Polymerization immortal

No separate step to form the enolate is required if an alkylthio TPP is used. High molecular weight polymer with low MWD is formed. The method was first used to polymerize oxiranes. No industrial applications have been reported, possibly due to the initiator expense and its deep red color. Immortal polymerization has been reviewed [57, 58]. 

---

Endo, M., Aida, T., and Inoue, S., Immortal polymerization of e-caprolactone initiated by aluminum porphyrin in the presence of alcohol. Macromolecules, 20, 2982-2988, 1987. 

PO proceeded in a living manner to yield highly regioregular polyethers with narrow MWDs. These authors also developed the immortal polymerization of epoxides where polymers with narrow MWDs were obtained with the number of polymer chains exceeding the number of initial aluminum-porphyrin complexes (Scheme I). The key in the immortal polymerization is a reversible chain transfer, which is much more rapid than the chain propagation. In the presence of an alcohol (R OH) as a chain-transfer reagent, an aluminum-porphyrin complex with a growing species reacts with R OH reversibly, so that the polymerization takes place from all the molecules of aluminum-porphyrin complex and R OH. 

Immortal polymerization of epoxides with la and an alcohol is also accelerated by co-use of bulky Lewis acid 2a. The polymerization of PO with la/2-propanol system ([PO]/[la]/[2-propanol] = 1000/1/49) in the presence of 2a ([PO]/[2a] = 1000/1) proceeds rapidly to achieve 86% conversion in 1.5 h, while the polymerization in the absence of 2a requires 380 h to reach 84% conversion (Table 1). The polyether produced in the presence of 2a has an of 900 gmoP and an MJM of 1.10, which indicates that almost all of la and 2-propanol participate in the initiation of the polymerization. Other protic chain-transfer reagents, such as methanol, benzyl alcohol, and 4-/ r/-butylphenol, are also applicable to the high-speed immortal polymerization to give similar results as 2-propanol. As a substrate, ECH is also employable. Polymerization of ECH ([EGH]/[la]/[2-propanol]/[2a] = 1000/1/49/1) gives a polymer with and/n of 1100gmol close to the value estimated from the conversion and [PO]/([la] + [2-propanol]) ratio, and a narrow M IM of 1.10, while the conversion is lower than the case of PO. 

Keywords Anionic polymerization. Living Polymerization, Immortal polymerization, Metalloporphyrin, Lewis acid... 

Visible Light Mediated Living and Immortal Polymerizations... 

Scheme 8) has been estimated to occur 10-times faster than the propagation reaction (Scheme ) [64]. Immortal polymerization of epoxide is therefore a highly efficient synthetic method to narrow MWD polyethers. Unfortunately, however, a practical problem exists in that the polymerization slows down considerably when a high mole ratio [chain transfer agent]q/[initiator]q such as 49 is applied. 

Fig. 35. Schematic representation of the concept and principle of immortal polymerization. H-Y Protic chain transfer agent M monomer rate constants of chain transfer...

This section describes the Lewis acid promoted immortal polymerization of epoxide by aluminum porphyrin-alcohol systems in the presence of an orga-noaluminum accelerator. 

Table 9. High-speed immortal polymerization of propylene oxide (PO) with the (TPP)AlCl (l,X=Cl)-2-propanol (2-PrOH) system in the presence of methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate (3e) ...

In immortal polymerization, a reversible chain transfer reaction takes place much more rapidly than a propagation reaction, thereby uniformity of the molecular weight of polymer is realized. The successful high-speed immortal polymerization assisted by a Lewis acid, mentioned above, suggests that not only the propagation step (Scheme 7) but also the chain transfer process (Scheme 8) is accelerated by a Lewis acid. 

Living and Immortal Polymerizations of Episulfide Initiated with Zinc Porphyrin [79]... 

Inoue, S. and Aida, T., Catalysts for Living and Immortal Polymerization , in Ring-Opening Polymerization, Carl Hanser Publishers, Munich, 1993, pp. 197-215. 

Very recently, a paper on immortal polymerization [7] has been published. This is a special (and so far rare) kind of polymerization where active centres... 

---