Acrylonitrile copolymerization thermal initiation

The ceiling temperature constraint in the homopolymerization of alphamethyl styrene (AMS) can be circumvented by copolymerization with acrylonitrile (AN) to prepare multicomponent random microstructures that offer higher heat resistance than SAN. The feasibility of a thermal initiation of free radical chain polymerization is evaluated by an experimental study of the terpolymerization kinetics of AMS-AN-Sty. Process considerations such as polyrates, molecular weight of polymer formed, sensitivity of molecular weight, molecular weight distribution, and kinetics to temperature were measured. 

Obtaining polyrotaxanes by the statistical method through polymerization of various monomers in the presence of macrocycles was attempted by Maciejewski who investigated the thermal radical copolymerization of vinylidene chbride, methyl methacrylate (MMA), acrylonitrile (AN), acrylamide, and thdr mixtures with ace-tonaphtylene in aqueous and dimethylformamide solutions in the presence of p-cyclodextrin or of its acylic derivative. All these attempts failed, however. Only, when copolymerization was initiated by y-radiation with an exposure dose of 5 Mrad, did some of the above-listed monomers form polymers exhibiting optical activity. However, the rotation of the initial p-cyclodextrin was 162°, while that of the obtained products only l°-6°. Such a small polarization plane rotation angle could result only from an insignificant amount of macrocycles in the synthesized compounds. Therefore, for the purpose of a more successful synthesis of cyclodextrin-based rotaxanes, a number of researchers tried to introduce elements of directionality into... 

Spontaneous copolymerization of cyclopentene (CPT) with sulfur dioxide (SOt) suggests the participation of a charge transfer complex in the initiation and propagation step of the copolymerization. The ESR spectrum together with chain transfer and kinetic studies showed the presence of long lived SOg radical. Terpolymerization with acrylonitrile (AN) was analyzed as a binary copolymerization between CPT-SOt complex and free AN, and the dilution effect proved this mechanism. Moderately high polymers showed enhanced thermal stability, corresponding to the increase of AN content in the terpolymer. 

Novel iron carbonyl monomer, r)4-(2,4-hexadien-l-yl acrylate)tricarbonyl-iron, 23, was prepared and both homopolymerized and copolymerized with acrylonitrile, vinyl acetate, styrene, and methyl methacrylate using AIBN initiation in benzene.70,71 72 The reactivity ratios obtained demonstrated that 23 was a more active acrylate than ferrocenylmethyl acrylate, 2. The thermal decomposition of the soluble homopolymer in air at 200°C led to the formation of Fe203 particles within a cross-linked matrix. This monomer raised the glass transition temperatures of the copolymers.70 The T)4-(diene)tricarbonyliron functions of 23 in styrene copolymers were converted in high yields to TT-allyltetracarbonyliron cations in the presence of HBF4 and CO.71 Exposure to nucleophiles gave 1,4-addition products of the diene group.71... 

In by far the largest number of cases of free radical copolymerization, the reactivity ratios are practically independent of the nature of the starting reaction (thermal, photochemical, radical-forming type) and the site of propagation (bulk, solution, emulsion). Ionic copolymerization, by contrast, leads to quite different parameters (Table 22-13). Thus copolymerizations can be employed as a diagnostic tool for initiators whose mode of action is unknown, differentiating between free radical copolymerization and the nonradical mechanism (Table 22-14). On such evidence, boron alkyls appear to be free radical initiators in the copolymerization of methyl methacrylate with acrylonitrile, whereas lithium alkyls are anionic initiators. 

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