Acrylonitrile terpolymerization

Terpolymerization, the simultaneous polymerization of three monomers, has become increasingly important from the commercial viewpoint. The improvements that are obtained by copolymerizing styrene with acrylonitrile or butadiene have been mentioned previously. The radical terpolymerization of styrene with acrylonitrile and butadiene increases even further the degree of variation in properties that can be built into the final product. Many other commercial uses of terpolymerization exist. In most of these the terpolymer has two of the monomers present in major amounts to obtain the gross properties desired, with the third monomer in a minor amount for modification of a special property. Thus the ethylene-propylene elastomers are terpolymerized with minor amounts of a diene in order to allow the product to be subsquently crosslinked. 

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. 

As a development of our studies on charge transfer complexes and polymerization, we reported on the spontaneous copolymerization of cyclopentene and sulfur dioxide (11), and kinetic evidence for the participation of the charge transfer complex in the copolymerization was presented. This paper discusses the terpolymerization of cyclopentene, sulfur dioxide, and acrylonitrile to give further evidence for the charge transfer... 

The terpolymerization of CPT-SO2 and acrylonitrile is shown in Table II. It was necessary to accelerate the polymerization by adding azobisisobutyronitrile (AIBN) as initiator. The nature of the propagating species may not be different with a different initiator. Polymerization ceased at a low conversion at 40 °C in toluene. The terpolymer composition calculated from elemental analysis of C, H, N, and S showed an equimolar ratio of CPT and S02. The terpolymers are white powders, soluble in DMF, can be cast into transparent film different from the CPT-SO2 copolymer, and showed melting temperature without decompo-... 

Considering the terpolymerization of CPT-SO2-AN system as a binary copolymerization of CPT-SO2 complex and free acrylonitrile, the copolymerization equation can be derived as follows, assuming a fast equilibrium. 

Several works [311-313, 200] are devoted to a circumstantial research of systems where terpolymerization of styrene and acrylonitrile with a third monomer (brominated acrylate or methacrylate) was studied. It was shown that the terminal model can be employed to describe such systems. One can see this from Table 6.10 and Figs. 20 and 21, where the conversion drifts of the average copolymer composition are presented. 

It is worth emphasizing in conclusion of this section that a similar analysis of the dynamic system (8.3), (8.4) could be also carried out for terpolymerization, since by now experimental data are available on the dependence of the copolymerization rate on monomer feed composition for terpolymers of methyl methacrylate and styrene with either diethyl maleate [344], N-vinylpyrrolidone [344], or acrylonitrile [346]. 

It may be true that many terpolymerizations are well described by these relations, for example the radical copolymerization of styrene, methyl methacrylate and acrylonitrile or vinyl chloride [205, 206] but the uncertainty of the basic assumptions (stationary state, non existence of monomer or active centre complexes, etc.) reduces the meaning of relation (116) to a mere illustration of a complicated copropagation. No way is known to derive the values of the six constants involved independently. Unless they are determined by independent procedures, it is very probable that a good agreement between experiment and the tested relation will be obtained by a suitable choice of these constants. The value of such an agreement should be regarded with caution. 

Recently, Akashi and coworkers [153, 154] synthesized novel spherical particles on which nano-projections are uniformly distributed over the whole surface like confetti by the one-step dispersion terpolymerization of acrylonitrile, styrene, and the PEO macromonomer 9a in ethanol/water media. The control of nanoparticle morphology by a one-step synthetic procedure is important to self-organization at the polymer chain level, which is a basis for the formation of biological nanoconstructs such as viruses and organelles. 

In the terpolymerization of styrene, methyl methacrylate and acrylonitrile (s/MMA/AN = 50/25/25 mole ratio) in the presence of EASC, the terpolymer composition is approximately 50/36/1 1, independent of the temperature within the range of 10-90°C, whether the reaction is conducted in the dark or under UV radiation (lO). However, the terpolymerization rate is increased 2-5 times under UV light. 

Charge transfer complexes of the monomers were studied in the terpolymer-ization of neutral monomers (N) with electron-donor (D) and electron-acceptor (A) monomers [18a]. For example, norbomene as (D) monomer, SO2 as (A) monomer, and acrylonitrile as (N) molecules were studied. Thus acrylonitrile may not be effective in copolymerization but can be terpolymerized with SO2 [18a]. 

The nature and the amount of solvent can influence the yield and the composition of the copolymers in these copolymerizations. 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. Another example is a terpolymerization of acrylonitrile with 2-chloroethyl vinyl ether and maleic anhydride or with p-diaxene-maleic anhydride. The amount of acrylonitrile in the teipolymer increases with an increase in the r-electron density of the solvent in the following order ... 

The monomer composition generally changes with conversion in copolymerizations since the more reactive monomer preferentially polymerizes thereby reducing its composition in the rest of the monomer mixture. Under certain conditions, the more reactive monomer is completely consumed long before higher conversions are reached, as can be seen in Figure 22-1 for the terpolymerization of butadiene, butyl acrylate, and acrylonitrile. As can be seen from the differential copolymer composition, new copolymer molecules formed at yields of more than 74% conversion do not contain any butadiene... 

Figure 22-1. Change in mole fraction of acrylonitrile (AN), butyl acrylate (BA), and butadiene (BU) in monomer mixture (atm ") and in copolymer (x ) as a function of yield for the free radical terpolymerization of an [AN]o [BA]o [BU]o - 0.5 0.25 0.25 mixture at 60 C. The copolymerization parameters are rANBU = 0.1, 2- buba 9.9, tbuan 3.5,...

Figure 22-5. Number-average sequence length of homosequences as a function of yield for the free radical terpolymerization of acrylonitrile (AN) butyl acrylate (BA), and butadiene (BU). Experimental conditions as for Figure 22-1.

Table 22 5. The Product of the Binary Copolymerization Parameters for the Free Radical Terpolymerization of the Conjugated Monomers Methyl Acrylate, Methyl Methacrylate, Acrylonitrile, and Styrene, as well as for the Nonconjugated Monomers Vinyl Acetate, Vinyl Chloride, and Vinylidene Chloride...

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.)...

Medyakova, L. V., Rzaev, Z. M. O., Giiner, A., and Kibarer, G. 2000. Gomplex-radical terpolymerization of acceptor-donor-acceptor systems Maleic anhydride (u-butyl methaciylate)-styrene-acrylonitrile. Journal of Polymer Science, Part A Polymer Chemistry 38 2652-2662. 

Butler and Campus [40] undertook a study to provide further evidence of the formation of the charge-transfer complex between the comonomers and of its participation in the cyclocopolymerization. The 1,4-diene used was divinyl ether (DVE) and the monoolefins were maleic anhydride (MA) and fumaronitrile (FN). The results of the determination of the composition of the charge-transfer complex formed between DVE-MA are shown in Figure 5. Acrylonitrile (AN) was used as the third monomer in the terpolymerization experiments. For comparison, the results of a complex study of styrene-maleic anhydride and ethyl vinyl ether (EVE)-maleic anhydride were also reported. The results of determination of the equilibrium constants for the DVE-MA and styrene-MA complexes by the NMR method are shown in Figure 6. The results... 

Fig. 8. Radical terpolymerization of divinyl ether (DVE)-maleic anhydride (MA)-acrylonitrile (AN).

Consider the preparation of styrene-acrylonitrile and methyl methacrylate terpolymer in a CSTR. There can be 3x3 = 9 possible dyads formed. These are AA, AS, SA, SS, SM, MS, AM, MA, and MM. The reactivity ratios can be read from Chapter lO, Table 10.1 The terpolymer composition can be calculated using the terpolymerization composition equations for a CSTR given in Equations (10.23-10.25). The dyad probabilities were calculated using an MS Excel spreadsheet and listed in Table 11.3. Let AN be denoted as monomer 1, styrene as monomer 2, and methyl methacrylate as monomer 3. Assuming that the bond formation order does not influence the rate, that is. 

Discuss the effect of chain sequence distribution on enthalpy of terpolymerization of alphamethyl-styrene acrylonitrile and styrene. 

K. R. Sharma, Thermal terpolymerization of alphamethyl styrene, acrylonitrile and styrene, Polymer, Vol. 41, 1305-1308, 2000. 

K. R. Sharma, Comparison of Experimental Data with Theoretical Model for the Terpolymerization of Alphamethylstyrene Acrylonitrile and Styrene, 32nd ACS Middle Atlantic Regional Meeting, Madison, NJ, May 1999. 

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. 

Jenner and Kellou recently studied the pressure effect on azeotropy in free-radical terpolymerization of MA with acrylonitrile, dielthyl fumarate, methyl acrylate, methyl methacrylate, methyl vinyl ketone, vinylidene chloride, norbornene, a-methylstyrene, indene, and vinyl acetate, with styrene as the second comonomer common in all cases. It was found that ternary azeotropes were only possible for those systems where the first comonomers had positive e values, i.e., diethyl fumarate, acrylonitrile, methyl acrylate, methyl methacrylate, methyl vinyl ketone, and vinylidene chloride. Surprisingly, the coordinates of the ternary azeotropes were very little affected by variations of the pressure from 1-3,000 bars. Since reactivity ratios in multi-component polymerizations are sensitive to pressure, causing terpolymer composition to also be pressure dependent, a shift of the ternary azeotropic point would be expected. Why this occurs awaits further clarification. 

---