Starch treatment with deep eutectic solvents, ionic liquids and glycerol. A comparative study

Eco-friendly and flexible polysaccharide-based packaging films for fruit preservation

Food safety and wastage caused by fruit deterioration is a serious global problem. Effective packaging systems for extending the freshness period of fruit play a key role in food safety. In this work, we constructed an eco-friendly and flexible polysaccharide-based packaging film based on hydroxypropyl guar (HPG), cellulose nanocrystals (CNCs), deep eutectic solvents (DES) and anthocyanin (Anth). DES could endow polysaccharide films with multiple hydrogen bond numbers and good stability. Hydroxypropyl guar/cellulose nanocrystals/anthocyanin with 0.2 g deep eutectic solvents (HCA-DES0.2) had good tensile properties, oxygen barrier properties (3.01 cm3/m2·day·Pa), water resistance (WCA 111.97°), antibacterial (CFU ˂ 103), and transparency (55.4 %). The preservation tests of grape and blueberry showed that the shelf life of these two fruits was 12-20 days, and the polysaccharide film had great application potential in fruit preservation.

Rapid preparation of anti-retrogradation starch by choline chloride based deep eutectic solvents: A comparative study

Legumes are a widespread and cheap source of starch. However, legume starches are prone to retrogradation in applications. Therefore, enhancing the resistance to retrogradation is important to ensure the quality of starch products. In this study, the effects of amines, alcohols, and carboxylic acids deep eutectic solvents (DESs) on the retrogradation properties of pea starch (PS) were investigated. The results showed that the starches treated with carboxylic acid DESs for only 30 min exhibited low paste viscosity, high paste clarity and anti-retrogradation. The carboxylic acid DESs treatment resulted in holes or cracks appearing on the starch surface, a decrease in molecular ordering, relative crystallinity, and amylose content. The thermal enthalpy of starch as well as the pasting viscosity were substantially reduced after the treatment. The paste clarity and the resistance to retrogradation were significantly improved. Conversely, the structure, pasting and retrogradation properties of starch treated with amine and alcohol DESs exhibited only slight differences compared to PS. The carboxylic acid DESs took a short time for the starch modification, and the modified starch paste with low viscosity, high clarity, and resistance to retrogradation. The study could provide an environmentally-friendly and cost-effective method for the preparation of starch with well anti-retrogradation properties.

Exploring urea as a prospective auxiliary for starch functionalization: A concise review on modified starch properties and the sustainable packaging films

Urea is also known as carbamide, an inexpensive and eco-friendly additive for starch functionalization. This article reviews the potential role of urea in starch modification, with the prominence of the mechanism of urea action, alterations in the starch structure and functional properties. In addition, current literature conveys the prospective effect of urea in fabricating starch films for food packaging, and the relevant areas that need to be covered in the forthcoming research are specified at the end of the article section. Urea can modify the diverse physico-chemical and functional properties of starch. Starch-based films exhibit pronounced effects on their mechanical and barrier properties upon the incorporation of urea, although this effect strongly depends on the urea content and degree of substitution (DS). Overall, urea holds great potential for use in the starch and bioplastic film industries, as it produces biocompatible derivatives with desirable performance.

Thermoplastic Starch Processed under Various Manufacturing Conditions: Thermal and Electrical Properties

Eco-friendly materials like carbohydrate-based polymers are important for a sustainable future. Starch is particularly promising because of its biodegradability and abundance but its processing to thermoplastic starch requires optimization. Here we developed thermoplastic maize starch materials based on three manufacturing protocols, namely: (1) starch/glycerol manual mixing and extrusion, (2) starch/glycerol manual mixing, extrusion, and kneading, (3) starch/glycerol/water manual mixing and kneading. The physical properties were investigated by differential scanning calorimetry, thermogravimetric analysis, and broadband dielectric spectroscopy. As expected from a partially miscible blend, the dielectric spectra revealed two distinct α-relaxations for the glycerol-rich and the starch-rich phases, respectively. By employing kneading after extrusion, the miscibility between the two phases was found to improve based on thermal and dielectric methods. Moreover, the addition of water during the premixing stage was observed to facilitate phase separation between starch and glycerol, with the α-relaxation dynamics of the latter being comparable to pure glycerol.

Development of starch-rich thermoplastic polymers based on mango kernel flour and different plasticizers

This work reports on the development of starch-rich thermoplastic based formulations produced by using mango kernel flour, avoiding the extraction process of starch from mango kernel to produce these materials. Glycerol, sorbitol and urea at 15 wt% are used as plasticizers to obtain thermoplastic starch (TPS) formulations by extrusion and injection-moulding processes. Mechanical results show that sorbitol and urea allowed to obtain samples with tensile strength and elongation at break higher than the glycerol-plasticized sample, achieving values of 2.9 MPa of tensile strength and 42 % of elongation at break at 53 % RH. These results are supported by field emission scanning electron microscopy (FESEM) micrographs, where a limited concentration of voids was observed in the samples with sorbitol and urea, indicating a better interaction between starch and the plasticizers. Thermogravimetric analysis (TGA) shows that urea and sorbitol increase the thermal stability of TPS in comparison to the glycerol-plasticized sample. Differential scanning calorimetry (DSC) and dynamic-mechanical-thermal analysis (DMTA) verify the increase in stiffness of the sorbitol and urea plasticized TPS and also illustrate an increase in the glass transition temperature of both samples in comparison to the glycerol-plasticized sample. Glass transition temperatures of 45 °C were achieved for the sample with sorbitol.

Biocomposites Based on Wheat Flour with Urea-Based Eutectic Plasticizer and Spent Coffee Grounds: Preparation, Physicochemical Characterization, and Study of Their Influence on Plant Growth

In this study, we conducted the first plasticization of wheat flour (WF) with the addition of choline chloride:urea (1:5 molar ratio) eutectic mixture as a plasticizer and spent coffee grounds (cf) as a filler. Thermoplastic wheat flour (TPWF) films were obtained via twin-screw extrusion and then thermocompression. Their physicochemical characterization included mechanical tests, dynamic mechanical thermal analysis (DMTA), and sorption tests. XRD analysis revealed that the eutectic plasticizer led to a high degree of WF amorphization, which affected the physicochemical properties of TPWF. The results indicated that it was easy for the TPWF biocomposites to undergo thermocompression even with a high amount of the filler (20 pph per flour). The addition of the cf into TPWF led to an increase in tensile strength and a decrease in the swelling degree of the biocomposites. Biodegradation tests in soil revealed that the materials wholly degraded within 11 weeks. Moreover, a study of cultivated plants indicated that the biocomposites did not exhibit a toxic influence on the model rowing plant.

Treatment and mechanism for hot melting starch by reducing the molecular chain winding and crystallinity

Unlike thermoplastic petroleum-based materials, starch-based materials rely on aqueous systems but are incapable of hot melting, resulting in low processing efficiency and limited large-scale industrial applications. In this study, the combination of α-amylase liquefaction and urea plasticization was used for the first time to obtain enzymatic thermoplastic starch (ETPS) for hot melting by changing the molecular chain of starch. ETPS showed an apparent hot melting phenomenon when heated below 200 °C. Differential scanning calorimetry revealed that heat absorption peaks were obviously reduced, and the hot melting phenomenon occurred easily depending on the combination of enzymatic hydrolysis and plasticization. Dynamic mechanical analysis indicated that the combined modification effectively increased the number of freely movable chains. The red shift of -OH stretching vibration peaks indicated the formation of strengthened hydrogen bonds in ETPS. X-ray diffraction showed that the crystallinity of ETPS was reduced to 5.68 %, effectively reducing the regenerative phenomenon. Gel permeation chromatography revealed that the molecular weight of ETPS decreased, and the entanglements between molecular chains were reduced. A tensile test showed that the elongation at break of ETPS was as high as 235.29 %, which was much higher than those of enzymatic hydrolysis starch and thermoplastic starch.

Preparation and characterization of chemically modified tapioca starch-ionic liquid antibacterial films

The plasticizing and antibacterial effects of ionic liquids (ILs) in the preparation of tapioca starch-IL films were studied for the first time. 1-Ethyl-3-methylimidazolium acetate ([Emim][OAc]) caused complete disruption of starch crystallites during thermal compression, while some crystallites remained after the plasticization of starch with choline acetate ([Ch][OAc]). Compared to native tapioca starch (NTS), the plasticization of acetylated tapioca starch (ATS) and cross-linked tapioca (CTS) was slightly promoted and inhibited, respectively. Starch-[Emim][OAc] films exhibited higher hydrophobicity and mechanical properties but lower antibacterial activity than starch-[Ch][OAc] films. CTS-[Ch][OAc] films presented higher mechanical strength and antibacterial activity than NTS-[Ch][OAc] and ATS-[Ch][OAc] films. From this study, we conclude that ILs can be used in the preparation of antibacterial starch films to play the roles of plasticization and antibacterial activity. The antibacterial activity of starch films depends on types of ILs and their interactions with starch during film preparation.

Compatibility of Sustainable Mater-Bi/poly(ε-caprolactone)/cellulose Biocomposites as a Function of Filler Modification

Despite their popularity and multiplicity of applications, wood-polymer composites (WPCs) still have to overcome particular issues related to their processing and properties. The main aspect is the compatibility with plant-based materials which affects the overall performance of the material. It can be enhanced by strengthening the interfacial adhesion resulting from physical and/or chemical interactions between the matrix and filler, which requires introducing a compatibilizer or a proper modification of one or both phases. Herein, the impact of cellulose filler modifications with varying contents (1-10 wt%) of hexamethylene diisocyanate (HDI) on the compatibility of Mater-Bi/poly(ε-caprolactone) (PCL)-based biocomposites was evaluated. An analysis of surface wettability revealed that the filler modification reduced the hydrophilicity gap between phases, suggesting compatibility enhancement. It was later confirmed via microscopic observation (scanning electron microscopy (SEM) and atomic force microscopy (AFM)), which pointed to the finer dispersion of modified particles and enhanced quality of the interface. The rheological analysis confirmed increased system homogeneity by the reduction in complex viscosity. In contrast, thermogravimetric analysis (TGA) indicated the efficient modification of filler and the presence of the chemical interactions at the interface by the shift of thermal decomposition onset and the changes in the degradation course.

Green composites based on thermoplastic starch reinforced with micro- and nano-cellulose by melt blending - A review

Starch is a biodegradable biopolymer, a sustainable material that can replace conventional petrochemical-based plastics. However, starch has some limitations, as it must be processed by heating and treated mechanically with a plasticizer to become thermoplastic starch (TPS). Different variables such as mixing speeds, amount, and kind of plasticizers play a vital role in preparing TPS by melting. Despite this, the properties of the TPS are not comparable with those of traditional plastics. To overcome this limitation, microcellulose or nanocellulose is added to TPS by melt mixing, including the extrusion and internal mixing process, which enables large-scale production. This review aims to compile several studies that evaluate the effect of plasticizers, as well as the relevance of incorporating different cellulosic fillers of different dimensions on the properties of TPS obtained by melt mixing. Potential applications of these materials in food packaging, biomedical applications, and other opportunities are also described.

The role of urea on the dissolution of starch in NaOH-urea aqueous solutions

Potato starch can be dissolved in NaOH-urea aqueous solutions to form a stable and homogeneous mixture to initiate further modification. The mechanism for the formation of such a solution was investigated by examining the interactions between urea and starch, using rheological tests, ¹³C NMR, FTIR, and a novel Kamlet-Taft solvation parameter analysis. It was found that the optimized dissolution condition was in aqueous 10% w/w NaOH-14% w/w urea, under which 97.4% light transmission was achieved. This was due to dispersive forces between urea and starch without the presence of strong hydrogen bond based interactions. DSC results further showed that the subtle dissolving facilitation of urea might be attributed to the heat released during urea hydrate formation. Compared with conventional hydrothermal gelatinized starch, the starch-NaOH-urea aqueous dispersion exhibited better stability. This highlighted the role of urea in forming a 'bridge' to combine starch with water molecules. This reduces the tendency for starch aggregation via its hydrophobic components. Intrinsic viscosity and GPC analysis indicated that the degradation of starch molecules was significantly reduced. This work provides new insights into the role of urea in starch-NaOH-urea aqueous dispersion. This type of starch solvent formulation will have significant potential for further preparation of starch-based materials for various applications.

Co-Plasticization of Starch with Glycerol and Isosorbide: Effect on Retrogradation in Thermo-Plastic Cassava Starch Films

Thermoplastic starch (TPS) has emerged as an essential alternative to produce environmentally friendly packaging; however, retrogradation is a disadvantage that affects its shelf life. This study analyzed the co-plasticizing effect of isosorbide on the mechanical, thermal, physicochemical, and microstructural properties and the retrogradation of films obtained by blown film extrusion from thermoplasticized starch with mixtures of glycerol and isosorbide in different ratios (3:0, 2:1, 1:2, and 0:3, respectively). The results showed that the higher concentration of isosorbide significantly increased the tensile strength; however, it reduced the elongation. Retrogradation modeled using the Avrami equation showed that the presence of isosorbide reduced the retrogradation rate (k) and modified the recrystallization mechanism (n). The relative crystallinity in the plasticized TPS films was reduced to 89%, and the adsorption significantly decreased. Isosorbide was very important in reducing the retrogradation of TPS. The best performance was obtained with the 2:1 ratio of glycerol/isosorbide due to the synergistic effect between the plasticizers. The results would allow tuning the properties of TPS films by combining glycerol/isosorbide in different ratios, which enables the design of materials tailored to potential application requirements.

Study on Physicochemical Properties of Biocomposite Films with Spent Coffee Grounds as a Filler and Their Influence on Physiological State of Growing Plants

The aim of the study was to plasticize corn starch with two selected urea (U)-rich plasticizers: choline chloride (CC):U or betaine (B):U eutectic mixtures at a molar ratio of 1:5 with a presence of spent coffee grounds as a filler. The biomaterials were prepared via a solventless one-step extrusion method and then extrudates were thermoformed using compression molding into sheets. The materials were characterized using mechanical and sorption tests, TGA, DMTA and FTIR. Additionally, a study on the biodegradation and remaining nitrogen content in soil was conducted. For the first time, an influence on physiological state of growing plants of the materials presence in soil was investigated. The addition of the coffee filler slightly increased the mechanical properties and decreased the swelling degree of the materials. The DMTA results indicated that biocomposites were easily thermoformable and the high filler addition (20 pph per polymer matrix) did not affect the processability. According to the biodegradation test results, the materials disappeared in soil within ca. 70 days. The results from this study on the physiological state of growing plants revealed that the materials, especially plasticized with CCU, did not exhibit any toxic effect on the yellow dwarf bean. The percentage of total nitrogen in the soil substrate in comparison with the control increased indicating an effective release of nitrogen from the TPS materials into the substrate.

Potato thermoplastic starch nanocomposite films reinforced with nanocellulose

Potato is a widely available feedstock with biocompatibility and biodegradability properties, making it a strong candidate for producing thermoplastic starch. The application of thermoplastic starch to replace petroleum-based plastic as a sustainable and environmentally friendly approach led to its further improvement through various techniques such as modification and filler reinforcement. Numerous studies have been done addressing the properties enhancement of potato thermoplastic starch through filler reinforcement including nanocellulose. This review focus on the recent and future potential of potato-based starch as one of the feedstocks for producing potato thermoplastic starch composites reinforced with nanocellulose.

Anaerobic Biodegradability of Commercial Bioplastic Products: Systematic Bibliographic Analysis and Critical Assessment of the Latest Advances

Bioplastics have entered everyday life as a potential sustainable substitute for commodity plastics. However, still further progress should be made to clarify their degradation behavior under controlled and uncontrolled conditions. The wide array of biopolymers and commercial blends available make predicting the biodegradation degree and kinetics quite a complex issue that requires specific knowledge of the multiple factors affecting the degradation process. This paper summarizes the main scientific literature on anaerobic digestion of biodegradable plastics through a general bibliographic analysis and a more detailed discussion of specific results from relevant experimental studies. The critical analysis of literature data initially included 275 scientific references, which were then screened for duplication/pertinence/relevance. The screened references were analyzed to derive some general features of the research profile, trends, and evolution in the field of anaerobic biodegradation of bioplastics. The second stage of the analysis involved extracting detailed results about bioplastic degradability under anaerobic conditions by screening analytical and performance data on biodegradation performance for different types of bioplastic products and different anaerobic biodegradation conditions, with a particular emphasis on the most recent data. A critical overview of existing biopolymers is presented, along with their properties and degradation mechanisms and the operating parameters influencing/enhancing the degradation process under anaerobic conditions.

Advances in green solvents for production of polysaccharide-based packaging films: Insights of ionic liquids and deep eutectic solvents

The problems with plastic materials and the good film-forming properties of polysaccharides motivated research in the development of polysaccharide-based films. In the last 5 years, there has been an explosion of publications on using green solvents, including ionic liquids (ILs), and deep eutectic solvents (DESs) as candidates to substitute the conventional solvents/plasticizers for preparations of desired polysaccharide-based films. This review summarizes related properties and recovery of ILs and DESs, a series of green preparation strategies (including pretreatment solvents/reaction media, ILs/DESs as components, extraction solvents of bioactive compounds added into films), and inherent properties of polysaccharide-based films with/without ILs and DESs. Major reported advantages of these new solvents are high dissolving capacity of certain ILs/DESs for polysaccharides (i.e., up to 30 wt% for cellulose) and better plasticizing ability than traditional plasticizers. In addition, they frequently display intrinsic antioxidant and antibacterial activities that facilitate ILs/DESs applications in the processing of polysaccharide-based films (especially active food packaging films). ILs/DESs in the film could also be further recycled by water or ethanol/methanol treatment followed by drying/evaporation. One particularly promising approach is to use bioactive cholinium-based ILs and DESs with good safety and plasticizing ability to improve the functional properties of prepared films. Whole extracts by ILs/DESs from various byproducts can also be directly used in films without separation/polishing of compounds from the extracting agents. Scaling-up, including costs and environmental footprint, as well as the safety and applications in real foods of polysaccharide-based film with ILs/DESs (extracts) deserves more studies.

Deep Eutectic Solvents for Biotechnology Applications

Deep eutectic solvents (DESs) are an alternative to traditional organic solvents and ionic liquids and meet the requirements of "green" chemistry. They are easy to prepare using low-cost constituents, are non-toxic and biodegradable. The review analyzes literature on the use of DES in various fields of biotechnology, provides data on the types of DESs, methods for their preparation, and properties. The main areas of using DESs in biotechnology include extraction of physiologically active substances from natural resources, pretreatment of lignocellulosic biomass to improve enzymatic hydrolysis of cellulose, production of bioplastics, as well as a reaction medium for biocatalytic reactions. The aim of this review is to summarize available information on the use of new solvents for biotechnological purposes.

Mater-Bi/Brewers' Spent Grain Biocomposites-Novel Approach to Plant-Based Waste Filler Treatment by Highly Efficient Thermomechanical and Chemical Methods

Thermoplastic starch (TPS) is a homogenous material prepared from native starch and water or other plasticizers subjected to mixing at a temperature exceeding starch gelatinization temperature. It shows major drawbacks like high moisture sensitivity, poor mechanical properties, and thermal stability. To overcome these drawbacks without significant cost increase, TPS could be blended with bio-based or biodegradable polymers and filled with plant-based fillers, beneficially waste-based, like brewers' spent grain (BSG), the main brewing by-product. Filler modifications are often required to enhance the compatibility of such composites. Herein, we investigated the impact of BSG thermomechanical and chemical treatments on the structure, physical, thermal, and rheological performance of Mater-Bi-based composites. Thermomechanical modifications enhanced matrix thermal stability under oxidative conditions delaying degradation onset by 33 °C. Moreover, BSG enhanced the crystallization of the polybutylene adipate terephthalate (PBAT) fraction of Mater-Bi, potentially improving mechanical properties and shortening processing time. BSG chemical treatment with isophorone diisocyanate improved the processing properties of the composites, expressed by a 33% rise in melt flow index. Depending on the waste filler's selected treatment, processing, and rheological performance, thermal stability or interfacial adhesion of composites could be enhanced. Moreover, the appearance of the final materials could be adjusted by filler selection.

Starch plasticization with choline dihydrogencitrate-based deep eutectic system

Two-component deep eutectic solvents (DES) based on choline dihydrogencitrate and glycerol or urea were tested as starch plasticizers. Thermal analysis techniques were applied to characterize the properties of starch/DES systems. The X-ray diffractometry measurements revealed a significant decrease in crystallinity indicating that used DES exhibited the ability to penetrate the ordered regions of potato starch, which is a necessary feature of a true plasticizer. However, the differential scanning calorimetry and dynamic thermal analysis results surprisingly showed an increase of Tg of starch materials indicating chemical crosslinking at elevated temperature. The eutectic solvents based on choline dihydrogencitrate could act as a plasticizer and a simultaneously crosslinking agent.

Deep Eutectic Solvents for Starch Treatment

In this review, the application of deep eutectic solvents (DESs) as starch solvents, plasticizers and for other treatment has been described. Starch, as one of the most abundant biopolymers, is considered for forming new biodegradable materials. This new approach, referring to applying deep eutectic solvents for dissolving starch, its plasticization and other modifications, was presented. A DES could be a good alternative for common starch plasticizers (e.g., glycerol, urea) as well as recently considered ionic liquids. The high variety of DES component combinations makes it possible to obtain materials with the properties specific for given applications.

Effect of natural deep eutectic solvents on thermal stability, syneresis, and viscoelastic properties of high amylose starch

This work aimed to use natural deep eutectic solvents to modify the thermal, textural, freeze-thaw, and rheological properties of high amylose rice starch. Three different natural deep eutectic solvents (NADES) composed of sugar and organic acids were applied to modify the properties of starch dispersion. In presence of NADES, the onset temperature of starch was decreased, in comparison with starch in aqueous and glycerol medium. During thermal decomposition, starch with the aqueous and glycerol systems showed two-step weight losses whereas with NADES starch showed single-stage weight losses or decomposition. Moreover, negligible syneresis was observed for starch-NADES dispersion after 3rd cycle of the freeze-thaw process. The flow behavior of starch-NADES dispersion follows Herschel-Bulkley models as R² (0.996 ≤ R² ≤ 0.999) are higher than the Mizrahi-Berk model. The flow behavior index (n) of starch-NADES dispersion was closer to 1, indicated a nearly Newtonian fluid. The loss modulus (G″) value of starch-NADES dispersions was markedly higher than the corresponding storage modulus (G') value and thus materials behaved like viscoelastic liquid. The present study manifested a green way to modify the properties of the high amylose starch to improve the processing stability.

Preparation and characterization of native and autoclaving-cooling treated Pinellia ternate starch and its impact on gut microbiota

The aim of this study was to investigate and compare the structural and physicochemical properties of native Banxia starch (BXS) and autoclaving-cooling treated Banxia starch (CTBXS) and its related impacts on production of short chain fatty acids (SCFAs) and human gut microbiota by in vitro fecal fermentation. BXS had semicircle to spherical granules, whereas CTBXS exhibited block-shape. According to XRD and TGA, BXS had a C-type crystalline pattern, while CTBXS had a B-type crystalline pattern. CTBXS had better thermal stability than BXS. In addition, BXS exhibited significantly higher solubility and swelling power than CTBXS, and CTBXS had higher content of SDS than BXS. Moreover, BXS and CTBXS could change the composition and abundance of gut microbiota, could also promote the production of SCFAs. This study is beneficial to well understand the in vitro digestion and fecal fermentation behaviors of BXS and CTBXS, and can be developed as a potential functional food with the aim of improving colonic health.

Deep eutectic solvents based on urea, polyols and sugars for starch treatment

Deep eutectic solvents (DES) based on urea (U), polyols (glycerol -G, sorbitol - S) and monosugars (glucose - Glu, fructose - Fru) were obtained, thermally characterized and used for potato starch treatment: dissolution and plasticization. The polysaccharide was dissolved in U/glycerol mixtures forming transparent, non-retrograded gels. The dissolution process was confirmed by microscopic observations and DSC analysis. Plasticizing efficiency of DES in thermoplasticized starch (TPS) via compression molding was investigated using mechanical tests, DMTA, XRD, TGA and FTIR analysis. Although all studied DES were able to plasticize starch effectively, the most flexible films were with urea/glycerol mixture: the highest elongation at break exceed 200%. XRD analysis confirmed high amorphization of starch with the urea-based DES after thermocompression. Moreover, introduction of urea as DES inhibited its recrystallization in the polysaccharide matrix.

Effect of ionic liquid 1-buyl-3-methylimidazolium halide on the structure and tensile property of PBS/corn starch blends

As a promising biodegradable resin, poly (butylene succinate) (PBS) is often blended with starch to reduce the cost. In this paper, 1-buyl-3-methylimidazolium halide pre-plasticized corn starch (CS) was blended with PBS to prepare PBS/corn starch blend material modified by ionic liquid (PBS/CS-IL). Ionic liquid (IL) acted as plasticizer and compatibilizer, and the effects of 1-butyl-3-methylimidazolium halide with different halogen anion on PBS/Starch blends were explored. The effects of IL on the structure and tensile property of PBS/Starch blends were evaluated by FTIR, SEM, DSC, TGA and XRD, respectively. Test results showed that the addition of IL significantly reduced the crystallinity of PBS/Starch blends, and the size of starch particles in the PBS matrix was also effectively reduced. IL also acted as a compatibilizer of starch and PBS, and induced the morphology of the blends to change from "sea-island" structure to homogeneous phase. The results of the tensile test showed that compared with the PBS/Starch blend without IL, the elongation at break of PBS/CS-IL increased from 22% to 93%. This study provided a simple and feasible method for the preparation of low-cost PBS bio-composite materials, and provided theoretical support for future industrial production.

A novel method to prepare chemical fibers by plasticizing cotton with 1-allyl-3-methylimidazolium chloride

In this study, we developed a novel method to prepare chemical fibers by plasticizing cotton with 1-allyl-3-methylimidazolium chloride (AMIMCl) under high temperature and pressure. Cotton was homogeneously mixed with AMIMCl by kneading in a certain mass proportion. It would be a sheet after hot-pressing and this process could be repeated several times. The morphologies of chemical fibers showed that cotton was successfully plasticized by AMIMCl with the crystallinity of the chemical fibers increased by about 15%. Differential scanning calorimetry (DSC) showed that the glass transition temperature (T_g) occurred in chemical fibers and we could further verify cotton was plasticized by AMIMCl. This simple and green method will be helpful to modify and broaden the application field of cotton.

Use of Ionic Liquids and Deep Eutectic Solvents in Polysaccharides Dissolution and Extraction Processes towards Sustainable Biomass Valorization

A shift to a bioeconomy development model has been evolving, conducting the scientific community to investigate new ways of producing chemicals, materials and fuels from renewable resources, i.e., biomass. Specifically, technologies that provide high performance and maximal use of biomass feedstocks into commodities with reduced environmental impact have been highly pursued. A key example comprises the extraction and/or dissolution of polysaccharides, one of the most abundant fractions of biomass, which still need to be improved regarding these processes' efficiency and selectivity parameters. In this context, the use of alternative solvents and the application of less energy-intensive processes in the extraction of polysaccharides might play an important role to reach higher efficiency and sustainability in biomass valorization. This review debates the latest achievements in sustainable processes for the extraction of polysaccharides from a myriad of biomass resources, including lignocellulosic materials and food residues. Particularly, the ability of ionic liquids (ILs) and deep eutectic solvents (DESs) to dissolve and extract the most abundant polysaccharides from natural sources, namely cellulose, chitin, starch, hemicelluloses and pectins, is scrutinized and the efficiencies between solvents are compared. The interaction mechanisms between solvent and polysaccharide are described, paving the way for the design of selective extraction processes. A detailed discussion of the work developed for each polysaccharide as well as the innovation degree and the development stage of dissolution and extraction technologies is presented. Their advantages and disadvantages are also identified, and possible synergies by integrating microwave- and ultrasound-assisted extraction (MAE and UAE) or a combination of both (UMAE) are briefly described. Overall, this review provides key information towards the design of more efficient, selective and sustainable extraction and dissolution processes of polysaccharides from biomass.