Nanostructured cellulose-xyloglucan blends via ionic liquid/water processing

Coarse-grained molecular dynamics model to evaluate the mechanical properties of bacterial cellulose-hemicellulose composites

The plant cell wall (PCW) inspires the preparation of fiber-based biomaterials, particularly emphasizing exploiting the intrinsic interactions within the load-bearing cellulose and hemicellulose network. Due to experimental difficulties in studying and interpreting the interaction between these polysaccharides, this research presents a numerical model based on coarse-grained molecular dynamics that evaluates the mechanical properties of fiber composites. To validate the model and explain the structural and mechanical role of hemicelluloses, bacterial cellulose (BC) was synthesized in the presence of different concentrations of xylan, arabinoxylan, xyloglucan, or glucomannan and subjected to nano- and macroscale structural and mechanical characterization. The data obtained were used to interpret the effects of each hemicellulose on the mechanics of the BC-hemicellulose composite based on the sensitivity of the model. The mechanical properties of the resulting simulated networks agreed well with the experimental observations of the BC-hemicellulose composites. Increased xylan and arabinoxylan contents increased the macroscale mechanical properties, fiber modulus (xylan), and fiber width (arabinoxylan). The addition of xyloglucan increased the mechanical properties of the composites in the elastic deformation phase, associated with an increase in the fiber modulus. Adding glucomannan to the culture medium decreased all the mechanical properties studied while the fiber width increased.

A study of the properties of hemicelluloses adsorbed onto microfibrillar cellulose isolated from apple parenchyma

Binding assays of commercially available hemicelluloses and pectins, and microfibrillar cellulose isolated form apple parenchyma were prepared. Initial studies showed that among all of the non-cellulosic polysaccharides examined, only the hemicelluloses (xyloglucan, xylan, glucomannan, ß-d-glucan) showed the ability to adsorb to microfibrillar cellulose. Among several adsorption models tested, the best fit was obtained for the Redlich-Peterson isotherm. Moreover, the linear vs. the branched structure and the size of the hemicelluloses have an influence over the extent of the adsorption to cellulose. The Fourier Transform Infrared and Raman spectra showed that a rather weak interaction took place between the hemicelluloses and cellulose. Also, the differential scanning calorimetry and the light scattering method results showed that after adsorption, cellulose has less mobility. Moreover, the mechanical properties of cellulose films changed after the addition of the chosen hemicelluloses and the films became less elastic but more resistant to a breaking force.

Microwave assisted preparation of a hemostatic gauze with mesoporous silica through in-situ synthesis

The medical disinfection cotton gauze is the most frequently used medical consumables for wound care. Here this ordinary commercial gauze was upgraded to a hemostatic gauze, which was loaded with mesoporous silica through in-situ synthesis and further microwave treatment. The original cotton gauze was pretreated with NaOH solutions for surface activation, soaked in double-silica source precursor solution for moderate in-situ synthesis, treated with microwave for quick template removement and dehydration. The final obtained hemostatic gauze (MS-G₁) showed superior physical, biocompatible and hemostatic advantages. The newborn mesoporous silica was firmly anchored onto the cotton fiber surface with <20% leaching after 10 min of sonication. The microwave treatment not only shortened the time for template removal but also promotes the formation of mesoporous structure. The clotting blood time (CBT) of MS-G₁ were only (62.00 ± 5.56 s), which was 23.14% shorter than that of original medical gauze, and even 3.6% shorter than Combat Gauze (CG). MS-G₁ also showed excellent biocompatibility in cytotoxicity tests of L-929 cells, with a 116% proliferation rate at the concentration of 5 mg/mL. Furthermore, the hemostatic performance was explored on a rabbit wound model of hemorrhagic liver injury, and MS-G₁ showed both shorter hemostasis time (113.75 s) and less blood loss (1.69 g) than that of CG (180.00 s, 5.13 g). The hemostatic gauze anchored with mesoporous silica was expected to be an excellent prehospital hemostatic dressing for field first aid.

High-Strength Regenerated Cellulose Fiber Reinforced with Cellulose Nanofibril and Nanosilica

In this study, a novel type of high-strength regenerated cellulose composite fiber reinforced with cellulose nanofibrils (CNFs) and nanosilica (nano-SiO₂) was prepared. Adding 1% CNF and 1% nano-SiO₂ to pulp/AMIMCl improved the tensile strength of the composite cellulose by 47.46%. The surface of the regenerated fiber exhibited a scaly structure with pores, which could be reduced by adding CNF and nano-SiO₂, resulting in the enhancement of physical strength of regenerated fibers. The cellulose/AMIMCl mixture with or without the addition of nanomaterials performed as shear thinning fluids, also known as "pseudoplastic" fluids. Increasing the temperature lowered the viscosity. The yield stress and viscosity sequences were as follows: RCF-CNF² > RCF-CNF²-SiO₂² > RCF-SiO₂² > RCF > RCF-CNF¹-SiO₂¹. Under the same oscillation frequency, G' and G" decreased with the increase of temperature, which indicated a reduction in viscoelasticity. A preferred cellulose/AMIMCl mixture was obtained with the addition of 1% CNF and 1% nano-SiO₂, by which the viscosity and shear stress of the adhesive were significantly reduced at 80 °C.

Ionic Liquid-Based Materials for Biomedical Applications

Ionic liquids (ILs) have been extensively explored and implemented in different areas, ranging from sensors and actuators to the biomedical field. The increasing attention devoted to ILs centers on their unique properties and possible combination of different cations and anions, allowing the development of materials with specific functionalities and requirements for applications. Particularly for biomedical applications, ILs have been used for biomaterials preparation, improving dissolution and processability, and have been combined with natural and synthetic polymer matrixes to develop IL-polymer hybrid materials to be employed in different fields of the biomedical area. This review focus on recent advances concerning the role of ILs in the development of biomaterials and their combination with natural and synthetic polymers for different biomedical areas, including drug delivery, cancer therapy, tissue engineering, antimicrobial and antifungal agents, and biosensing.

Tailoring renewable materials via plant biotechnology

Plants inherently display a rich diversity in cell wall chemistry, as they synthesize an array of polysaccharides along with lignin, a polyphenolic that can vary dramatically in subunit composition and interunit linkage complexity. These same cell wall chemical constituents play essential roles in our society, having been isolated by a variety of evolving industrial processes and employed in the production of an array of commodity products to which humans are reliant. However, these polymers are inherently synthesized and intricately packaged into complex structures that facilitate plant survival and adaptation to local biogeoclimatic regions and stresses, not for ease of deconstruction and commercial product development. Herein, we describe evolving techniques and strategies for altering the metabolic pathways related to plant cell wall biosynthesis, and highlight the resulting impact on chemistry, architecture, and polymer interactions. Furthermore, this review illustrates how these unique targeted cell wall modifications could significantly extend the number, diversity, and value of products generated in existing and emerging biorefineries. These modifications can further target the ability for processing of engineered wood into advanced high performance materials. In doing so, we attempt to illuminate the complex connection on how polymer chemistry and structure can be tailored to advance renewable material applications, using all the chemical constituents of plant-derived biopolymers, including pectins, hemicelluloses, cellulose, and lignins.

A Concise Review on the Physicochemical Properties of Biopolymer Blends Prepared in Ionic Liquids

An enhancement of environmental concern lately has improved the awareness of researchers in employing eco-friendly solvents for processing biopolymers. Recently, ionic liquids have been utilized to prepare biopolymer blends as they are non-volatile and recyclable. Biopolymers such as cellulose, chitin, chitosan, keratin, lignin, silk, starch, and zein are widely used for the preparation of biopolymer blends via dissolution in ionic liquids, followed by coagulation procedure. In this concise review, three types of ionic liquids based on imidazolium cations combined with different counter anions that are frequently utilized to prepare biopolymer blends are described. Moreover, three types of biopolymer blends that are prepared in ionic liquids were classified, specifically polysaccharide/polysaccharide blends, polysaccharide/polypeptide blends, and polysaccharide/bioplastic blends. The physicochemical properties of biopolymer blends prepared in different imidazolium-based ionic liquids are also concisely reviewed. This paper may assist the researchers in the polymer blend area and generate fresh ideas for future research.

Fabrication of water-soluble loose-fill foam from tamarind (Tamarindus indica L.) seed polysaccharide by mechanical frothing and freeze-drying process

The water-soluble loose-fill foam obtained from tamarind seed polysaccharide (TSP) was successfully prepared by a combination of mechanical frothing and freeze-drying process. The effects of TSP concentration, plasticizer content, and surfactant content on the cellular morphology, physical properties, mechanical properties, and moisture absorption were investigated. The cellular structure of TSP foam exhibited an open cell structure with a non-uniform size of the cell window, and the density varied in a range of ∼0.006–0.106 g/cm3. Foam preparation with high TSP concentration, low plasticizer as well as glycerol content enhanced the mechanical properties of the obtained foam, including tensile strength, compressive strength, and hardness. The high compressive strength of TSP foams up to ∼1.03 MPa can be produced which demonstrates that TSP foam is capable to use as a loose-fill product.

Towards High-performance Materials Based on Carbohydrate-Derived Polyamide Blends

A bio-derived monomer called 2,3:4,5-di-O-isopropylidene-galactarate acid/ester (GalXMe) has great potential in polymer production. The unique properties of this molecule, such as its rigidity and bulkiness, contribute to the good thermal properties and appealing transparency of the material. The main problem, however, is that like other biobased materials, the polymers derived thereof are very brittle. In this study, we report on the melt blending of GalXMe polyamides (PAs) with different commercial PA grades using extrusion as well as blend characterization. Biobased PA blends showed limited to no miscibility with other polyamides. However, their incorporation resulted in strong materials with high Young moduli. The increase in modulus of the prepared GalXMe blends with commercial PAs ranged from up to 75% for blends with aliphatic polyamide composed of 1,6-diaminohexane and 1,12-dodecanedioic acid PA(6,12) to up to 82% for blends with cycloaliphatic polyamide composed of 4,4′-methylenebis(cyclohexylamine) and 1,12-dodecanedioic acid PA(PACM,12). Investigation into the mechanism of blending revealed that for some polyamides a transamidation reaction improved the blend compatibility. The thermal stability of the biobased PAs depended on which diamine was used. Polymers with aliphatic/aromatic or alicyclic diamines showed no degradation, whereas with fully aromatic diamines such as p-phenylenediamine, some degradation processes were observed under extrusion conditions (260/270 °C).

Biopolymer-Based Composite Materials Prepared Using Ionic Liquids

Biopolymer-based composite materials have many potential applications in biomedical, pharmaceutical, environmental, biocatalytic, and bioelectronic fields, owing to their inherent biocompatibility and biodegradability. When used as solvents, ionic liquids can be used to fabricate biopolymers such as polysaccharides and proteins into various forms, including molded shapes, films, fibers, and beads. This article summarizes the processes for preparing biopolymer-based composite materials using ionic liquids. The processes include biopolymer dissolution using ionic liquids, regeneration of the biopolymer by an anti-solvent, formation of shapes, and drying of the regenerated biopolymer. In particular, the preparation and applications of biopolymer blend-based composite materials containing two or more biopolymers are addressed.