Reverse iodine transfer polymerization of vinyl acetate and vinyl benzoate: synthesis and characterization of homo- and copolymers

Abstract

Homo-and copolymers of vinyl esters including vinyl acetate (VAc) and vinyl benzoate (VBz) were synthesized via the reverse iodine transfer radical polymerization technique. Polymerization was carried out in the presence of iodine as the in situ generator of the transfer agent and 2,2 ′ -azobis(isobutyronitrile) as the initiator at 70 ∘ C. Reverse iodine transfer radical homopolymerization of VAc and VBz led to conversions of 76 and 57%, number-average molecular weights of 8266 and 9814 g mol −1 and molecular weight distributions of 1.58 and 1.49, respectively. The microstructure of the synthesized polymers was investigated in detail using gel permeation chromatography, 1 H NMR, 13 C NMR and distortionless enhancement of polarization transfer (135 ∘ decoupler pulse) techniques. Relatively narrow molecular weight distribution and controlled and predictable trend of molecular weight versus conversion were observed for the synthesized polymers, showing that reverse iodine transfer radical homo-and copolymerization of VAc and VBz proceeded with controlled characteristics. Results of molecular weight and its distribution along with the 1 H NMR spectra recorded for homo-and copolymers indicated that side reactions can occur during the course of polymerization with a significant contribution when VAc, even in a small amount, was present in the reaction mixture. This can result in polymer chains with aldehyde dead end and broadening of the molecular weight distribution.

Iodine-influenced morphological evolution of micrometer-sized poly(methyl methacrylate)-block-poly(vinyl acetate) particles upon hydrolysis

“…Nevertheless, low conversion and an increase in M n were gained after sms ITP (Table 1), which can be attributed to inherent defects formed by ITP. As reported by Iovu et al 36 and Abdollahi et al, 37 PVAc with an iodine end group (PVAc-I) is very sensitive to humidity, which could accelerate the degradation of the terminal iodine end, as the side reaction shown in Fig. S3.…”

Synthesis of micrometer-sized poly(vinyl acetate) particles through microsuspension iodine transfer polymerization: effect of iodine species in a water medium

“…Abdollahi et al reported that in a bulk system, poly(vinyl acetate) with an iodine end group (PVAc-I) was very sensitive to humidity. 19 As described in Scheme 1, a portion of the living chains having an iodide end group is inevitably degraded into aldehyde, hydroiodic acid (HI), and acetic acid due to the reaction with water at high temperature (Scheme 1(a)). The resulting side product, PVAc having an aldehyde end group, produces a double bond between the carbonyl group at α and β positions and acetic acid through an aldol reaction (Scheme 1(c)).…”

“…Although the synthesis of PVAc through RDRP has been achieved to meet the emerging demands, 17 the high reactivity of VAc (unconjugated monomer) radicals makes the polymerization more difficult to control than that of (meth)acrylates and styrene, which are conjugated monomers. Specifically, the highly active propagating radicals of VAc easily undergo combination termination, degradation, 18,19 and chain transfer to the methine or the methyl groups on the polymer. [20][21][22] Owing to this drawback, the most widely used RDRP method to polymerize VAc is reversible addition-fragmentation chain transfer (RAFT) polymerization, 23,24 which is tolerant toward unprotected functional groups.…”

Radical polymerization of butadiene mediated by molecular iodine: a kinetic study of solution homopolymerization

“…Thermal radical initiator is necessary to supply sufficient radical flux during the polymerization. Iodine DT can be used for polymerization of most of the monomers [37][38][39][40]. Iodide-mediated radical polymerization has successfully been used in the homogeneous or heterogeneous mediums [37][38][39][40][41][42].…”

“…Iodine DT can be used for polymerization of most of the monomers [37][38][39][40]. Iodide-mediated radical polymerization has successfully been used in the homogeneous or heterogeneous mediums [37][38][39][40][41][42]. These techniques (ITP and RITP) are performed under catalyst-free condition; resulting in easy purification of product [42].…”