Covalent Cross-linking Research Articles

Influence of hydrogen bonding interactions, entanglement, and covalent crosslinking on the viscoelasticity of acrylic viscoelastomers containing urea group

The structure–property relationship of acrylic clear viscoelastomer films (acrylic CVFs) as foldable optical clear adhesives (OCAs) has always been unclear. In our work, a series of acrylic CVFs with different hydrogen-bonding interactions (H-bondings) and cross-linking densities (namely, CL-H-copolymers) were synthesized. The effects of entanglement, H-bonding, and covalent crosslinking on the recovery and adhesive properties of CL-H copolymers were analyzed by rheology, equilibrium swelling, and tensile stress–strain tests (tensile tests). The structural parameter Mx/MeH was obtained by combining the affine deformation model, the Flory-Rehner equation, and the UCM-Gent model, where Mx is the molecular weight between covalent crosslinkers and MeH is the a physical crosslinking molecular weight affected by H-bondings. The experimental results showed that the CL-H-copolymers had an obvious dependence on Mx/MeH. Recovery properties tended to stabilize (>90 %) at Mx/MeH < 1, while adhesion strengths continued to decrease with decreasing Mx/MeH. This conclusion and methodology are instructive for the design of foldable OCAs with high elasticity and high adhesion performance.

Locust bean gum glutarate nanocomposite hydrogel microspheres of gliclazide: Optimization by box-Behnken design and preclinical evaluation of anti-diabetic efficacy

In this study, carboxymethyl locust bean gum was synthesized and nanocomposite hydrogel microspheres (GHMs) of gliclazide were produced based on nanosilicate reinforcement and aluminium-ion driven gelation process, followed by covalent crosslinking with glutaric anhydride (GA). The effect of three independent variables (polymer and GA concentration, incubation time) on the drug entrapment efficiency (DEE%) and percent drug release at 8 h, was optimized using Box-Behnken design. The highest DEE (%) and lowest drug release was achieved at the following optimized conditions: polymer (2.43 %), GA (0.34 %), and incubation (27 min). The nanoscilicate-enriched matrix provided a maximum of 75.13 % DEE, 92.33 % gel fraction, and excellent flowability. The optimized microspheres had virtually spherical morphology, according to FE-SEM analysis. FTIR study indicated a hydrogen bonding interaction between the drug and other formulation components. X-ray and DSC measurements suggested that the crystallinity of the drug decreased following integration into the matrix. The optimized GHM demonstrated anomalous diffusion of gliclazide in simulated gastrointestinal fluids for 12 h without disintegration. In streptozotocin (50 mg/kg BW)-induced diabetic rats, the optimized formulation diminished blood glucose level by about 72 % in 12 h. Thus, the nanocomposite GHMs created by combining nanosilicate with GA had an outstanding potential for long-term control of diabetes.

Myosin supramolecular self-assembly: The crucial precursor that manipulates the covalent aggregation, emulsification and rheological properties of myosin

The transformation of molecular conformation and self-assembly properties of myosin during the heating process at different ionic strengths (0.2 M, 0.4 M and 0.6 M NaCl) and its effect on rheological behavior and emulsification properties were investigated. Under incubation temperatures between 40 °C and 50 °C, myosin underwent a supramolecular self-assembly stage dominated by noncovalent forces (hydrogen bonding, ionic bonding and hydrophobic interactions). Higher ionic strength facilitated molecular rearrangement through enhanced swelling of myosin heads and head-to-head assemblies, which contributed to enhanced ordering and homogeneity of myosin covalent aggregates (above 60 °C) and manifested itself macroscopically as enhanced gel viscoelasticity and emulsion stability. In contrast, at lower ionic strength, the tail-to-tail assemblies of myosin led to the preferential formation of covalent cross-links in the tails, which resulted in the inability of molecular rearrangement and the formation of disordered aggregates and finally led to the deterioration of the gel and the destabilization of the emulsion. In conclusion, the supramolecular self-assembly behavior of myosin, as an intermediate process in myosin’s sol–gel transition, is crucial for the orderliness of myosin assemblies, gel network strengthening, and emulsion stability. The obtained insight provides a reference for the precise implementation of quality improvement strategies for meat products.

An NAD+ with Dually Modified Adenine for Labeling ADP-Ribosylation-Specific Proteins

Protein adenosine diphosphate (ADP)-ribosylation participates in various pivotal cellular events. Its readers and erasers play key roles in modulating ADP-ribosylation-based signaling pathways. Unambiguous assignments of readers and erasers to individual ADP-ribosylated proteins provide insightful knowledge on ADP-ribosylation biology and require the development of tools and technologies for this goal. Herein, we report the design and the synthesis of a nicotinamide adenine dinucleotide (NAD+) carrying a photoactive and a clickable group. Functioning as a substrate for poly-ADP-ribosylation (PARylation), this NAD+ mimic with dually modified adenine enables covalent crosslinking and labeling of proteins bound to PARylation, representing a new photoaffinity probe for studying this critical post-translational modification.

β-cyclodextrin-modified carboxymethyl chitosan/hyaluronic acid-based crosslinked composite nanogels as a dual responsive carrier for targeting anti-tumor therapy.

Advanced nanosized drug delivery systems can significantly improve efficacy and safety of first-line chemotherapeutics by enhancing tumor targeting. Herein, one-pot covalent crosslinking approach was developed to generate biodegradable tumor-targeted composite Nanogels from carboxymethyl chitosan, hyaluronic acid, cystamine and 6-ethylene-diamine-6-deoxy-β-cyclodextrin loaded with doxorubicin (DOX) for controlled intracellular DOX release. The optimized synthetic procedures generated Nanogels of about 190 nm in size and 28.3 % drug loading capability. DOX-loaded Nanogels was effectively internalized into tumor cells mainly by CD44 receptor-mediated endocytosis and rapidly released DOX in response to the high level of GSH in cytoplasm and acidic intracellular environments. DOX-loaded Nanogels significantly inhibited the tumor growth especially without appreciable side toxicities in 4 T1 tumor-bearing mice model owing to CD44 receptor-mediated active targeting and the passive targeting of Nanogels by enhanced permeation and retention effect. Overall, our newly developed composite Nanogels might be employed as a potentially effective therapeutic strategy for tumor therapy.

Metal‐Organic Framework‐Derived Elastic Solid Polymer Electrolytes Enabled by Covalent Crosslinking for High‐Performance Lithium Metal Batteries

AbstractThe key issue in utilizing solid polymer electrolytes for high‐energy‐density lithium metal batteries is to balance the conflicting demands of superior processability, adequate ionic conductivity, and mechanical stability. Inspired by molecular structure design, a metal‐organic framework‐derived polyether poly(urethane urea) solid polymer electrolyte (denoted as ePU@H SPE) has been synthesized via a facile polycondensation method involving covalent crosslinking. The reduced crystallinity and numerous polar groups in ePU@H SPEs enhance Li salt dissociation and create efficient Li+ ion diffusion channels, yielding remarkable ionic conductivity (1.48 × 10−4 S cm−1). The polymer backbones, incorporating covalent bonds and dynamic hydrogen bonds, provide superb mechanical strength (5.12 GPa), high toughness (1240%), and excellent resilience, which suppress lithium dendrite growth and buffer electrode volume fluctuations during cycling. Leveraging these attributes, the well‐designed ePU@H SPE enables ultra‐high durability in lithium plating/stripping over 2300 h. Moreover, the integrated LFP|ePU@H|Li batteries, generating delicate electrode/electrolyte interfacial contact, deliver an exceptionally long lifespan (86% retention over 500 cycles at 1 C). Moreover, the LFP|ePU@H|Li pouch cell operates reliably even under severe deformation and external damage. Impressively, the stable cycling performance of full batteries incorporating high‐voltage LCO and high‐capacity S cathodes further verifies the significant potential of advanced ePU@H SPEs for practical applications.

Probing the Interplay of Protein Self-Assembly and Covalent Bond Formation in Photo-Crosslinked Silk Fibroin Hydrogels.

Covalent crosslinking of silk fibroin via native tyrosine residues has been extensively explored; however, while these materials are very promising for biomedical, optical, soft robotics, and sensor applications, their structure and mechanical properties are unstable over time. This instability results in spontaneous silk self-assembly and stiffening over time, a process that is poorly understood. This study investigates the interplay between self-assembly and di-tyrosine bond formation in silk hydrogels photo-crosslinked using ruthenium (Ru) and sodium persulfate (SPS) with visible light. The effects of silk concentration, molecular weight, Ru/SPS concentration, and solvent conditions are examined. The Ru/SPS system enables rapid crosslinking, achieving gelation within seconds and incorporating over 90% of silk into the network, even at very low protein concentrations (≥0.75%wt/v). A model emerges where silk self-assembly both before and after crosslinking affects protein phase separation, mesoscale structure, and dynamic changes in the hydrogel network over time. Silk concentration has the greatest impact on hydrogel properties, with higher silk concentration hydrogels experiencing two orders of magnitude increase in stiffness within 1 week. This new understanding and ability to tune hydrogel properties and dynamic stiffening aids in developing advanced materials for 4D biofabrication, sensing, 3D cancer models, drug delivery, and soft robotics.

Harnessing Extreme Internal Damping in Polyrotaxane‐Incorporated Liquid Crystal Elastomers for Pressure‐Sensitive Adhesives

AbstractLiquid crystal elastomers (LCEs) exhibit extraordinary energy dissipation due to their unique viscoelastic response, resulting from the rotation of mesogens under mechanical stress. While recent studies demonstrate the LCE‐based pressure‐sensitive adhesives (PSAs) by exploiting the enhanced damping, all previous studies have focused on LCEs with covalent crosslinks. Here, a new class of PSAs is developed by integrating movable polyrotaxane crosslinkers into an LCE matrix (PRx‐LCEs). Dynamic viscoelastic measurements reveal that PRx‐LCE exhibits a remarkably high energy dissipation, as indicated by a large tan δ. Interestingly, the secondary tan δ peak associated with LCE damping is more pronounced than the primary peak of the glass transition. The exceptional energy dissipation in PRx‐LCE results in superior adhesion strength (≈1864 N m−1), which is 3.5 times higher than conventional LCEs and 13 times higher than commercial PSAs in the peel test. Additionally, PRx‐LCEs demonstrate thermally reversible adhesion, enabling clean removal at elevated temperatures. Furthermore, the sliding effect in PRx‐LCE enhances both deformability and stress relaxation under load, resulting in deeper indentation, and superior adhesion during the probe tack test. The combination of LCE and slidable crosslinks provides robust and switchable adhesion, making them promising for applications in biomedical engineering, display, and semiconductor industries.

Proximity Effects and Aggregation of Hamilton-Receptor Barbiturate Host-Guest Complexes Probed by Cross-Metathesis and ESI MS Analysis.

The molecular environment around supramolecular bonding systems significantly affects their stability and the assembly of host-guest complexes, most prominent for hydrogen bonds (H-bonds). Hamilton receptor-barbiturate host-guest complexes are well-known in solution, typically forming a 1:1 molar ratio complex. However, within a polymer matrix, these complexes can form higher-order assemblies, deviating from the standard 1:1 complex, which are challenging to characterize and often require lab-intensive methods. In this study, a novel Hamilton receptor (H) was equipped with cyclopentene moieties and used as a host to form host-guest complexes (H-B) with allobarbital (B), followed by covalent crosslinking. UV-Vis spectroscopy titration experiments in different solvents and at various temperatures revealed that polar solvents containing additional H-bonding sites significantly reduce the formation of the 1:1 H-B complex, as indicated by a reduced association constant. Higher-order aggregates (HH-dimer, HHH-trimer) were subsequently detected via an alkene cross-metathesis (CM) reaction to fix the assemblies covalently, followed by analysis via electrospray ionization mass spectrometry (ESI MS). This two-step method, firstly via CM fixation followed by ESI MS, was extended to study the H-B model complex within a polyisobutylene (PIB) matrix, presenting a direct method to analyze the complex host-guest assembly in solvent-free (polymer) environments.

Mechanically Tunable, Compostable, Healable and Scalable Engineered Living Materials.

Advanced design strategies are essential to realize the full potential of engineered living materials, including their biodegradability, manufacturability, sustainability, and ability to tailor functional properties. Toward these goals, we present mechanically engineered living material with compostability, healability, and scalability - a material that integrates these features in the form of a stretchable plastic that is simultaneously flushable, compostable, and exhibits the characteristics of paper. This plastic/paper-like material is produced in scalable quantities (0.5-1 g L-1), directly from cultured bacterial biomass (40%) containing engineered curli protein nanofibers. The elongation at break (1-160%) and Young's modulus (6-450 MPa) is tuned to more than two orders of magnitude. By genetically encoded covalent crosslinking of curli nanofibers, we increase the Young's modulus by two times. The designed engineered living materials biodegrade completely in 15-75 days, while its mechanical properties are comparable to petrochemical plastics and thus may find use as compostable materials for primary packaging.

Dynamic covalent bonds enabled recyclable chitosan oligosaccharide-based wood adhesive with high adhesion and anti-mildew performances

Biomass wood adhesives have emerged as a promising alternative to traditional synthetic resins due to their ability to address issues related to formaldehyde pollution and reliance on petrochemical resources. However, these adhesives are generally not recyclable and require high curing temperatures. Herein, a novel eco-friendly, strong, and recyclable chitosan oligosaccharide (CS)-based wood adhesive named CS-PB was developed using CS, lignin-derived 3,4-dihydroxybenzaldehyde, and 1,4-phenylenediboronic acid. The cohesive strength and recyclability of the adhesive were significantly enhanced by the dynamic borate ester and imine networks formed through catalyst-free covalent cross-linking. The adhesive exhibited a maximum bonding strength of 5.60 MPa, surpassing many synthetic and biomass adhesives. Moreover, the recycled adhesive retained 88 % of its original strength. Even under extreme conditions such as 100 °C, −196 °C the CS-PB adhesive can still maintain high bonding strength. Notably, the CS-PB adhesive demonstrated low-temperature curing properties, achieving a high bonding strength of 5.21 MPa when cured at 90 °C, since imine bonds can be formed under mild conditions. Furthermore, the adhesive displayed excellent mildew resistance attributed to the synergistic effects of amino, boronic acid, and benzene rings. The proposed straightforward design strategy provides valuable insights for constructing high-strength and recyclable biomass adhesives.

Extracellular matrix mimetic supramolecular hydrogels reinforced with covalent crosslinked mesoporous silica nanoparticles.

The extracellular matrix (ECM) is a dynamic environment that is primarily built up from fibrous proteins (e.g., elastins, fibronectins, collagens, and laminins) and plays a vital role in tissue regeneration processes. Therefore, the development of supramolecular hydrogels that can mimic the ECM's dynamicity and fibrous structure is of great interest in regenerative medicine. However, such hydrogels generally have weak mechanical properties and poor structural stability, which significantly limits their potential applications. To overcome this drawback, we developed a new type of hybrid network composed of supramolecular assemblies with covalent nanoparticle-based crosslinkers. The ECM mimetic hydrogels were created through UV-initiated thiol-ene crosslinking between norbornene functionalized benzene-1,3,5-tri carboxamide (NBTA) macromonomers and thiol functionalized mesoporous silica nanoparticles (MSN). We hypothesized that the MSN would improve the mechanical properties by crosslinking the NBTA supramolecular fibrous hydrogels. Notably, the covalent incorporation of MSNs did not disrupt the fibrous morphology of the resulting NBTA-MSN nanocomposites. Furthermore, these supramolecular nanocomposites demonstrated higher structural stability and elasticity compared to pristine NBTA hydrogels. Rheology studies showed that the mechanical properties of NBTA-MSN hydrogels could be tuned by adjusting MSN wt%. Interestingly, NBTA-MSN nanocomposites exhibited self-healing and injectability despite the covalent crosslinking of MSNs. In vitro studies confirmed that NBTA-MSN nanocomposites showed good cytocompatibility and maintained the viability of encapsulated MG63 cells. As a proof of concept, we also demonstrated that MSNs could act as ion reservoirs for calcium and phosphate within the hydrogel networks in addition to being covalent crosslinkers. Taken together, our work offers a promising strategy to create hybrid, biomimetic supramolecular nanocomposite materials for various applications such as injectable materials for bone tissue engineering, and reinforced bioinks for 3D printing applications.

Homozygous synonymous FAM111A variant underlies an autosomal recessive form of Kenny-Caffey syndrome.

FAM111A (family with sequence similarity 111 member A) is a serine protease and removes covalent DNA-protein cross-links during DNA replication. Heterozygous gain-of-function variants in FAM111A cause skeletal dysplasias, such as the perinatal lethal osteocraniostenosis and the milder Kenny-Caffey syndrome (KCS). We report two siblings born to consanguineous parents with dysmorphic craniofacial features, postnatal growth retardation, ophthalmologic manifestations, hair and nail anomalies, and skeletal abnormalities such as thickened cortex and stenosis of the medullary cavity of the long bones suggestive of KCS. Using exome sequencing, a homozygous synonymous FAM111A variant, NM_001312909.2:c.81 G > A; p.Pro27=, that affects the last base of the exon and is predicted to alter FAM111A pre-mRNA splicing, was identified in both siblings. We identified aberrantly spliced FAM111A transcripts, reduced FAM111A mRNA levels, and near-complete absence of FAM111A protein in fibroblasts of both patients. After treatment of patient and control fibroblasts with different concentrations of camptothecin that induces covalent DNA-protein cross-links, we observed a tendency towards a reduced proportion of metabolically active cells in patient compared to control fibroblasts. However, under these culture conditions, we did not find consistent and statistically significant differences in cell cycle progression and apoptotic cell death between patient and control cells. Our findings show that FAM111A deficiency underlies an autosomal recessive form of FAM111A-related KCS. Based on our results and published data, we hypothesize that loss of FAM111A and FAM111A protease hyperactivity, as observed for gain-of-function patient-variant proteins, may converge on a similar pathomechanism underlying skeletal dysplasias.

Coarse-Grain Model of Ultrarigid Polymer Rods Comprising Bifunctionally Linked Peptide Bundlemers.

Computationally designed homotetrameric helical peptide bundles have been functionalized at their N-termini to achieve supramolecular polymers, wherein individual bundles ("bundlemers") are the monomeric units. Adjacent bundles are linked via two covalent cross-links. The polymers exhibit a range of conformational properties, including formation of rigid-rods with micrometer-scale persistence lengths. Herein, a coarse-grained model is used to illuminate how molecular features affect the rod-like behavior of the polymers. With increasing affinity between bundlemer ends, a sharp transition in the persistence length is observed. Doubly linked chains exhibit larger persistence lengths and more robust formation of rigid-rod structures than singly linked chains. Chain stiffness increases with decreasing temperatures. Increasing the length of the cross-linker results in more flexible chains. This model provides insights into how molecular features control the structural properties of chains comprising doubly linked rigid bundlemers.

Reversible Schiff-base chemistry enables thermosetting smart composites with versatile properties

Fibre-reinforced polymer composites have become indispensable structural materials in modern life and global industry due to their superior specific properties and improved energy efficiency. However, the irreversibility of commercially available thermoset matrices, characterized by covalent cross-linking, poses challenges to both the recyclability and the enhancement of functionality. Herein, inspired by living tissues, we demonstrated recyclable, reprocessing, self-growing, and thermally/water modulated carbon fibre reinforced polyimine composites at low processing temperatures (≤110 °C, without any catalyst), realizing the intelligent composites. The tensile strength and average friction coefficients of our composites were 129.1 MPa and 0.52, respectively. Moreover, the chemical welding and self-growing mechanism of our system were deeply explored. The process enabled the recovery of clean and intact carbon fibres. We aim for this work to further deepen the understanding of dynamic polyimine networks with semi-aromatic skeleton, and facilitate the preparation of smart, adaptive and pluripotent composites.

Drug-Eluting and Antibacterial Core-Shell Polycaprolactone/Pectin Nanofibers Containing Ti3C2Tx MXene and Medical Herbs for Wound Dressings.

Fibrous scaffolds capable of delivering natural drugs and herbs show great promise for tissue regeneration and wound care, particularly in personalized medicine. This study presents the fabrication and characterization of drug-eluting antibacterial core-shell mats composed of polycaprolactone (PCL) and pectin nanofibers produced through coaxial electrospinning. Berberine chloride (BBR), an herbal compound with antineoplastic, anti-inflammatory, antilipidemic, and antidiabetic properties, served as the model drug. Poly(vinyl alcohol) (PVA) was blended with pectin to enhance the mechanical properties of the core fibers. The shell was modified with two-dimensional Ti3C2Tx (MXene) nanosheets and subjected to covalent and ionic cross-linking. Structural analysis confirmed the successful production of bead-free fibers with diameters ranging from 160 to 350 nm, depending on composition. The PCL core fibers were uniformly coated with a pectin/PVA shell approximately 90 nm thick. The inclusion of BBR and MXene increased the fiber diameter. Drug-release kinetics, modeled by using Korsmeyer-Peppas, revealed a two-stage release mechanism. An initial burst release occurred within the first 24 h (kinetic exponent n = 1.36), followed by sustained release over 2 weeks (n = 0.48). The release mechanisms were identified as case-II relaxational release in the first stage, transitioning to quasi-Fickian diffusion in the second. Incorporating MXene into the shell further prolonged drug release. The mechanical strength of the scaffolds improved significantly by a factor of 7 and 4 in wet and dry conditions, respectively. In vitro biocompatibility assays using L929 cells demonstrated excellent cell attachment and compatibility. Additionally, antibacterial tests against Escherichia coli showed that the inclusion of MXene enhanced antibacterial activity by 30%. These results suggest that the functional biocomposite scaffolds hold the potential for developing innovative, drug-eluting wound dressings.

A novel bio-aerogel based on agroforestry waste chestnut shell for enhanced oil-water separation performance

Bio-based aerogels have attracted much attention due to their biodegradability and excellent oil-water separation properties. However, the preparation of inexpensive green aerogels with high separation efficiency is still a great challenge. In this paper, low-density, high-adsorption capacity and superhydrophobic chestnut shell-based bio-aerogels were prepared by chemical cross-linking and chemical vapor deposition using agricultural and forestry waste chestnut shells as the precursor of aerogels to achieve high efficiency of oil-water separation and to achieve the goal of “treating waste with waste”. The covalent cross-linking of chestnut shell cellulose and cross-linking agent to form silicone-containing functional groups improved the pore structure, hydrophobicity and mechanical properties of chestnut shell cellulose, and under the action of capillary force, the oil was retained in the pores of the bio-aerogels, which achieved the selective adsorption of oil and organic solvents in the oil-water mixture, with a separation efficiency of more than 98 %. After 10 cycles, the bio-aerogel still has good reusability. This eco-friendly and low-cost aerogel provides a practical method for resource conversion and recycling, as well as a green and innovative way for the treatment of oily wastewater.

Tunable macroscopic self-healing of supramolecular gel through host–guest inclusion

Supramolecular gels (SGs) consisted of noncovalent cross-linking network structures are fascinating due to their efficient energy dissipation and reversible self-healing properties. However, it is unknown how the noncovalent interactions alter the macroscopic self-healing and mechanical properties of SGs. Herein, the peculiar nature of SGs manufactured by combining covalent and noncovalent (host–guest inclusion of β-cyclodextrin and C16 hydrophobic chain) cross-linking structures was studied and compared with covalent cross-linking preformed particle gels. The macroscopic self-healing behaviors, rheology, mechanical tensile properties, as well as the tunable mechanisms of self-healing were explored by visual inspection, rheological, and atomic force microscopy probing methods. The results show that the SGs exhibit excellent self-healing efficiency and mechanical strength after interfacial cutting. Moreover, the SGs exhibited excellent mechanical tensile properties, including loading–unloading, successive loading–unloading, and recovery loading–unloading tensile performances. Notably, the macroscopic self-healing of SGs has good tunability by changing the covalent and noncovalent crosslinker contents and salt contents. This peculiar phenomenon is attributed to certain host–guest inclusion forces (4.7 and 0.3 nN) between different SGs under the distilled and high-salinity water conditions, respectively. This study is beneficial for the development of stimuli–response supramolecular gels in different applications, such as oil recovery in fractured reservoirs.

A concise strategy for enhancing the performance of bio-based polyurethane aerogels using melamine-modified sodium alginate via Aza-Michael addition reaction

Bio-based waterborne polyurethane (PU) has garnered significant attention as a sustainable alternative petroleum-derived counterpart, offering environmentally friendly alternatives. In this work, a new approach is proposed to fabricate two kinds of composite aerogels of lowly/highly melamine-modified sodium alginate (SAML/SAMH) with methacrylate-terminated PU (SAML-PU and SAMH-PU) through dynamic covalent cross-linking via Aza-Michael addition reactions. We aim to improve the poor compatibility of polysaccharide and PU associated with traditional blending methods and impart the resulting aerogels with good biodegradability, compressive strength, thermal insulation, flame-retardant, and self-healing. Comprehensive characterizations, including Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy collectively demonstrate the successful derivatization of alginate and the effective synthesis of the Aza-Michael addition copolymer involving derivate alginate and PU. Substantial improvements in compressive strength and thermal properties are realized at comparable densities. Higher compressive strength, higher decomposition temperature and lower thermal conductivity are significantly achieved for SAML-PU (0.35 MPa, 410 °C and 0.024 W/m/K at 0.13 g/cm3) and SAMH-PU (0.58 MPa, 427 °C and 0.022 W/m/K at 0.12 g/cm3) compared to pristine PU foams (0.15 MPa, 330 °C and 0.031 W/m/K at 0.15 g/cm3). Additionally, molecular simulations of the Aza-Michael addition reaction and finite element simulations of aerogel thermal-insulation properties are conducted to corroborate experimental results. Notably, the dynamic polymers of SAML-PU and SAMH-PU exhibited excellent self-healing, recycling, biodegradability, and flame-retardant attributes. The elucidated preparation methodology and the exceptional performance and versatile applications of sodium alginate-based PU aerogels suggest a promising trajectory for future research endeavors and industrial implementation.

Impact of Probiotic Fermentation on the Physicochemical Properties of Hemp Seed Protein Gels.

Hemp seed protein isolates (HPI) were used to produce a gel through probiotic fermentation. This study assessed how fermentation time (ranging from 0 to 16 h) affected the physicochemical properties of the HPI gel. The results indicated that gel formation began after 8 h of fermentation, as demonstrated by a pH decrease, an increase in particle size, and the development of aggregation observed through fluorescence and scanning electron microscopy. The gel produced after 16 h of fermentation showed the highest viscosity, storage modulus, and gel strength, attributed to stronger molecular interactions, including non-covalent and covalent crosslinking. However, the gel produced after 12 h of fermentation showed the highest water-holding capacity, and extending the fermentation beyond 12 h caused a decrease in water-holding capacity. Additionally, the subunits tended to form polymers after fermentation, suggesting that gel formation was influenced by both acidification and specific covalent crosslinking. These findings propose that HPI could serve as a viable alternative for developing plant-based gel products.