Enhancing thermal stability and mechanical resilience in gelatin/starch composites through polyvinyl alcohol integration

In practical scenarios, destabilizing the physical attributes of natural polymers such as gelatin and starch occurs readily when exposed to specific moisture levels and heat. In this context, this work was carried out to assess the impact of PVA addition (up to 13 wt%) on the structure and physical properties of a 6:4 (w/w) gelatin/starch blend. The inclusion of PVA unfolded the molecular chains of gelatin and starch, thereby disrupting gelatin α-helices and impeding biopolymer crystallization. This facilitated hydrogen-bonding interaction between PVA and the two biopolymers, enhancing the stability of the molecular network structure. Rheological results indicate that composites (added with 4 % or 7 % PVA) with good compatibility exhibited excellent mechanical properties and deformation resistance. The addition of PVA elevated the gelling temperature (Tgel) of the composites from 41.31 °C to 80.33 °C; the tensile strength and elongation at break were increased from 2.89 MPa to 3.40 MPa and 341.62 % to 367.56 %, respectively; and the thermal stability was also apparently improved, signifying the effective enhancement of the physical properties of gelatin/starch-based composites and the broadening of their application scope. This work could provide insights into the development of biodegradable natural/synthetic polymer composites with application-beneficial characteristics

Natural polymer starch-based materials for flexible electronic sensor development:A review of recent progress

In response to the burgeoning interest in the development of highly conformable and resilient flexible electronic sensors capable of transducing diverse physical stimuli, this review investigates the pivotal role of natural polymers, specifically those derived from starch, in crafting sustainable and biocompatible sensing materials. Expounding on cutting-edge research, the exploration delves into innovative strategies employed to leverage the distinctive attributes of starch in conjunction with other polymers for the fabrication of advanced sensors. The comprehensive discussion encompasses a spectrum of starch-based materials, spanning all-starch-based gels to starch-based soft composites, meticulously scrutinizing their applications in constructing resistive, capacitive, piezoelectric, and triboelectric sensors. These intricately designed sensors exhibit proficiency in detecting an array of stimuli, including strain, temperature, humidity, liquids, and enzymes, thereby playing a pivotal role in the continuous and non-invasive monitoring of human body motions, physiological signals, and environmental conditions. The review highlights the intricate interplay between material properties, sensor design, and sensing performance, emphasizing the unique advantages conferred by starch-based materials, such as self-adhesiveness, self-healability, and re-processibility facilitated by dynamic bonding. In conclusion, the paper outlines current challenges and future research opportunities in this evolving field, offering valuable insights for prospective investigations.</p

Oxidation-induced starch molecular degradation:A comprehensive kinetic investigation using NaClO/NaBr/TEMPO system

Starch degradation often coincides with its chemical modification, and understanding how chemical modification influences starch degradation is vital for determining the properties of the resultant modified products. This work investigates the effect of oxidation on starch molecular degradation, examining factors such as oxidation degree, reaction kinetics, and degradation patterns during 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated starch oxidation under varying conditions, including reaction time, pH, temperature, and concentrations of NaBr, TEMPO, and NaClO. Results emphasize that extended reaction durations primarily lead to β-elimination, causing α-1,4 linkage cleavages. pH 8.5 favored non-selective oxidation, while pH 11 enhanced β-elimination, both slowing the reaction rate and severely damaging starch chains (Mw of 8.8 × 105 g/mol and 7.2 × 105 g/mol, respectively). Elevated temperature from 0 to 30 °C significantly expedited both selective and non-selective oxidation, dramatically reducing molecular mass to 8.1 × 105 g/mol. Increasing concentrations of NaBr and TEMPO boost the reaction rate with minimal impact on molecular mass. Meanwhile, increasing NaClO concentration from 0.2 to 2.2 mmol/g-starch not only affects the reaction rate but also reinforces β-elimination, enhancing molecular degradation. This study is insightful for starch modification to achieve desired oxidation levels and chain lengths by controlling reaction conditions, offering potential advancements in oxidized starch-based materials like nano micelles

Effect of rheological properties of potato, rice and corn starches on their hot-extrusion 3D printing behaviors

In this study, the relationship between rheological properties and printability of three types of starch (potato, rice and corn starch) for hot-extrusion 3D printing (HE-3DP) were systematically investigated. Each starch sample showed a shear-thinning behavior, self-supporting property, as well as the feature of a substantial decrease at higher strains and a recovery at lower strains in storage modulus (G′), which indicated the suitability of starch for HE-3DP. Besides, the flow stress (τf), yield stress (τy), and G′ increased with a higher starch concentration. We found that starch suspensions with concentrations of 15–25% (w/w) heated to 70–85 °C possessed preferable values of τf (140–722 Pa), τy (32–455 Pa), and G' (1150–6909 Pa) for HE-3DP, which endowed them with excellent extrusion processability and sufficient mechanical integrity to achieve high resolutions (0.804–1.024 mm line width). Overall, our results provided useful information to produce individualized starch-based food by HE-3DP

Structure and properties of thermomechanically processed silk peptide and nanoclay filled chitosan

While chitosan has great potential for biomedical and wider application due to its appealing characteristics such as biocompatibility and inherent antimicrobial activity, its properties usually need to be further tailored for specific uses. In this study, the effect of inclusion of silk peptide (SP) and nanoclays (montmorillonite, MMT and sepiolite, SPT) on the properties of thermomechanically processed chitosan were examined. Blending SP with chitosan led to a material with greater elasticity and surface wettability. For the chitosan matrix, addition of either MMT or SPT resulted in increased mechanical properties with MMT being more effective, likely due to its 2D layered structure. For the chitosan/SP matrix, while inclusion of MMT caused increased mechanical properties and thermal stability, SPT was more effective than MMT at reducing surface hydrophilicity and SPT fully counteracted the increased surface hydrophilicity caused by SP. Thus, this work shows the different effects of MMT and SPT on chitosan-based materials and provides insights into achieving balanced properties

Ionic liquids for the preparation of biopolymer materials for drug/gene delivery : a review

Biopolymers are particularly suitable for drug applications due to their biocompatibility, biodegradability and low immunogenicity. There has been growing interest in using biopolymers to achieve the controlled release of therapeutics. However, the solubility and processability of biopolymers remain to be challenging due to their structural heterogeneity and dense networks of inter- and intramolecular interactions. Fortunately, ionic liquids (ILs), regarded as green solvents, have been increasingly appreciated for their unparalleled power for biopolymer processing. By dissolution of biopolymers in ILs, various materials including sponges, films, microparticles (MPs), nanoparticles (NPs), and aerogels can be generated as potential drug delivery carriers. Besides, ILs can be used as reaction mediums and/or catalysts for biopolymer chemical reactions, which shows enhanced reaction efficiency. In addition, because of their unique physicochemical (e.g., polarity, hydrophobicity, amphipathicity) and biological properties (e.g., antibacterial activity), ILs can assist or participate in the formation of drug delivery carriers. To cover all these aspects of research, this review provides an overview of the recent progress in using ILs for the engineering of next-generation drug/gene delivery carrier materials. The tunable properties of ILs as affected by their structure are highlighted. Also, the key principles, challenges and prospects in this area are presented

Ionic liquid (1-ethyl-3-methylimidazolium acetate) plasticization of chitosan-based bionanocomposites

The structure and properties of different biopolymer composites based on chitosan and chitosan/carboxymethyl cellulose (CMC) are governed by multiple structure–property relationships associated with different phase interactions. Plasticization of these matrices with ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) played a dominant role, increasing the mobility of biopolymer chains as well as ions and associated dipoles but reducing biopolymer chain interactions, crystallinity, and thermal stability. These structural changes led to higher matrix ionic conductivity, shorter electrical relaxation time, and greater matrix ductility. The inclusion of graphene oxide (GO) and reduced GO (rGO) also influenced the structure and properties of these bionanocomposites by disrupting the biopolymer hydrogen bonding and/or polyelectrolyte complexation (PEC) and interacting with [C2mim][OAc]. The impact of GO/rGO was more evident for 20 wt % [C2mim][OAc], such as increased crystallinity and thermal stability of chitosan. PEC was hindered with excess (40 wt %) [C2mim][OAc] added and further hindered again when rGO was included. This study shows that the structure and properties of bionanocomposites are not just determined by the surface chemistry of GO/rGO but can also be influenced by multiple interactions involving plasticizers such as ILs and additional biopolymers

Cellulose-starch hybrid films plasticized by aqueous ZnCl2 solution

Starch and cellulose are two typical natural polymers from plants that have similar chemical structures. The blending of these two biopolymers for materials development is an interesting topic, although how their molecular interactions could influence the conformation and properties of the resultant materials has not been studied extensively. Herein, the rheological properties of cellulose/starch/ZnCl2 solutions were studied, and the structures and properties of cellulose-starch hybrid films were characterized. The rheological study shows that compared with starch (containing mostly amylose), cellulose contributed more to the solution’s viscosity and has a stronger shear-thinning behavior. A comparison between the experimental and calculated zero-shear-rate viscosities indicates that compact complexes (interfacial interactions) formed between cellulose and starch with ≤50 wt % cellulose content, whereas a loose structure (phase separation) existed with ≥70 wt % cellulose content. For starch-rich hybrid films prepared by compression molding, less than 7 wt % of cellulose was found to improve the mechanical properties despite the reduced crystallinity of the starch; for cellulose-rich hybrid films, a higher content of starch reduced the material properties, although the chemical interactions were not apparently influenced. It is concluded that the mechanical properties of biopolymer films were mainly affected by the structural conformation, as indicated by the rheological results. View Full-Tex

Ultrasonication improves the structures and physicochemical properties of Cassava starch films containing acetic acid

Cassava starch films are fabricated with acetic acid treatment and ultrasonication. Different ultrasound power levels from 200 to 750 W are used and the effects of ultrasonication on the morphology, microstructures, and properties of the starch–acetic acid films are investigated. Scanning electron microscopy shows a cohesive and compact structure of the films resulting from ultrasonication. X‐ray diffraction analysis reveals that the crystalline index is decreased by acid treatment and increased by ultrasonication. The tensile strength and elongation at break of the films first increase and then decrease with increasing ultrasound power level. Ultrasonication also results in higher opacity, higher water barrier performance, and lower water adsorption of the films. Thus, the results show that ultrasonication can be used as a simple and efficient way to modify the morphology, microstructure, and performance of starch–acetic acid films to better meet the application needs