polystyrene and poly(ethylene oxide) compositions but different connection sequence by the efficient Williamson reaction

“…(B1 and B2) gave the monomodal peaks, and the low PDIs (<1.05) of PS‐ b ‐PEO copolymers proved that the ROP of EO monomers initiated by the co‐initiation system of PS‐OH and DPMK was well controlled. The molecular weight of PS‐ b ‐PEO copolymers determined by SEC using THF as eluent was unreliable because THF was not a good solvent for the PEO segment and the PS‐ b ‐PEO might be aggregated into micellar structures by self‐association in THF solvent . Alternatively, the most reliable method to determine the actual molar mass of PS‐ b ‐PEO copolymers was the 1 H NMR spectrum.…”