Cyclic derivatives of D-glucose and tartaric acid as building blocks for renewable polyesters

Three series of aromatic copolyesters derived from poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT) and poly(hexamethylene terephthalate) (PHT) have been synthesized by melt polycondensation in which the terephthalate and oxyalkylene units have been partially or totally replaced by monocyclic and bicyclic diacids and diols obtained by derivatization of renewable monomers such as tartaric acid and D-glucose respectively. Another series of aliphatic copolyesters derived from poly(butylene sebacate) has been prepared by both melt polycondensation and enzymatic polymerization in solution where both the sebacate and butylene units have been partially or totally replaced by the bicyclic diacid or diol derived from D-glucose. All series of polyesters and copolyesters were characterized by FTIR and NMR in solution. The chemical composition of the copolyesters was determined by 1H NMR. On the other hand the microstructure, determined by 13C NMR was observed to be at random for all series. The molecular weights determined by intrinsic viscosimetry and gel permeation chromatography (GPC) were high but decreasing when the content of the sugar monomer increased. The thermal properties were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis. It was observed that the thermal stability was not affected when the oxyalkylene unit was the replaced unit, but decreased slightly when the terephthalate unit was replaced one. The new copolyesters showed higher glass transition temperatures than the parent poly(alkylen terephthalate)s, being superiors for the copolyesters obtained from the bicyclic derivative of D-glucose than for the monocyclic derivative of tartaric acid. All copolyesters were less crystalline than the parent homopolyesters, with both melting and enthalpies decreasing with the increased content of the sugar units. The crystalline structure determined by X-ray diffraction was similar to the PET, PBT and PHT polyesters. Finally it was studied the hydrolytic and enzymatic degradability by weight loss, molecular weight determinations and scanning electron microscopy (SEM). All new copolyesters showed enhanced degradability in water and biodegradability.En esta Tesis se han sintetizado mediante reacción de policondensación en masa tres series de copoliesteres aromáticos derivados del poli(etilen tereftalato) (PET), poli(butilen tereftalato) (PBT) y poli(hexametilen tereftalato) (PHT) en los que se han sustituido parcial o totalmente las unidades tereftalicas o las unidades oxialquilénicas por diácidos y dioles cíclicos y bicíclicos obtenidos por derivatización de monómeros de origen natural como son el ácido tartárico y la D-glucosa. También se han sintetizado mediante policondensación en masa y en disolución por vía enzimática una serie de copoliesteres alifáticos derivados del poli(butilen sebacato) en los que las unidades oxibutilénicas y sebácicas se han reemplazado por dioles y diácidos bicíclicos derivados de la D-glucosa. Todas las series se han caracterizado espectroscópicamente mediante FTIR y RMN en disolución. Mediante RMN de 1H se ha determinado la composición de los copolímeros. Por otro lado mediante RMN de 13C se ha estudiado la microestructura de los mismos. Dicho estudio reveló que todos los copolímeros eran al azar. Los pesos moleculares determinados mediante cromatografía de permeabilidad en gel y viscosimetría capilar resultaron ser aceptables, aunque en todos los casos disminuían a medida que aumentaba el contenido del monómero de origen renovable. Las propiedades térmicas se han evaluado mediante calorimetría diferencial de barrido (DSC) y análisis termogravimétrico. Se ha observado que la estabilidad térmica no se ve apenas afectada cuando la sustitución se realiza sobre la unidad oxialquilénica y que por otro lado desciende cuando es la unidad tereftálica la sustituida. Los nuevos copolímeros presentaron temperaturas de transición vítrea superiores, observándose que este aumento era superior en los copolímeros que incorporaban el diol o el diácido bicíclico derivado de la D-glucosa que en los que incorporaban el diol o el diácido monociclico derivado del ácido tartárico. Los copolimeros eran por lo general menos cristalinos, menos cristalizables y con temperaturas de fusión inferiores. La estructura cristalina de los mismos determinada mediante difracción de rayos-X era semejante a la de los homopolimeros PET, PBT y PHT. Se ha estudiado la degradabilidad hidrolitica y la biodegradabilidad de todos ellos mediante medidas de pérdida de peso, pesos moleculares, microscopía electrónica de barrido (SEM), observándose un aumento de ambas propiedades para los nuevos copolímeros

Aromatic Polyesters from Cyclic Diacetalized Glucose

The development of polymers based on monomers from renewable feedstock, and more specifically from carbohydrates, is a steadily growing field of interest because of the properties that can generate these unique structures. They are promising materials with novel technical possibilities and improved properties, such as biocompatibility and biodegradability1,2 2,4:3,5-Di-O-methylidene-D-glucitol is a carbohydrate-based diol suitable for the preparation of linear polycondensates. This compound is readily prepared from Dgluconolactone by acetalization and subsequent reduction.4The fused bicyclic dioxolane rings provide rigidity to the molecule making it an interesting candidate for replacing aromatic rings in conventional aromatic polyesters. A series of copolyesters made of dimethylterephthalate, 1,6-hexanediol and 2,4:3,5-di-O-methylidene-D-glucitol (PHxGlxyT) with gludioxol contents ranging between 5 and 32 mol % were synthesized by melt polycondensation and characterized by NMR and FTIR spectroscopy, GPC and viscosimetry. The copolyesters had a random microstructure and number-average molecular weights ranging from 5,000 to 15,000. The influence of the content in gludioxol on the synthesis results, structure and thermal properties of the novel copolyesters was comparatively evaluated and discussed

Aromatic Polyesters from Cyclic Diacetalized Glucose

The development of polymers based on monomers from renewable feedstock, and more specifically from carbohydrates, is a steadily growing field of interest because of the properties that can generate these unique structures. They are promising materials with novel technical possibilities and improved properties, such as biocompatibility and biodegradability1,2 2,4:3,5-Di-O-methylidene-D-glucitol is a carbohydrate-based diol suitable for the preparation of linear polycondensates. This compound is readily prepared from Dgluconolactone by acetalization and subsequent reduction.4The fused bicyclic dioxolane rings provide rigidity to the molecule making it an interesting candidate for replacing aromatic rings in conventional aromatic polyesters. A series of copolyesters made of dimethylterephthalate, 1,6-hexanediol and 2,4:3,5-di-O-methylidene-D-glucitol (PHxGlxyT) with gludioxol contents ranging between 5 and 32 mol % were synthesized by melt polycondensation and characterized by NMR and FTIR spectroscopy, GPC and viscosimetry. The copolyesters had a random microstructure and number-average molecular weights ranging from 5,000 to 15,000. The influence of the content in gludioxol on the synthesis results, structure and thermal properties of the novel copolyesters was comparatively evaluated and discussed

Aromatic Polyesters from Cyclic Diacetalized Glucose

The development of polymers based on monomers from renewable feedstock, and more specifically from carbohydrates, is a steadily growing field of interest because of the properties that can generate these unique structures. They are promising materials with novel technical possibilities and improved properties, such as biocompatibility and biodegradability1,2 2,4:3,5-Di-O-methylidene-D-glucitol is a carbohydrate-based diol suitable for the preparation of linear polycondensates. This compound is readily prepared from Dgluconolactone by acetalization and subsequent reduction.4The fused bicyclic dioxolane rings provide rigidity to the molecule making it an interesting candidate for replacing aromatic rings in conventional aromatic polyesters. A series of copolyesters made of dimethylterephthalate, 1,6-hexanediol and 2,4:3,5-di-O-methylidene-D-glucitol (PHxGlxyT) with gludioxol contents ranging between 5 and 32 mol % were synthesized by melt polycondensation and characterized by NMR and FTIR spectroscopy, GPC and viscosimetry. The copolyesters had a random microstructure and number-average molecular weights ranging from 5,000 to 15,000. The influence of the content in gludioxol on the synthesis results, structure and thermal properties of the novel copolyesters was comparatively evaluated and discussed

Manual práctico para realizar denuncias ambientales en Ecuador

<p>Manual práctico para realizar denuncias ambientales en Ecuador</p&gt

Bio-based poly(hexamethylene terephthalate) copolyesters containing cyclic acetalized tartrate units

A cyclic acetal of dimethyl l-tartrate (dimethyl 2,3-di-O-methylene l-threarate, Thx) was used as comonomer of dimethyl terephthalate (DMT) in the polycondensation with 1,6-hexanediol (HD) in the melt. Random copolyesters PHTxThxy with contents in tartrate units up to 50% were obtained with satisfactory molecular weights (Mw between 20,000 and 50,000) and dispersities slightly above 2, and without apparent discoloration. The copolyesters started to decompose above 300 °C. The Tg of the copolyesters oscillated between +9 and −9 °C with values steadily decreasing with increasing contents in Thx units. All the copolyesters as well as the homopolyester entirely made of tartrate units were semicrystalline with Tm falling from ∼145 °C for PHT to ∼70 °C for PHThx with intermediate values decreasing as the content in Thx increased. Copolyesters containing up to 30% of tartrate units were able to crystallize from the melt at crystallization rates that were delayed by the presence of tartrate units. The PHT70Thx30 copolyester displayed significant hydrodegradability when incubated in aqueous buffer and also certain biodegradability when subjected to the action of porcine pancreas lipases.Peer ReviewedPostprint (published version

Copolyesters Made from 1,4-Butanediol, Sebacic Acid, and d-Glucose by Melt and Enzymatic Polycondensation

Biotechnologically accessible 1,4-butanediol and vegetal oil-based diethyl sebacate were copolymerized with bicyclic acetalized d-glucose derivatives (Glux) by polycondensation both in the melt at high temperature and in solution at mild temperature mediated by polymer-supported <i>Candida antarctica</i> lipase B (CALB). Two series of random copolyesters (PB_<i>x</i>Glux_<i>y</i>Seb and PBSeb_<i>x</i>Glux_<i>y</i>) were prepared differing in which d-glucose derivative (Glux diol or Glux diester) was used as comonomer. The three parent homopolyesters PBSeb, PBGlux, and PGluxSeb were prepared as well. Both methods were found to be effective for polymerization although significant higher molecular weights were achieved by melt polycondensation. The thermal properties displayed by the copolyesters were largely dependent on composition and also on the functionality of the replacing Glux unit. The thermal stability of PBSeb was retained or even slightly increased after copolymerization with Glux, whereas crystallinity and melting temperature were largely depressed. On the contrary, the glass-transition temperature noticeably increased with the content in Glux units. PGluxSeb distinguished in displaying both <i>T</i>_g and <i>T</i>_m higher than PBSeb because a different crystal structure is adopted by this homopolyester. The hydrolytic degradability of PBSeb in water was enhanced by copolymerization, in particular, when biodegradation was assisted by lipases