Polyesters cyclic

The synthesis of block copolymers of polysaccharides and aliphatic polyesters has also been tried. But, many successful results were not reported because the reactivity of many hydroxyl groups on polysaccharides was an obstacle to the ROP of cyclic polyester or coupling reactions using terminal-activated polysaccharides. Li and Zhang reported the synthesis of maltoheptaose-b-PCL copolymers by ROP... 

Bryant, J. J. L., and Semiyen, J. A., Cyclic polyesters 6. Preparation and characterization of two series of cyclic oligomers from solution ring-chain reactions of polyethylene terephthalate), Polymer, 38, 2475 (1997). 

Hamilton, S. C., Semiyen, J. A. and Haddleton, D. M., Cyclic polyesters 8. Preparation and characterization of cyclic oligomers in six aromatic ester and ether-ester systems, Polymer, 39, 3241 (1998). 

The workhorse polyester is polyethylene terephthalate) (PET) which is used for packaging, stretch-blown bottles and for the production of fibre for textile products. The mechanism, catalysis and kinetics of PET polymerization are described in Chapter 2. Newer polymerization techniques involving the ring-opening of cyclic polyester oligomers is providing another route to the production of commercial thermoplastic polyesters (see Chapter 3). 

Kricheldorf has studied extensively cholesteric polyesters 60 prepared from the mentioned dianhydroalditols even cyclic polyesters from 1 were isolated by a selective extraction of the linear polymers [39]. 

Method of preparing random poly(amide-fe-ester) derivatives through depoly merization/repolymerization of cyclic polyesters then coreacting with lactam derivatives using a nonmetallic carbene catalyst This method for preparing polyester amides is unreported. 

Fig. 43 Three types of cyclic tin initiators for synthesizing cyclic polyesters...

Fig. 50 Synthesis of cyclic polyester using anionic ion-exchange resin...

Tarasova G.I., Fractionation of Cyclic Polyesters. Chemistry and Technology of High-molecular Compounds, Coll., Comp. Teplyakov M.S., Ed. Korshak V.V., Moscow, VINITI, 1973, vol. 4, p. 109. (Rus)... 

All polyester polyols have in their composition a very small quantity of low MW cyclic polyesters. Non-fogging polyesters for the automotive industry were obtained by thin film distillation in high vacuum of finished polyesters. In this way the low MW, volatile species and cyclic oligomers were eliminated [1]. 

During screening studies for antibiotics with pesticidal action, Ando et al. (1971a 1971b) isolated a new antibiotic, tetranactin, from the filter cake of Streptomyces aureus Waksman et Henrici, along with two other structurally related substances. All three compounds belong to the class of macrotetrolide antibiotics. Tetranactin consists of four units of homoactic acid (44) linked to form a cyclic polyester. Its structure determined by NMR and mass spectrometry proved to be... 

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