Bio-based polyesters from cyclic monomers derived from carbohydrates

Polyesters are extremely versatile polymers which can be used in a wide variety of applications ranging from high performance materials to recyclable and degradable polymers. The preparation of polyesters from renewable feedstock is currently receiving increasing attention in both industrial and academic research. This Thesis is specifically addressed to the development of aliphatic and aromatic polyesters with enhanced properties made from carbohydrate-based cyclic acetalized monomers, i.e. a bicyclic acetalized aldaric acid derived from D-galactose, bicyclic acetalized alditols derived from D-galactose and D-mannose, and a cyclic acetalized alditol derived from L-tartaric acid. The novel aliphatic polyesters derived from bicyclic acetalized galactaric acid and D-mannitol, which are biodegradable materials, are distinguished by presenting an enhanced rigidity compared to the aliphatic polyesters commonly used so far, which invariably influences their whole thermal and mechanical behavior. Bicyclic acetalized carbohydrate-based compounds are also used as comonomers in the preparation of random poly(alkylene terephthalate) copolyesters by melt polycondensation (MP). Since linear a,¿-alkanediols with varying length are employed, and the copolymerizations with bicyclic monomers are carried out for a wide range of compositions, a detailed structure-properties study is described. The effect of the presence of the carbohydrate-based comonomer on thermal and mechanical properties of the polyester is largely dependant on which unit, the diol or the diacid, is replaced. The incorporation of acetalized alditols increases the thermal stability, the glass-transition temperature and the mechanical modulus. On the contrary, these parameters are diminished when the terephthalate units are replaced by bicyclic acetalized galactaric acid. Also the hydrolytic and enzymatic degradability depends on the units introduced into the polyester backbone. The incorporation of cyclic acetalized carbohydrate-based alditols into the amorphous phase of poly(butylene terephthalate) by the solid-state modification (SSM) technique is reported, which leads to increases in glass-transition temperature. The resulting SSM-prepared copolyesters have a unique block-like chemical microstructure that endows them with superior thermal properties when compared to their random counterparts obtained by MP. Given the structural proximity between isosorbide and bicyclic acetalized alditols, as well as their common potential use as polycondensation monomers, a comparative evaluation of their suitability for the synthesis of aromatic polyesters is carried out in this Thesis. The greater facility of bicyclic acetalized alditols compared to isosorbide to react under the conditions employed is highlighted. Also the influence of the symmetry and stiffness of the bicyclic structure on the thermal behavior of the copolyesters is discussed.Los poliésteres son polímeros extremadamente versátiles que se usan en una amplia variedad de aplicaciones, desde materiales de altas prestaciones a polímeros reciclables o degradables. La preparación de poliésteres a partir de fuentes renovables genera cada vez más interés, tanto en la industria como en el mundo académico. En esta Tesis se emplean fuentes naturales para desarrollar nuevos poliésteres alifáticos y aromáticos con propiedades mejoradas, a partir de monómeros cíclicos derivados de carbohidratos, i.e. un ácido aldárico acetalizado bicíclico derivado de D-galactosa, alditoles acetalizados bicíclicos derivados de D-galactosa y D-manosa, y un alditol acetalizado cíclico derivado de ácido L-tartárico. Los nuevos poliésteres alifáticos derivados de ácido galactárico y D-mannitol acetalizado bicíclico, que son materiales biodegradables, destacan por presentar una rigidez mejorada respecto a los poliésteres alifáticos comúnmente usados hasta ahora, hecho que influencia invariablemente sus propiedades térmicas y mecánicas. También se reporta el uso de monómeros bicíclicos acetalizados derivados de carbohidratos para la preparación de copoliésteres poli(alquilen tereftalato)s con microestructura al azar, mediante policondensación en fundido (MP). Se emplean α,ω-alcanodioles lineales con diferentes longitudes, y las copolimerizaciones con monómeros bicíclicos se llevan a cabo en un amplio rango de composiciones, lo que permite desarrollar un estudio estructura-propiedades detallado. El efecto de la unidad renovable en las propiedades térmicas y mecánicas del poliéster depende de qué unidad no renovable, diol o diácido, reemplaza. La incorporación de alditoles acetalizados aumenta la estabilidad térmica, la temperatura de transición vítrea y el módulo elástico. Por contra, estos parámetros disminuyen cuando las unidades tereftálicas se reemplazan por ácido galactárico acetalizado bicíclico. Las unidades renovables introducidas afectan también a la degradabilidad hidrolítica y enzimática de los poliésteres. Mediante la técnica de modificación en estado sólido (SSM), se incorporan alditoles cíclicos acetalizados a la fase amorfa del poli(butilen tereftalato), lo cual conlleva a un aumento de su temperatura de transición vítrea. Los copoliésteres resultantes presentan una microestructura en bloques, que los dota de propiedades térmicas superiores respecto a los copoliésteres análogos con microestructura al azar preparados mediante MP. En esta Tesis también se comparan las características y propiedades del monómero isosorbide y los alditoles acetalizados bicíclicos para la síntesis de poliésteres aromáticos, debido a su proximidad estructural, así como a su uso potencial como monómeros en policondensaciones. Se destaca la mayor facilidad de reacción en las condiciones empleadas de los alditoles acetalizados bicíclicos comparados con isosorbide. También se estudia la influencia de la simetría y rigidez de la estructura bicíclica en las propiedades térmicas de los copoliésteresEls polièsters són polímers extremadament versàtils que s’usen en una àmplia varietat d’aplicacions, des de materials d’altres prestacions a polímers reciclables o degradables. La preparació de polièsters a partir de fonts renovables genera cada vegada més interès, tant a la indústria com al món acadèmic. En aquesta Tesi s’utilitzen fonts naturals per desenvolupar nous polièsters alifàtics i aromàtics amb propietats millorades, a partir de monòmers cíclics derivats de carbohidrats, i.e. un àcid aldàric acetalitzat bicíclic derivat de D-galactosa, alditols acetalitzats bicíclics derivats de D-galactosa i D-manosa, i un alditol acetalitzat cíclic derivat d’àcid L-tartàric. Els nous polièsters alifàtics derivats d’àcid galactàric i D-mannitol acetalitzat bicíclic, que són materials biodegradables, destaquen per presentar una rigidesa millorada respecte als polièsters alifàtics comunament usats fins al dia d’avui, fet que influencia invariablement les seves propietats tèrmiques i mecàniques. També es reporta l’ús de monòmers bicíclics acetalitzats derivats de carbohidrats per a la preparació de copolièsters poli(alquilen tereftalat)s amb microestructura a l’atzar, mitjançant policondensació en estat fos (MP). S’utilitzen α,ω-alcanodiols lineals de diferents longituds, i les polimeritzacions amb monòmers bicíclics es duen a terme en un ampli rang de composicions, fets que permeten desenvolupar un estudi estructura-propietats detallat. L’efecte de la unitat renovable en les propietats tèrmiques i mecàniques del polièster depèn de quina unitat no renovable, diol o diàcid, substitueix. La incorporació d’alditols acetalitzats augmenta l’estabilitat tèrmica, la temperatura de transició vítria i el mòdul elàstic. D’altra banda, aquests paràmetres disminueixen quan les unitats tereftàliques es substitueixen per àcid galactàric acetalitzat bicíclic. Les unitats renovables introduïdes afecten també la degradabilitat hidrolítica i enzimàtica dels polièsters. Mitjançant la tècnica de modificació en estat sòlid (SSM), s’incorporen alditols cíclics acetalitzats a la fase amorfa del poli(butilen tereftalat), fet que augmenta la seva temperatura de transició vítria. Els copolièsters resultants presenten una microestructura en blocs, que els proporciona unes propietats tèrmiques superiors respecte als copolièsters anàlegs amb microestructura a l’atzar preparats mitjançant MP. En aquesta Tesi també es comparen les característiques i propietats del monòmer isosorbide i els alditols acetalitzats bicíclics per a la síntesi de polièsters aromàtics, degut a la seva proximitat estructural, així com el seu ús potencial com a monòmers en policondensacions. Es destaca la major facilitat de reacció en les condicions estudiades dels alditols acetalitzats, i també s’avalua la influència de la simetria i la rigidesa de l’estructura bicíclica en les propietats tèrmiques dels copolièsters

Internet com a laboratori virtual dins de l'ensenyament d'Enginyeria de Materials

L'objectiu principal d'aquest projecte és seleccionar i exposar una sèrie de recursos disponibles a Internet, que permetin complementar o facilitar l'aprenentatge dels continguts de la titulació d'Enginyeria de Materials. Al llarg del treball es presenten un total de 124 animacions de diferents temàtiques. La majoria d'elles provenen de pàgines web d'universitats i centres involucrats en l'estudi de materials. També s'exposa una animació d'elaboració pròpia, així com el fonament teòric en què es basa. Cal destacar que l'ús d'applets en l'ensenyament d'Enginyeria de Materials no implica una despesa econòmica extra, i que està d'acord amb les directrius de generar els mínims residus i de fomentar la reducció en origen, establertes en el Pla d'Acció Local per a la Sostenibilitat de la UAB. Gràcies també a la facilitat d'ús, els applets tenen un futur prometedor en l'ensenyament de moltes matèries.The aim of this project is to select and expose a wide range of online available resources, which allow you to complement or facilitate learning Materials Engineering's contents. This work presents 124 animations about different topics. Most of them are from websites of universities and centers which are involved in the study of materials. In addition, a self-made animation, as well as the main theory behind it, is presented. The use of applets for teaching Materials Engineering involves no extra costs, and it also agrees with the guidelines of generating minimum waste and promoting reduction in the source, established in the UAB's Plan for the Sustainability. Furthermore, applets have a promising future in education due to their facility of use.Nota: Aquest document conté originàriament altre material i/o programari només consultable a la Biblioteca de Ciència i Tecnologia

Carbohydrate-based PBT copolyesters from a cyclic diol derived from naturally occurring tartaric acid: a comparative study regarding melt polycondensation and solid-state modification

2,3-O-Methylene-L-threitol (Thx) is a cyclic carbohydrate-based diol prepared by acetalization and subsequent reduction of the naturally occurring tartaric acid. The structure of Thx consists of a 1,3-dioxolane ring with two attached primary hydroxyl groups. Two series of partially bio-based poly(butylene terephthalate) (PBT) copolyesters were prepared using Thx as a comonomer by melt polycondensation (MP) and solid-state modification (SSM). Fully random copolyesters were obtained after MP using mixtures of Thx and 1,4-butanediol in combination with dimethyl terephthalate. Copolyesters with a unique block-like chemical microstructure were prepared by the incorporation of Thx into the amorphous phase of PBT by SSM. The partial replacement of the 1,4-butanediol units by Thx resulted in satisfactory thermal stabilities and gave rise to an increase of the Tg values, this effect was comparable for copolyesters prepared by MP and SSM. The partially bio-based materials prepared by SSM displayed higher melting points and easier crystallization from the melt, due to the presence of long PBT sequences in the backbone of the copolyester. The incorporation of Thx in the copolyester backbone enhanced the hydrolytic degradation of the materials with respect to the degradation of pure PBT.Peer ReviewedPostprint (published version

Synthesis, characterization and biodegradability of aliphatic polyesters from cyclic diacetalized galactose

The use of carbohydrate derivatives for polymer synthesis has attracted much attention not only because of the huge abundance and renewable character of these resources, but also due to the degradable and biocompatible behavior that can be expected for such polymers. The cyclic monomer dimethyl 2,4:3,5-di-O-methylene galactarate, which was synthesized from galactaric acid, has several attractive features linked to its rigidity, chirality, non-toxicity and hydrophilicity. Aliphatic homopolyesters poly(alkylene 2,4:3,5-di-O-methylene galactarate)s were prepared from dimethyl 2,4:3,5-di-O-methylene galactarate and the aliphatic α,ω-diols 1,6- hexanediol; 1,8-octanediol; 1,10-decanediol and 1,12-dodecanediol; and were characterized by NMR, FT-IR, viscosimetry and GPC. According to the asymmetric constitution of the galactarate unit, these polyesters displayed optical activity in solution. The thermal behavior, mechanical properties and biodegradability of these polyesters were evaluated and compared with those displayed by their homologues dimethyl adipatederived homopolyesters. All poly(alkylene 2,4:3,5-di-O-methylene galactarate)s and poly(alkylene adipate)s from synthesis were semicrystalline. Glass transition temperatures of poly(alkylene 2,4:3,5-di-Omethylene galactarate)s were higher than those observed for poly(alkylene adipate)s. The introduction of ring acetal groups improved the thermal stability and caused an increase in the elastic modulus and the tensile strength of the polyesters, and produced a reduction in the elongation at break at the same time. Finally, the degradation study revealed that poly(alkylene 2,4:3,5-di-O-methylene galactarate)s were biodegradable polyesters, and that they degraded faster than poly(alkylene adipate)s

Internet com a laboratori virtual dins de l'ensenyament d'Enginyeria de Materials

L’objectiu principal d’aquest projecte és seleccionar i exposar una sèrie de recursos disponibles a Internet, que permetin complementar o facilitar l’aprenentatge dels continguts de la titulació d’Enginyeria de Materials. Al llarg del treball es presenten un total de 124 animacions de diferents temàtiques. La majoria d’elles provenen de pàgines web d’universitats i centres involucrats en l’estudi de materials. També s’exposa una animació d’elaboració pròpia, així com el fonament teòric en què es basa. Cal destacar que l’ús d’applets en l’ensenyament d’Enginyeria de Materials no implica una despesa econòmica extra, i que està d’acord amb les directrius de generar els mínims residus i de fomentar la reducció en origen, establertes en el Pla d’Acció Local per a la Sostenibilitat de la UAB. Gràcies també a la facilitat d’ús, els applets tenen un futur prometedor en l’ensenyament de moltes matèries.The aim of this project is to select and expose a wide range of online available resources, which allow you to complement or facilitate learning Materials Engineering’s contents. This work presents 124 animations about different topics. Most of them are from websites of universities and centers which are involved in the study of materials. In addition, a self-made animation, as well as the main theory behind it, is presented. The use of applets for teaching Materials Engineering involves no extra costs, and it also agrees with the guidelines of generating minimum waste and promoting reduction in the source, established in the UAB’s Plan for the Sustainability. Furthermore, applets have a promising future in education due to their facility of use.Nota: Aquest document conté originàriament altre material i/o programari només consultable a la Biblioteca de Ciència i Tecnologia

Synthesis, characterization and biodegradability of aliphatic polyesters from cyclic diacetalized galactose

The use of carbohydrate derivatives for polymer synthesis has attracted much attention not only because of the huge abundance and renewable character of these resources, but also due to the degradable and biocompatible behavior that can be expected for such polymers. The cyclic monomer dimethyl 2,4:3,5-di-O-methylene galactarate, which was synthesized from galactaric acid, has several attractive features linked to its rigidity, chirality, non-toxicity and hydrophilicity. Aliphatic homopolyesters poly(alkylene 2,4:3,5-di-O-methylene galactarate)s were prepared from dimethyl 2,4:3,5-di-O-methylene galactarate and the aliphatic α,ω-diols 1,6- hexanediol; 1,8-octanediol; 1,10-decanediol and 1,12-dodecanediol; and were characterized by NMR, FT-IR, viscosimetry and GPC. According to the asymmetric constitution of the galactarate unit, these polyesters displayed optical activity in solution. The thermal behavior, mechanical properties and biodegradability of these polyesters were evaluated and compared with those displayed by their homologues dimethyl adipatederived homopolyesters. All poly(alkylene 2,4:3,5-di-O-methylene galactarate)s and poly(alkylene adipate)s from synthesis were semicrystalline. Glass transition temperatures of poly(alkylene 2,4:3,5-di-Omethylene galactarate)s were higher than those observed for poly(alkylene adipate)s. The introduction of ring acetal groups improved the thermal stability and caused an increase in the elastic modulus and the tensile strength of the polyesters, and produced a reduction in the elongation at break at the same time. Finally, the degradation study revealed that poly(alkylene 2,4:3,5-di-O-methylene galactarate)s were biodegradable polyesters, and that they degraded faster than poly(alkylene adipate)s

Synthesis, characterization and biodegradability of aliphatic polyesters from cyclic diacetalized galactose

The use of carbohydrate derivatives for polymer synthesis has attracted much attention not only because of the huge abundance and renewable character of these resources, but also due to the degradable and biocompatible behavior that can be expected for such polymers. The cyclic monomer dimethyl 2,4:3,5-di-O-methylene galactarate, which was synthesized from galactaric acid, has several attractive features linked to its rigidity, chirality, non-toxicity and hydrophilicity. Aliphatic homopolyesters poly(alkylene 2,4:3,5-di-O-methylene galactarate)s were prepared from dimethyl 2,4:3,5-di-O-methylene galactarate and the aliphatic α,ω-diols 1,6- hexanediol; 1,8-octanediol; 1,10-decanediol and 1,12-dodecanediol; and were characterized by NMR, FT-IR, viscosimetry and GPC. According to the asymmetric constitution of the galactarate unit, these polyesters displayed optical activity in solution. The thermal behavior, mechanical properties and biodegradability of these polyesters were evaluated and compared with those displayed by their homologues dimethyl adipatederived homopolyesters. All poly(alkylene 2,4:3,5-di-O-methylene galactarate)s and poly(alkylene adipate)s from synthesis were semicrystalline. Glass transition temperatures of poly(alkylene 2,4:3,5-di-Omethylene galactarate)s were higher than those observed for poly(alkylene adipate)s. The introduction of ring acetal groups improved the thermal stability and caused an increase in the elastic modulus and the tensile strength of the polyesters, and produced a reduction in the elongation at break at the same time. Finally, the degradation study revealed that poly(alkylene 2,4:3,5-di-O-methylene galactarate)s were biodegradable polyesters, and that they degraded faster than poly(alkylene adipate)s

Block-sequence-specific polypeptides from α-amino acid N-carboxyanhydrides:synthesis and influence on polypeptide properties

\u3cp\u3eSequential addition of benzyl-l-glutamate and tert-butyl-l-glutamate N-carboxyanhydrides (NCAs) under optimized reaction conditions was used to synthesize block-sequence-defined polypeptides. Alternating octablock, tetrablock, and diblock as well as statistical polypeptides were obtained with comparable total compositions and total number of units. All of them were able to adopt helical secondary structures. Selective deprotection of the tert-butyl side chain yielded polypeptides with alternating benzyl-l-glutamate and l-glutamic acid block sequences available for further selective modification of individual block sequences. This was exploited for the conjugation with PEG side chains selectively on the glutamic acid block sequences. A detailed investigation revealed significant differences in properties as a function of the block-sequenced composition. Polypeptides with shorter alternating block sequences showed better water solubility. Dynamic light scattering revealed the presence of individual polypeptide chains in water in the case of the octablock polypeptide, while increasing aggregation was observed with increasing block length as well as for the statistical polypeptide. Moreover, the octablock polypeptide displayed a defined cloud point at 60°C, while no defined transition could be observed with any of the other polypeptide block sequences. The results demonstrate the dependence of polypeptide properties on their block-sequenced composition and open opportunities for a polymerization approach complementary to the stepwise synthesis of peptidomimetics.\u3c/p\u3

Internet com a laboratori virtual dins de l'ensenyament d'Enginyeria de Materials

L'objectiu principal d'aquest projecte és seleccionar i exposar una sèrie de recursos disponibles a Internet, que permetin complementar o facilitar l'aprenentatge dels continguts de la titulació d'Enginyeria de Materials. Al llarg del treball es presenten un total de 124 animacions de diferents temàtiques. La majoria d'elles provenen de pàgines web d'universitats i centres involucrats en l'estudi de materials. També s'exposa una animació d'elaboració pròpia, així com el fonament teòric en què es basa. Cal destacar que l'ús d'applets en l'ensenyament d'Enginyeria de Materials no implica una despesa econòmica extra, i que està d'acord amb les directrius de generar els mínims residus i de fomentar la reducció en origen, establertes en el Pla d'Acció Local per a la Sostenibilitat de la UAB. Gràcies també a la facilitat d'ús, els applets tenen un futur prometedor en l'ensenyament de moltes matèries.The aim of this project is to select and expose a wide range of online available resources, which allow you to complement or facilitate learning Materials Engineering's contents. This work presents 124 animations about different topics. Most of them are from websites of universities and centers which are involved in the study of materials. In addition, a self-made animation, as well as the main theory behind it, is presented. The use of applets for teaching Materials Engineering involves no extra costs, and it also agrees with the guidelines of generating minimum waste and promoting reduction in the source, established in the UAB's Plan for the Sustainability. Furthermore, applets have a promising future in education due to their facility of use.Nota: Aquest document conté originàriament altre material i/o programari només consultable a la Biblioteca de Ciència i Tecnologia

Renewable terephthalate polyesters from carbohydrate-based bicyclic monomers

Poly(alkylene terephthalate)s, PET and PBT in particular, are materials of great relevance and growing projection in the thermoplastic field but are today almost totally produced from fossil resources. The current huge consumption of these polyesters necessitates urgent actions addressed to make them renewable by using naturally-occurring raw materials. Among the different approaches that are being followed to develop bio-based poly(terephthalate)s, the use of bicyclic carbohydrate-derived difunctional compounds as building-blocks is receiving much attention in the last few years because partially renewable polyesters with high Tg may be thus obtained. This review presents a critical account of the terephthalate homopolymers and copolymers that have been synthesized using the two types of carbohydrate-based bicyclic monomers, isohexides and diacetals, explored to date. The properties displayed by the novel bio-based poly(terephthalate)s in relation to the bicyclic structure of the used monomers are comparatively reviewed and their potential as emergent materials for thermoplastic applications is evaluated.Peer ReviewedPostprint (published version