Universal xanthate‐mediated controlled free radical polymerizations of the “less activated” vinyl monomers

Abstract

The living free radical polymerizations of three “less activated” monomers (LAMs), vinyl acetate, N‐vinylcarbazole, and N‐vinylpyrrolidone, were successfully achieved in the presence of a disulfide, isopropylxanthic disulfide (DIP), using 2,2′‐azoisobutyronitrile (AIBN) as the initiator. The living behaviors of polymerizations of LAMs are evidenced by first‐order kinetic plots and linear increase of molecular weights (Mns) of the polymers with monomer conversions, while keeping the relatively low molecular weight distributions, respectively. The effects of reaction temperatures and molar ratios of components on the polymerization were also investigated in detail. The polymerization proceeded with macromolecular design via interchange of xanthate process, where xanthate formed in situ from reaction of AIBN and DIP. The architectures of the polymers obtained were characterized by GPC, 1H NMR, UV–vis, and MALDI‐TOF‐MS spectra, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

Synthesis and Reactivity of Mononuclear Iron Models of [Fe]‐Hydrogenase that Contain an Acylmethylpyridinol Ligand

“…The series of less intensive peaks (Figure 9b) cannot be ascribed to any chain‐end structures expected. The presence of these peaks is probably due to the occurrence of the fragmentation during ionization in the MALDI–TOF MS analysis, as reported by other authors 36–41…”

MALDI of synthetic polymers with labile end‐groups

“…reported a major distribution of sodiated intact dormant species, holding either the other CTA fragment or a part of the AIBN initiator as the α termination (Zhou et al, ). In contrast, studying oligomers expected to carry the same O ‐ethylxanthate ω end‐group, Yan et al could not observe any intact species although using the same matrix (Yan et al, ), and only very low abundance dormant species adducted with lithium were obtained by Fandrich et al, preparing the MALDI sample with indole acrylic acid (IAA) or dihydroxybenzoic acid (DHB) (Fandrich et al, ). It should be noted, however, that in these three cases, additional oligomeric distributions were systematically assigned to side‐reaction products formed during polymerization.…”

“…Two studies were found to report opposite results on MALDI of poly( N ‐vinyl pyrrolidone) produced by RAFT/MADIX. Quite high abundance, although not major, sodium adducts of intact dormant chains (holding an O ‐ethylxanthate termination) were produced using dithranol as the matrix (Yan et al, ), whereas expected oligomers holding the same –S(CS)OC 2 H 5 group were detected with very minor abundance as compared to species with unsaturated end‐group in MALDI mass spectra obtained with 4‐(4‐nitrophenylazo)resorcinol (Guinaudeau et al, ).…”

RAFT Polymerization of Vinyl Esters: Synthesis and Applications

“…Alternatively, the RAFT agent can be synthesized in situ, as exemplified by the use of isopropylxanthic disulfide [71,93]. Addition of a poly(vinyl ester) radical to either of the C=S double bonds of the disulfide results in formation of a xanthate RAFT agent and a thiocarbonylthiyl radical which does not reinitiate polymerization.…”