Synthesis of Poly(carbonate-polyesters)

Biocatalytic methods to poly(carbonate-polyesters) were developed that have important advantages relative to conventional chemical routes (Jiang et al, 2007; Zini et al, 2008). Synthesis of random aliphatic poly(carbonate-co-esters) from conventional monomer feeds (e.g., diethyl carbonate, aliphatic diester and diol) were performed under mild reaction conditions (60-to-95 ºC) using an immobilized metal-free enzyme catalyst (Jiang et al, 2008; Zini et al, 2008). These polymers were prepared with excellent control of end-group structure as well as with low polydispersity (≤ 2.0). The ratio of carbonate and ester repeating units is adjustable over a wide range, i.e. from 15:85 to 85:15 mol/mol. The synthesized, random poly(butylenecarbonate-co-butylenesuccinate), P(BC-co-BS), copolymers possess higher thermal stability than poly(butylenecarbonate), but are less thermally stable than poly(butylenesuccinate). The morphology of these copolymers varied from semicrystalline to near completely amorphous as a function of the polymer composition selected. Results of process-variable studies demonstrated effective methods to control the end group structures of the copolymers, and allowed preparation of predominately hydroxyl-terminated macromers. Aliphatic poly(carbonate-co-ester) diols are important intermediates for production of new polyurethanes with tunable properties.

Scheme 8. Lipase-catalyzed synthesis of poly(ester-carbonates): two-stage process for terpolymerization of DEC, aliphatic diester, and diol.

References

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