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Abstract: Ionic coupling of bacterial poly(γ‐glutamic acid) (PGGA) with alkyltrimethylphosphonium surfactants is reported to render comb‐like PGGA complexes with a biphasic‐layered structure displaying periodicity at the nanoscopic scale. In this work, nanocomposites made of PGGA and montmorillonite, and covering a wide variety of compositions, are prepared by using either dodecyl‐ or eicosyl‐trimethylphosphonium surfactant as a third component with a double purpose, that is, ionic complexation of PGGA and organo‐modification of the nanoclay. Thermogravimetric analysis ascertains the compositions of these three‐component nanocomposites and evidences their excellent thermal stability. The nanocomposite structure with PGGA and clay more or less intercalated according to composition and thermal history is evidenced by both X‐ray diffraction and transmission electron microscopy. Simultaneous thermal SAXS/WAXS analysis at real time reveals extensive intermixing of the two phases that become notably enhanced by heating treatment. Thermal transition characteristics of the surfactant–PGGA complex are not significantly altered in the nanocomposites, but elastic moduli and strength to yield are found to increase proportionally to the content of clay. [ABSTRACT FROM AUTHOR]

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]

The biocide agent LAE (ethyl αN-lauroyl L-arginate chloride) was coupled with poly( -glutamic acid) (PGGA) to form stable ionic complexes with LAE:PGGA ratios of 1 and 0.5. The nanostructure adopted by these complexes and its response to thermal changes were examined in detail by Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) using synchrotron radiation in real time. A layered biphasic structure with LAE filling the space between the polypeptidic sheets was adopted in these complexes. The complexes were stable up to above 250 °C, non-water soluble, and were able to form consistent transparent films. The release of LAE from the complexes upon incubation in aqueous buffer was examined and found to depend on both pH and complex composition. The antibacterial activity of films made of these complexes against Gram-positive (L. monocytogenes and S. aureus) and Gram-negative (E. coli and S. enterica) bacteria was preliminary evaluated and was found to be very high against the formers and only moderate against the later. The bactericide activity displayed by the LAE·PGGA complexes was directly related with the amount of LAE that was released from the film to the environment. [ABSTRACT FROM AUTHOR]

Two series of aliphatic-aromatic copolyesters derived from succinic and 2,5-furandicarboxylic acids, and di-O-2-(hydroxyethyl) resorcinol as diol substituent of either 1,4-butanediol or ethylene glycol, respectively, were obtained by ring opening polymerization(ROP) performed in bulk and catalyzed by Sn(Oct)2. Cyclic oligomers of furandicarboxylate of di-O-2-(hydroxyethyl) resorcinol were successfully synthesized by high-dilution condensation, and then copolymerized with cyclic oligomers of either butylene or ethylene succinate. The synthesized resorcinol-containing succinate-furanoatecopolyesters had Mw oscillating between 50,000 and 30,000 g.mol-1 depending on composition, and they all displayed a nearly random microstructure. They showed an excellent thermal stability with onset decomposition temperatures near 300 °C. They are amorphous with Tg increasing monotonically with the content in resorcinol in both series with values ranging from -30 or -13 °C for butylene and ethylene-based copolyesters, respectively, up to around 45 °C. The resorcinol-containing succinate-furanoate copolyesters showed appreciable hydrolytic degradation when incubated for a few weeks in water under physiological conditions, a behavior that was notably enhanced in the presence of lipases. [ABSTRACT FROM AUTHOR]

Quaternary organophosphonium salts bearing long alkyl chains are cationic surfactants of interest owing to their physical and biological properties. In the present work, the crystal structure and thermotropic behavior of the homologous series of alkyltrimethylphosphonium bromides (nATMP·Br), with the alkyl chain containing an even number (n) of carbon atoms from 12 to 22, have been examined within the 0–300 °C range of temperatures. These compounds were shown to be resistant to heat up to ∼390 °C. The phases adopted at different temperatures were detected by DSC, and the structural changes involved in the phase transitions have been characterized by simultaneous WAXS and SAXS carried out in real-time, and by polarizing optical microscopy as well. Three or four phases were identified for n = 12 and 14 or n≥ 16, respectively, in agreement with the heat exchange peaks observed by DSC. The phase existing at room temperature (Ph-I) was found to be fully crystalline and its crystal lattice was determined by single-crystal X-ray diffraction methods. Ph-II consisted of a semicrystalline structure that can be categorized as Smectic-B with the crystallized ionic pairs hexagonally arranged in layers and the molten alkyl chain confined in the interlayer space. Ph-II of 12ATMP·Br and 14ATMP·Br directly isotropicized upon heating at ∼220 °C, whereas for n≥ 16, it converted into a Smectic-A phase (Ph-III) that needed to be heated above ∼240 °C to become isotropic (Ph-Is). The correlation existing between the thermal behavior, phase structure and length of the alkyl side chain has been demonstrated. [ABSTRACT FROM AUTHOR]

Three series of polyalkanoates (adipates, suberates and sebacates) were synthesized using as monomers three sugar-based bicyclic diols derived from D-glucose (Glux-diol and isosorbide) and D-mannose (Manx-diol). Polycondensations were conducted in the melt applying similar reaction conditions for all cases. The aim was to compare the three bicyclic diols regarding their suitability to render aliphatic polyesters with enhanced thermal and mechanical properties. The ensuing polyesters had molecular weights (Mw) in the 25,000–50,000 g mol−1 range with highest values being attained for Glux-diol. All the polyesters started to decompose above 300 °C and most of them did not display perceivable crystallinity. On the contrary, they had glass transition temperatures much higher than usually found in homologous polyesters made of alkanediols, and showed a stress–strain behavior consistent with their Tg values. Glux-diol was particularly effective in increasing the Tg and to render therefore polyesters with high elastic modulus and considerable mechanical strength. [ABSTRACT FROM AUTHOR]

A series of low-molecular-weight poly(butylene succinate- co-glutarate- co−2-trimethylammonium chloride glutarate) terpolyester ionomers containing 35% mol of total glutarate units but varying in the content of charged units were synthesized by polycondensation at mild temperatures using a scandium catalyst. The terpolyester ionomers started to decompose at the temperatures of >175°C and all of them were semicrystalline and have glass transition temperature similar to poly(butylene succinate) (PBS). These terpolyesters were used to compatibilize the nanocomposites made of PBS-cloisite (CL) prepared by melt extrusion. X-ray diffraction revealed that an intercalated structure was present in these nanocomposites. The thermal properties of the three-component mixtures did not differ substantially from those of PBS-CL but the mechanical properties were significantly improved by the addition of the ionomer, in particular tenacity. The beneficial effect afforded by the terpolyester ionomer was attributed to its ability for strengthening the binding between the PBS and the nanoclay. POLYM. COMPOS., 37:2603-2610, 2016. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Renewable polyesters derived from a sugar alcohol (i.e., sorbitol) were synthesized by solvent-free polycondensation. The aim was to prepare linear polyesters with pendant hydroxyl groups along the polymer backbone. The performance of the sustainable biocatalyst SPRIN liposorb CALB [an immobilized form of Candida antarctica lipase B (CALB); SPRIN technologies] and the organo-base catalyst 1,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD) were compared with two metal-based catalysts: dibutyl tin oxide (DBTO) and scandium trifluoromethanesulfonate [also known as scandium triflate, Sc(OTf)3]. For the four catalytic systems, the efficiency and selectivity for the incorporation of sorbitol were studied, mainly using 13C and 31P NMR spectroscopies, whereas side reactions, such as ether formation and dehydration of sorbitol, were evaluated using MALDI-TOF-MS. Especially the biocatalyst SPRIN liposorb CALB succeeded in incorporating sorbitol in a selective way without side reactions, leading to close-to-linear polyesters. By using a renewable hydroxyl-reactive curing agent based on l-lysine, transparent and glossy poly(ester urethane) networks were successfully synthesized offering a tangible example of bio-based coatings. [ABSTRACT FROM AUTHOR]

A series of poly(butylene succinate) (PBS) ionomers containing up to 14 mol% of sulfonated succinate units have been synthesized by polycondensation in the melt-phase. The copolyesters were obtained with weight average molecular weights oscillating between 33,000 and 72,000 g•mol-1. All copolyesters were semicrystalline with melting temperatures and enthalpies decreasing and glass transition temperatures increasing with the content of ionic units. The thermal stability of PBS was slightly reduced by the incorporation of these units, and it was also found that the copolyesters were stiffer but also more brittle than PBS. The hydrolytic degradability of PBS was enhanced by copolymerization, an effect that was much more pronounced in basic media. [ABSTRACT FROM AUTHOR]

The use of NMR spectroscopy in solution to investigate the chemical structure of engineering poly(alkylene terephthalate)s such as poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), and poly(butylene terephthalate) (PBT) is reviewed. Chemical defects present in the polyester chain, such as oxydialkylene units, as well as accompanying side products such as cyclic oligomers generated in the polycondensation, are well detected in 1H NMR spectra. The technique is also demonstrated to be effective for identifying, and even for quantifying in certain cases, the end groups of these polyterephthalates, including those that are generated in small amounts as a consequence of thermal degradation. The application of NMR to the study of the chemical microstructure of copolyesters derived from such polyterephthalates is also reviewed for its unique ability to determine comonomeric sequence lengths and degree of randomness ( R). Copolyesters synthesized by either melt polycondensation or entropically driven ring opening polymerization, in addition to those prepared by solid-state modification or melt blending, are the object of this review. [ABSTRACT FROM AUTHOR]

A set of copolyesters (PHTxGluxy) with compositions ranging between 90/10 and 50/50 in addition to the parent homopolyesters poly(hexamethylene terephthalate) (PHT) and PHGlux, are prepared by the melt polycondensation of 1,6-hexanediol (HD) with mixtures of dimethyl terephthalate (DMT) and dimethyl 2,4:3,5-di- O-methylene- d-glucarate (Glux). The copolyesters have [ABSTRACT FROM AUTHOR]

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 biobased 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. [ABSTRACT FROM AUTHOR]

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 blocklike 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. [ABSTRACT FROM AUTHOR]

ABSTRACT The backbone of poly(butylene terephthalate) (PBT) was modified with 2,4:3,5-di- O-methylene- D-glucitol (Glux) using solid-state modification (SSM). The obtained copolyesters proved to have a non-random overall chemical microstructure. The thermal properties of these semicrystalline, block-like, Glux-based materials were extraordinary, showing higher melting points, and glass transition temperatures compared with other sugar-based copolyesters prepared by SSM. These remarkable thermal properties were a direct result of the inherently rigid structure of Glux and the relatively slow randomization of the block-like chemical microstructure of the Glux-based copolyesters in the melt. SSM proved to be a versatile tool for preparing partially biobased copolyesters with superior thermal properties. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 164-177 [ABSTRACT FROM AUTHOR]

A series of poly(hexamethylene terephthalate- co-hexamethylene 5-sodium sulfoisophthalate) copolyesters containing from 5 to 50 mol % of sulfonated units as well as the two parent homopolymers are prepared by melt polycondensation. The polyesters are obtained with high molecular weights, which decrease with the increased content of sulfonated units in the copolymer. Polyesters with 5 and 10 mol % of sulfonated units are semicrystalline whereas for contents equal or above 20 mol % they are unable to crystallize from the melt. Thermogravimetric analysis show that the thermal stability decreases with the content in sulfonated units. Isothermal crystallizations of semicrystalline copolyesters show that the insertion of the sulfonated units causes a reduction of crystallizability, most probably due to the occurrence of ionic aggregations. It is observed a synergistic effect on the mechanical properties for copolymers with contents of around 5 mol % where the elongation at break increases drastically. Moreover, the hydrolytic degradation of the copolymer is enhanced with the content in sulfonated units. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Three carbohydrate-based bicyclic diols, 1,4:3,6-dianhydro-d-glucitol (isosorbide, Is), 2,3:4,5-di-O-methylene-galactitol (Galx) and 2,4:3,5-di-O-methylene-d-mannitol (Manx), were made to react in the melt and under the same conditions with dimethyl terephthalate and 1,4-butanediol to produce respectively three series of PBxIsyT, PBxGalxyT and PBxManxyT random copolyesters. Five different copolymerizations, with molar feed ratios of 1,4-butanediol to sugar-based diols of 90 : 10, 80 : 20, 70 : 30, 60 : 40 and 50 : 50, were carried out for each bicyclic diol in order to make a comparative study on their reactivity and properties of the resulting copolyesters. Molecular weights and compositions data of the copolyesters revealed the greater facility of diacetalized diols to react under these conditions compared to isosorbide. The three bicyclic diols contributed to increase the thermal stability and also the glass-transition temperature of PBT. The replacement of 40% of 1,4-butanediol by sugar-based diols increased the glass transition temperature of PBT from 31 °C to ∼60 °C in the case of Galx and up to ∼90 °C regarding Is and Manx. All PBxGalxyT copolyesters as well as PBxIsyT and PBxManxyT ones with contents of Is and Manx of up to 32% and 41%, respectively, were semicrystalline. [ABSTRACT FROM AUTHOR]

We report on a series of novel poly(γ-glutamic acid) (PGGA) esters, in which the chemical structure and composition, and the molecular weight are systematically changed. Modification of PGGA of microbial origin, used either as the sodium salt or in the free acid form, by means of alkylation with highly reactive bromides under SN2 conditions, affords copolymers with an essentially random microstructure. These reaction conditions are applied iteratively to achieve full esterification, obtaining allyl or propargyl ester functionalities within the polymer backbone, diluted with inert functional groups, such as benzyl, ethyl, or hexyl ester functionalities. The copolymers have been characterized regarding their chemical structure and thermal and bulk properties using nuclear magnetic resonance, thermogravimetry, differential scanning calorimetry, and X-ray diffraction techniques. We demonstrate that allyl and propargyl ester groups can be efficiently transformed using click chemistries, such as thiol-ene or copper(I)-catalyzed azide-alkyne cycloaddition reactions; such efficient conjugation strategies will be required to transform the native bacterial biopolymer into a material with tailored properties for bulk scale or biomedical applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

Microbial poly( β, L-malic acid) was modified with either L-leucine ethyl ester (L) or L-phenylalanine methyl ester (F) to produce amphiphylic copolymers. The degradation of these copolymers in aqueous buffer took place under physiological conditions in a few weeks by hydrolysis of the side chain ester group followed by cleavage of the main chain. Spherical nanoparticles with diameters ranging between 70 and 230 nm were prepared from these copolymers by the dialysis-precipitation method. No alteration of the cell viability was observed after incubation of these nanoparticles in different cell lines. Anticancer drugs temozolomide and doxorubicin were encapsulated in the nanoparticles. Temozolomide was released within several hours whereas doxorubicin took several weeks to be completely liberated. [ABSTRACT FROM AUTHOR]

A set of linear polyurethanes containing isosorbide units were synthesized by polymerization in solution from HDI and MDI diisocyanates and 1,4-butanediol (BD), isosorbide (Is) or diisosorbide diurethanes (Is2HDI and Is2MDI) as diols. The thermal transitions, thermal stability, and crystal structure of the polyurethane homopolymers and copolymers containing isosorbide were evaluated and compared with those displayed by their polyurethane analogues entirely made of BD. It was found that incorporation of Is units in the polyurethane chain produced significant changes in T g, T m, and T d but no significant differences were noticed between copolymers made from Is or Is2 monomers. Degradation assays revealed that the presence of Is units increased slightly the hydrolysis rate of polyurethanes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

An overview on the synthesis, structure and properties of polyamides and aromatic copolyesters produced by using monomers derived from carbohydrates is provided. Two examples are selected for illustration: (a) aliphatic polyamides prepared from aldaric acids and (b) aromatic copolyesters containing alditols units. Polycondensation in solution of n-alkanediamines (n taking even values from 6 to 12) with activated pentaric (l-arabino and xylo) and hexaric (galacto and d-manno) acids bearing the secondary hydroxyl groups protected as methyl ether, afforded linear polyaldaramides PA-nSu with Mw oscillating between 25 000 and 150 000 g mol−1. They are stable above 300°C and are semicrystalline even so only PA-nMn are stereoregular. Melting temperatures of PA-nSu range between 140 and 230°C and most of them are able to crystallize from the melt at a rate that increases with the length of the polymethylene segment. Both melting and glass transition temperatures decrease with the content in sugar units. Spherulitic films, oriented fibers and lamellar single crystals could be obtained from PA-nSu. All these polyamides seem to adopt a common crystal structure made of hydrogen-bonded sheets with the sugar residue skewed to attain an efficient side-by-side packing of the polymer chains. Aromatic homopolyesters and copolyesters derived from terephthalic acid and mixtures of butylene glycol and O-methylated alditols were prepared by polycondensation in the melt with Mw in the 20 000–50 000 g mol−1 range and a random microstructure. The thermal properties of PBT containing alditols units are very depending on the sugar constitution and copolyester composition. In general they are thermally stable above 300°C and display crystallinity for contents in alditols up to 30%. Melting temperatures decrease with the content in alditols whereas an opposite trend is observed for glass transition temperatures. The crystalline structure of PBT is preserved in the crystalline copolyesters whereas a different crystal lattice is adopted by homopolyesters entirely made of alditol units. In general, polyamides and polyesters containing sugar derived units are widely soluble in organic solvents, markedly hydrophilic and more susceptible to hydrolysis than their parent polymers. [ABSTRACT FROM PUBLISHER]

A set of polyurethanes containing isosorbide units were synthesized by polymerization in solution from HDI and MDI diisocyanates and 1,4-butanediol (BD), isosorbide (Is) or diisosorbide diurethanes (Is2HDI and Is2MDI) as diols. The thermal properties and stability, and crystal structure of the polyurethane homopolymers and copolymers containing isosorbide were evaluated and compared with those of the polyurethane analogues entirely made of BD. Incorporation of isosorbide produced significant changes in Tg, Tm and Td but no noteworthy differences were found between copolymers made from Is or Is2 monomers. Degradation assays revealed that incorporation of Is units increased slightly the hydrolysis rate. [ABSTRACT FROM AUTHOR]

Three series of terephthalate polyesters (copolyesters and terpolyesters) containing 70, 80, and 90 mol % of ethylene glycol respectively, 1,4-cyclohexanedimethanol (CHDM) and isosorbide in varying ratios, were synthesized by melt polycondensation. It was found that only ∼75 mol % of the feeding isosorbide was incorporated in the resulting polyesters and that their content in diethylene glycol oscillated between 2 and 4 mol %. The polyesters had weight-average molecular weights in the 25,000-33,000 g mol−1 range and polydispersities between 2 and 2.5. The combined 1H and 13C NMR analysis revealed that the microstructure of all these polyesters was at random. They showed good thermal stability with decomposition temperatures above 400 °C. Their glass-transition temperatures were observed to increase with the content in cyclic diols, this effect being more pronounced when isosorbide was the replacing comonomer. Only the series containing 90 mol % of ethylene terephthalate units was able to crystallize upon cooling from the melt. Compared isothermal crystallizations revealed that isosorbide was more effective than CHDM in repressing the crystallizability of PET. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 [ABSTRACT FROM AUTHOR]

The article presents a study which prepared a series of poly(ethylene terephthalate-co-isophthalate) copolymers with up to 50 percent mole of isophthalic units by polycondensation from ethylene terephthalate and ethylene isophthalate fractions of linear oligomers. Carbon-nuclear magnetic resonance (C-NMR) examined the microstructure of the copolyesters as a function of reaction time. It was found that the crystallization rate of copolyesters decreased with the content in isophthalic units.

The article presents information on a study which compared the effect of the preparation method and composition on the structure and some properties of new thermoplastic segmented poly(ester-urethane)s, whereby the hard segment is made of D-glucitol-derived extenders. A review of the related literature is given. Diisocyanates used for the synthesis were 1,6-hexamethylene diisocyanate (HDI) or 4,4'-methylene-bis(phenyle isocyanate) (MDI). A detailed discussion on the findings is presented.

This study focused on the preparation and evaluation of nanoparticles made of alkyl esters of microbial poly(γ-glutamic acid) (PGGA) to be used as drugs and proteins carrier and delivery systems. Racemic PGGA of bacterial origin was fully methylated or partially esterified to render non-water-soluble polymers. A set of co-polymers containing poly(glutamic acid) and ethyl, hexyl, dodecyl and octadecyl glutamate units with alkyl contents of 50 and 75% was prepared. Spherical nanoparticles with a diameter of 200–250 nm and a narrow distribution were generated from the alkylated polymers by the precipitation-dialysis method. These nanoparticles readily degraded hydrolytically upon incubation in simulated physiological medium at a rate dependent on the alkylation degree and the length of the alkyl group. All these nanoparticles were able to encapsulate efficiently erythromycin. Those made of carboxyl containing polyglutamates were also effective to load α-chymotrypsin. The release of such compounds from nanoparticles upon incubation proceeded essentially following the same profile that is followed in the hydrolysis of the corresponding substrate polymers. The loss of enzyme activity of the incubated protein diminished significantly upon encapsulation in these systems. [ABSTRACT FROM AUTHOR]

The synthesis, characterization, and some properties of new copolyesters analogous to poly(butylene terephthalate) (PBT), based on L‐arabinaric and galactaric acids, are described. These copolyesters were obtained by polycondensation reaction in the melt of mixtures of methyl 2,3,4‐tri‐O‐methyl‐L‐arabinarate or methyl 2,3,4,5‐tetra‐O‐methyl‐galactarate and dimethyl terephthalate with 1,4‐butanediol. Their weight‐average molecular weights ranged between 10,000 and 34,000, with polydispersities ranging from 1.4 to 2.2. The composition of all the copolymers was analyzed by NMR, and was found to have a statistical microstructure. All these copolyesters were thermally stable, with degradation temperatures well above 300 °C. The melting temperature and crystallinity decreased in both series, and the glass transition temperature increased and decreased respectively, for the PBTGa and PBTAr series with increasing amounts of aldaric units in the copolyester chain. Only PBT‐derived copolyesters containing a maximum of 30% aldaric units showed discrete scattering characteristic of crystalline material. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1168–1177, 2009 [ABSTRACT FROM AUTHOR]