Emulsion polymerization of vinyl acetate using iodine‐transfer and RAFT radical polymerizations

Abstract

This study deals with control of the molecular weight and molecular weight distribution of poly(vinyl acetate) by iodine‐transfer radical polymerization and reversible addition‐fragmentation transfer (RAFT) emulsion polymerizations as the first example. Emulsion polymerization using ethyl iodoacetate as the chain transfer agent more closely approximated the theoretical molecular weights than did the free radical polymerization. Although 1H NMR spectra indicated that the peaks of α‐ and ω‐terminal groups were observed, the molecular weight distributions show a relatively broad range (Mw/Mn = 2.2–4.0). On the other hand, RAFT polymerizations revealed that the dithiocarbamate 7 is an excellent candidate to control the polymer molecular weight (Mn = 9.1 × 103, Mw/Mn = 1.48), more so than xanthate 1 (Mn = 10.0 × 103, Mw/Mn = 1.89) under same condition, with accompanied stable emulsions produced. In the Mn versus conversion plot, Mn increased linearly as a function of conversion. We also performed seed‐emulsion polymerization using poly(nonamethylene L‐tartrate) as the chiral polyester seed to fabricate emulsions with core‐shell structures. The control of polymer molecular weight and emulsion stability, as well as stereoregularity, is also discussed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Controlled/Living Radical Polymerization in Dispersed Systems: An Update

“…Zhao et al employed a novel water-soluble RAFT agent, the acidified (with HCl) version of methyl 3-[(morpholin-4-yl carbonothioyl)­thio]­propanoate, but the MWDs were generally broad. Nomura et al used low molecular weight xanthate RAFT agents (known to perform well with VAc in homogeneous systems) and poly­(vinyl alcohol) as surfactant, and the MWDs were again generally broad with M n ≈ M n,th , although the best result was M w / M n = 1.36, and the emulsions were colloidally stable. Hlalele et al reported emulsion copolymerization of 1,3-butadiene with acrylonitrile (yielding nitrile-butadiene rubber, an important elastomer) using 2-(((dodecylsulfanyl)­carbonothioyl)­sulfanyl)­propanoic acid as RAFT agent and oleic acid/potassium hydroxide as surfactant, i.e., resulting in in situ formation of the surfactant potassium oleate. , …”

RAFT/MADIX emulsion copolymerization of vinyl acetate and N-vinylcaprolactam: towards waterborne physically crosslinked thermoresponsive particles

“…In fact, the use of water as continuous phase facilitates heat transfer of the exothermic polymerization, decreases the viscosity of the final product which facilitates polymer recovery from the reactor at the end of the polymerization, and is more environmentally safe by limiting the amount of volatile organic compounds. As reported in several reviews, [15][16][17] most of the investigations focused on controlling the polymerization in aqueous dispersed media of (meth)acrylic or styrenic monomers, while very few studies concerned less activated monomers (LAM) such as vinyl acetate (VAc) [18][19][20][21][22][23][24][25] or vinyl chloride (VC). 26 Note that, despite the interesting features of the biocompatible thermoresponsive poly(N-vinylcaprolactam) (PVCL), 27 controlled radical polymerization of VCL by polymerization in aqueous dispersed media has never been investigated up to now.…”

RAFT Polymerization of Vinyl Esters: Synthesis and Applications

“…Finally, Nomura et al [134] compared the effectiveness of a series of xanthates and dithiocarbamates in controlling the emulsion polymerization of VAc. Polymerizations were moderately well controlled by O-isopropyl xanthates with S-benzyl (5, Scheme 10) or S-(ethyl 2-propionyl) (6) substituents, with good agreement between targeted and theoretical M n and dispersities of around 1.6-2.0.…”