P-Dioxene-maleic anhydride

Similar results have been noted in terpolymerizations involving the p-dioxene-maleic anhydride (49, 51, 52) and vinyl ether-maleic anhydride (45, 49) and vinyl ether-fumaronitrile (49) monomer pairs. Iwatsuki and Yamashita (46) concluded that the molecular complex formed between p-dioxene and maleic anhydride is attacked on the p-dioxene side by a radical to yield the maleic anhydride radical which is considered to be the main growing radical. Thus, a monoradical propagation step is considered operative. 

Both the polymerization rate and the composition of the copolymer also depend on the solvent. Solvents can determine the position of the complex equilibrium (see also Table 22-7). Thus, for example, the homopolymerization of a CT complex can be converted into a copolymerization of the CT complex with one of its two monomers, or even convert to a terpolymerization with both of its monomers when the solvent is changed. Such effects may, for example, be responsible besides the dilution effect for the variation in the acrylonitrile content of the terpolymer produced by the joint polymerization of acrylonitrile/p-dioxene/maleic anhydride when the kind and concentration of solvent used are changed (see Figure 22-10). 

Figure 22-10. Dependence of the acrylonitrile content of the terpolymer produced in the terpolymerization of p-dioxene, maleic anhydride, and acrylonitrile in different solvents. (After data from S. Iwatsuki and Y. Yamashita.)...

The nature and the amount of solvent can influence the yield and the composition of the copolymers in these copolymerizations. Thus, copolymerization of phenanthrene with maleic anhydride in benzene yields a 1 2 adduct. In dioxane, however, a 1 1 adduct is obtained. In dimethyl formamide, no copolymer forms at all [193]. Another example is a terpolymerization of acrylonitrile with 2-chloroethyl vinyl ether and maleic anhydride or with p-dioxene-maleic anhydride. The amount of acrylonitrile in the terpolymer increases with an increase in the 7t-electron density of the solvent in the following order [194] ... 

CPT-SO > System. Bulk copolymerization of CPT and SO> takes takes place spontaneously at a remarkable rate even at —15 °C. In comparison with the thermal initiation of p-dioxene and maleic anhydride which proceeds through a similar charge transfer complex at room temperature (13), the interaction between CPT and S02 seems more pronounced, giving the propagating species at a lower temperature. 

Iwatsuki and Yamashita (46, 48, 50, 52) have provided evidence for the participation of a charge transfer complex in the formation of alternating copolymers from the free radical copolymerization of p-dioxene or vinyl ethers with maleic anhydride. Terpolymerization of the monomer pairs which form alternating copolymers with a third monomer which had little interaction with either monomer of the pair, indicated that the polymerization was actually a copolymerization of the third monomer with the complex (45, 47, 51, 52). Similarly, copolymerization kinetics have been found to be applicable to the free radical polymerization of ternary mixtures of sulfur dioxide, an electron donor monomer, and an electron acceptor monomer (25, 44, 61, 88), as well as sulfur dioxide and two electron donor monomers (42, 80). 

The interactions of a-olefins or styrene with sulfur dioxide (16) or a-olefins (24, 58, 78), frans-stilbene (64), styrene (1,63), p-dioxene (52), 2,2-dimethyl-l,3-dioxole (17), or alkyl vinyl ethers (1, 63) with maleic anhydride yield charge transfer complexes which are stable and generally readily detectable either visually or by their ultraviolet absorption spectra. However, under the influence of a sufficiently energetic attack in the form of heat or free radicals, the diradical complexes open, and alternating copolymers are formed. 

Chlorine is virtually absent in the copolymer produced in the azobisisobutyronitrile (AIBN) catalyzed copolymerization of styrene and maleic anhydride in the presence of chloroform or carbon tetrachloride (3, 4), or of p-dioxene and maleic anhydride in the presence of acrylonitrile in chloroform (5). This absence indicates that trichloromethyl radicals generated by the reaction of the chlorinated hydrocarbons with the radicals from AIBN are not incorporated into the polymer chain. Similarly, there is little or no cnlorine in the alternating copolymer that is formed in the copolymerization of styrene and methyl methacrylate in the presence of ethylaluminum sesquichloride (EASC) in the presence of chloroform and carbon tetrachloride, and with or without a peroxide initiator (6). 

Figure 22-9, Absorptivity, A CT, of the charge transfer complex from p-dioxene, PD, and maleic anhydride, MAH, as a function of the volume fraction, 0m ah maleic anhydride in chloroform Initial concentrations 0.5045 (mol PD)/liter and 0.5082(mol MAH)/liter. (After S. Iwatsukiand Y. Yamashita.)...

On the other hand, the joint polymerization of a series of electron-accepting and electron-donating monomers leads to alternating copolymers, mostly as a mixture with the head-to-head cycloaddition products. Electron-accepting maleic anhydride, fumaric ester, sulfur dioxide, or carbon dioxide in combination with electron-donating butadiene, isobutylene, vinyl ether, and p-dioxene or vinyl acetate belong to this series. 

Maleic anhydride terpolymerization cont.) with p-oxathiene and />-dioxene, 414 with m-piperylene and trans-piperylene, 289 with propylene and dicyclopentadiene, 537 with propylene and pentaerythritol triacrylate, 523... 

Poly(dimethylvinylethynyl carbinol-alt-MA), 334 Poly(2,3-dimethyI- 1-vinylindole-alt-MA), 336 Poly(p-dioxene-alt-MA), 315, 320 Poly(l,3-dioxep-5-ene-alt-MA), 325, 327 Poly(l,3-dioxep-5-ene-co-maleimide), 325 Poly(2,5-dioxotetrahydrofuran-3,4-diyl) see poly(maleic anhydride) Poly(l,l-diphenylethylene-alt-MA), 373 grafted to saturated polymers, 474 Poly(ci5-dipropenyl ether-co-MA), 326 Poly(l,3-dithiolane-alt-MA), 388 Poly(divinylbenzene-co-MA), 273 Poly(divinylcyclopentamethylenesilane-co-MA),... 

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