Esterification Of Anhydride Research Articles

Fabrication of clickable bamboo-sourced cellulose nanofibrils for diverse surface modifications: Hydrophobicity and fluorescence functionalities

Surface functionalization of cellulose nanofibrils (CNF) is crucial for expanding their practical application. However, most functionalization processes are complicated and laborious. Herein, this work presents a facile surface engineering strategy to create a range of functionalized CNF via thiol-ene click reaction. Initially, clickable CNF was produced by grafting a compound with both carboxylate- and norbornene groups onto bamboo cellulose via norbornene-dicarboxylic anhydride esterification followed by homogenization. The introduction of negatively charged carboxylates facilitated nanofibrillation, resulting in CNF with a diameter of 3 nm and an aspect ratio of up to 600. The introduction of norbornenes enabled diverse functionalization of CNF through click reaction. Subsequently, hexadecanethiol successfully clicked with norbornene-grafting CNF, enhancing its hydrophobicity and dispersion in organic solvents. 7-mercapto-4-methyl coumarin was also able to click with norbornene-grafting CNF, yielding fluorescence-labeled CNF while maintaining excellent aqueous dispersibility. The fluorescence-labeled CNF was demonstrated to be utilized as an eco-friendly sensor for the detection of Fe3+ ions. Additionally, it could be converted into fluorescent films or intelligent inks suitable for anti-counterfeiting purposes. This study demonstrates that the proposed surface engineering strategy provides an effective approach for producing clickable CNF and fabricating cellulosic materials with diverse functionalities that meet the demands of various applications.

Tunning the hydrophobic performance and thermal stability of pectin film by acetic anhydride esterification

Pectin, a polysaccharide found in plant cell walls, is characterized by a high abundance of hydroxyl groups and carboxylic acid groups, which results in a strong affinity for water and limits its suitability as a film material. This study aimed to modulate the esterification degree of PEC films by adjusting the concentration of acetic anhydride, and assess the impact of acetic anhydride esterification modification on the properties of the resultant PEC films. The results demonstrated successful grafting of acetic anhydride onto the galacturonic acid ring in the PEC molecule through the esterification process. The hydrophobicity, thermal stability, barrier properties, and mechanical properties of the esterified PEC films were investigated. Among the various concentrations tested, the E-PEC-0.25 film exhibited the highest contact angle of 103.46° and tensile strength of 33.44 MPa, showcasing optimal performance. The E-PEC-0.1 film achieved the highest esterification degree of 0.94 and elongation at a break of 21.11 %. It also exhibited the transparency of 11.66 and the lowest water vapor transmission rate of 0.56 g·mm/(m2·h·kpa). Additionally, TGA and DSC tests revealed enhanced thermal stability of the esterification-prepared films. These findings highlight the potential of acetic anhydride tuning as a promising strategy for optimizing pectin film production.

Effect of hornification on the isolation of anionic cellulose nanofibrils from Kraft pulp via maleic anhydride esterification

Cellulose nanofibrils (CNF) isolation based on a catalyst-free maleic anhydride esterification has proven to be effective, however, the effects of pulp hornification on CNF isolation by this strategy have yet to be explored, which could present significant impacts for CNF isolation. Herein, dried northern bleached softwood Kraft pulp (D-NBSK) and never-dried northern bleached softwood Kraft pulp (ND-NBSK) were selected as the substrates. After esterification with maleic anhydride (MA), the esterified ND-NBSK pulp (E-ND) shows a significantly smaller size and more fragmented structure than the esterified D-NBSK pulp (E-D). Meanwhile, higher degree of esterification can be realized for the never dried pulp as compared to the dried pulp, which is corroborated by the significantly stronger characteristic peaks of CO (1720 cm−1) and -COO− (1575 cm−1) from the FTIR spectra and the higher surface charge content (0.86 ± 0.04 mmol/g vs. 0.55 ± 0.05 mmol/g). A comparison of the characteristics of the resulting CNF similarly demonstrated the negative impact of hornification. Overall, this work indicates that hornification tends to reduce the accessibility of chemical reagents to the pulp, leading to insufficient deconstruction. Such negative impact of hornification should be considered when performing nanocellulose isolation, especially when using pulp as feedstock.

Anhydride esterification to regulate water migration and reduce ice crystal formation in κ-carrageenan gel during freezing

In this study, κ-carrageenan was chemically modified by acid anhydride esterification to produce acid anhydride-esterified κ-carrageenan, and its properties were subsequently determined. Acid anhydride-esterified κ-carrageenan can improve the water retention properties of gels and limit the deterioration of gel textural performances during the freezing process. Scanning electron microscopy results before and after freezing showed that the frozen esterified κ-carrageenans had a more regular and less fibrous network structure, which suggests that the esterified κ-carrageenans better maintained the gel network structure. These phenomena were studied in relation to intermolecular forces, water movement, and ice crystal formation. The intermolecular force analysis showed that the esterification of anhydride disrupted the hydrogen bond formed between κ-carrageenan molecules, enhanced hydrophobic interactions among κ-carrageenan molecules, and resulted in stronger electrostatic repulsion. Low-field nuclear magnetic resonance analysis showed that acid anhydride-esterified κ-carrageenan more effectively bound to water molecules during freezing. Differential scanning calorimetry results showed that acid anhydride-esterified κ-carrageenan reduced the amount of freezing water and lowered the eutectic point of the gel. The results showed that hydrogen bonding, electrostatic interactions, and hydrophobic interactions modified the structure of the acid anhydride-esterified κ-carrageenan gel network and its binding to water molecules. This phenomenon allowed acid anhydride-esterified κ-carrageenan to better maintain binding with water molecules during the freezing process, which in turn delayed and reduced the formation of ice crystals and greatly decreased the effect of ice crystals on the structure of the gel network.

Esterified styrene-maleic anhydride ester copolymer–modified MWCNTs dispersion with excellent dispersibility and long storage stability

Esterified styrene-maleic anhydride ester copolymer–modified MWCNTs dispersion with excellent dispersibility and long storage stability

Sustainable route to prepare functional lignin-containing cellulose nanofibrils

With nano-dimension, high aspect ratio, and high mechanical properties, cellulose nanofibrils (CNFs) are emerging sustainable nanomaterials with potential applications in films and composites. However, their preparation often involves a series of chemical treatments such as delignification, bleaching and harsh chemical pretreatments, and treats lignin as waste. Herein, we report a sustainable method to prepare high-quality lignin-containing cellulose nanofibrils (LCNFs) from bamboo chips, using a one-step maleic anhydride esterification treatment without any toxic organic solvent or catalyst. The resultant LCNFs have high lignin content (24%), high surface charge (2.25 mmol/g), fine diameter (∼2.5 nm), and high aspect ratio (>400). These superior properties can be translated into the corresponding nanopaper films with high optical transmittance (85% at 600 nm), UV shielding (<10% transmittance at 200–350 nm), hydrophobicity (water contact angle 75°), thermal stability (maximal weight loss temperature at 338 °C), and mechanical properties. Importantly, such films show the best reported tensile strength (290 MPa) among all the LCNF films, and it still outperforms conventional CNF films after 5 rounds of recycling. Furthermore, as sustainable nanofillers, such LCNFs can be directly incorporated into a hydrophobic polyester matrix, and significantly enhances the UV shielding and mechanical properties of the final nanocomposites. Altogether, with eco-friendly production and multiple functions, these LCNFs are a new class of nanocelluloses with high industrial relevance.

Eco-friendly cellulose nanofibrils with high surface charge and aspect ratio for nanopaper films with ultrahigh toughness and folding endurance

A one-pot eco-friendly method was developed based on maleic anhydride esterification to produce high quality cellulose nanofibrils and high performance nanopaper films.

OSA improved the stability and applicability of emulsions prepared with enzymatically hydrolyzed pomelo peel insoluble fiber

Insoluble fibers are not commonly used as emulsion stabilizers because of their compact physical structure and strong hydrophilicity. In this study, pomelo insoluble fibers (PISFs) prepared via cellulase hydrolysis and cellulase hydrolysis followed by octenyl succinic anhydride esterification were used as emulsifiers. The fabricated fibers are denoted as MPISF and OMPISFs, respectively. Unlike MPISF, the OMPISFs with different degrees of substitution (i.e., OMPISF(I) and (II)) increased in the ζ-potentials and contact angles but decreased in the oil-water interfacial tensions to different degrees. Furthermore, an 0.5 wt% OMPISF(II) content was required to prepare a stable non-creaming emulsion, whereas the corresponding MPISF and OMPISF(I) contents were 0.75 wt%. The OMPISF(II)-stabilized emulsions did not undergo creaming after three freeze-thaw treatment cycles. Therefore, the properties of the OMPISF(II)-stabilized emulsions were superior to those of the MPISF- and OMPISF(I)-stabilized emulsions. Additionally, the final amount of free fatty acids released by the OMPISF(II)-stabilized emulsion was 13.3% lower than that released by the MPISF-stabilized emulsion during simulated gastrointestinal digestion. During lipid oxidation processes, the amounts of lipid hydroperoxide and thiobarbituric acid reactive substance produced in the OMPISF(II)-stabilized emulsion were 41.3% and 40.0% lower, respectively, than those in the MPISF-stabilized emulsion. OMPISFs improved the emulsion properties by increasing the oil–water interface stability, forming more solid three-dimensional structures, and promoting electrostatic repulsion between emulsion droplets. These findings indicate that pomelo peel dietary fiber is a promising emulsifier with excellent application potential for the preparation of emulsion stabilizers. • Dual modification of OSA and cellulase endowed PISF an excellent emulsibility. • Freeze-thaw, digestion and oxidative stability of emulsions were improved by OSA. • Higher DS provide emulsions with higher stabilization and application properties. • Improved network, interface layer and electrostatic value were the main mechanism. • This study facilitates the development of utilization of pomelo peel as emulsifier.

Derivatizing of Fast Pyrolysis Bio-Oil and Coprocessing in Fixed Bed Hydrotreater

In several countries forest-based biofuels are being developed and to some extent also deployed. Fast pyrolysis bio-oil produced from, for example, sawdust, has now been coprocessed in fluid catalytic cracking refinery units in a number of commercial trials. However, this application is limited to about 10% of the total feed, and coprocessing in conventional fixed bed hydrotreaters is necessary to reach the high potential with this feedstock. Feeding and upgrading of fast pyrolysis bio-oil in a fixed bed reactor configuration is still problematic due to the inherent bio-oil properties. Stabilization of reactive compounds in fast pyrolysis bio-oil and mild hydrotreatment in a separate refining unit prior to refinery integration has therefore been developed the past decade. Another approach, presented here, involves complete dewatering of fast pyrolysis bio-oil by azeotropic distillation using mesityl oxide as the solvent, followed by conversion of the abundant hydroxyl compounds via mixed anhydride esterification methodology using an external source of mixed carboxylic acids of different chain lengths originating from renewable tall oil fatty acids, providing a lipophilic feed component. Dewatering and derivatizing were carried out in reactors up to 50 dm3 with a mass ratio of fast pyrolysis bio-oil to tall oil fatty acid of 10:13. The produced lipophilic oils were miscible with a petroleum light gas oil fraction and exhibited superior stability even after accelerated aging at elevated temperature (80 °C). The derivatized oils were thus mixed with light gas oil, with a proportion of 30 wt % derivatized oil in final blends and hydrotreated continuously in pilot fixed bed reactors for 14 days at 4 operating conditions without plugging or excessive exotherms. The test conditions were varied; the reactor pressure was either 55 or 80 bar, temperature 380 or 400 °C, and liquid hourly space velocity either 1 or 2 h–1 during the hydrotreatment. Successful hydrodeoxygenation and desulfurization were accomplished, whereas an increasing nitrogen concentration could be observed in the liquid products with the particular catalyst and reaction conditions employed. The observed hydrogen consumption (15–20 g/kg feed) was compared with the stoichiometric consumption for direct deoxygenation and with typical consumptions for industrial hydrotreated vegetable oil processing. The measured biogenic carbon content in hydrotreated liquid products (26.7%) agreed extremely well with the calculated biogenic carbon content in the hydrotreating feed (26.6%) that consisted of the blend of derivatized oil and petroleum light gas oil. The overall results are very promising since simple unit operations can be used to produce derivatized fast pyrolysis bio-oils that do not need additional standalone hydrotreating units but can be coprocessed in existing ones.

Synthesis and Characterization of Functional Monomer N‐Vinyl Formamide (NVF)

AbstractN‐vinyl formamide (NVF) is successfully synthesized by using the intermediate polystyrene maleic anhydride ester. The prepared NVF owns high purity and the diacid as a by‐product of synthesis can be reused. N‐a‐hydroxyethyl formamide (NHEF) is synthesized by using acetaldehyde and formamide as raw materials in the presence of basic catalyst. Acetaldehyde is purified by distillation under reduced pressure and dried with anhydrous magnesium sulfate. Low molecular weight styrene/maleic anhydride copolymer (SMA) is synthesized by the reaction of styrene and maleic anhydride in the presence of benzoyl peroxide initiator using acetone as solvent. The intermediate polystyrene maleic anhydride ester (NHEF–ADDUCT) is synthesized with SMA and NHEF as raw materials. Finally, the obtained NHEF–ADDUCT is cracked and the target product NVF is isolated and purified. The NVF is characterized by Fourier transform infrared spectroscopy, gas chromatography (GC), 1H‐NMR, and 13C‐NMR. The purity of NVF is 86.7% as measured by iodometric method and GC internal standard method, indicating the small amount of impurity formamide in it.

Influence of gelatinization degree and octenyl succinic anhydride esterification on the water sorption characteristics of corn starch

The effects of gelatinization degree (GD) and octenyl succinic anhydride (OSA) esterification in the sorption-desorption characteristics of normal corn starch (NCS) were studied. NCS was subjected to different GD (53, 70, and 96%) with an extruder and lyophilized. FTIR analysis revealed that GD increased the hydrated (995/1022 ratio) and decreased the short-range ordered (1022/1047 ratio). The equilibrium sorption-desorption curve of starches was obtained for water activities up to 0.95 and fitted with the Guggenheim-Anderson-de Boer (GAB) model. Gelatinization of corn starch decreased its water sorption capacity, increased its sorption hysteresis and decreased its monolayer moisture content. OSA treatment of NCS reduced the water sorption capacity, hysteresis, and monolayer moisture content as reflected by slight variations of these parameters with the GD. A principal component analysis showed that GD and OSA esterification are mutually independent treatments, which can provide different effects on the water sorption characteristics of NCS.

Plasticizers: Synthesis of phthalate esters via FeCl3-catalyzed nucleophilic addition of alcohols to phthalic anhydride

Phthalates are esters of phthalic anhydride. Phthalic anhydride (1) has been reacted with alcohols 2 to synthesize phthalate monoesters 3 and diesters 4 with the favor of latter compound that primarily used as plasticizers worldwide. This two-steps process operates in single pot, in the presence of 10 mol% of FeCl3 as a catalyst. Mechanistically, the first step is the formation of phthalate monoesters 3 that involves a facile addition-displacement pathway, and the second step is essentially underwent a Lewis acid catalysis providing phthalate diesters 4 with very good yields. Application of the present reaction is demonstrated by synthesizing a macrolide 5 through the ring-closing metathesis of diallyl phthalate (4b) using the Grubb’s 2nd generation catalyst.

Fabrication of hydrophobic and high-strength packaging films based on the esterification modification of galactomannan

There is an increasing interest in substituting current packaging films with biologically-derived films without compromising mechanical properties and hydrophobicity. In this work, the esterified galactomannan (E-GM) films with good hydrophobicity, excellent oxygen barrier performance and high tensile mechanical strength were synthesized using anhydride esterification method prior to film formation. The hydrophobicity, mechanical properties, barrier properties, thermal stability and ultraviolet absorption of the prepared films were determined to fully investigate the features of galactomannan-based films. The results indicated that GM films can be successfully obtained by esterification. Compared to neat GM film, E-GM-1.5 film (acetic anhydride to GM of 1.5:1) achieved the highest degree of esterification (0.05), hydrophobicity (107°) and mechanical strength (92.0 MPa). In addition, the esterified GM films had lower toxicity for macrophages cells. The prepared E-GM films may provide more opportunities for further advancement and applications in the development of food packaging from natural resources.

Novel Green Synthesis of Octenyl Succinic Anhydride Esters of Granular Starch

Granular starch octenyl succinic anhydride (OSA) esters have most often been prepared in aqueous media, resulting in low reaction efficiencies and degree of substitution. In this study, granular ma...

Facile Synthesis and Biological Evaluation of New Thieno[2,3‐g]indolizine Derivatives

AbstractAn effective approach to the synthesis of thieno[2,3‐g]indolizine derivatives has been developed. A wide variety of reagents such as unsaturated aldehydes, methylvinylketone, esters of acrylic acid, maleic anhydride, methyl propiolate, dimethyl and diethyl acetylenedicarboxylates in the construction of functionally diverse rarely encountered tricyclic system has been used. A high number of structurally various thieno[2,3‐g]indolizines has been obtained in domino reactions with medium and high yields, the influence of solvents on the course of transformations has been studied, and the presence of moderate cytotoxic activity for a number of compounds has been established.

Photo-crosslinked anhydride-modified polyester and –ethers for pH-sensitive drug release

Photo-crosslinkable polymers have a great potential for the delivery of sensitive drugs. They allow preparation of drug releasing devices by photo-crosslinking, thus avoiding high processing temperatures. In this study, the hydrolysis behavior and drug release of three different photo-crosslinkable poly(ether anhydride)s and one poly(ester anhydride) were investigated. Three-arm poly(ethylene glycol) or polycaprolactone was reacted with succinic anhydride to obtain carboxylated macromers, and further functionalized with methacrylic anhydride to form methacrylated marcromers with anhydride linkages. The synthetized macromers were used to prepare photo-crosslinked matrices with different hydrolytic degradation times for active agent release purposes.The hydrolysis was clearly pH-sensitive: polymer networks degraded slowly in acidic conditions, and degradation rate increased as the pH shifted towards basic conditions. Drug release was studied with two water-soluble model drugs lidocaine (234 mol/g) and vitamin B12 (1355 g/mol). Vitamin B12 was released mainly due to polymer network degradation, whereas smaller molecule lidocaine was released also through diffusion and swelling of polymer network. Only a small amount of vitamin B12 was released in acidic conditions (pH 1.3 and pH 2.1). These polymers have potential in colon targeted drug delivery as the polymer could protect sensitive drugs from acidic conditions in the stomach, and the drug would be released as the conditions change closer to neutral pH in the intestine.

Structural properties of lotus seed starch prepared by octenyl succinic anhydride esterification assisted by high hydrostatic pressure treatment

This paper describes a new method for combining high hydrostatic pressure (HHP) and octenyl succinic anhydride (OSA) esterification for starch modification. The degree of substitution (DS) was 0.0148–0.0389 when the OSA concentration increased from 3% to 9%, whereas after HHP treatment, the DS decreased, especially for H-OSA-9%, from 0.0389 to 0.0125. Scanning electron microscopy indicated that OSA with combined HHP treatment destroyed the surface morphology of the starch. FTIR spectroscopy revealed two new absorption peaks at 1526 cm−1 and 1728 cm-1. The particle size of OSA-LS and H-OSA-LS increased significantly (P < 0.05), except H-OSA-9%, owing to the hydrophobic groups introduced into the starch during the esterification reactions; consequently, the starch powders tended to swell and aggregate in aqueous solution. The Mw, Mn, and Mw/Mn of amylose decreased slightly with OSA treatment. The X-ray diffraction patterns confirmed that the crystalline patterns of OSA-LS and H-OSA-LS were preserved, but the crystallinity decreased to different degrees. These results indicated that H-OSA-LS provided conditions for encapsulating lipophilic substances, thus providing a potential direction for further research.

Starch-based Janus particles: Proof-of-concept heterogeneous design via a spin-coating spray approach

The asymmetric nature of Janus particles made from synthetic polymers gives them intriguing properties that have found applications in a wide variety of fields, such as drug delivery, emulsion stabilization, and environmental decontamination. The potential of using natural biopolymers as base materials for Janus particles in the food industry, however, has not yet been fully explored. Here we demonstrate for the first time the design of a starch-only-based Janus particle. Using a spin-coating spray approach, we produced both large (12.2 μm) half-porous, waxy cornstarch Janus granules by alpha-amylase treatment and small (1.2 μm) half-hydrophobic, amaranth starch Janus granules by octenyl succinic anhydride esterification. Optical microscopy, scanning electron microscopy, super resolution-structured illumination spectroscopy, and infrared spectroscopy were used to confirm the binary nature of these particles. A methylene blue adsorption test further showed that the untreated (non-porous), half-porous Janus, and fully porous waxy cornstarch granules had five-hour adsorption rates of 20.5, 72.1, and 100%, respectively, and adsorption capacities of 0.82, 2.88, and 3.96 mg/g. Meanwhile, untreated amaranth starch granules were shown not to interact with each other in water, while >68% of the half-hydrophobic granules self-assembled into wormlike strings and micelles, and >66% of the fully hydrophobic granules aggregated into spherical, complex supermicelles. While the low yield typical of Janus particle formation prevents a more detailed characterization of these starch-based Janus particles, the unique properties they displayed here may open exciting, future applications in the food industry as texturants or surface-active agents, as well as in other fields requiring such uncanny materials.

Catalytic and ionic cross-linking actions of l-glutamate salt for the modification of cellulose by 1,2,3,4-butanetetracarboxylic acid

The sodium l-glutamate is reported as an efficient catalyst for the cross-linking between 1,2,3,4-butanetetracarboxylic acid (BTCA) and cellulose. Results presented ester absorbance of the treated fabrics strongly increased in the presence of the homemade l-glutamate salt, a mixture of l-glutamic acid (LGA) and NaOH at a specific ratio. Importantly, anti-wrinkle properties of the treated fabrics were significantly improved. Based on the relative concentration calculation, l-glutamate promoted the reaction of BTCA with cellulose by accelerating the formation of BTCA anhydrides and the esterification of anhydrides with cellulose. Besides, the improved anti-wrinkle property was partially attributed to the fact that the generated LGA reacted with cellulose and formed ionic cross-linking networks through amino groups with carboxyl groups in BTCA, which was confirmed by the Fourier transform infrared spectra and the computational calculations. Through detailed comparisons, l-glutamate catalyzed fabrics showed as good durability as sodium hypophosphite, indicating a possible alternative for phosphorus-containing catalysts.

Oxygen surface groups analysis of carbonaceous samples pyrolysed at low temperature

The basis of recently developed quantitative TG-MS analysis was used for the evaluation of TPD-MS measurements in order to characterize the changes in the surface chemistry of carbon cryogels after the oxidation/activation treatment. This methodology was applied to the analysis of partially pyrolysed carbon cryogels (400 °C), which were oxidized/activated in four different ways (phosphoric acid, Fenton like reaction, ammonium persulfate with sulfuric acid and nitric acid with hydrogen peroxide). The quantitative TPD-MS evaluation enables analysis of all the evolved gases during the sample heating (without the calibration of all gases) and distinguishes the carbonization process from the decomposition of the more thermally stable oxygen surface groups (analysis of the effect of oxidation/activation reagents). The activation by H3PO4 results in the hydrolysis and esterification of anhydrides, lactones and phenols and creation of phosphoric acid esters (C-O-P), which decompose into C3-P=O linkages with the CO evolution. All the oxidation treatments had a similar effect on the surface chemistry. The amounts of carboxylic acids and anhydrides increased significantly, while the amount of lactones and phenol groups decreased (oxidized into carbonyls). Application of TG-MS fundamentals to the evaluation of TPD-MS profiles from a wide range of samples allows determining all the gaseous products.