Copolymerization of aziridines

Aziridines represent another group of cyclic monomers that are capable of copolymerizing with C02 to potentially provide useful polymeric materials, namely polyurethanes. Early studies of the reactions of aziridines with C02 led to the production of cyclic urethanes [72] and polymers [73, 74], but the polymeric product was shown to consist of both urethane and amine linkages, as depicted in Equation 8.7. However, because the rate of homopolymerization of aziridines is similar to that of the copolymerization of aziridines and C02, the urethane linkages were limited to -30%. 

IHA Ihata, 0., Kayaki, Y., and Ikariya, T., Aliphatic poly(methane-amine)s synthesized by copolymerization of aziridines and supercritical carbon dioxide. Macromolecules,... 

The ring-opening copolymerization of propylene oxide and carbon monoxide forms the polyester poly(p-hydroxybutyrate) (PHA, Equation 17.52). The physical and mechanical properties of some PHAs are similar to those of isotactic polypropylene. This polymerization was first reported by Furukawa and co-workers in 1965, and more recent studies have been reported by Osakada, Rieger, and Alper. These polymerizations have been conducted with Co2(CO)j and additives. The combination of Co2(CO)j, a 1,10-phenan-throline derivative, and benzyl bromide afforded polyester with an value of 19.4 kg/ mol and M /M of 1.41. In addition to propylene oxide, 1,2-epoxybutane was successfully copolymerized with CO to yield the corresponding poly(3-hydrox5 entanoate) with an value of 16.7 kg/mol and a M /M of 1.28. The role of benzyl bromide is unclear. Related copolymerizations of aziridines and CO to form polyamides have also been reported. Polymer values as high as 27.5 kg/mol have been reported, and tjqjical M /M values varied from 1.11 to 1.64. 

Scheme 6.26 Copolymerization of aziridines with CO2. Reprinted from [181]...

Watanabe, N., Sakai, M., SakaMbara, Y., and Uchino, N. (1970) Polymerization and copolymerization of aziridine derivatives possessing carbon-carbon double bond. Kogyo Kagaku Zasshi, 73,1056-1058. 

Copolymers of carbon monoxide, carbon dioxide, sulfur dioxide or carbon disulfide are frequently formed in combination with oxiranes, thiiranes or aziridines. Copolymerization of carbon monoxide and ethylenimine was carried out under radiation and the formation of 3-nylon was observed238. ... 

Copolymerization of Epoxides and Aziridines with Carbon Monoxide... 

Copolymerization of carbon dioxide possibly also belongs to this class of polymerizations. Carbon dioxide copolymerizes with epoxides to polyanhydrides, with aziridines to polyurethanes, and with vinyl ethers to poly-ketoethers, i.e.. 

Carbon dioxide is an interesting synthetic feedstock, it can be copolymerized with heterocycles, such as epoxides, aziridines, and episulfides. In 1969, Inoue reported the zinc catalyzed sequential copolymerization of carbon dioxide and epoxides as a new route to polycarbonates (5,15). The reaction is shown in Figure 1.1. 

Polyurethanes can also be obtained via copolymerization of cyclic amines such as aziridines (analogous to epoxides) and azetidines (analogous to oxetanes) with CO2, according to Scheme 6.26 [190, 191]. 

These resins were prepared by the method as described by Manecke and Heller based on the copolymerization of a bis-aziridine with a monofunctional one [16], namely 1,4-bis (j3-propyleniminoethyl)benzene and methyl l-(2-methylaziridinyl)acetate, in a molar ratio 0.18 to 0.27, in the presence of diethylsulfate as catalyst. The scheme of the reaction is as follows ... 

As mentioned in the experimental part, these resins were synthesized by copolymerization of a bis-aziridine with methyl l-(2-methylaziridinyl)acetate. The resins were saponified, transformed into their amphoteric ionic form, and sieved in order to obtain particle sizes with a diameter 0.25—0.50 mm adequate for the complexation experiments. These resins permit the determination of the ionic binding capacity of PPG i.e. the ratio of the number of actually bound metal ions to the theoretical number, based on the analytical composition of the resins and assuming a coordination number four. 

Sulfur dioxide and carbon dioxide, either of which is unable to homopolymerize, are known to easily give copolymers with cyclic compounds. In this way C02 copolymerizes cationically with aziridines 90) ... 

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