Ternary copolymerization

Terpolymerizations or ternary copolymerizations, as the names suggest, are polymerizations involving three monomers. Most industrial copolymerizations involve three or more monomers. The statistics of terpolymerization were worked out by Alfrey and Goldfinger in 1944.111 If we assume terminal model kinetics, ternary copolymerization involves nine distinct propagation reactions (Scheme 7.9). 

Azeotropic compositions are rare for terpolymerization and Ham 14 has shown that it follows from the simplified eqs. 38-40 that ternary azeotropes should not exist. Nonetheless, a few systems for which a ternary azeotrope exists have now been described (this is perhaps a proof of the limitations of the simplified equations) and equations for predicting whether an azeotropic composition will exist for copolymerizations of three or more monomers have been formulated.20113 This work also shows that a ternary azeotrope can, in principle, exist even in circumstances where there is no azeotropic composition for any of the three possible binary copolymerizations of tire monomers involved. 

Baramboim and coworkers (42) performed a low temperature copolymerization of a frozen polyethylene terephthalate suspension in acrylic acid, obtaining block copolymers and ternary acid resistant products. 

Brandley and Schnaar [140] immobilized a synthetic nonapeptide, Tyr- Ala-Val Thr-Gly Arg-Gly-Asp-Ser, on a polyacrylamide gel, which had been prepared by a ternary copolymerization of acrylamide, bisacrylamide and the acrylic ester of. V-hydroxysuccinimide. They reported that Balb/c 3T3 mouse fibroblast cells (in Hepes-buffered Dulbecco s modified Eagle medium) adhered readily to the peptide-derivatized surfaces, even in the absence of serum, although long-term cell growth required the presence of serum. It was noticed that reference nonapeptide. Tyr-Arg-Leu-Glu-Asp-Pro-Ala-Met-Trp, which has no RGD sequence, failed to promote cell-attachment. 

In many binary copolymerizations, there is a pronounced tendency for the two types of monomer unit to alternate along the copolymer chain. In extreme cases, there is almost perfect alteration, notably for pairs of monomers, e.g, maleic anhydride and stilbene, which do not polymerize on their own. Ternary copolymenzations are of practical importance die kinetic treatments developed for binary copolymerizations can be extended to diese systems. 

In addition to the polymerization of dienes the versatility of NdP-based catalysts is exceptional regarding the number of different non-diene monomers which can be polymerized with these catalysts. Acetylene is polymerized by the binary catalyst system NdP/AlEt3 [253,254]. Lactides are polymerized by the ternary system NdP/AlEt3/H20 [255,256]. NdP/TIBA systems are applied in the copolymerization of carbon dioxide and epichlorhy-drine [257] as well as for the block copolymerization of IP and epichloro-hydrin [258]. The ternary catalyst system NdP/MgBu2/TMEDA allows for the homopolymerization of polar monomers such as acrylonitrile [259] and methylmethacrylate [260]. The quaternary system NdP/MgBu2/AlEt3/HMPTA is used for the polymerization of styrene [261]. 

Shen et al. determined the BD/IP copolymerization parameters for the polymerization with the ternary catalyst system NdN/TIBA/EASC at 50 °C ted = 1.4 and np = 0.6 [92]. Over a wide range of BD/IP copolymer compositions the experimentally determined Tg values significantly deviate from the theoretical curve which was calculated by the Fox equation for random copolymers. Only for IP-contents < lOwt. % does the experimentally determined data coincide with the theoretical curve. Shen et al. also succeeded to synthesize block copolymers comprising poly(butadiene) and poly(isoprene) building blocks [92]. 

The use of ternary NdP-based catalyst systems for the copolymerization of BD and IP was reported by Laubry (Michelin) [270,271]. Also gas-phase polymerization was recently applied for the preparation of IP/BD block copoly-... 

It is interesting to note, that there are publications on the Nd-catalyzed copolymerization of BD and styrene (St) as well as on the selective polymerization of BD which is performed in the presence of St as the solvent. The copolymerization of BD and St cannot be achieved with standard binary or ternary catalyst systems which yield BR with a high cis- 1,4-content. This... 

Copolymerizations of BD with 1-alkenes such as 1-octene and 1-dodecene aim at short chain branching of BR. Kaulbach et al. used the ternary catalyst system NdO/TIBA/EASC (htiba/ Nd = 25, nci/nNd = 3) for the respective copolymerizations of BD/l-octene and BD/l-dodecene [508]. These authors showed that only small amounts of 1-alkenes are incorporated and that no neighboring 1-alkene moieties are present in the copolymer. The copolymerization parameters have been determined by the method of Kelen-Tiidos rBD = 25 and ri-octene 0 rBD = 18 and r dodecene = 0.1. With increasing amounts of 1-alkene in the monomer feed catalyst activity decreases drastically. The cis- 1,4-contents of the BD units in the copolymer were around 90% and were barely affected by increases of the 1-alkene content in the monomer feed. 

Radical copolymerization of MCM obtained by the reaction of Co(OCOCH3)2 with N,A -bis[4 -(p-vinylbenzoyloxy)salicylaldehyde]-l,2-diaminocyclohexane with St and DVB gave a ternary product of with twenty St and DVB units per MCM unit [90]. 

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). 

Catalysts of the Ziegler type have been used widely in the anionic polymerization of 1-olefins, diolefins, and a few polar monomers which can proceed by an anionic mechanism. Polar monomers normally deactivate the system and cannot be copolymerized with olefins. However, it has been found that the living chains from an anionic polymerization can be converted to free radicals in the presence of peroxides to form block polymers with vinyl and acrylic monomers. Vinylpyridines, acrylic esters, acrylonitrile, and styrene are converted to block polymers in good yield. Binary and ternary mixtures of 4-vinylpyridine, acrylonitrile, and styrene, are particularly effective. Peroxides are effective at temperatures well below those normally required for free radical polymerizations. A tentative mechanism for the reaction is given. 

On the other hand copolymer with a trioxane unit at the cationic chain end (Pi+) may be converted intp P2+ by cleavage of several formaldehyde units. These side reactions change the nature of the active chain ends without participation of the actual monomers trioxane and dioxo-lane. Such reactions are not provided for in the kinetic scheme of Mayo and Lewis. In their conventional scheme, conversion of Pi+ to P2+ is assumed to take place exclusively by addition of monomer M2. Polymerization of trioxane with dioxolane actually is a ternary copolymerization after the induction period one of the three monomers—formaldehyde— is present in its equilibrium concentration. Being the most reactive monomer it still exerts a strong influence on the course of copolymerization (9). This makes it impossible to apply the conventional copolymerization equation and complicates the process considerably. 

It is worth noting that the above-mentioned expressions (4.5-4.7) contain, as particular cases, the results obtained both for binary [54] and ternary [112] copolymerization. However, the general formulae (4.6) and (4.7) for indexes of sequential homogeneity of multicomponent copolymers with any m were not obtained earlier by the author of Refs. [Ill, 113], who investigated this problem theoretically. The approaches applied in the above papers result in cumbersome formulae and are not needed since Eqs. (4.6) and (4.7) can be immediately obtained [6] from the Markov chain theory. 

TERNARY COPOLYMERIZATION AND COPOLYMERIZATION OF MORE THAN THREE MONOMERS... 

Zwitterions formed in this way can mutually combine yielding a ternary, periodic copolymer. An example of this kind of copropagation is the copolymerization of the three units... 

Hou and Wakatsuki [197] reported a cationic ternary system composed of samarocene aluminate Cp 2Sm( j,-Me)2AlMe2 (95) and TIBA and [PhsC] [B(C6Fs)4], showing living mode for the copolymerization of butadiene and styrene... 

When ternary clathrates form, the structural problem concerning the arrangement of guests in the channel remains undefined. From this point of view useful information can be derived just from copolymerization, which acts as an unconventional probe for structural analysis. If we admit that interchange between included monomers is slow, the sequence of monomer units in the copolymer corresponds to that of the guests in the channel before polymerization. The polymer chain behaves as a recording tape or a permanent copy of an otherwise elusive intermolecular arrangement (23). 

When evaluating the results of ternary copolymerizations by means of the Alfrey-Gold-finger scheme, the stationary character of copropagation should be critically established. With non-stationary processes, the uncertainty of interpretation becomes more serious, even when the experimental results agree with theory. 

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