Showing papers by "Luc Avérous published in 2017"
TL;DR: In this paper, the effect of the glycerol content on the microstructure and properties of alginate-based materials was examined, and it was shown that glycerols increased the mobility and increased the crystallization of the alginates with structural reorganization.
118 citations
TL;DR: In this paper, the potential of cyclic carbonates for functionalization of lignins and condensed tannins was studied in detail, and four different cyclic carates, namely, ethylene, propylene, vinyl ethylene and glycerol carbonates, were evaluated.
Abstract: The potential of cyclic carbonates for the functionalization of lignins and condensed tannins was studied in detail. Four different cyclic carbonates, namely, ethylene, propylene, vinyl ethylene, and glycerol carbonates, were evaluated. Full conversion of the phenolic hydroxyl groups was observed within very short reaction times (less than 2 h and as low as 15 min with ethylene carbonate). Comparison among the different cyclic carbonates shows that the substituent influences the reactivity as follows: —CH3 < —CH═CH2 < —CH2—OH < H. The developed method is a safe alternative to the use of organohalides or epoxides for the introduction of functional groups of interest onto lignins and tannins. The prepared derivatives expose primary or secondary hydroxyl groups, vinyl groups, 1,2- and 1,3-diols, or five-membered cyclic carbonates. All of the derivatives have an enhanced thermal stability and a lowered glass transition temperature (Tg) compared to the neat lignins and condensed tannins and thus present a high...
76 citations
TL;DR: In this paper, the Diels−Alder (DA) reaction was used to obtain thermogravimetric networks from tannins, an aromatic biobased polyphenol, by reacting furan-bearing tannin and telechelic oligomers with maleimide end groups.
Abstract: Thermo-reversible networks were obtained for the first time from tannins, an aromatic biobased polyphenol, by reacting furan-bearing tannins and telechelic oligomers with maleimide end groups, using the Diels−Alder (DA) reaction. Condensed tannins from mimosa (Acacia mearnsii) were functionalized with furfuryl glycidyl ether and thoroughly characterized by 1H, 31P NMR, and FTIR spectroscopy. The accessibility of the grafted furan groups was confirmed by a model reaction with N-methylmaleimide. Different cross-linked networks were then obtained by DA reaction with three PPO and PPO-b-PEO-b-PPO oligomers and evidenced by FTIR spectroscopy. The thermal properties of the obtained networks were evaluated with differential scanning calorimetry (DSC) and thermogravimetric analysis. Then, the reversibility of the cross-linking was shown by a quick return to the liquid state upon heating at 120 °C. The retro Diels−Alder reaction was studied by size exclusion chromatography and DSC.
68 citations
TL;DR: In this article, polarized light optical microscopy (PLOM) was employed to observe superstructural morphology while their thermal and structural properties were studied by differential scanning calorimetry (DSC) and in situ synchrotron X-ray diffraction at wide and small angles (WAXS and SAXS).
Abstract: Poly(butylene succinate-ran-butylene adipate) random copolymers (PBSA) were prepared by melt polycondensation in a wide composition range. Polarized light optical microscopy (PLOM) was employed to observe their superstructural morphology while their thermal and structural properties were studied by differential scanning calorimetry (DSC) and in situ synchrotron X-ray diffraction at wide and small angles (WAXS and SAXS). The morphological study revealed negative spherulitic superstructures with (PBS-rich) and without (PBA-rich) ring band patterns depending on composition. The crystallization temperature, melting temperature, and related enthalpies display a pseudoeutectic behavior as a function of composition. WAXS studies demonstrated that these random copolymers are isodimorphic, as their unit cell parameters are composition dependent and switch from PBS-like unit cells to β-PBA-like unit cells around the pseudoeutectic point. For PBA-rich compositions, the inclusion of butylene succinate units in the co...
64 citations
TL;DR: For multiphase systems, the successful use of natural sepiolite brought a clear benefit, without the need of any modifications or additional processes to produce advanced nano-biocomposites.
61 citations
TL;DR: The bacteria inhibitory property of the chitosan derivatives exhibited a remarkable improvement compared to unmodified chitan, and has been assessed by determining their minimal inhibitory concentration upon Escherichia coli and Staphylococcus aureus.
58 citations
TL;DR: In this article, the preparation and in-depth characterization of thermo-reversible healable materials based on lignin, a major naturally occurring aromatic biopolymer, is reported.
51 citations
TL;DR: In this article, the effects of the addition of TiO 2 nanoparticles on the properties of the nano-biocomposites, such as crystallinity, thermal stability, morphology and optical, mechanical and surface properties were investigated.
Abstract: Thermoplastic chitosan-based materials were successfully prepared by thermo-mechanical treatment in an internal mixer using volatile (water) and non-volatile (glycerol) plasticizer, and a destructuring agent (acidic solution). TiO 2 -based nanoparticles were incorporated at varying contents (1–10 wt%) into the chitosan-based matrix to obtain different nano-biocomposites. The effects of the addition of TiO 2 nanoparticles on the properties of the nano-biocomposites, such as crystallinity, thermal stability, morphology and optical, mechanical and surface properties were investigated. The crystallinity of the biopolymer-based matrix decreased as a consequence of the incorporation of TiO 2 nanoparticles. The morphological characterization showed a good dispersion of the nanofiller into the polymer matrix and a clear dependence on the TiO 2 nanoparticle content. The nano-biocomposites resulted in UV shielding materials as a consequence of the TiO 2 incorporation. Moreover, the mechanical properties of the plasticized chitosan were enhanced by the incorporation of TiO 2 nanoparticles and were related strongly to the TiO 2 nanoparticles content.
49 citations
TL;DR: Fully biobased aliphatic random poly(butylene succinate-ran-butylene adipate) (PBSA) copolyesters and the corresponding homopolyesters were synthesized with different succinic acid/adipic acid (SA/AA) molar ratio by transesterification in melt, using titanium (IV) isopropoxide as an effective catalyst as mentioned in this paper.
46 citations
TL;DR: An environmentally friendly approach to transforming renewable feedstocks into value-added materials is proposed, which showed that varying the degree of functionality of the linker and the linking structure allowed accurate tailoring of the thermal and mechanical properties of the final materials, thus providing interesting perspectives for lignin in functional aromatic polymers.
Abstract: In the present work we propose an environmentally friendly approach to transform renewable feedstocks into value-added materials. This transformation pathway is conducted under green conditions, without the use of solvents and catalyst. First, controlled modification of lignin, a major biopolymer present in wood and plants, was achieved through the esterification with 11-maleimidoundecylenic acid (11-MUA), a derivative from ocastor oil that contains maleimide groups. Different degrees of substitution were achieved by using various amounts of the 11-MU acyl chloride leading to an efficient conversion of lignin hydroxyl groups as demonstrated by 1H and 31P NMR analyses. These fully biobased maleimide-lignin derivatives were reacted through an extremely fast (about one minute) thiol-ene "click" polymerization with thiol-containing linkers. Aliphatic and aromatic thiol-linkers bearing from 2 to 4 thiol groups were used in order to tune the reactivity and crosslinking density. The properties of the resulting materials were evaluated by swelling tests, thermal and mechanical analyses showing that varying the linker functionality and structure allows to accurately tailor the thermal and mechanical properties of the final materials, thus providing interesting perspectives for lignin towards functional aromatic polymers.
37 citations
TL;DR: In this article, a series of high molar mass biobased aliphatic copolyesters were synthesized with different 1,3-propanediol/1,4-butanediol (1, 3-PDO/1 4-BDO) molar ratio by transesterification in melt, using titanium (IV) isopropoxide as catalyst.
TL;DR: In this article, the successful enzymatic ring opening copolymerization of e-caprolactone (e-CL) and e-thiocaprolacton(e-TCL) catalyzed by Novozyme 435, immobilized lipase B from Candida antarctica was presented.
TL;DR: This work showed that thermo-mechanical mixing is a promising method to produce, at large scale, plasticized alginate-based films with improved properties.
TL;DR: In this article, a two-step esterification of polyurethane foams from sorbitol was proposed. But the results showed that the polyester polyols architecture has a strong influence on the foam tack free time, which varied from 50 to 235 s for the studied PUF.
TL;DR: This work showed the capacity of two Aspergillus species to yield both acids by solid-state fermentation and simultaneous saccharification and fermentation, and the yield of A. oryzae is the highest reported in the literature for simultaneous solid- state fermentation without sugar supplements.
Abstract: The production of high-value chemicals from natural resources as an alternative for petroleum-based products is currently expanding in parallel with biorefinery. The use of lignocellulosic biomass as raw material is promising to achieve economic and environmental sustainability. Filamentous fungi, particularly Aspergillus species, are already used industrially to produce organic acid as well as many enzymes. The production of lignocellulose-degrading enzymes opens the possibility for direct fungal fermentation towards organic acids such as itaconic acid (IA) and fumaric acid (FA). These acids have wide-range applications and potentially addressable markets as platform chemicals. However, current technologies for the production of these compounds are mostly based on submerged fermentation. This work showed the capacity of two Aspergillus species (A. terreus and A. oryzae) to yield both acids by solid-state fermentation and simultaneous saccharification and fermentation. FA was optimally produced at by A. oryzae in simultaneous saccharification and fermentation (0.54 mg/g wheat bran). The yield of 0.11 mg IA/g biomass by A. oryzae is the highest reported in the literature for simultaneous solid-state fermentation without sugar supplements.
TL;DR: Different plasticized and nucleated polylactide (PLA) systems were prepared and characterized by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and polarized optical microscopy (POM) as discussed by the authors.
Abstract: Different plasticized and nucleated polylactide (PLA) systems were prepared and characterized. Two PLA with different l-lactic acid contents (96 and 99.5%) were plasticized with dioctyl adipate (DOA) and nucleated by talc, ethylene bis(stearamide) (EBS), or d-lactic acid-based PLA (PDLA). Crystallization behaviour was studied by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and polarized optical microscopy (POM). The combination of plasticizer and nucleating agent was proved to be a very effective approach to improve crystallization velocity of different PLA matrices. Within the studied crystallization temperature range, faster crystallization rates were achieved at lower temperatures. WAXS results indicated the coexistence of α and α′ crystals in all studied systems, except those which showed very low crystallization degrees. Avrami exponent remained constant at around n ≈ 3 for all systems, suggesting equivalent three-dimensional spherulitic growth behaviour regardless crystallization temperature, nucleating agent, and the stereochemistry of the matrix used. Usually, injection-moulding process, where molten polymer is under high pressure, is used for PLA polymer processing. To analyze the effect of pressure on the crystallization process, pressure volume temperature (PVT) measurements were carried out on the systems that showed the fastest crystallization process under atmospheric pressure by DSC. Results showed that the crystallization process was considerably accelerated under pressure.
TL;DR: In this article, the influence of the PHB-diol chain length, the Pether/Pester ratio, the polyether segment nature and the PEG chain length on the thermal properties and crystalline structures of PEEUs was investigated.
Abstract: Telechelic hydroxylated poly(3-hydroxybutyrate) (PHB-diol) oligomers have been successfully synthesized in 90–95% yield from high molar mass PHB by tin-catalyzed alcoholysis with different diols (mainly 1,4-butanediol) in diglyme. The PHB-diol oligomers structure was studied by nuclear magnetic resonance, Fourier transformed infrared spectroscopy MALDI-ToF MS, and size exclusion chromatography, whereas their crystalline structures, thermal properties and thermal stability were analyzed by wide angle X-ray scattering, DSC, and thermogravimetric analyses. The kinetic of the alcoholysis was studied and the influence of (i) the catalyst amount, (ii) the diol amount, (iii) the reaction temperature, and (iv) the diol chain length on the molar mass was discussed. The influence of the PHB-diol molar mass on the thermal stability, the thermal properties and optical properties was investigated. Then, tin-catalyzed poly(ester-ether-urethane)s (PEEU) of Mn = 15,000–20,000 g/mol were synthesized in 1,2-dichloroethane from PHB-diol oligomers (Pester) with modified 4,4'-MDI and different polyether-diols (Pether) (PEG-2000, PEG-4000, and PPG-PEG-PPG). The influence of the PHB-diol chain length, the Pether/Pester ratio, the polyether segment nature and the PEG chain length on the thermal properties and crystalline structures of PEEUs was particularly discussed. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017
TL;DR: The developed method was compared with previously published protocols for the introduction of vinyl groups on lignin, and shows promising advances toward the modification of biobased polyphenols according to green chemistry principles.
Abstract: Various biobased polyphenols (lignins and condensed tannins) were derivatized with vinyl ethylene carbonate, a functional cyclic carbonate, to obtain multifunctional aromatic polymers bearing vinyl groups. The reaction was optimized on a condensed tannin and soda lignin. In both cases, full conversion of the phenol groups was achieved in only 1 h at 150 °C without solvent and with K2 CO3 as a cheap and safe catalyst. This reaction was later applied to other condensed tannins and technical lignins (Kraft and organosolv), showing only little dependence on the chemical structure of the polyphenols. The obtained derivatives were thoroughly characterized by 1 H and 31 P NMR spectroscopy, FTIR spectroscopy, and size-exclusion chromatography. The developed method was compared with previously published protocols for the introduction of vinyl groups on lignin, and shows promising advances toward the modification of biobased polyphenols according to green chemistry principles. The obtained macromolecules show great potential as highly versatile biobased aromatic building blocks for the synthesis of polymers through, for example, radical, metathesis, or thiol-ene reactions.
TL;DR: The influence of the monomer structure on the CALB activity was investigated in this article, where Biobased short aliphatic diols and diethyl carboxylates were enzymatically polymerized in solution at mild temperature using the immobilized form of Candida antarctica lipase B as biocatalyst.
TL;DR: In this article, different polyesters, poly(1,4-butylene succinate-ran-2,3-butane succinate) (PBB’S), were enzymatically copolymerized at different 1,4 butanediol (1, 4-BDO)/2, 3-butanediol 2, 3 -BDO molar ratios, with immobilized Candida antarctica lipase B (CALB).
TL;DR: An original method to functionalize PCL nanofibers, making them reactive for bioconjugation of proteins or other molecules of interest in water under mild conditions, is reported here.
Abstract: Polycaprolactone (PCL) electrospun fibers are widely developed for biomedical applications. However, their hydrophobicity and passivity towards cell growth is an important limitation. An original method to functionalize PCL nanofibers, making them reactive for bioconjugation of proteins or other molecules of interest in water under mild conditions, is reported here. This method involves the preparation of pseudo-polyrotaxanes (pPRs) of cyclodextrin (CD) and PCL. Core:shell PCL:pPR fibers were then prepared by coaxial electrospinning in order to bring available reactive hydroxyl groups from the CD to the fiber surface. Different pPR architectures (star, miktoarm and block-copolymer-like) were synthesized to study the effect of the pPR structure on fiber morphology and surface reactivity by grafting fluorescein isothiocyanate (FITC). Finally, bicyclononyne groups were grafted onto the star-pPR based fibers allowing the conjugation of a fluorescent dye by click chemistry in water without any copper catalyst proving the potential of the method for the biofunctionalization of PCL-based fibers.
TL;DR: Fully biobased aliphatic random poly(1,3propylene succinate-ran-1, 3-propylene adipate) (PPSA) copolyesters with high molar mass were synthesized with different macromolecular architectures based on various succinic acid/adipic acid (SA/AA) molar ratio, by transesterification in melt.
Abstract: Fully biobased aliphatic random poly(1,3-propylene succinate-ran-1,3-propylene adipate) (PPSA) copolyesters with high molar mass were synthesized with different macromolecular architectures based on various succinic acid/adipic acid (SA/AA) molar ratio, by transesterification in melt. Titanium (IV) isopropoxide was used as an effective catalyst. All synthesized copolyesters were fully characterized by different chemical and physicochemical techniques including NMR, size exclusion chromatography, FTIR, wide angle X-ray scattering, differential scanning calorimetry, and thermogravimetric analysis. The final copolyesters molar compositions were identical to the feed ones. The different sequences based on succinate and adipate segments were randomly distributed along the chains. All the corresponding copolyesters showed an excellent thermal stability with a degradation onset temperature higher than 290 °C, which increased with the adipate content. According to their compositions and architectures, PPSA copolyesters can exhibit or not a crystalline phase, at room temperature. Tg of copolyesters decreased with the adipate content due to the decrease in the chains mobility, following the Gordon–Taylor relation. PPSA showed a pseudo eutectic melting behavior characteristic of an isodimorphic character. Finally, PPSA copolyesters were not able to crystallize during the cooling or the second heating run, due to the 1,3-propanediol chemical structure, which led to amorphous materials with the exception of the polyester based solely on AA. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017
TL;DR: Fully biobased copolyesters were synthesized by transesterification between small chain length PHB and poly(butylene dicarboxylate)s with different molar masses, different HB/BA (or HB/BS) molar ratios, in solution or in bulk, using titanium (IV) isopropoxide (TTIP) as an effective catalyst.
Journal Article•
Patent•
27 Jul 2017TL;DR: In this paper, a method for manufacturing an isocyanurate polyurethane-modified foam, called PUIR, is described, which requires at least 50% by weight of the fatty acid having a carbon chain of C18 or more, the fatty acids having an overall iodine number I iodine of at least 100 g of I 2 /100 g, and epoxidating 50% of the double bonds in the oil to form the corresponding epoxides.
Abstract: Disclosed is a method for manufacturing an isocyanurate polyurethane-modified foam, called “PUIR,” including: a) providing an oil or oil mixture at least 50% by weight of the fatty acids having a carbon chain of C18 or more, the fatty acids having an overall iodine number I iodine of at least 100 g of I 2 /100 g; b) epoxidating at least 50% of the double bonds in the oil to form the corresponding epoxides; and c) directly reacting, in situ, the epoxides that are obtained above with isocyanate or diisocyanate groups for obtaining corresponding oxazolidone derivatives, without passing through the intermediate formation of polyols obtained from epoxides, in the presence of at least one suitable catalyst and at least one expanding agent, so as to obtain the isocyanurate polyurethane-modified foam “PUIR” Also disclosed are products, such as rigid insulation material, in particular as a material or panels of rigid insulation for roofing