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ABSTRACT Cyclic oligo(butylene 2,5-furandicarboxylate) and ɛ-caprolactone were copolymerized in bulk at 130-150 °C by enzymatic ring opening polymerization using CALB as catalyst. Copolyesters within a wide range of compositions were thus synthesized with weight-average molecular weights between 20,000 and 50,000, the highest values being obtained for equimolar or nearly equimolar contents in the two components. The copolyesters consisted of a blocky distribution of the ɛ-oxycaproate (CL) and butylene furanoate (BF) units that could be further randomized by heating treatment. The thermal stability of these copolyesters was comparable to those of the parent homopolyesters (PBF and PCL), and they all showed crystallinity in more or less degree depending on composition. Their melting and glass-transition temperatures were ranging between those of PBF and PCL with values increasing almost linearly with the content in BF units. The ability of these copolyesters for crystallizing from the melt was evaluated by comparative isothermal crystallization and found to be favored by the presence of flexible ɛ-oxycaproate blocks. These copolyesters are essentially insensitive to hydrolysis in neutral aqueous medium but they became noticeably degraded by lipases in an extend that increased with the content in CL units. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 290-299 [ABSTRACT FROM AUTHOR]

Abstract: Nanocomposites of poly(hexamethylene terephthalate) (PHT) and montmorillonite organo-modified with alkylammonium cations bearing two primary hydroxyl functions, i.e., Cloisite® 30B (CL30B) were synthesized. Organoclay incorporation was performed either by dispersion in the PHT matrix via melt blending or by in situ ring-opening polymerization of hexamethylene terephthalate cyclic oligomers c(HT). An additional procedure combining the two methods, preparation of a highly enriched inorganic “PHT–CL30B” nanohybrid masterbatch by in situ ring-opening polymerization and blending of the masterbatch with additional PHT was explored. The obtained nanocomposites contain 3% (w/w) of inorganics and displayed a mixture of intercalated morphology and exfoliated nanolayers as evidenced by X-ray diffraction and transmission electron microscopy. The nanocomposite obtained by the masterbatch technique exhibited a higher degree of exfoliation and displayed slightly higher glass transition temperatures, better mechanical properties and higher flame resistance. The improved results achieved with the “masterbatch route” are a consequence of the reactions occurring between the nanocomposite constituents allowing for the grafting of PHT chains onto the organoclay surface. [Copyright &y& Elsevier]

Block and graft poly(macrolactone)‐poly(α‐amino acid) copolymers made of l‐alanine and pentadecalactone or globalide respectively, are prepared. A sequential ring‐opening polymerization (ROP) copolymerization route consisting of two stages, the first devoted to the preparation of the amino‐functionalized poly(macrolactone) and the second to the amino‐initiated polymerization of l‐alanine N‐carboxyanhydride (Ala‐NCA), is followed for the synthesis of both types of copolymers. Poly(l‐alanine) segment lengths are accurately controlled by adjusting the macroitiator/Ala‐NCA ratio used for reaction in the second stage. Block copolymers are semicrystalline with the poly(pentadecalactone) block crystallizes well in a separate phase and the poly(α‐amino acid) block arranged in either the α‐helical or β‐sheet structure in a ratio that is depending on composition and temperature. Graft copolymers are amorphous but with the poly(α‐amino acid) side chains arranged in a more or less regular conformation. Nanoparticles with a diameter of around 300 nm and moderate positive Z‐potential can be obtained from the block copolymers by self‐assembling in water whereas graft copolymers are unable to render recognizable objects of nanometer‐dimension under similar conditions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: Poly(hexamethylene terephthalate) was cyclo-depolymerized in solution by heating to yield a fraction of cyclic oligomers of hexamethylene terephthalate (c(HT)2–5) with a content around to 95% in dimer to pentamer. Ring-opening polymerization in the melt of c(HT)2–5, either neat or in mixtures with ε-caprolactone (CL) covering a range of HT/CL ratios from 9/1 to 1/9 was carried out to produce polyesters with molecular weights above 30,000 in high yields. The copolyesters had a comonomer composition according to the feed and the microstructure evolved from random to blocky as the content in CL increases. The thermal and mechanical properties of the copolyesters were evaluated for a variety of compositions. Results obtained in this work were compared to those previously obtained by us in the ring-opening copolymerization of CL with a cyclic oligomeric fraction enriched in hexamer and heptamer (c(HT)6–7). Although the polyesters resulting from the use of these two fractions were similar, significant differences were found in polymerization rate evidencing a lower reactivity of c(HT) n with decreasing values of n. [Copyright &y& Elsevier]

In this paper, the preparation of PBS- ran -PCL copolyesters by enzymatic ring opening polymerization is presented for the first time. The copolyesters were produced in a wide composition range and free of metallic contaminants, so they may be regarded as potential biomaterials. The copolymers have been characterized by proton and carbon nuclear magnetic resonance ( 1 H and 13 C NMR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), polarized light optical microscopy (PLOM) and wide angle X-ray scattering (WAXS). The PBS- ran -PCL copolyesters were able to crystallize in the entire composition range and displayed a pseudo-eutectic region. Most copolymers away from the pseudo-eutectic region exhibited a single crystalline phase (PBS-rich or PCL-rich crystalline phase), while within the pseudo-eutectic region the copolymers were double crystalline. Observations by PLOM, during isothermal crystallization showed that both nucleation density and spherulitic growth rate of the copolyesters are determined by the component that constitutes the majority phase. WAXS studies revealed that d spacings of selected crystallographic planes depend on composition. Therefore, both DSC and WAXS results suggest that the copolymers are probably isodimorphic, as the PBS-rich crystalline phase may contain small inclusions of PCL co -units, while the PCL-rich crystalline domains may also contain a minor quantity of PBS co -units inside. [ABSTRACT FROM AUTHOR]

ABA triblock copolyesters were synthesized by ring-opening polymerization (ROP) of l -lactide in solution initiated by a telechelic d -glucose-based polyester macroinitiator. The macroinitiator with a number-average molecular weight about 2500 g mol −1 was synthesized by non-stoichiometric polycondensation in the melt of 2,4:3,5-di- O -methylene- d -glucitol and dimethyl succinate. Two triblock copolyesters of M n ranging between ∼6000 and ∼9000 g mol −1 , and differing in the length of the polylactide blocks were prepared. These copolyesters started to decompose when heated at ∼220 °C and degraded slowly upon aqueous incubation under physiological conditions. They did not display any perceivable crystallinity and showed a single glass transition temperature ( T g ) around 60 °C with the higher value corresponding to the larger content in glucitol units. The copolyesters were able to form nanoparticles with average diameters of ∼100–130 nm and satisfactory dispersity. The effect of the block lengths on size, ζ -potential values and physical stability of the nanoparticles was evaluated. A molecular dynamics simulation study allowed modelling the two-phase structure of the nanoparticles and evidenced the preference of the glucose-based block to be peripherally located. [ABSTRACT FROM AUTHOR]