Oxazoline Saegusa

Certain combinations of nucleophiles and electrophiles undergo polymerization without the need for initiator [Culbertson, 2002 Kobayashi and Saegusa, 1985 Kobayashi and Uyama, 2002 Saegusa, 1977, 1979, 1981]. The polymerization, referred to as zwitterion polymerization, proceeds via zwitterion intermediates. For example, polymerization between 2-oxazo-line and P-propiolactone involves nucleophilic attack of 2-oxazoline on P-propiolactone to form the dimer zwitterion LXXXIX, which reacts with itself to form the tetramer zwitterion LXXXX. The latter reacts with itself and with LXXXIX to form octamer and hexamer... 

A very recent paper by Saegusa, 7) describes a method of synthesizing polyoxyethylene macromonomers bearing a polymerizable heterocycle at the chain end. Here again the method involves initiation of the oxirane polymerization by means of an alcoholate (derived from 2-p-hydroxyphenyl)-oxazoline). As metalation agent butyllithium, was used since lithium alcoholates are not very reactive towards oxirane. Indeed, the macromonomers obtained exhibit very low degrees of polymerization. Deactivation was performed with methyl iodide ... 

According to Saegusa et al. [13], linear polyamines (PEI and PPI) were synthesized starting from oxazolines or 1,3-oxazines with subsequent hydrolysis or methylation, respectively [11]. The degree of polymerization was varied between 10 and 20. Here we present results of investigations on PEI withPn= 8-9 and on PPI withP = 12 - 13. 

In the cationic polymerization several systems were studied, in which both covalent and ionic growth have been simultaneously studied. For the first time the covalent growth was described for oxazolines by Saegusa (23). 

Saegusa T, Ikeda H, Fujii H. Isomerization polymerization of 2-Oxazoline. I. Preparation of unsubstituted 2-Oxazoline polymer. Polym J 1972 3 35-39. 

Saegusa et al. invented a new method of preparing linear polyEI67). This method involves the izomerization polymerization of cyclic iminoethers (cf. Chap. 12), followed by alkaline hydrolysis, leading to perfectly linear crystalline polymers. Using oxazoline (x = 2) and oxazine (x = 3), polyEI and poly(trimethyleneamine) were prepared ... 

Commercial polyethyleneimine 1 is prepared by ring-opening polymerization of ethyleneimine [Eq. (6—1)]. This polymer is a highly branched, relatively compact, water-soluble macromolecule, and approximately contains 25% primary, 50% secondary, and 25% tertiary nitrogen atoms 112). The averse structure is therefore represented as i ven below. Recently, Saegusa et al. succeeded in preparing linear, crystalline polyethyleneimine by polymerization of 2-oxazoline and subsequent hydrolysis [Eq. (6-2)] (ii5). 

Poly(iV-alllinear poly(isopropylenimine) (PiPI) back in 1974 based on the hydrolysis of poly(2,5-dimethyl-2-oxazoline), prepared by living CROP of the corresponding 2-oxazoline monomer. The PiPI is of interest as it is the simplest PAI with a chiral main-chain structure. Even though this specific example yielded a racemic PiPI, this synthetic procedure also provides access to a PiPI with controlled stereochemistry if... 

Figure 22-8. Number-average degree of polymerization as a function of conversion, w, for the joint polymerization of a 1 1 mixture of 2-oxazoline and jS-propiolactone to alternating copolymers at 25° C in acetonitrile ( ) and in dimethyl formamide at 40° C (O). After practically complete conversion in stage I, the same amount and concentration of monomers was added for stage II. The degrees of polymerization here refer to the repeating units, and not to the monomeric units. , = Theoretical curve for a true polycondensation. (After data from T. Saegusa, Y. Kimura, and S. Kobayashi.)...

Kobayashi S, Kaku M, Saegusa T (1988) Grafting of 2-oxazolines onto cellulose and cellulose diacetale. Macnnnolecules 21(7) 1921—1925... 

Recently both the research group of Saegusa and Kobayashi, and our research group became engaged in the use of the two functional groups of m- and p-(hydroxyphenyl)-2-oxazolines for the development of new functional pol3rmers. It is the purpose of this paper to review the work of both groups in this area. 

Poly(El) and related compounds has become important in industrial, agricultural, and biological fields. Conventional poly(El) [l] obtained from ethylenimine (El) is, however, amorphous, or sticky liquid if it is a low molecular weight material, because many branches along the polymer chain suppress crystallization (l-5). On the other hand, poly(El) [II] obtained from 2-oxazoline, which was first prepared by Saegusa et al. (6), is highly crystalline owing to the linear structure. 

Forder, C., Patrickios, C.S., Billingham, N.C. and Armes, S.P. (1996) Novel hydrophilic-hydrophilic block copolymers based on poly(vinylalcohol). Chem. Commun., 7, 883-884. Saegusa, T. and Ikeda, H. (1973) Preparation of block copolymer of 2-oxazoline and butadiene. Macromolecules, 6, 805-809. 

Guinot, P., Bryant, L., Chow, T.Y., and Saegusa, T. (1996) Random and block 2-alkyl-2-oxazolines telecheUc macromonomers. Macromolecular Chemistry and Physics, 197,1-17. 

Miyamoto, M., Naka, K., Tokumizu, M., and Saegusa, T. (1989) End capping of growing species of poly(2-oxazoline) with carboxylic acid A novel and convenient route to prepare vinyl- and carboxy-tenninated macromonomers. 

Ring-opening polymerization evidently constitutes another method for the synthesis of regular internal structures [8]. In order to obtain a strictly linear polyampholyte with a repeating unit as small as possible, A -alkyl substituted ethylenimines have to be used, since conventional unsubstituted polyethylenimine has a highly branched structure. The synthesis of strictly linear polyethylenimine has, however, been described recently by Saegusa and coworkers by isomerization polymerization of 2-oxazoline [9]. 

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