Scheme 2. (a) Lactide Polymerization Coinitiated by Carbohydrates; (b) Copolymerization of Lactone Derived from D-Gluconolactone and ε-Caprolactone (CL) Scheme 3. Polyesters Based on Pentitols and Pentaric Acid Scheme 4. Protein-Resistant Polyesters Based on Galactitol and D-Mannitol Scheme 5. Polyesters Based on L-Tartaric Acid Derivatives Scheme 6. PBS Copolyesters Based on L-Tartaric Acid Derivatives Scheme 7. Erythritol-Based Polyesters Containing Triazol Rings

2,4:3,5-Di-O-methylene-D-mannitol, abbreviated as Manx, is a D-mannitol-derived compound with the secondary hydroxyl groups acetalized with formaldehyde. The bicyclic structure of Manx consists of two fused 1,3-dioxane rings, with two primary hydroxyl groups standing free for reaction. A homopolyester made of Manx and dimethyl terephthalate as well as a set of copolyesters of poly(butylene terephthalate) (PBT) in which 1,4-butanediol was replaced by Manx up to 50% were synthesized and characterized. The polyesters had M w in the 30 000−52 000 g mol −1 range and a random microstructure and were thermally stable up to nearly 370°C. They displayed outstanding high T g with values from 55 to 137°C which steadily increased with the content in Manx. Copolyesters containing up to 40% of Manx were semicrystalline and adopted the crystal structure of PBT. Their stress− strain parameters were sensitively affected by the presence of carbohydrate-based units with elongation at break decreasing but tensile strength and elastic moduli steadily increasing with the degree of replacement.

The dimethyl ester of 2,3:4,5-di-O-methylene-galactaric acid (Galx) was made to react in the melt with 1,n-alkanediols HO(CH 2 ) n OH containing even numbers of methylenes (n from 6 to 12) to produce linear polycyclic polyesters. Two sets of poly(alkylene 2,3:4,5-di-O-methylenegalactarate) polyesters (PE-nGalx) with weight-average molecular weights in the ∼5000À10000 and ∼35000À45000 ranges were obtained using TBT and DBTO catalysts, respectively. For comparative purposes a set of poly(alkylene adipate) polyesters (PE-nAd) was also synthesized with molecular weights in the higher range using a similar procedure. The thermal stability of PE-nGalx was greater than that of PE-nAd although it notably decayed as molecular weight decreased. The replacement of Ad by Galx in the polyesters caused increases in T g of up to 70 °C, and almost doubled the tensile mechanical parameters. All PE-nGalx were semicrystalline but only those made from 1,12-dodecanediol were able to crystallize from the melt with a crystallization rate that diminished as the molecular weight increased. In general, the galactarate containing polyesters displayed higher solubility and wettability than polyadipates, they hydrolyzed faster and exhibited comparable sensitivity to the action of lipases. ' NOTE ADDED AFTER ASAP PUBLICATIONThis article posted ASAP on May 25, 2011. It was discovered that the bicyclic acetal was not 2,4:3,5 as first formulated, but rather 2,3:4,5. This change affects the abstract, paragraph 3 in the Introduction, paragraphs 1, 3, 4, 5, 6, 7 in the Experimental Section, paragraphs 1, 5, 12 in the Results and Discussion, and the Conclusions paragraph. Other changes include the Table of Contents graphic, Figures 1, 2, 3, 11, 12, and the Supporting Information file. The corrected version posted on June 23, 2011.

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The diacetalized diol 2,4:3,5-di-O-methylene-D-glucitol (Glux), a bicyclic compound derived from D-glucose, was used as a comonomer of 1,6-hexanediol in polycondensation in the melt with dimethyl terephthalate to produce a set of aromatic copolyesters (PHxGluxyT) with Glux contents ranging from 5 to 32%-mole. These sustainable copolyesters had molecular weights within the 12,000 to 45,000 g mol-1 range, and polydispersities between 2.0 and 2.5. They all had a random microstructure and displayed slight optical activity. PHxGluxyT showed a good thermal stability and were semicrystalline with both crystallinity degree and crystallization rate decreasing as the content in Glux increased. Conversely, Tg increased with the incorporation of Glux going from 8 oC in PHT to near 60 oC in the copolyester containing 32%-mole Glux. Compared to PHT, PHxGluxyT copolyesters showed not only an enhanced susceptibility to hydrolysis but also an appreciable biodegradability in the presence of lipases.Ministerio de Economía y Competitividad MAT2009-14053-C02AGAUR 2009SGR146

Random poly(hexamethylene terephthalate-co-galactarate)\ud s and poly(dodecamethylene terephthalate-co-galactarate)\ud s copolyesters covering the whole range of compositions\ud were obtained with weight-average molecular weights of\ud 30,000–50,000 g mol 1 by melt polycondensation. They were\ud thermally stable above 300 C, and displayed Tg in the þ20 to 20\ud C range with values steadily decreasing with the content in galactarate\ud units. All the copolyesters were semicrystalline with Tm\ud between 50 and 150 C and those made from dodecanediol were\ud able to crystallize from the melt at a crystallization rate depending\ud on composition. Copolyesters containing up to 50% of galactaric\ud units retained the crystal structure of their respective polyterephthalate\ud homopolyesters, whereas they adopted the structure of\ud the respective polygalactarates when the content in Galx units\ud reached 70%. Stress-strain essays revealed decay in the mechanical\ud parameters as the aromatic units were replaced by Galx. Incubation\ud in aqueous buffer revealed that hydrolysis of the\ud polyesters were largely enhanced by copolymerization and evidenced\ud the capacity of the Galx unit for making aromatic polyesters\ud susceptible to biodegradation. A detailed NMR analysis\ud complemented by SEM observations indicated that hydrolysis\ud took place by preferred splitting of galactarate ester bonds with\ud releasing of alkanediol and Galx-diacid.Peer ReviewedPostprint (published version