The relative reactivities of vinyl monomers in low-temperature copolymerizations and terpolymerizations with S$ in the presence of tert-butyl hydroperoxide as initiator were compared. The highest copolymerization rates were found in systems containing an electron-donor monomer of low resonance stabilization, and the resulting products have an alternating structure. In reactions with monomers of high resonance stabilization and electron-acceptor properties, mainly homopropagation of the comonomer proceeds. In the terpolymerization of S q with two electron-donor monomers, the relative reactivity of monomers depends mainly on their resonance stabilization. In the terpolymerization in systems S$ /electron-donor monomer/electron-acceptor monomer the relative reactivity of acceptor monomers decreases with increasing inductive effect in the molecule.
The copolymerization of sulfur dioxide with methyl, ethyl, butyl or 2-ethylhexyl acrylate was studied. The influence of the composition of monomer feed and reaction temperature on the composition of the copolymers was investigated. The maximum content of sulfonyl units in the copolymers, obtained at -78 "C, was found to be ca. 30 mol-Yo and to decrease with increasing temperature. The sequence distribution in the copolymers was determined by I3C NMR spcctroscopy. It was proved that acrylates do not undergo alternating propagation with SO,, and the minimum number of acrylate monomeric units in a homosequence is 2. The results obtained were compared with those obtained from studies on the copolymerization of SO, with other monomers, and are discussed in terms of the alternating copolymerization theory and the penultimate model. Experimental partThe method of purification of the monomers and solvents and also the copolymerization procedure and copolymer isolation were described previously"). The copolymer compositions were determined by elemental analyses and on the basis of I3C ['HI NMR spectra of the products. NMR spectra were recorded at room temperature on a Varian NFT-20 spectrometer.Deuterochloroform was used as solvent and HMDS as an internal standard. The signal area in the carbon resonance was compared by the peak weighing method. 0025-1 16)88/$03.00 P x' P 3.
The radical terpolymerization of sulfur dioxide and methyl acrylate with 1,3-butadiene, 2-methylpropene, propene, I -hexene, 1 -octene and vinyl chloride was studied by comparing the composition of terpolymers obtained under different reaction conditions and by analysis of I3C NMR spectra of selected terpolymers and copolymers. In the majority of systems studied, products are formed in which the ratio of SO, monomeric units to vinyl monomeric units is near to unity. The content of methyl acrylate monomeric units can change over a very wide range and depends mainly on the electron-donor properties of the vinyl monomer used, feed composition and conversion. An increase of the methyl acrylate content is also observed in many systems with a rise of the reaction'temperature. The results obtained are interpreted in terms of a mechanisms involving the addition of individual monomers and reversibility of steps in which carbon-sulfur bonds are formed.There is only a limited number of literature reports on the reactivity of monomers in systems containing SO2 and a competitive electron-acceptor monomer9~ I I ) . In a previous paperto), we reported the results of studies on the relative reactivity of SO, and different electron-acceptor monomers in the terpolymerization with 1 -hexene or 1,3-butadiene at -78 "C. Maleic anhydride, acrylonitrile, acrylic acid, methyl acrylate and methyl methacrylate were used as acceptor monomers. In systems with maleic anhydride, alternating copropagation of the electron-donor monomer proceeds with both electron-acceptor monomers, of which SO, is more reactive. In systems with acrylic monomers, the alternating copropagation of both acceptors with
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