Xylan Derivative Research Articles

Barrier and Antimicrobial Properties of Coatings Based on Xylan Derivatives and Chitosan for Food Packaging Papers

This paper analyzes the potential of coatings based on xylan derivatives and chitosan to provide barrier properties and antimicrobial protection for paper food packaging and also to substitute the synthetic materials currently used in the food packaging industry. Colloidal dispersions of xylan derivatives (hydrophobized xylan with alkyl ketene dimers—XyAKD—and acetylated xylan—XyAc) and a chitosan biopolymer (Ch) were applied as coatings in single and two successive layers on a paper substrate using a laboratory automatic film applicator. The assessment of the water and fatty compound barrier properties of coated paper samples showed differences in effectiveness among xylan derivatives and their combination with chitosan. Generally, xylan derivative coatings improved the barrier and antimicrobial features of coated papers compared with native xylan. However, important improvements were obtained by adding to the coating formula a chitosan biopolymer. Thus, the best barrier properties for water, water vapors, oils and greases were obtained for paper coated with the acetylated xylan and chitosan formula in a single layer, where values of 30 g/m2.day for the water vapor transmission rate (WVTR), a 92.8° contact angle (CA) and a KIT rating of 8 were achieved. All coated paper samples exhibited the total inhibition of Bacillus sp. both after 24 and 48 h. Based on the obtained results in this study, one can conclude that the area of application of xylan hemicelluloses could be extended. Their utilization in appropriate chemical structures and combinations as coatings for paper can be a sustainable alternative for the food packaging industry.

Synthesis and structural characterization of xylan acetate ester and its antinephritic effects in rats with experimental chronic kidney disease

Acetic acid has been shown to be effective in chronic kidney disease (CKD). However, it is a low-molecular-weight compound that allows it to be absorbed in the upper digestive tract so that it cannot function in colon. To overcome these deficiencies, an acetate-releasing xylan derivative, xylan acetate ester (XylA), was synthesized and selected in this study for its potential in the treatment of CKD. IR, NMR and HPGPC were used to characterize the structure of XylA and its antinephritic effects was evaluated in vivo. The results showed that acetate was successfully grafted onto the C-2 and C-3 positions of xylan and with a molecular weight at 69157 Da. XylA treatments could relieve the symptoms of CKD in an adenine-induced chronic renal failure (CRF) model and an adriamycin-induced focal segmental glomerulosclerosis (FSGS) model in SD rats. Further study indicated that XylA could upregulate the short-chain fatty acids (SCFAs) in vitro and vivo. Nevertheless, the relative abundance of Phascolarctobacterium in colon was increased after XylA treatment. XylA could upregulate G-protein-coupled receptor 41 (GPR41) expression, inhibit glomerular cell apoptosis and promoting proliferation. Our study expands the application of xylan and provides a new idea for the treatment of CKD with acetic acid.

A highly stretchable, UV resistant and underwater adhesive hydrogel based on xylan derivative for sensing

Hydrogels with fascinating adhesion have been demonstrated great potential in various applications. However, most hydrogels lose their adhesion in wet or underwater environments due to the influence of interfacial water. Inspired by mussel, an underwater adhesive hydrogel was facilely fabricated by introducing electrostatic interactions, which consisted of poly (acrylic acid) (PAA), quaternized xylan (QAX) and tannic acid (TA). In this hydrogel, -COO− from PAA, -N+(CH3)3 from QAX and catechol group from TA resembled amino acids with negative and positive charges and 3,4-dihydroxyphenylalanine units in mussel, which endowed the hydrogels with great underwater adhesion through multiple interactions. Notably, acrylic acid (AA) played a key role in the dispersion of the system. QAX, a biomass derived from plants with excellent properties, worked with PAA to construct hydrogel networks. The resultant hydrogels exhibited excellent mechanical properties including remarkable stretchability (>4000 %) and compressibility. Moreover, the hydrogels had superior UV-blocking (~99.96 %), and showed good adhesion both in air and underwater. The hydrogels can be exploited as a wearable sensor to monitor human motions and even subtle motions, which have the potential to be explored in human health monitoring.

Constructing a Novel Xylan-Based Film with Flexibility, Transparency, and High Strength.

Xylan-based films have great potential to replace petroleum-based polymers used for packaging and coatings due to their excellent biocompatibility, biodegradability, and good gas barrier properties. However, fabricating a xylan-based film with flexible, transparent, water-proof, and excellent mechanical properties is an enormous challenge. Herein, we manufactured a series of degradable films with adjustable properties via solution-casting using a water-soluble xylan derivative. This is the first report of a pure xylan-based film with high performance, requiring no additives. The tensile strength of the xylan-based film could be controlled by adjusting the aldehyde content, which varied from 105.0 to 132.6 MPa. The smallest initial water contact angle of the xylan-based films is 93.26°, indicating that these films are hydrophobic. This work shows a simple and viable route toward manufacturing xylan-based films with high tensile strength, flexibility, and transparency, which can be used for packaging materials and coatings.

Effect of xylan sulfate on the responsive swelling behavior of poly(methacrylatoethyl trimethyl ammonium chloride)-based composite hydrogels

Xylan sulfate, one important xylan derivative, was prepared using microfluidic reactor system and incorporated in situ under the polymerization of methacroylcholine chloride (DMC), resulting in composite hydrogels containing variable amount of xylan sulfate. The introduction of xylan sulfate imparts enhanced temperature-swelling responsiveness to the hydrogels, and substantially increases their water swelling ratio up to > 200 g/g, which is twice higher than the neat polyDMC hydrogel. Such swelling behavior may relate to the electrostatic interaction between the –SO3− in xylan sulfate and the –NH4+ in polyDMC. This interaction significantly improves the formation of porous architecture and the tensile toughness of the hydrogels. The composite hydrogels exhibit responsive swelling behavior at different salt, pH, and solvent conditions due to osmotic pressure decline, charge shielding and salting-out effect. They load 2.2 times amount of tetracycline hydrochloride and show 50.3% slower release rate than the neat polyDMC hydrogel, which shows great potential for drug delivery applications.

An orally administered butyrate-releasing xylan derivative reduces inflammation in dextran sulphate sodium-induced murine colitis

Butyrate has been shown to be effective in ulcerative colitis (UC). However, its oral administration is rare due to its rancid odour and unpleasant taste. In this study, the effect of a butyrate-releasing polysaccharide derivative, xylan butyrate ester (XylB), was evaluated in a dextran sodium sulphate (DSS)-induced UC model in C57BL/6 mice. Linear xylan was extracted from corn cobs. The C-2 and C-3 positions of the linear xylan were esterified with butyrate, forming XylB. The protective and therapeutic effects of XylB against UC were determined in a DSS-induced mouse model. The results showed that XylB treatments reversed the imbalance between pro- and anti-inflammatory cytokines. Moreover, XylB rebalanced the gut microbiota that interfered with DSS treatment and significantly decreased the relative abundance of the genera Oscillibacter, Ruminococcaceae UCG-009, Erysipelatoclostridium, and Defluviitaleaceae UCG-01. XylB increased butyrate content in the colon, upregulated G-protein coupled receptor 109A protein expression, inhibited histone deacetylase (HDAC) activity, and exerted anti-inflammatory activity through autophagy pathway activation and nuclear factor-κB (NF-κB) inhibition. XylB reduces inflammatory intestinal damage in mice, suggesting that it would be a potential drug for the treatment of UC and could be used to overcome the limitations of the oral administration of sodium butyrate.

Biomass Nanomicelles Assist Conjugated Polymers/Pt Cocatalysts To Achieve High Photocatalytic Hydrogen Evolution

Conjugated polymers are emerging as promising organic photocatalysts for photocatalytic hydrogen evolution; however, they are suffering from poor water dispersabilities. Herein, this problem is addressed in an easy and green way with the assistance of a biomass-derived material. An amphipathic xylan derivative that can be self-assembled into nanomicelles was employed as carriers to encapsulate a series of conjugated polymers to form uniform composite micelles in water. By this way, the hydrophobic conjugated polymers and their blends were successfully dispersed into water and thus enabling efficient hydrogen evolution. Moreover, the energy level offsets of these conjugated polymers enable the formation of photoinduced charge transfer (PCT) process and fluorescence resonance energy transfer (FRET) process in their composite micelles. The photocatalytic experimental results showed that in these composite micelles, conjugated polymer blends with PCT characteristic delivered much higher photocatalytic hydroge...

Synthesis of Cationic Xylan Derivatives and Application as Strengthening Agents in Papermaking

Cationic xylan derivatives were prepared by etherification using 3-chloro-2-hydroxypropyltrimethylammonium chloride as the cationic reagent under an alkaline condition. These derivatives were utilized as strengthening agents to enhance the mechanical strength properties of paper. Cationic xylan derivatives with different degree of substitution (DS) values (0.11 to 0.35) that corresponded to different cationic charge densities (0.51 mmol/g to 0.85 mmol/g) were successfully synthesized, and the reaction parameters were optimized based on the DS and charge density. The cationic xylan derivatives were characterized by means of elemental analysis, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectrometry. The xylan derivatives had a good performance in strengthening the physical properties of the paper, such as the tensile, tear, and burst strengths. When the DS of the cationic xylan derivative was higher, the strengthening effectiveness was better. At a 2.4-wt.% (based on dried pulp) dosage with the xylan derivative that had a DS of 0.32, the tensile, tear, and burst indices of the pulp increased by 63%, 58%, and 42%, respectively. For the pulps with different beating degrees, the cationic xylan derivative was more beneficial to the pulps with a lower beating degree.

Correlation between cellulose thin film supramolecular structures and interactions with water.

Water interactions of ultra-thin films of wood-derived polysaccharides were investigated by using surface sensitive methods, Quartz Crystal Microbalance with Dissipation (QCM-D) and Atomic Force Microscopy (AFM). These approaches allow systematic molecular level detection and reveal information on the inherent behaviour of biobased materials with nanosensitivity. The influence of structural features of cellulose films i.e. crystallinity, surface roughness and porosity on water interactions was clarified. Cellulose films were prepared using spin-coating and Langmuir-Schaefer deposition to obtain thin films of equal thickness, identical cellulose origin, simultaneously with different supramolecular structures. The uptake/release of water molecules and swelling were characterized using QCM-D, and the structural features of the films were evaluated by AFM. More crystalline cellulose film possessed nanoporosity and as a consequence higher accessible surface area (more binding sites for water) and thus, it was capable of binding more water molecules in humid air and when immersed in water when compared to amorphous cellulose film. Due to the ordered structure, more crystalline cellulose film remained rigid and elastic although the water binding ability was more pronounced compared to amorphous film. The lower amount of bound water induced softening of the amorphous cellulose film and the elastic layer became viscoelastic at high humidity. Finally, cellulose thin films were modified by adsorbing a layer of 1-butyloxy-2-hydroxypropyl xylan, and the effect on moisture uptake was investigated. It was found that the supramolecular structure of the cellulose substrate has an effect not only on the adsorbed amount of xylan derivative but also on the water interactions of the material.

2-Hydroxypropyltrimethylammonium xylan adsorption onto rod-like cellulose nanocrystal

Chemical incompatibility and relatively weak interaction between lignocellulosic fibers and synthetic polymers have made studies of wood fiber-thermoplastic composite more challenging. In this study, adsorption of 2-hydroxypropyltrimethylammonium xylans onto rod-like cellulose nanocrystals are investigated by zeta-potential measurements, and polarized and depolarized dynamic light scattering as a factor for better understanding of lignocellulosic fibers and cellulose nanocrystals. Zeta-potential measurements show xylan derivative adsorption onto cellulose nanocrystals. Decay time distributions of the ternary system and binary system from dynamic light scattering show that aggregates exist in the binary system and they disappear in the ternary system. At low 2-hydroxypropyltrimethylammonium xylan concentrations relative to that of cellulose nanocrystal, xylan derivatives adsorbed onto some of the cellulose nanocrystal. Hence, more xylan derivatives adsorbed onto cellulose nanocrystal increased with increasing xylan derivative concentration. Also, the concentration dependence of the ratio of the rotational diffusion coefficient to the translational diffusion coefficient revealed a strong adsorptive interaction between xylan derivatives and the cellulose nanocrystals.

Carboxymethylated-, hydroxypropylsulfonated- and quaternized xylan derivative films

Under alkaline/water conditions carboxymethyl, 2-hydroxypropylsulfonate and trimethylammonium-2-hydroxypropyl groups were introduced into xylan in one step with the goal to prepare film specimens. The materials were characterized by NMR, SEC-MALS, TG/DTG/DTA, AFM and mechanical testing. The properties of triple, double and mono-substituted materials were compared. The numerical molar masses of the specimens were from 12.3 to 17.6kg/mol with Mw/Mn from 1.27 to 1.34. The elastic modulus values are decreasing in order: xylan (X; 7354MPa)>carboxymethyl xylan (CX; 6090MPa)>2-hydroxypropylsulfonate xylan (SX; 6000MPa)>carboxymethyl/2-hydroxypropylsulfonate xylan (CSX; 4490MPa)>quaternized xylan (QX; 3600MPa)>carboxymethyl/quaternary/2-hydroxypropylsulfonate xylan (CQSX; 3380MPa)>carboxymethyl/quaternary xylan (CQX; 2805MPa). The onset temperatures of SX (214°C), CQSX (212°C), QSX (211°C) and CQX (207°C) were higher than for X (205°C). The roughness values of the film surfaces (3.634 – 18.667nm) are higher on top than on the bottom of the specimen.

Dual-Component System Dimethyl Sulfoxide/LiCl as a Solvent and Catalyst for Homogeneous Ring-Opening Grafted Polymerization of ε-Caprolactone onto Xylan

The preparation of xylan-graft-poly(ε-caprolactone) (xylan-g-PCL) copolymers was investigated by homogeneous ring-opening polymerization (ROP) in a dual-component system containing Lewis base LiCl and strong polar aprotic solvent dimethyl sulfoxide (DMSO). DMSO/LiCl acted as solvent, base, and catalyst for the ROP reaction. The effects of the parameters, including the reaction temperature, molar ratio of ε-caprolactone (ε-CL) to anhydroxylose units (AXU) in xylan, and reaction time, on the degree of substitution (DS) and weight percent of PCL side chain (WPCL) were investigated. The results showed that xylan-g-PCL copolymers with low DS in the range of 0.03-0.39 were obtained under the given conditions. The Fourier transform infrared spectroscopy (FTIR), (1)H nuclear magnetic resonance (NMR), (13)C NMR, (1)H-(1)H correlation spectroscopy (COSY), and (1)H-(13)C correlation two-dimensional (2D) NMR [heteronuclear single-quantum coherence (HSQC)] characterization provided more evidence of the attachment of side chains onto xylan. Only one ε-CL was confirmed to be attached onto xylan with each side chain. Integration of resonances assigned to the substituted C2 and C3 in the HSQC spectrum also indicated 69.23 and 30.77% of PCL side chains attached to AXU at C3 and C2 positions, respectively. Although the attachment of PCL onto xylan led to the decreased thermal stability of xylan, the loss of unrecovered xylan fractions with low molecular weight because of the high solubility of xylan in DMSO/LiCl resulted in the increased thermal stability of the samples. This kind of xylan derivative has potential application in environmentally friendly and biodegradable materials considering the good biodegradability of xylan and PCL.

Quaternized and sulfated xylan derivative films

Xylan quaternized sulfate films were prepared from beech xylan (X) and compared with fully sulfated xylan films (XS). When quaternized xylan (QX) was prepared in the first step (DSQ=0.55), than by sulfation of QX in the second step the fully substituted ampholytic derivative (QXS; DSQ=0.33; DSS=1.67) could be obtained. By sulfation in first step, xylan sulphate (SX, DSS=0.70) was obtained and by subsequent quaternization, SXQ film with DSQ=0.55 and DSS=0.33 which contained partially unsubstituted hydroxyls. The molar masses (Mn) of the film's soluble parts were increasing in order X<SX<SXQ<QX<XS<QXS. In all films there were some insoluble particles present as determined by the amount of recovered masses by SEC-MALS. The materials were further characterized by AFM, XRD, TG/DTG/DTA, NMR and mechanical testing. QXS and SXQ could form mechanically more stable films than XS specimens.

Hydroxyalkylated xylans – Their synthesis and application in coatings for packaging and paper

This paper demonstrates opportunities for wood-based xylan derivatives to be used in coating applications. A route for extraction and purification of white and pure xylan from bleached birch kraft pulp is described as a part of the production of high adsorption and high crystalline pulp. Derivatization of the xylan during the extraction step was also demonstrated. Efficient derivatization of xylan to water soluble derivatives was achieved and promising results were obtained in primary application tests as a coating component in barrier coatings on board and as a binder component in pigment coating of offset paper. With the best xylan derivate coating, the barrier properties were better than with a commercial biopolymer coating, while oxygen permeability was roughly one third of that for a polyethylene terephthalate coating. Likewise, surface strength close to the reference latex as a binder in pigment coatings was achieved by a xylan derivative. This work is part of a platform of hemicellulose derivatives enabling novel application for this medium to high molar mass hemicellulose of high purity.

Structural Features and Water Interactions of Etherified Xylan Thin Films

In this paper, the model film approach was used to investigate the structural features and humidity induced changes of the etherified xylan derivatives by using surface sensitive methods. Two routes to modify the birch xylan to generate either cross-linking xylan or more hydrophobic xylan were mastered via allylation and butylation, respectively. Thin nanometer scale model films were prepared by spin-coating and the films were further treated by UV-radical treatment and heat. The structural changes and wetting behaviour of the films before and after the post-treatment procedures were studied using atomic force microscopy and water contact angle measurements. In addition, the water vapour uptake of the xylan derivative films was monitored using quartz crystal microbalance with dissipation (QCM-D) equipped with the humidity module. With the QCM-D, the mass uptake due to the water vapour binding was defined. Simultaneously the changes in the viscoelastic properties of the films when subjected to different relative humidity conditions were determined. We show that the water sensitivity and wetting behaviour of the water soluble xylan derivatives can be altered by cross-linking the film structure and through the molecular rearrangements. Cross-linking and the conformational rearrangements of the allylated xylan reduced the water vapour uptake ability approximately 80 %. Butylated xylan as being a more hydrophobic derivative showed lower ability to uptake water vapour when compared to more hydrophilic xylan derivative. This ability was even further reduced after the post-treatments mainly due to the reassembly of the hydrophobic groups.

Studies on the fibre surfaces modified with xylan polyelectrolytes

Xylan was isolated from birch wood chips by using pressurized hot water extraction (PHWE). The extracted xylan was chemically modified yielding three different xylan derivatives (XDs): xylan sulfate (XS), carboxymethyl xylan (CMX) and xylan-4-[N,N,N-trimethylammonium]butyrate chloride (XTMAB). The structure and molecular weight of XDs was determined by using NMR spectroscopy and size exclusion chromatography (SEC). The potential utilization of xylan polyelectrolytes for modifying fibre surfaces was assessed by sorption experiments using bleached pine Kraft pulp as substrate. Polyelectrolyte titration method was chosen for estimating the amount of sorbed XDs onto the fibres. The cationic xylan derivative XTMAB had a strong interaction with fibres while the anionic derivatives did not show any sorption. X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS) were selected as advanced surface analyses for studying the amount of surface anionic groups and the surface distribution of the XTMAB. XPS and polyelectrolyte titration results suggested that the XTMAB is sorbed onto the fibre surfaces. ToF-SIMS imaging showed that XTMAB was evenly distributed on fibre surfaces.

The use of N,N′-diallylaldardiamides as cross-linkers in xylan derivatives-based hydrogels

N,N′ -Diallylaldardiamides (DA) were synthesized from galactaric, xylaric, and arabinaric acids, and used as cross-linkers together with xylan (X) derivatives to create new bio-based hydrogels. Birch pulp extracted xylan was derivatized to different degrees of substitution of 1-allyloxy-2-hydroxy-propyl (A) groups combined with 1-butyloxy-2-hydroxy-propyl (B) and/or hydroxypropyl (HP) groups. The hydrogels were prepared in water solution by UV induced free-radical cross-linking polymerization of derivatized xylan polymers without DA cross-linker (xylan derivative hydrogel) or in the presence of 1 or 5 wt % of DA cross-linker (DA hydrogel). Commercially available cross-linker (+)- N,N′-diallyltartardiamide (DAT) was also used. The degree of substitution (DS) of A, B, and HP groups in xylan derivatives was analyzed according to 1H NMR spectra. The DS values for the cross-linkable A groups of the derivatized xylans were 0.4 (HPX-A), 0.2 (HPX-BA), and 0.4 (X-BA). The hydrogels were examined with FT-IR and elemental analysis which proved the cross-linking successful. Water absorption of the hydrogels was examined in deionized water. Swelling degrees up to 350% were observed. The swollen morphology of the hydrogels was assessed by scanning electron microscopy (SEM). The presence of cross-linkers in DA hydrogels had only a small impact on the water absorbency when compared to xylan derivative hydrogels but a more uniform pore structure was achieved.

Novel Xylan Gels Prepared from Oat Spelts

AbstractGels and pastes are used in many areas including application in the cosmetic, pharmaceutical and medical industries. A xylan derivative with pasty consistency was prepared in addition to the synthesis of xylan ethers and esters. The water content of the gel can be widely varied. The gel is formed although the xylan contains no cross‐linking group. The hydrophobic and hydrophilic nature of the xylan gel can be adjusted by modifying the xylan. All of the gels can be dried using different methods (air drying, solvent exchange as well as freeze drying) and the dried gels can again disperse in water. The gels were characterised by porosity measurements (mercury intrusion), dynamic vapour sorption (DVS), scanning electron microscopy (SEM) and dispersion stability investigation respectively.