Methylene Bisacrylamide Research Articles

The thermal stability mechanism of MBA-crosslinked PPGs: Insights from macroscopic phenomena to chemical reactions

Preformed particle gels (PPGs) is one of the most efficient enhanced oil recovery techniques used for conformance control. Evaluating the thermal stability of PPGs and understanding their thermal stability mechanism are crucial for the development and application of high-temperature-resistant PPGs. We focused on conventional N, N′-methylene-bis-acrylamide (MBA) crosslinked PPGs, systematically analyzing the macroscopic state changes, microstructural changes, and chemical reactions occurring during the ageing process in 1 % NaCl solution at different temperatures, and delved into their thermal stability mechanism. Our findings revealed that the swelling ratio (SR) of PPGs during ageing is correlated with temperature, showing three distinct patterns: a stable SR at low temperatures (<60 °C), a period of unchanged swelling followed by a continuous increase within the intermediate temperature range (70–90 °C), and a rapid swelling leading to sol conversion at high temperatures (>95 °C). Scanning electron microscope observations and elastic modulus analysis confirmed that the microstructure of PPGs remains stable when the SR was unchanged, while continuous increases in the SR indicated damage to the gel's micro-network structure. X-ray photoelectron spectrum and carbon nuclear magnetic resonance spectroscopy indicated that no chemical reactions occurred in PPGs at temperatures not exceeding 60 °C. When temperature was 70–100 °C, a small amount of acrylamide (AM) hydrolysis occurred initially, which then sequentially triggered the hydrolysis of MBA crosslinkers and 2-Acrylamido-2-methylpropane sulfonic acid (AMPS) due to the catalytic effect of undissociated carboxyl. At temperatures above 100 °C, hydrolysis reactions occurred simultaneously in AM, MBA crosslinkers, and AMPS. The thermal stability of MBA-crosslinked PPGs is indeed related to the thermal stability of the MBA, but it can be reduced by the influence of other non-temperature-resistant monomers, such as AM. This study provides insights into the thermal stability mechanisms of PPGs and guidance for the development of high-temperature-resistant PPGs.

Fabrication, optimization, and in vitro validation of penicillin-loaded hydrogels for controlled drug delivery

Bacterial infections present a major global challenge. Penicillin, a widely used antibiotic known for its effectiveness and safety, is frequently prescribed. However, its short half-life necessitates multiple high-dose daily administrations, leading to severe side-effects. Therefore, this study aims to address these issues by developing hydrogels which control the release of penicillin and alleviate its adverse effects. Various combinations of aspartic acid and acrylamide were crosslinked by N′, N′-methylene bisacrylamide through a free radical polymerization process to prepare aspartic acid/acrylamide (Asp/Am) hydrogels. The fabricated hydrogels underwent comprehensive characterization to assess physical properties and thermal stability. The soluble and insoluble fractions and porosity of the synthesized matrix were evaluated by sol-gel and porosity studies. Gel fraction was estimated at 88–96%, whereas sol fraction was found 12–4% and porosity found within the 63–78% range for fabricated hydrogel formulations. Maximum swelling and drug release were seen at pH 7.4, demonstrating a controlled drug release from hydrogel networks. The results showed that swelling, porosity, gel fraction, and drug release increased with higher concentrations of aspartic acid and acrylamide. However, integration of N′, N′-methylene bisacrylamide exhibited the opposite effect on swelling and porosity, while increasing gel fraction. All formulations followed the Korsymer–Peppas model of kinetics with ‘r’ values within the range of 0.9740–0.9980. Furthermore, the cytotoxicity study indicated an effective and safe use of hydrogel because the cell viability was higher than 70%. Therefore, these prepared hydrogels show promise candidates for controlled release of Penicillin and are anticipated to be valuable in clinical applications.

Optimizing modified natural rubber in starch-based hydrogels: A cost-effective approach for high-performance sustainable slow-release fertilizer coatings

Effective compatibility between natural rubber (NR) and cassava starch (CSt) is crucial for enhancing the water swelling and retention properties of CSt/NR-based hydrogels. In this study, NR was modified by grafting glycidyl methacrylate (NR-g-GMA, NRG) at 3, 6, and 9 parts per hundred rubber (phr) for blending with CSt. Subsequently, CSt was grafted with acrylamide (AM), crosslinked with N,N′ − methylene-bis-acrylamide (MBA), and interpenetrated with NRG to produce CSt-g-PAM/NRG hydrogels. The resulting CSt-g-PAM/NRGx (x = phr of GMA) hydrogels were characterized using FTIR, XRD, TGA, tensile testing, and water swelling measurements. Results revealed that CSt-g-PAM/NRG3 exhibited the highest equilibrium water swelling at 3300 %, surpassing CSt-g-PAM/NR (1430 %) and demonstrated the highest mechanical strength (0.92 MPa), desirable biodegradability (69 % at 30 days), and good water retention. These properties are attributed to the superior compatibility and stronger interactions between NRG and the CSt-g-PAM networks. Additionally, the WUHNRG3 (urea coated with CSt-g-PAM/NRG3 and wax layers) fertilizer demonstrated good biosafety, an acceptable slow-release rate (50.26 % at 30 days), and effectively promoted the growth of chili plants at a reasonable cost. This study demonstrates that modifying NR with optimal GMA content provides an effective CSt-g-PAM/NRG coating membrane, suitable for sustainable slow-release fertilizers and green agricultural practices.

Carboxymethyl cellulose-based preformed particle gels for water management in oil and gas reservoirs

Carboxymethyl cellulose (CMC) based materials have been proposed as preformed particle gels (PPGs) for reducing excessive water production in oil and gas reservoirs. Multi-sized dry particles ranging between 100 and 1180 μm have been synthesized using microwave-assisted grafting copolymerization of CMC and acrylamide (AM)/n,n''-methylene-bisacrylamide (MBA). FTIR and SEM confirmed CMC crosslinked polyacrylamide's chemical structure and morphology (CMC/CPAM). Thermo-gravimetric analysis has demonstrated the thermal stability of dry PPGs up to 309 °C. CMC/CPAM showed slightly high absorbency in brine 2 (TDS = 67.3 g/L) compared to brine 1 (TDS = 33.65 g/L), 1% NaCl, and deionized water, with swelling ratios (SR) between 7.1 and 12.9 g/g at room temperature regulated by MBA weight ratio. The effect of particle size, pH, temperature, and aging on SR and mechanical strength was investigated and discussed based on the CMC/CPAM structures. The swollen PPGs showed excellent resistance to temperatures up to 100 °C with a storage modulus of 9 kPa. The particle size was estimated based on salinity, pH, and temperature and controlled between 118 μm and 3 mm at high temperature (100 °C) and high salinity (TDS = 67.3 g/L) conditions to match the need for carbonate reservoirs. Core flooding experiments demonstrated the effective plugging efficiency of the PPG in open fracture models.

A smart capecitabine imprinted nanocontainer with the dual-responsive performance to pH/NIR light

Capecitabine (CAP) is a kind of prodrug that can be metabolized into 5-fluorouracil (5-FU) in vivo, so it is usually classified as the antimetabolite fluoropyrimidine deoxynucleoside analog. In this paper, CAP, upconversion nanoparticles (UCNPs), 3,5-dicarboxy-4-methacrylate-based azobenzene (MAPDIA)/acrylic acid-functionalized gelatin, N,N′-methylene bisacrylamide (MBA), and ammonium persulfate (APS) were used as template, light trigger, bifunctional monomers, cross-linking agent and initiator, respectively. By using the free-radical polymerization and the molecular imprinting technique, the potential drug delivery nanocontainer CAP-MIP with the dual-responsive performance to pH/near infrared light (NIR) was successfully prepared. Furthermore, the characterization of CAP-MIP was also carried out by the modern instrumental analysis such as FTIR, XRD, TGA, BET and so on. The stimulus-responsive release experiment in vitro indicated the maximum cumulative release rate of CAP changed from 1.71 % to 89.54 % when the pH value in medium varied from 1.2 to 8.3, and the equilibrium release time point also greatly prolonged to 420 min from 40 min, respectively. When irradiated by 980 nm monochromatic NIR light in the same solution of pH 6.8, the maximum release rate of the sample could reach 96.21 % at 180 min, which respectively corresponded to the data of 41.84 % at 420 min under the condition of the absence of additional NIR light. In addition, CAP-MIP also had the excellent specific adsorption for CAP with the selectivity factor of 2.904 and the maximum CAP-loaded capacity of 7 mg•g−1. The above information denoted the target material should be of some potential in drug delivery system application.

Structure and thermal properties of acrylic copolymer gels: effect of composition and cross-linking method

Two approaches to the synthesis of hydrogels based on polyacrylamide (pAAm) with copolymers were compared in the paper—traditional chemical cross-linking and physical cross-linking with montmorillonite (MMT). The main aim of the work was to find an adequate replacement of the chemical toxic cross-linking agent MBAAm (N,N'-methylene-bis-acrylamide) by using non-toxic—natural clay MMT for synthesis of pAAm gels, which are planned to be used as soil conditioners. A series of hydrogels based on acrylic monomers (acrylamide (AAm), acrylonitrile (AN), acrylic acid (AA)) physically cross–linked by MMT and chemically cross-linked were synthesized. For the synthesized gels, the influence of the synthesis method on the formation of the structure and the mechanism of thermal destruction in the presence of air was analyzed using a set of physicochemical methods: FTIR, XRD, SEM, DSC and TG/DTG. According to FTIR and XRD data, pAAm-MMT and pAAm-AN-MMT samples formed an intercalated/exfoliated structure, whereas pAAm-AA-MMT had an intercalated structure. The endothermic reaction of decomposition of xerogels based on acrylic polymers with and without MMT was observed using DSC and derivative thermogravimetry analyses, coupled with measurement of FTIR spectra of volatile products of thermolysis. All studied composites were relatively thermoresistant, which had three distinct regions of phase transitions and their thermal decomposition occurred at a temperature range 310–465 °C.Graphical

Synthesis and Physicochemical Properties of Thermally Sensitive Polymeric Derivatives of N-vinylcaprolactam.

Six derivatives of poly-N-vinylcaprolactam (PNVCL) P1-P6 were synthesized via surfactant-free precipitation polymerization (SFPP) at 70 °C, with potassium persulfate (KPS) as the initiator. P5 and P6 were synthesized using the cross-linker N,N'-Methylenebisacrylamide (MBA). The conductivity was measured to monitor the polymerization process. The hydrodynamic diameters (HDs) and polydispersity indexes (PDIs) of aqueous dispersions of P1-P6 were determined using dynamic light scattering (DLS) and zeta potential (ZP) using electrophoretic mobilities. At 18 °C for P1-P6, the HDs (nm) were 428.32 ± 81.30 and PDI 0.31 ± 0.19, 528.60 ± 84.70 (PDI 0.42 ± 0,04), 425.96 ± 115.42 (PDI 0.56 ± 0.08), 440.34 ± 106.40 (PDI 0.52 ± 0.09), 198.39 ± 225.35 (PDI 0.40 ± 0.19), and 1201.52 ± 1318.05 (PDI 0.71 ± 0.30), the and ZPs were (mV) 0.90 ± 3.23, -4.46 ± 1.22, -6.44 ± 1.82, 0.22 ± 0.48, 0.18 ± 0.79, and -0.02 ± 0.39 for P1-P6, respectively. The lower critical solution temperature ranged from 27 to 29 °C. The polymers were characterized using the ATR-FTIR method. The study concluded that the physicochemical properties of the product were significantly affected by the initial reaction parameters. Polymers P1-P4 and P6 have potential for use as drug carriers for skin applications.

Fabrication of dopamine/TiO2 nanocomposite hydrogel using fenugreek gum for efficient photocatalytic degradation of organic pollutants under visible light irradiation

The efficient removal of organic pollutants from wastewater is a global challenge and poses a significant threat to public health and ecosystems. In this study, we synthesized a novel fenugreek gum-based polymer functionalized with dopamine (DA) and monomers dimethylamino ethyl methacrylate (DMA), acrylamide, and N, N, methylene bis acrylamide (MBA) as a crosslinker and TiO2 nanocomposite hydrogel photocatalytic degradation for environmental remediation. The nanocomposite hydrogel was determined using various analytical techniques such as FT-IR, XRD, FESEM, EDX, DRS-UV, TEM, LC-MS, and XPS. The optical band gap was at 2.81 eV, calculated from UV–visible DRS spectra. The XRD confirmed the crystalline and anatase phases. TEM, EDX, and XPS analyses defined the size, shape, chemical composition, and purity of synthesized FNG/DDM/TiO2 nanocomposite hydrogel. The resulting nanocomposite hydrogel photocatalyst effectively degraded hazardous pollutants such as methylene blue (MB) and Congo red (CR) organic dyes under visible light irradiation. The decomposition efficiency of Congo red is 95.27 % within 75 min and methylene blue is 73.26 % within 150 min. Moreover, the results of the trapping experiment revealed that the active species in the photocatalytic degradation process are holes (h+) and super oxide radicals (.O2-), more reactive species. The probable degradation intermediates and the degradation pathway were analyzed by LCMS analysis, and the degradation fragments formed during Congo red (CR) dye degradation were identified. The recyclability and stability were studied in the presence of a photocatalyst, achieving 90.5 % degradation after four cycles. The FNG/DDM/TiO2 hydrogel also effectively removed dyes from wastewater containing organic pollutants. The novel FNG/DDM/TiO2 nanocomposite hydrogel, synthesized through an environmentally friendly polymer, demonstrated high efficiency in degrading organic dyes, excellent recyclability with robust structural stability, and significant potential for photocatalytic degradation of wastewater across various industries.

Influence of the Crosslinker Hydrophobicity on the Swelling Kinetics of Poly(Acrylic Acid) Microgels

AbstractSuperabsorbent polymer gels are widely used in commercial areas, such as in hygiene products. A key aspect in these and other applications is the gel swelling kinetics, and a key factor of influence on that is the hydrophobicity of the gel. This paper reports on the synthesis of superabsorbent polymer microgel particles with four differently hydrophobic crosslinkers: N,N’‐methylenebisacrylamide (MBAA), N,N’‐ethylenebisacrylamide (EBAA), N,N’‐propylenebisacrylamide (PBAA), and N,N’‐butylenebisacrylamide (BBAA). This work uses droplet‐based microfluidics to produce uniform and well‐defined microgel specimen and study the influence of the crosslinker hydrophobicity on the swelling kinetics. In particular, this work determines swelling constants and their dependencies on the temperature of the swelling medium as well as the activation energies of swelling in relation to the crosslinker hydrophobicity. This work finds two competing effects, leading to a narrow window in which the activation energy of the swelling of the microgels decreases with increasing crosslinker hydrophobicity.

On the dual crosslinking for functionality enhancement of poly (acrylamide-co-acrylic acid)/chitosan-aluminum (III) ions and its characterization and sensory hydrogel fibers

In this report, we present a dual crosslinking hydrogel fiber made from polyamine saccharides chitosan (CS), synthesized through UV polymerization. This process utilizes Irgacure 2959 and N,N′-Methylenebisacrylamide (MBAA) as initiators, followed by immersion in an aluminum chloride (AlCl3) solution. The resulting hydrogel incorporates a dual crosslinking mechanism, quantitatively studied via Nuclear Magnetic Resonance (NMR) spectroscopy. This mechanism involves chemical crosslinking through radical graft polymerization of acrylamide and acrylic acid onto CS in the presence of MBAA, and physical crosslinking through hydrogen bonding interactions between P(AAm-co-AA) and a metal coordination bond. The mechanical properties of the hydrogel fiber enable it to withstand stresses up to 656 kPa and strains exceeding 300 %. Additionally, the hydrogel fiber exhibits conductivity at 1.96 Scm−1. Serving as a multifunctional material, it acts as a strain sensor and finds utility in optics. Remarkably, it demonstrates the capability to detect human motions such as finger bending and minor deformations like vibrations of the vocal cords. Furthermore, its ability to guide dynamic light makes it promising for optical applications. Consequently, this multifunctional hydrogel fiber emerges as a highly promising candidate for diverse applications in fields such as bioengineering and electronics.

Synergistic effects of covalent crosslinking and hydrophobic association on enhancing thermal and salt resistance of polymeric filtrate reducer

Traditional linear polymeric filtrate reducers for water-based drilling fluids (WBDFs) are insufficient for drilling engineering requirements, even with adjustments in the type and proportion of functional groups in the copolymer, especially under high-temperature and high-salinity conditions. In this study, a dual cross-linked copolymer (named AAS-L4%-M0.5‰) was synthesized through free radical copolymerization using lauryl methacrylate (LMA) as hydrophobic associated segments and N, N’-methylene bisacrylamide (MBA) as the chemical crosslinker. The synergistic effect of covalent micro-crosslinking and hydrophobic association in AAS-L4%-M0.5‰ were systematically investigated and demonstrated. After aging at 220 °C for 16 h, the WBDFs containing 1 % AAS-L4%-M0.5‰ exhibited high-temperature/high-pressure filtration loss (FLHTHP) and American Petroleum Institute filtration loss (FLAPI) of 34 mL and 10 mL, respectively, representing reductions of 50 % and 38 % compared to the linear polymer AAS-L0-M0. Even after aging at 200 °C in saturated salt solution conditions, the WBDFs containing AAS-L4%-M0.5‰ maintain excellent filtration properties with FLAPI value of 7.5 mL, achieving an 83 % reduction compared to AAS-L0-M0. Moreover, because of the three-dimensional spatial network structure formed by dual cross-linking, AAS-L4%-M0.5‰ effectively inhibits unwanted foaming caused by the polyelectrolyte effect. Therefore, this work provides a simple but effective approach to develop temperature-resistant and salt-tolerant filtrate reducers with excellent workability.

Recycling leachate nanofiltration concentrate and preparing a novel and low-cost absorbent dried gel by graft polymerization

Leachate nanofiltration concentrate (LNC), characterized by its complex composition and recalcitrant contaminants, poses a significant environmental challenge. This study explores the synthesis of absorbent gels via free radical polymerization, utilizing LNC as the solvent. Employing urea as the modified material, acrylic acid (AA) as the monomer, N, N′-Methylenebisacrylamide (MBA) as the cross-linking agent, and potassium persulfate (KPS) as the initiator, the resulting gel is stable below 180 °C. It demonstrates an impressive absorbency (Q) exceeding 14.50 g/g with key gel synthesis conditions optimized via response surface methodology (RSM). Subsequent application of the prepared LNC gel in LNC treatment via low-temperature evaporation achieves remarkable pollutant removal, meeting relevant water quality standards. This gel-based LNC treatment method achieves notable reductions in carbon emission and cost to 39.2 kgCO2/kgCOD and 3.4 $/kgCOD, respectively. This study provides a cost-effective and environment-friendly approach for LNC reutilization, and exemplifies the concept of utilizing waste to treat waste, thereby mitigating environmental impact of LNC and advancing gel technology in environmental remediation.

Smartphone-Based Rapid Quantitative Detection Platform with Imprinted Polymer for Pb (II) Detection in Real Samples.

This paper reports the successful development and application of an efficient method for quantifying Pb2+ in aqueous samples using a smartphone-based colorimetric device with an imprinted polymer (IIP). The IIP was synthesized by modifying the previous study; using rhodizonate, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), N,N'-methylenebisacrylamide (MBA), and potassium persulfate (KPS). The polymers were then characterized. An absorption study was performed to determine the optimal conditions for the smartphone-based colorimetric device processing. The device consists of a black box (10 × 10 × 10 cm), which was designed to ensure repeatability of the image acquisition. The methodology involved the use of a smartphone camera to capture images of IIP previously exposed at Pb2+ solutions with various concentrations, and color channel values were calculated (RGB, YMK HSVI). PLS multivariate regression was performed, and the optimum working range (0-10 mg L-1) was determined using seven principal components with a detection limit (LOD) of 0.215 mg L-1 and R2 = 0.998. The applicability of a colorimetric sensor in real samples showed a coefficient of variation (% RSD) of less than 9%, and inductively coupled plasma mass spectrometry (ICP-MS) was applied as the reference method. These results confirmed that the quantitation smartphone-based colorimetric sensor is a suitable analytical tool for reliable on-site Pb2+ monitoring.

Anti-fouling underwater superoleophobic membranes based on hierarchical double networks for high efficiency oil–water separation

Oil fouling is a key problem of superwettable oil–water separation membranes because the membranes are inevitably susceptible to varying degrees of oil contamination during the ongoing separation processes, which usually results in a severe impact on separation performance. Consequently, it is a great challenge to construct oil-removal membranes with superior resistance to oil contamination. Herein, we fabricated hierarchical double networks (HDT)-modified porous glass membrane with superhydrophilicity/underwater superoleophobicity. Firstly, a layer of silicone nanofilament (SNF) network bearing tremendous C = C double bonds were fabricated on a porous glass membrane surface by one-step chemical vapor deposition (CVD) using vinyltrichlorosilane (VTCS) as a precursor. Subsequently, the second network layer was constructed by copolymerization of the C = C double bonds on the SNF network and those in sulfobetaine-derived monomer (sulfobetaine methacrylate, SBMA), using N,N′-methylenebisacrylamide (MBA) as the cross-linkering agent. It was observed that the obtained HDT-modified glass membranes displayed excellent superhydrophilicity/underwater superoleophobicity accompanied with superior self-cleaning performance and oil-resistance properties. As a result, the HDT-modified membranes showed high separation flux and high efficiency for both oil/water mixtures (7500 L m−2h−1, above 99.98%) and surfactant-stabilized oil-in-water emulsions (1100 L m−2h−1, above 99.96%) with excellent cyclability. The outstanding advantages with characteristics of excellent oil resistance and superior separation performance enable the HDT-modified glass membrane promising applications in a wide range of industries related to oil–water separations.

Development and evaluation of lysine-crosslinked re-crosslinkable particle gel for water control in high-temperature reservoirs

Preformed particle gel (PPG) treatment is a cost-effective technology for controlling excessive water production. However, PPG exhibits limited plugging efficiency when dealing with open fractures at high temperatures. This paper reports a novel environmentally friendly, high-temperature resistant re-crosslinkable PPG (EF-HT-RPPG). The polymer backbone of EF-HT-RPPG is methylene bisacrylamide crosslinked poly (acrylamide-co N-vinylpyrrolidone). The secondary crosslinker is pre-embedded during the synthesis process, and the hydrated gel particles can reform a bulk gel at high temperatures through chemical re-crosslinking between polymer chains and the secondary crosslinker which is lysine. This study investigated the swelling, re-crosslinking behavior, hydrolytic thermal stability, and plugging performance of the EF-HT-RPPG. Bottle tests were conducted to determine the swelling kinetics, re-crosslinking time, and thermal stability data. The plugging efficiency was assessed using a fracture model. EF-HT-RPPG could re-crosslink at 80–130 °C within a reasonable time. The storage modulus (G′) of the re-crosslinked gel with a swelling ratio of 10 was measured at 477 Pa. Additionally, gels prepared in Ekofisk formation water remained stable at 130 °C for over 350 days. The plugging test demonstrated that EF-HT-RPPG could be readily injected into the fracture, with a water breakthrough pressure gradient of 70 psi/ft.

Optimization of preparation conditions and performance of a new degradable soil water retaining agent

Using polyaspartic acid (PAsp) and bentonite (BT) as the main raw materials, a new type of degradable soil water retaining agent (PAsp-AA/BT) was synthesized by microwave radiation. The optimum synthesis conditions and comprehensive properties of PAsp-AA/BT were discussed and the structure and surface characteristics of PAspsp-AA/BT were characterized by FTIR, SEM, XRD and TGA in the paper. The results showed that the optimum synthesis conditions of PAsp-AA/BT were as follows: the dosages of polyaspartic acid (PAsp), bentonite (BT), initiator potassium persulfate, crosslinking agent N,N′-methylene bisacrylamide was 5, 3, 0.3, 0.03%, respectively, the neutralization degree of acrylic acid was 75%, and the microwave power was 490W. Under this condition, the absorption ratio of the synthesized PAspsp-AA/BT in deionized water and 0.9% NaCl solution was 953 and 164 g/g, respectively. The synthesized PAsp-AA/BT had a high water absorption rate, good water retention and repeated water absorption, and the degradation rate in soil within 30 days reached 32.75%, with good degradation effect. The analysis of SEM, FT-IR, XRD and TGA showed that: the surface of PAsp-AA/BT was rough and had obvious pore structure, which was conducive to the diffusion of water molecules; polyaspartic acid, bentonite and acrylic acid were polymerized; the cross-linking structure was formed between polyaspartic acid, bentonite and acrylic acid; the product of PASP-AA/BT had good thermal stability. This study provides a new soil water retaining agent, which is helpful for the better development of soil water retaining agent research.

A superabsorbent and pH-responsive copolymer-hydrogel based on acemannan from Aloe vera (Aloe barbadensis M.): A smart material for drug delivery

Combining natural polysaccharides with synthetic materials improves their functional properties which are essential for designing sustained-release drug delivery systems. In this context, the Aloe vera leaf mucilage/hydrogel (ALH) was reacted with acrylic acid (AA) to synthesize a copolymerized hydrogel, i.e., ALH-grafted-Polyacrylic acid (ALH-g-PAA) through free radical copolymerization. Concentrations of the crosslinker N,N′-methylene-bis-acrylamide (MBA), and the initiator potassium persulfate (KPS) were optimized to study their effects on ALH-g-PAA swelling. The FTIR and solid-state NMR (CP/MAS 13C NMR) spectra witnessed the formation of ALH-g-PAA. Scanning electron microscopy (SEM) analysis revealed superporous nature of ALH-g-PAA. The gel fraction (%) of ALH-g-PAA was directly related to the concentrations of AA and MBA whereas the sol fraction was inversely related to the concentrations of AA and MBA. The porosity (%) of ALH-g-PAA directly depends on the concentration of AA and MBA. The ALH-g-PAA swelled admirably at pH 7.4 and insignificantly at pH 1.2. The ALH-g-PAA offered on/off switching properties at pH 7.4/1.2. The metoprolol tartrate was loaded on different formulations of ALH-g-PAA. The ALH-g-PAA showed pH, time, and swelling-dependent release of metoprolol tartrate (MT) for 24 h following the first-order kinetic and Korsmeyer-Peppas model. Haemocompatibility studies ascertained the non-thrombogenic and non-hemolytic behavior of ALH-g-PAA.

Rationally designed β-cyclodextrin-crosslinked polyacrylamide hydrogels for cell spheroid formation and 3D tumor model construction

In vitro tumor models are essential for understanding tumor behavior and evaluating tumor biological properties. Hydrogels that can mimic the tumor extracellular matrix have become popular for creating 3D in vitro tumor models. However, designing biocompatible hydrogels with appropriate chemical and physical properties for constructing tumor models is still a challenge. In this study, we synthesized a series of β-cyclodextrin (β-CD)-crosslinked polyacrylamide hydrogels with different β-CD densities and mechanical properties and evaluated their potential for use in 3D in vitro tumor model construction, including cell capture and spheroid formation. By utilizing a combination of β-CD-methacrylate (CD-MA) and a small amount of N,N′-methylene bisacrylamide (BIS) as hydrogel crosslinkers and optimizing the CD-MA/BIS ratio, the hydrogels performed excellently for tumor cell 3D culture and spheroid formation. Notably, when we co-cultured L929 fibroblasts with HeLa tumor cells on the hydrogel surface, co-cultured spheroids were formed, showing that the hydrogel can mimic the complexity of the tumor extracellular matrix. This comprehensive investigation of the relationship between hydrogel mechanical properties and biocompatibility provides important insights for hydrogel-based in vitro tumor modeling and advances our understanding of the mechanisms underlying tumor growth and progression.

Design and Synthesis of P(AAm-co-NaAMPS)-Alginate-Xanthan Hydrogels and the Study of Their Mechanical and Rheological Properties in Artificial Vascular Graft Applications.

Cardiovascular diseases (CVDs) are the number one cause of mortality among non-communicable diseases worldwide. Expanded polytetrafluoroethylene (ePTFE) is a widely used material for making artificial vascular grafts to treat CVDs; however, its application in small-diameter vascular grafts is limited by the issues of thrombosis formation and intimal hyperplasia. This paper presents a novel approach that integrates a hydrogel layer on the lumen of ePTFE vascular grafts through mechanical interlocking to efficiently facilitate endothelialization and alleviate thrombosis and restenosis problems. This study investigated how various gel synthesis variables, including N,N'-Methylenebisacrylamide (MBAA), sodium alginate, and calcium sulfate (CaSO4), influence the mechanical and rheological properties of P(AAm-co-NaAMPS)-alginate-xanthan hydrogels intended for vascular graft applications. The findings obtained can provide valuable guidance for crafting hydrogels suitable for artificial vascular graft fabrication. The increased sodium alginate content leads to increased equilibrium swelling ratios, greater viscosity in hydrogel precursor solutions, and reduced transparency. Adding more CaSO4 decreases the swelling ratio of a hydrogel system, which offsets the increased swelling ratio caused by alginate. Increased MBAA in the hydrogel system enhances both the shear modulus and Young's modulus while reducing the transparency of the hydrogel system and the pore size of freeze-dried samples. Overall, Hydrogel (6A12M) with 2.58 mg/mL CaSO4 was the optimal candidate for ePTFE-hydrogel vascular graft applications due to its smallest pore size, highest shear storage modulus and Young's modulus, smallest swelling ratio, and a desirable precursor solution viscosity that facilitates fabrication.

Utilizing methacrylated lignin as a sustainable macro-crosslinker for synthesizing innovative PVA/AMPS composites crosslinked hydrogel nanofibers: A potential application for lithium-ion battery separators

There are significant issues with commercial separators that must be resolved before they can be used in high-energy-density batteries. These problems include low porosity, poor electrolyte wetting, and low mechanical properties. This study presents a facile method for preparing composite crosslinked hydrogel nanofibers of polyvinyl alcohol (PVA) with 2-acrylamide-2-methylpropanesulfonic acid (AMPS) for lithium-ion battery separators by utilizing methacrylated lignin (LMA) as a bio-based crosslinker. Initially, LMA was synthesized by grafting glycidyl methacrylate (GMA) onto lignin via esterification. Subsequently, a crosslinked hydrogel nanofiber membrane (PVA/AMPS-LMA) was electrospun with varying LMA fractions, which were polymerized by combining free radical copolymerization and esterification reactions. The effectiveness of LMA as a crosslinker was assessed against the N, N′-methylene bisacrylamide (MBA). The study showed that using LMA as a crosslinker significantly improved the membrane's properties. The PVA/AMPS-LMA separator displayed superior features such as mechanical strength, thermal stability, porosity, electrolyte uptake, ionic conductivity, and lithium-ion transference number, when compared with PVA/AMPS, PVA, and Celgard separators. Specifically, the PVA/AMPS-LMA separator demonstrated a high mechanical strength of 24.9 MPa, strong thermal stability at 170 °C with no shrinkage, high porosity (84.3 %), and electrolyte uptake (661.4 %). It also exhibited exceptional ionic conductivity (2.75 mS/cm) and a notable lithium-ion transference number (tLi+ = 0.717). In coin batteries, the PVA/AMPS-LMA separator retained over 96 % capacity (142.4 mAh/g) after 200 cycles at 1C. This performance exceeded that of PVA/AMPS, PVA, and Celgard separators, suggesting that PVA/AMPS-LMA separators have the potential to replace their commercial counterparts.