Crosslinker Concentration Research Articles

Thermomechanical response of liquid crystal elastomers: role of crosslinker density

In this work thermomechanical properties of main-chain liquid crystal elastomers (MC-LCEs) with different degrees of crosslinking were investigated, and gradual loss of thermomechanical response was observed on repetitive measurements. Specifically, six samples of MC-LCEs were prepared, with crosslinker-to-mesogen relative concentration ranging from 5% to 10% in steps of 1%. The obtained results were then compared to thermomechanical response of side-chain liquid crystal elastomers (SC-LCEs). Additionally, thermomechanical response of polymer dispersed main-chain liquid crystal elastomers (MC-PDLCEs) was investigated. Results indicate that in MC-LCEs the concentration of crosslinker defines thermomechanical response and affects stability of the system. The loss of thermomechanical response is negligible in the case of crosslinker to mesogen ratio being the smallest, namely in 5% sample, and it is unaffected by glasslike to nematic phase transition. SC-LCEs do not show any sign of such behaviour and remain stable after several cycles of thermomechanical measurements.

Suspension electrospinning of SBR latex combined with photo-induced crosslinking: control of nanofiber composition, morphology, and properties

Suspension electrospinning of a styrene-butadiene rubber (SBR) latex coupled with photo-induced crosslinking in ambient conditions is proposed as a rapid method to prepare ultrafine shape-stable rubber fibrous membranes. Polyethylene oxide (PEO) is used as template polymer and can eventually be removed from the nanostructured membrane by a simple water treatment. A multifunctional thiol crosslinker and an appropriate photo-initiating system are added to the latex to allow the fast and efficient photo-induced crosslinking of the nanofibers, based on thiol addition to the SBR double bonds, as demonstrated by real-time Infrared spectroscopy analyses. It is proved that by varying the PEO template polymer and the thiol crosslinker content, a fine control of the chemical composition, morphology, water solubility, and thermal properties of the nanofibrous membranes is ensured. Moreover, comparable mechanical properties to those of fibrous membranes produced by conventional electrospinning of organic solvent-based solutions are obtained, clearly showing the attractiveness of the present method, especially in terms of process sustainability.Graphical abstract

Optimization of the mass ratio of siloxane crosslinkers for poly(2,6-dimethyl-1,4-phenylene oxide) anion exchange membranes to improve acid enrichment by electrodialysis

Proton blocking anion exchange membranes (AEMs), which are employed in electrodialysis technology, show promise in acid recovery from industrial waste. A series of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) membranes were prepared using (3-aminopropyl)trimethoxysilane (APTMS) and weakly functionalized bases including N-butylimidazole (N-BuIm). Were networked to create AEMs with low leak rates. It was discovered that the appropriate concentration of siloxane crosslinker raised the membrane matrix's density and lowered the AEM matrix's hydrophilicity. Thermogravimetric measurements and water absorption have confirmed this, and the membranes in this series even swell up to 8.61 %. The maximum H+ concentration concentrated by the cross-linked AEM (BPPO/5Si) during the ED with a current density of 10 mA∙cm−2 was 2.35 M, which was higher than the concentration concentrated by the uncross-linked AEM (BPPO/OSi), which was 1.90 M (beginning concentration: 1.00 M). The current efficiency was 44.8 % and the energy consumption was only 1.81 kW ∙h∙kg−1. A balance between proton blocking and SO42− ions transport was achieved by the optimized AEM, which exhibited increased hydrophobicity and smaller ion clusters. The improved AEM was found to have fewer ionic clusters and greater hydrophobicity. For cross-linked AEMs, a trade-off between SO42− ions transport and proton blocking was thus accomplished. This work is thought to offer direction for developing sophisticated proton blocking AEMs.

Directional Adhesion of Monodomain Liquid Crystalline Elastomers.

Pressure-sensitive adhesives (PSAs) are widely employed in consumer goods, health care, and commercial industry. Anisotropic adhesion of PSAs is often desirable to enable high force capacity coupled with facile release and has typically been realized through the introduction of complex surface and/or bulk microstructures while also maintaining high surface conformability. Although effective, microstructure fabrication can add cost and complexity to adhesive fabrication. Here, we explore aligned liquid crystalline elastomers (LCEs) as directional adhesives. Aligned LCEs exhibit direction-dependent stiffness, dissipation, and nonlinear deformation under load. By varying the cross-link content, we study how the bulk mechanical properties of LCEs correlate to their peel strength and peel anisotropy. We demonstrate up to a 9-fold difference in peel force measured when the LCE is peeled parallel vs perpendicular to the alignment axis. Opportunities to spatially localize adhesion are presented in a monolithic LCE patterned with different director orientations.

Impact of Protein Corona Formation on the Thermoresponsive Behavior of Acrylamide-Based Nanogels.

The ability to fine-tune the volume phase transition temperature (VPTT) of thermoresponsive nanoparticles is essential to their successful application in drug delivery. The rational design of these materials is limited by our understanding of the impact that nanoparticle-protein interactions have on their thermoresponsive behavior. In this work, we demonstrate how the formation of protein corona impacts the transition temperature values of acrylamide-based nanogels and their reversibility characteristics, in the presence of lysozyme, given its relevance for the ocular and intranasal administration route. Nanogels were synthesized with N-isopropylacrylamide or N-n-propylacrylamide as backbone monomers, methylenebis(acrylamide) (2.5-20 molar %) as a cross-linker, and functionalized with negatively charged monomers 2-acrylamido-2-methylpropanesulfonic acid, N-acryloyl-l-proline, or acrylic acid; characterization showed comparable particle diameter (c.a.10 nm), but formulation-dependent thermoresponsive properties, in the range 28-54 °C. Lysozyme was shown to form a complex with the negatively charged nanogels, lowering their VPTT values; the hydrophilic nature of the charged comonomer controlled the drop in VPTT upon complex formation, while matrix rigidity only had a small, yet significant effect. The cross-linker content was found to play a major role in determining the reversibility of the temperature-dependent transition of the complexes, with only 20 molar % cross-linked-nanogels displaying a fully reversible transition. These results demonstrate the importance of evaluating protein corona formation in the development of drug delivery systems based on thermoresponsive nanoparticles.

Differentiation, maturation, and collection of THP-1-derived dendritic cells based on a PEG hydrogel culture platform

PurposeDendritic cell (DC) is a spearhead responsible for immune response and surrounded by extracellular matrix in three-dimensional (3D) tissue. Nevertheless, conventional DC culture has relied on suspension or two-dimensional (2D) tissue culture plate (TCP)-based culture system. This culture condition often fails to recapitulate the physiological behavior of DC in real tissue. In this work, the effect of culture condition on DC physiology was explored with varying 3D hydrogel property (i.e., degradability, adhesion, and stiffness). In particular, DC differentiation and maturation in 3D were evaluated comparing the conventional TCP-based culture condition.MethodTHP-1 cells were encapsulated in poly(ethylene glycol) (PEG) hydrogel via thiol-ene photocrosslinking with non-degradable or proteolytically degradable peptide crosslinker. Hydrogel stiffness was manipulated by controlling the concentration of crosslinker. The metabolic activities and cytotoxicity of the encapsulated cells were measured by resazurin and Live/Dead assays, respectively. Cell harvesting was conducted via enzymatic degradation using α-chymotrypsin, and differentiation and maturation of the liberated DCs were evaluated by quantitative polymerase chain reaction and flow cytometry.ResultsTHP-1 cells well proliferated in the soft degradable hydrogel with a higher metabolic activity. However, the stiff matrix inhibited cell growth in 3D. The gene expression assay indicated that the 3D hydrogel condition was superior to 2D culture in terms of differentiation and maturation of DC. Interestingly, the stiffness of matrix was important factor in DC function. In the stiff hydrogel, the expression levels of differentiation and maturation markers were higher compared to the low stiffness hydrogel. The mature DCs caged in the hydrogel matrix were harvested after short enzymatic digestion of hydrogel and the liberated cells had over 90% viability. The flow cytometric result revealed that the proportion of CD80 + /CD86 + cells from the stiff hydrogel was relatively higher than cells either from 2D or soft hydrogel in 3D.ConclusionThe collected evidence indicated that the proteolytically degradable PEG hydrogel matrix promoted DC differentiation and maturation. In addition, the matrix stiffness control could manipulate the marker expressions of differentiation and maturation. Particularly, the mature DC was successfully collected from the hydrogel matrix. These results highlighted the PEG hydrogel-based DC culture might be a useful tool for potential DC-based immunotherapies.

Synthesis of Superabsorbent Hydrogels with Predefined Geometries and Controlled Swelling Properties for Versatile 3D Cell Culture Scaffolds.

This research presents a simple but general method to prepare water-soluble-polymer-based superabsorbent hydrogels with predefined microscale geometries and controlled swelling properties. Unlike conventional hydrogel preparation methods based on bulk solution-phase cross-linking, poly(vinyl alcohol) is homogeneously mixed with polymer-based cross-linkers in the solution phase and thermally cross-linked in the solid phase after drying; the degree of cross-linking is modulated by controlling the cross-linker concentration, pH, and/or thermal annealing conditions. After the shape definition process, cross-linked films or electrospun nanofibers are treated with sulfuric acid to weaken hydrogen bonds and introduce sulfate functionality in polymer crystallites. The resultant superabsorbent hydrogels exhibit an isotropic expansion of the predefined geometry and tunable swelling properties. Particularly, hydrogel microfibers exhibit excellent optical transparency, good biocompatibility, large porosity, and controlled cell adhesion, leading to versatile 3D cell culture scaffolds that not only support immortalized cell lines and primary neurons but also enable stiffness-modulated cell adhesion studies.

Scalable fabrication of lightweight carbon nanotube aerogel composites for full X-band electromagnetic wave absorption

Electromagnetic waves (EMWs) from advanced electronic devices can hinder normal operation of other electronic equipment, negatively affecting their performance and cause harmful impacts on human health by breaking down DNA strands and causing cancer. In this study, we thrivingly prepared new lightweight EMW absorbing aerogel composites by first blending polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), carbon nanotube (CNT), reduced graphene oxide (rGO), and carbonyl iron (CI), followed by freeze-drying. The materials are promising for up-scale production with the current pilot-scale samples sizing 35 cm × 35 cm. The effects of CNT types, CNT, rGO, CI, and crosslinker contents on EMW absorption ability are comprehensively investigated. The obtained aerogel composites exhibit a 3D porous structure with low densities (0.088–0.210 g/cm3), high thermal stability (227 °C), and high Young's modulus (670.9 kPa) compared to past aerogels. Notably, the materials with 3.0–3.5 mm in thickness achieve the minimum reflection loss (RLmin) of up to −42 dB (99.99 % EMW energy lost) and provide coverage across the entire X-band (8.2–12.4 GHz) with RL < −10 dB, indicating a 90 % attenuation of EMW energy. Compared to commercial Ni/CNT and other existing composites, our materials boast a broader effective bandwidth of 1.2–2.2 GHz. These properties make our aerogel composites highly promising for valuable commercial use, offering lightweight, durable, and efficient EMW absorption capabilities.

Charge Transfer Kinetics of Redox-Active Microgels.

Polymer microgel particles decorated with redox-active functional groups are a new and promising object for electrochemical applications. However, the process of charge exchange between an electrode and a microgel particle carrying numerous redox-active centers differs fundamentally from charge exchange involving only molecular species. A single act of contact between the microgel and the electrode surface may not be enough to fully discharge the microgel, and partial charge states are to be expected. Understanding the specifics of this process is crucial for the correct analysis of the data obtained from electrochemical experiments with redox-active microgel solutions. In this study, we employed coarse-grained molecular dynamics to investigate in detail the act of charge transfer from a microgel particle to a flat electrode. The simulations take into account both the mobility of functional groups carrying the charge, which depend on the microgel architecture and the charge exchange between the groups, which can accelerate the propagation of charge within the microgel volume. A set of different microgel systems were simulated in order to reveal the impact of their characteristics: fraction of redox-active groups, microgel molecular mass, cross-linker content, cross-linking topology, and solvent quality. We have found trends in microgel composition leading to the most efficient charge transfer kinetics. The obtained results would be useful for understanding experimental results and for optimizing the design of redox-active microgel particles aimed at faster discharge rates.

Sawdust-derived cellulose nanofibrils with high biosafety for potential bioprinting

Cellulose is a sustainable biopolymer with potential to reduce the adverse environmental impact of non-biodegradable plastics and promote a circular economy. Nanocellulose, a representative biobased nanomaterial, is considered as a promising material in biomedical applications due to its outstanding biocompatibility and low toxicity. However, the presence of some leachable immunogenic contaminants, such as endotoxin and (1,3)-β-D-glucan, in nanocellulose will often pose a potential risk in biomedical applications, particularly to the human body in 3D printing. In line with this challenge, a novel nanocellulose fabricating method was innovatively developed from the source of sawdust biomass to minimize the possible immunogenic contaminants presented in the cellulose nanofibrils (CNFs), which will ensure its biocompatibility of the material in applications. The resulting CNFs exhibited a very low level of leachable contaminants, recorded with endotoxin at 1.39 EU/g and (1,3)-β-D-glucan at 2.82 μg/g, respectively, which fall within the acceptable levels of Pharmacopoeia. In the following evaluation with the fabricated CNFs, the printability of the CNF hydrogel scaffolds was further optimized with hydrogel concentration at 5 %, printing pressure at 37 kPa, nozzle size setting up at 25 G, and crosslinker concentration at 200 mM, respectively. As an important property of 3D printed hydrogel scaffold, its biocompatibility was further evaluated and observed through cell culture in vitro, where the extract of hydrogel scaffold demonstrated a 36 % higher cell viability in promoting cell growth and proliferation when compared with that in pure culture medium. This exploration would suggest a possible application in the biomedical field that may not only secure a sound biocompatibility of CNFs produced from sawdust biomass, but also ensure the following 3D-printed scaffold with a viable cell growth and proliferation.

Modeling calcium diffusion and crosslinking dynamics in a thermogelling Alginate-Gelatin-Hyaluronic acid ink: 3D bioprinting applications

Alginate-based inks are widely used in 3D bioprinting. Its crosslinking by Ca2+ ions is extremely important to achieve scaffolds with optimal mechanical properties. Notably, despite previous studies on calcium diffusion in alginate systems, there have been no reported data regarding the effect of temperature on the diffusion and crosslinking dynamics of thermogelling alginate-based hydrogels. This study focuses on investigating the kinetics of the crosslinking front and Ca2+ diffusion within a matrix of Alginate-Gelatin-Hyaluronic acid ink, exploring the impact of temperature and Ca2+ concentration. The Ca2+ diffusion rate or ink crosslinking rate increase as the crosslinker concentration and ink temperature increase. Additionally, the mechanical properties of the scaffolds, assessed through compression, tension, and dynamic tests, were correlated with the crosslinking time.The innovative aspect of this study lies in the development of a code that simulates the diffusion of Ca2+ ions from the exterior to the interior of a hydrogel structure. Specifically, the code facilitates the calculation of the crosslinking time for a cylindrical structure up to a specified thickness, providing valuable insights for the production of airways or blood vessels. Furthermore, the Python script, incorporating the numerical model, manages to simulate the crosslinking dynamics of scaffolds of any shape, and properly fits the rheological measurements of dynamic moduli during the crosslinking process. This represents a significant advance for the precise and controlled scaffold fabrication process using 3D bioprinting.

In-situ swelling of pH-responsive microgel particles during photopolymerization to mitigate shrinkage stress of UV-cured materials

This paper utilizes a soap-free emulsion polymerization process to prepare microgel particles that can swell in response to in-situ generated acid in photocurable resin. By controlling the type and concentration of end-capping agents and the content of cross-linking agents, pH-responsive microgel particles with significantly increased particle size in acidic environments are synthesized. The strong protonic acid generated by the photoacid upon exposure to ultraviolet light can reduce the pH of the UV-curable resin, leading to an enlargement of the particle size. This can compensate for the volume shrinkage of the resin, ultimately reducing shrinkage stress. The research findings indicate that the addition of 5 wt% of pH-responsive particless and 2 wt% of photoacid to the UV-curable resin results in a reduction of approximately 40% in shrinkage stress and shrinkage rate.

Poly(ethylene glycol) Methyl Ether Acrylate-Grafted Chitosan-Based Micro- and Nanoparticles as a Drug Delivery System for Antibiotics.

Nanotechnology is the science of creating materials at the nanoscale by using various devices, structures, and systems that are often inspired by nature. Micro- and nanoparticles (MPs, NPs) are examples of such materials that have unique properties and can be used as carriers for delivering drugs for different biomedical applications. Chitosan (CS) is a natural polysaccharide that has been widely studied, but it has a problem with low water solubility at neutral or basic pH, which limits its processability. The goal of this work was to use a chemically modified CS with poly(ethylene glycol) methyl ether acrylate (PEGA) to prepare CS micronic and submicronic particles (MPs/NPs) that can deliver different types of antibiotics, respectively, levofloxacin (LEV) and Ciprofloxacin (CIP). The particle preparation procedure employed a double crosslinking method, ionic followed by a covalent, in a water/oil emulsion. The studied process parameters were the precursor concentration, stirring speeds, and amount of ionic crosslinking agent. MPs/NPs were characterized by FT-IR, SEM, light scattering granulometry, and Zeta potential. MPs/NPs were also tested for their water uptake capacity in acidic and neutral pH conditions, and the results showed that they had a pH-dependent behavior. The MPs/NPs were then used to encapsulate two separate drugs, LEV and CIP, and they showed excellent drug loading and release capacity. The MPs/NPs were also found to be safe for cells and blood, which demonstrated their potential as suitable drug delivery systems for biomedical applications.

Probing the influence of crosslinkers on the properties, response, and degradation of enzymatic hydrogels for electrochemical glucose biosensing through fluorescence analysis.

Drop-cast crosslinked hydrogels are a common platform for enzymatic electrochemical biosensors. Despite the widespread use of these complex systems, there are still several questions about how their physicochemical properties affect their performance, stability, and reproducibility. In this work, first-generation faradaic biosensors composed of glucose oxidase and branched polyethyleneimine (BPEI) are prepared using either glutaraldehyde (GA) or ethylene glycol diglycidyl ether (EGDGE) as crosslinkers. While EGDGE gels present an increasing electrochemical response with increasing crosslinker concentration, the current of GA gels decreases at high crosslinker concentration probably due to the hampered diffusion on tightly networked gels. We compared different strategies to use fluorescence microscopy to gain insight into the gel structure either by labeling the gel components with fluorophores or taking advantage of the intrinsic fluorescence of the imines formed upon crosslinking with GA. By monitoring the fluorescence of the crosslinking bonds and the electrochemical response, we demonstrate that hydrolysis, a common hydrogel degradation mechanism, is not responsible for the loss of electrical current over time in gels prepared with glutaraldehyde. Most hydrogel-based electrochemical biosensor studies do not perform specific experiments to determine the cause of the degradation and instead just infer it from the dependence of the current on the preparation conditions (most commonly concentrations). We show that, by taking advantage of several analytical techniques, it is possible to gain more knowledge about the degradation mechanisms and design better enzymatic biosensors.

Preparation and Antifiltration Performance of Organic Zirconium Crosslinker for Guar Gum‐Fracturing Fluid

Aiming at the characteristics of low shear resistance and high filtration loss of guar gum‐fracturing fluid, a high‐efficiency organic zirconium crosslinker was prepared. In addition, the effects of different factors on the filtration coefficient and apparent viscosity of fracturing fluid were studied, and this study explores the micro mechanisms of various factors affecting the filtration coefficient from a molecular dynamics perspective. The results show that the antifiltration ability of guar gum‐fracturing fluid is inversely proportional to the fluid viscosity. The increase of crosslinker content and reservoir pressure is beneficial to improve the viscosity and antishear ability of guar gum‐fracturing fluid. When the crosslinker content is 0.25% and pressure is 30 MPa, the fracturing fluid parameters are 145 mPa·s and 2.1 × 10−2 m3 · min1/2, respectively, while the increase of reservoir temperature and the shear rate reduces the rheology and shear resistance of guar gum‐fracturing fluid, so that the viscosity and filtration coefficient of fracturing fluid at 180°C and 200 s-1 are 123 mPa·s and 2.3 × 10-2 m3·min1/2, respectively. This work not only paves a new avenue for synthesizing organic zirconium as a crosslinker but also provides an efficient measure to reduce the filtration of guar gum‐fracturing fluid on the oil and gas reservoirs.

Optimizing the synthesis conditions of aerogels based on cellulose fiber extracted from rambutan peel using response surface methodology

&lt;p&gt;A cellulose-based aerogel has been synthesized from rambutan peel to mitigate environmental pollution caused by agricultural waste, rendering it an eco-friendly material with potential applications in oil spill remediation as well as enhancing the value of this fruit. The objective of this study was to extract cellulose from rambutan peel using chlorination and alkalization processes, followed by optimizing the synthesis conditions of cellulose-based aerogels from rambutan peel through experimental designs to improve oil removal efficiency. In this research, cellulose-based aerogel material was synthesized using the sol-gel method, utilizing waste from rambutan peel as the substrate and polyvinyl alcohol as the cross-linking agent, followed by freeze-drying. A central composite design with 30 different experimental setups was employed to investigate the influence of cellulose content (1.0–2.0%), cross-linking agent (polyvinyl alcohol) content (0.1–0.3%), ultrasonic time (5–15 min), and ultrasonic power (100–300W) on the oil adsorption capacity (g/g) of cellulose-based aerogels from rambutan peel. The research findings demonstrated successful extraction of cellulose from rambutan peel through chlorination, followed by softening with 17.5% (w/v) sodium hydroxide. Response surface plots indicated that maximizing the cellulose component could lead to a maximum diesel oil adsorption capacity of up to 52.301 g/g. Cellulose-based aerogel exhibits ultra-lightweight properties (0.027±0.002 g/cm&lt;sup&gt;3&lt;/sup&gt;), high porosity (97.88±0.19), hydrophobicity (water contact angle of 152.7°), and superior oil selective adsorption compared to several commercially available materials in the market, demonstrating promising potential for application in treating oil-contaminated water in real-world scenarios.&lt;/p&gt;

Molecular structure and composition elucidation of an industrial humin and its fractions.

Humins, (side-)products of the acid-catalysed dehydration of carbohydrates, will be produced in substantial quantities with the development of industrial biorefining processes. Most structural knowledge about such humins is based on synthetic model humins prepared at lab-scale from typical carbohydrate(-derived) compounds. Here, we report the first extensive characterisation study of an industrial humin. The soluble humin was generated from pilot plant-scale methanolic cyclodehydration of D-fructose to 5-methoxymethyl-2-furfural (MMF), as part of the Avantium YXY® process to produce FDCA. Purification of the industrial humin followed by fractionation allowed isolation of a water-insoluble, high molecular weight fraction (WIPIH) and a water-soluble, low-to-middle molecular weight soluble fraction (WES). Characterisation by elemental analysis, thermogravimetry, IR and NMR spectroscopy and size exclusion chromatography provided a detailed picture of the humin structure in both fractions. Aided by a comprehensive NMR spectral library of furanic model compounds, we identified the main furanic building blocks and inter-unit linkages and propose a structure for this industrial humin sample. The WIPIH and WES fractions were found to be composed of furanic rings interconnected by short aliphatic chains containing a wide range of functionalities including alcohols, ethers, carboxylic acids, esters, aldehydes and ketones. The low level of crosslinking and high functional group content of the industrial humin differ from the more extensively studied, (highly over-)condensed synthetic model humins, towards which they can be considered intermediates. The structural and compositional insights into the nature of an actual industrial humin open up a broad spectrum of valorisation opportunities.

Water Reduction of Biodegradable Plastic From Bagasse By‐Product With Synergistic Effect of Graphene Oxide Reinforcement and Citric Acid Crosslinking

In today’s world, plastics are vital as they are used in a wide range of applications although packaging is the most prevalent. Most of the plastics that are used for packaging applications are derived from petrochemicals. These plastics meet most of the requirements for good packing applications. However, they are not completely biodegradable. This consequently pollutes the environment. As a result, biodegradable plastics have emerged as an alternative to conventional plastics. Cellulose is one of the potential materials that are used for making biodegradable plastics. However, making plastic from cellulose causes deforestation. In this work, plastic was produced from cellulose bagasse, which is an industrial waste. Since bagasse is an industrial by‐product, it causes neither deforestation nor scarcity of food. However, the plastic made from bagasse showed high water absorption and low tensile strength. To overcome this problem, the plastic, which is made from bagasse, was reinforced with various concentrations of graphene oxide (GO) and crosslinked with various concentrations of citric acid (CA) at different crosslinking temperatures and crosslinking times. The water absorption and biodegradability of the films were studied. Furthermore, the synergistic effect of crosslinking and reinforcement was used to improve the interfacial bonding between the two. The water absorption of pure cellulose, cellulose crosslinked with 10% CA, cellulose reinforced with 15% GO reinforcement, and synergy of 10% CA crosslinking and 15% GO reinforcement at crosslinking temperature of 130°C and crosslinking time of 25 min was found to be 99.02%, 56.4%, 44.275%, and 36.78%, respectively. The biodegradability at the optimal values of crosslinker concentration, crosslinking time, and crosslinking temperature of pure cellulose of bagasse, 10% CA crosslinked bagasse, and 10% CA crosslinked bagasse with 15% GO reinforcement in 30 days were found to be 94.0397%, 56.91%, and 40.81%, respectively. The result of the study shows that water‐resistant biodegradable plastic can be produced with the synergistic effect of crosslinking and reinforcement.

Stringiness morphology for crosslinked polyacrylic pressure‐sensitive adhesives measured by peel testing with constant rate

AbstractTo clarify the formation mechanism of front frame‐type morphology, the stringiness of crosslinked random copolymers of poly(n‐butyl acrylate‐acrylic acid) during a 180° peel test with a constant tensile rate was examined for various crosslinker contents and rates using a quartz adherend. Cohesive failure occurred for lower crosslinker content and rate, whereas interfacial failure with sawtooth‐type stringiness without a frame was observed for higher crosslinker content and rate. Front frame‐type stringiness was formed at the boundary of cohesive and interfacial failures. To clarify the formation mechanism, observation was conducted from the start of peel test until the equilibrium state. The sawtooth‐type stringiness with branches first formed at the tip. The adjoining branches were connected and the 2D frame was formed only on the adherend surface. The formed 2D frame developed toward the 3D walls and the front frame‐type was then completed. This is caused by the surface tension that acts to restrain the increase in the surface area. However, the surface area of the front frame‐type morphology was larger than the no frame‐type. The larger absorption of peeling stress by the formation of this morphology is expected to contribute to peel strength improvement.

Engineering a mussel-inspired hemostatic sealant with a strong tissue anchor as a first-aid tissue adhesive

During injury, achieving quick hemostasis, while maintaining adhesive performances on wet tissue and providing appropriate dynamical mechanical properties remain crucial clinical requests for the current tissue adhesives. Here, we design a double-crosslinking tissue adhesive with tunable degradation rate, adhesion strength, mechanical properties, and cell responses, using thiolated gelatin (Gel-SH) or gelatin and tannic acid (TA). We also investigate the role of different concentrations of gelatin (70 and 150 mg/ml), TA (7, 20, and 70 mg/ml), and crosslinkers (sodium periodate (11.3 and 16.8 mg/ml) and Fe3+ ions (1.7 and 4.8 mg/ml)) to provide a balance of covalent and noncovalent interactions leading to establish muscular tissue adhesive strength and superior hemostasis. Our findings reveal that the Gel-SH(gelatin)/TA adhesives have a range of swelling ability (300–700 %), compressive modulus (0.2–1.2 kPa), strength (0.1–0.8 kPa), and toughness (10–15 kJ/m3). In addition, Gel-SH/TA sample shows rapid self-healing ability and offers robust adhesiveness to wet cow skin and cardiac tissue (50–70 kPa) compared to others mainly owing to the improved cohesive strength originating from the range of chemical interaction within the adhesive network and abundant phenolic hydroxyl groups, surface water removal, and dynamic phenol-quinone balance at the tissue interfaces. Meanwhile, Gel-SH/TA adhesive also exhibits high hemocompatibility and hemostatic properties and appropriate in vitro biocompatibility. Notably, Gel-SH/TA adhesive could support attachment, viability and proliferation, of H9c2 cells. Overall, the multifunctional Gel-SH/TA adhesive hydrogel, owing to the range of molecular interactions opens a new opportunity for quick sealing hemostasis and wound healing and could potentially be harnessed for the development of clinically relevant tissue adhesives.