Anionic ring‐opening polymerization of adipic anhydride initiated by potassium poly(ethylene glycol)ate

Abstract

Poly(adipic anhydride) (PAA) was prepared by the ring-opening polymerization of adipic anhydride (AA) initiated by potassium poly(ethylene glycol)ate. The effects of various factors, such as the amount of initiator, concentration of the monomer, reaction time and temperature, and polarity of the solvent on the polymerization were investigated. The crude polymerized product was a mixture of PAA homopolymer and poly(ethylene glycol)-poly(adipic anhydride) block copolymer, as confirmed by 1 H-NMR and gel permeation chromatography. Chain-transfer reactions occurred intensively for the AA polymerization in both the nonpolar solvent toluene and the polar solvents CHCl 3 and tetrahydrofuran, which predominantly determined the molecular weight and the monomer conversion for the polymerized product. The lower monomer conversion in toluene was ascribed to a lower livingness for the initiator in the nonpolar solvent when compared with other two, polar solvents.

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“…The random copolymerization of ε‐CL and AA was considered as a strategy to increase the molecular weight of PAA and to lower the crystallinity of PCL. However, the precipitation of the synthesized polymer from THF was observed; this was similar to the ring‐opening polymerization of AA initiated by PEGOK 10. The white powder obtained was characterized by FTIR [Fig.…”

“…ε‐CL, D,L ‐LA, and AA can be polymerized quickly in the presence of PEGOK 6–10. Furthermore, biodegradable block copolymers based on D,L ‐LA and ε‐CL have been prepared with PEGOK as an initiator 9.…”

“…AA was prepared as described elsewhere 2, 3, 10, 11. In a typical reaction, a solution of 30 g of adipic acid in 300 mL of acetic anhydride in a dry reaction vessel equipped with a reflux condenser and a magnetic stirrer was heated for 4 h while nitrogen was continuously bubbled through the solution.…”

“…In addition, the corresponding alcoholate has been shown to be an alternative to SnOct 2 in the ring‐opening polymerization of lactones and lactides because of its low toxicity. In our recent studies, the macroinitiator potassium poly(ethylene glycol)ate (PEGOK) has successfully been used in the ring‐opening polymerization of D,L ‐lactide ( D,L ‐LA), ε‐CL, and AA 6–10. As an extension of that work, this article mainly deals with the synthesis of block copolymers based on ε‐CL and AA.…”

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“…Block copolymers of adipic anhydride with ecaprolactone (Ropson et al, 1997) and trimethylene carbonate (Edlund and Albertsson, 1999) have been formed by this synthetic route. Deng et al (2003) have cleverly surmounted the chemistry limitation by using potassium poly(ethylene glycol)ate as a macroinitiator, thereby synthesizing a poly(adipic acid-Moc&-ethylene glycol) copolymer. The same group has also recently studied the use of dibutylmagnesium as an alternative initiator .…”