Poly(ethylene succinate) (PES) with weight-average molecular weight above 60,000 g mol-1 was efficiently obtained by enzymatic ring opening polymerization of cyclic oligo(ethylene succinate)s c(ES)n, which in turn were prepared by lipase-catalysed cyclocondensation in solution of dimethyl succinate and ethylene glycol. The methodology was demonstrated to be also applicable to the synthesis of high molecular weight PES-copolyesters containing butylene succinate, e-hydroxycaproate or L-lactate units with a random distribution.
Poly(butylene 2,5-furandicarboxylate-co-succinate) copolyesters (coPBFxSy) have been synthesized by
ring opening polymerization (ROP). Cyclic butylene 2,5-furandicarboxylate and butylene succinate
oligomer mixtures, to be used as monomers for ROP, were prepared by high dilution condensation
and enzymatic cyclization reactions, respectively. Two different catalytic systems, tin dioctanoate and
supported Candida antarctica lipase B (CALB), were used for polymerization. Thus two series of copolyesters
covering the whole range of compositions were prepared and their properties comparatively
examined. In both cases, random copolyesters with compositions close to those used in their respective
feeds were obtained. The influence of composition on reaction kinetics with respect to time and
temperature was evaluated for the two series. Chemically catalyzed ROP rendered copolyesters with Mw
in the ~50 000–65 000 g mol-1 range, whereas values between 15 000 and 45 000 g mol-1 were attained
when the ROP reaction was assisted by CALB. The thermal behavior of coPBFxSy obtained by ROP was
similar to that reported for such copolymers prepared by melt polycondensation. They all start to decompose
above 300 °C and display melting enthalpy and temperatures that decrease with copolymerization,
attaining minimum values when the comonomer contents are approximate to balance. On the
contrary, the glass-transition temperature increased almost linearly with the content of butylene furandicarboxylate
units, covering the whole range of values between those of the two parent homopolyesters.
Small deviations in thermal properties observed between the two series could be attributed to their differences
in molecular weights. Hydrolytic and enzymatic degradation studies revealed that coPBFxSy
became more degradable with increasing content of succinic units, whereas the homopolyester PBF
remained practically unaffected when incubated under similar conditions.
In this work, the synthesis of both c(BF)n and c(BT)n has been performed using the high dilution cyclization technique and these cycles have been then used for the preparation of the homopolyesters PBF and PBT, as well as of a series of poly(butylene 2,5-furandicarboxylate-co-terephthalate) (coPBFxTy) with a wide range of compositions (Fig. 1). Results are compared with those obtained from similar copolyesters prepared by melt polycondensation, which have been recently reported
In this communication we wish to report on the synthesis of PBFxSy copolyesters by ring opening polymerization (ROP) using either organometallic catalysts or enzymes. The ROP of macrocyclic oligomers (MCOs) has been demonstrated to offer significant advantages over the traditional polycondensation method. The synthesis of MCOs of butylene succinate c(BS)n is known from long whereas MCOs of butylene 2,5-furandicarboxylate (c(BF)n) have not been reported until very recently. In this work, the synthesis of c(BF)n and c(BS)n has been performed using high dilution condensation (HDC) and enzymatic cyclization, respectively. Mixtures of dimer to tetramer and dimer to nonamer were obtained for c(BF)n and c(BS)n respectively.
Morales, J.; Martinez de Ilarduya, A.; Muñoz, S. ACS sustainable chemistry & engineering Vol. 4, num. 9, p. 4965-4973 DOI: 10.1021/acssuschemeng.6b01302 Data de publicació: 2016-09-01 Article en revista
A series of poly(butylene 2,5-furandicarboxylate-co-terephthalate) copolyesters coPBFxTy covering the whole range of compositions has been prepared via ring opening polymerization (ROP). Cyclic oligomers of butylene 2,5-furandicarboxylate c(BF)n and butylene terephthalate c(BT)n, both mainly consisting of a mixture of dimer, trimer, and tetramer species, were synthesized by the high dilution condensation method. Random copolyesters with the targeted compositions and weight-average molecular weights within the 55¿000–80¿000 g·mol–1 range were obtained by ROP of c(BF)n/c(BT)n mixtures in periods of time much shorter than those required by melt polycondensation. The thermal properties of these copolyesters were consistent with their compositions and comparable to their isocompositional analogs obtained by polycondensation. A comparative kinetics study of the isothermal crystallization of the homopolyesters and copolyesters differing in composition revealed that the presence of the 2,5-furandicarboxylate units decreased the crystallization rate of PBT. Nevertheless, coPBFxTy copolyesters with moderate contents in BF units were still able to crystallized rapidly from the melt
The preparation of cyclic ethylene and butylene 2,5-furandicarboxylate oligoesters and their conversion to furan-based polyesters poly(ethylene furanoate) (PEF) and poly(butylene furanoate) (PBF) by ring-opening polymerization (ROP) are described. The cyclic oligoesters were obtained in high yields by both high dilution condensation and thermal cyclodepolymerization methods, and they consisted of mixtures of small size species. Cyclic dimer, trimer and tetramer oligoesters were isolated by semipreparative chromatography and found to be crystalline compounds melting within the 140–200 °C range. ROP catalyzed by Sn(Oct)2 of both mixtures and individual species afforded PEF and PBF with weight-average molecular weights between 50,000 and 60,000 g mol-1. Polymerization rate was found to be higher for butylene than for ethylene cyclic oligofuranoates, and also to increase slightly as cycle size decreased. The thermal properties of PEF and PBF prepared by ROP were in full agreement with those reported for these polyesters obtained by melt polycondensation.