Acrylic Acid Research Articles

Relation of acrylic acid polymerization behavior in deep eutectic solvent to water content: Computer simulation and experiment

Polymerizable deep eutectic solvents (DES) are promising starting materials for preparation of eutectogels and hydrogels that can be applied in drug delivery, as strain sensors and various components of soft electronics. However, the understanding of relationship between the molecular structure, physicochemical properties and polymerization behavior of such systems in pure state and in their mixtures with water is not well studied yet. In this work we report the results of both computer simulation and experimental investigations for polymerizable choline chloride/acrylic acid DES and its mixtures with water. Molecular dynamics was applied to reveal the influence of water on the structure of polymerizable DES at the molecular and supramolecular levels. The diffusion coefficients of DES components with different water content were measured using NMR. The course of photoinduced polymerization of DES/water mixtures was traced using FTIR spectroscopy, while the molar mass and hydrodynamic characteristics of obtained polyacrylic acid were studied by means of static and dynamic light scattering. It was found that addition of water leads to a gradual decrease in size of the acrylic acid clusters that exist in pure DES and is accompanied by an increase in orientation mobility and diffusion coefficients of components. The maximal molar mass was obtained for the polymer prepared by polymerization of DES with 5 wt% of water. This can be attributed to the optimal combination of acrylic acid clusters size and increased mobility of components.

Magnetic Nanoparticles in Biopolymer Fibers: Fabrication Techniques and Characterization Methods.

Hybrid nanocomposites combining biopolymer fibers incorporated with nanoparticles (NPs) have received increasing attention due to their remarkable characteristics. Inorganic NPs are typically chosen for their properties, such as magnetism and thermal or electrical conductivity, for example. Meanwhile, the biopolymer fiber component is a backbone, and could act as a support structure for the NPs. This shift towards biopolymers over traditional synthetic polymers is motivated by their sustainability, compatibility with biological systems, non-toxic nature, and natural decomposition. This study employed the solution blow spinning (SBS) method to obtain a nanocomposite comprising poly(vinyl pyrrolidone), PVA, and gelatin biodegradable polymer fibers incorporated with magnetic iron oxide nanoparticles coated with poly(acrylic acid), PAA2k, coded as γ-Fe2O3-NPs-PAA2k. The fiber production process entailed a preliminary investigation to determine suitable solvents, polymer concentrations, and spinning parameters. γ-Fe2O3-NPs were synthesized via chemical co-precipitation as maghemite and coated with PAA2k through the precipitation-redispersion protocol in order to prepare γ-Fe2O3-NPs-PAA2k. Biopolymeric fibers containing coated NPs with sub-micrometer diameters were obtained, with NP concentrations ranging from 1.0 to 1.7% wt. The synthesized NPs underwent characterization via dynamic light scattering, zeta potential analysis, and infrared spectroscopy, while the biopolymer fibers were characterized through scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis. Overall, this study demonstrates the successful implementation of SBS for producing biopolymeric fibers incorporating iron oxide NPs, where the amalgamation of materials demonstrated superior thermal behavior to the plain polymers. The thorough characterization of the NPs and fibers provided valuable insights into their properties, paving the way for their potential applications in various fields such as biomedical engineering, environmental remediation, and functional materials.

Flexible high electrochemical collagen/lignin composite hydrogel for sensing and supercapacitor applications

Synthesis of polymer-based highly conductive hydrogels from natural and renewable sources with robust mechanical performances in flexible electronics remains a great challenge. In this research, a dynamic redox system is designed by using collagen (CL), sulfonate lignin (SL), acrylic acid (AA), and Al3+ to synthesize CL/PAA/SL/Al hydrogels. The formation of effective complexes of Al3+ with the abundant functional groups of CL, SL and PAA, the prepared hydrogel delivers various specific properties, for example, excellent ionic conductivity (4.61 S·m−1), stretchability and antimicrobial performance. The CL/PAA/SL/Al hydrogel demonstrates good mechanical strength, while the maximum tensile strength of the hydrogels is ∼604 kPa at a stretching of 1254 %, and the maximum compressive strength is ∼0.45 MPa, with the maximum stretching of 59.6 %. The CL/PAA/SL/Al hydrogel acts as a flexible strain sensor with high sensitivity. Enough hydroxyl and carboxyl groups in the hydrogels are essential for delivering the maximum 191 mV of open circuit voltage (Voc) rendered during moisture spraying. The supercapacitor assembled from CL/PAA/SL/Al hydrogel manifests specific capacitance (Cs), maximum energy density (Ed) and power density (Pd) of 268.75 F·g−1, 23.89 Wh·kg−1 and 2.4 kW·kg−1, respectively. The supercapacitor can retain its capacitance of 95.8 % after 5000 consecutive charge-discharge cycles.

A Fast Self-Healing Binder for Highly Stable SiOx Anodes in Lithium-Ion Batteries.

Silicon oxide-based (SiOx-based) materials show great promise as anodes for high-energy lithium-ion batteries due to their high specific capacity. However, their practical application is hindered by the inevitable volumetric expansion during the lithiation/delithiation process. Constructing high-performance binders for SiOx-based anodes has been regarded as an efficient strategy to mitigate their volume expansion and preserve structural integrity. In this work, we propose a green water-solution PAA-LS binder composed of poly(acrylic acid) (PAA) and sodium lignosulfonate (LS) with fast self-healing properties. The designed binder can be restored due to the strong affinity between Fe3+-catechol coordination bonds, thereby effectively alleviating the volumetric strain of SiOx-based anodes. Notably, with an optimized LS content of 0.5%, the SiOx@PAA-LS electrode exhibits excellent performance, delivering a high capacity of 997.3 mAh g-1 after 450 cycles at 0.5 A g-1. Furthermore, the SiOx||NCM622 full cell also demonstrates superior cycling stability, maintaining a discharge capacity of 147.58 mAh g-1 after 100 cycles at 0.5 A g-1, with an impressive capacity retention rate of 82.72%.

Enzymatically Triggered Drug Release from Microgels Controlled by Glucose Concentration.

This study aims to design microgels for controlled drug release via enzymatically generated pH changes in the presence of glucose. Modern medicine is focused on developing smart delivery systems with controlled release capabilities. In response to this demand, we present the synthesis, characterization, and enzymatically triggered drug release behavior of microgels based on poly(acrylic acid) modified with glucose oxidase (GOx) (p(AA-BIS)-GOx). TEM images revealed that the sizes of air-dried p(AA-BIS)-GOx microgels were approximately 130 nm. DLS measurements showed glucose-triggered microgel size changes upon glucose addition, which depended on buffer concentration. Enzymatically triggered drug release experiments using doxorubicin-loaded microgels with immobilized GOx demonstrated that drug release is strongly dependent on glucose and buffer concentration. The highest differences in release triggered by 5 and 25 mM glucose were observed in HEPES buffer at concentrations of 3 and 9 mM. Under these conditions, 80 and 52% of DOX were released with 25 mM glucose, while 47 and 28% of DOX were released with 5 mM glucose. The interstitial glucose concentration in a tumor ranges from ∼15 to 50 mM. Normal fasting blood glucose levels are about 5.5 mM, and postprandial (2 h after a meal) glucose levels should be less than 7.8 mM. The obtained results highlight the microgel's potential for drug delivery using the enhanced permeability and retention (EPR) effect, where drug release is controlled by enzymatically generated pH changes in response to elevated glucose concentrations.

Curving-Stretching Induced Alignment in Hydrogel Actuators for Enhanced Grip Strength and Rapid Response.

Natural tissues, like ligaments and tendons, display not just robust mechanical performance but also complex anisotropic structures extending beyond one-directional arrangements. However, fabricating hydrogel actuators with biomimetic three-dimensional anisotropy remains challenging. Herein, a simple strategy involving curving-stretching induced alignment is proposed to prepare anisotropic Fe3+-cross-linked poly(acrylic acid)-poly(acrylamide) hydrogel actuators. These hydrogels exhibit exceptional mechanical properties, boasting a fracture stress of 7.1 MPa and a superior modulus of 33.2 MPa when prestretched to 200% strain, which are 2.3 times and 4.9 times higher than their unstretched counterparts. The stretched anisotropic hydrogel gripper, stronger than its unstretched counterpart, can lift heavy objects while also achieving rapid responsiveness to stimuli. This work introduces a novel and effective method for fabricating anisotropic hydrogels, highlighting their broad applicability in fields such as soft robotics, biomedical devices, and beyond.

Dual-Column Stopped-Flow GC Method for Quantification of Permanent Gases, Water, and Organic Acids from a Single Injection.

Analysis of permanent gases and organic acids is typically performed with separate methods due to challenges in achieving sufficient resolution when using GC columns that are chemically compatible with acids. We developed a method to analyze samples containing high levels of water, organic acids, oxygenates, and permanent gases (CO, CO2, and C2H4) using a single injection. Resolution is achieved using two columns: (1) an HP-FFAP column resistant to water and acids, which separates compounds based on hydrogen-bonding affinity, and (2) a GS-CarbonPLOT column capable of separating permanent gases. We employed a column isolation methodology using rotary valves to allow a heart cut of permanent gases, which coelute off the HP-FFAP column, to be trapped on the CarbonPLOT column. After separation and analysis of water, organic acids, and oxygenates via the HP-FFAP column, flow is resumed on the CarbonPLOT column, and the permanent gases are separated independently. By utilizing the unique combination of columns and the stopped-flow sequence, we achieved separation and quantification of the wide array of compounds occurring during lactic acid dehydration to acrylic acid from a single injection without the need for a sophisticated flow modulator or multiple GCs or detector arrays. This GC apparatus serves as an economical in-line analysis method for our catalytic studies and is applicable to a wide array of samples relevant to biobased fuels and chemicals.

Easy reversible clustering of gold nanoparticles via pH-Induced assembly of PVP-b-PAA copolymer

The growing demand of novel hybrid organic/inorganic systems with exciting properties has contributed to an increasing need for simplifying production strategies. Here, we report a simple method to obtain controlled three-dimensional hybrid architectures, in particular hybrid supracolloids (hSC), formed by gold nanoparticles and a double hydrophilic block copolymer, specifically the poly(acrylic acid)-block-poly(N-vinyl-2-pyrrolidone) (PAA-b-PVP), directly in aqueous medium. The ubiquitous pH-sensitive poly(acrylic acid) (PAA) block initiates the assembly through pH changes, while the poly(N-vinyl-2-pyrrolidone) block assures the close affinity with the AuNPs. We demonstrate that the formation of hybrid supracolloids (hSC) is the result of the synergetic behavior of the two specific polymeric blocks. Additionally, the entire process shows spontaneous and fast switchability. The nanostructured copolymer behaves like a highly swollen hydrogel and displays a disordered internal structure. The driving force for the association of the copolymer chains is induced by the synergetic effects of the decrease in solubility of the poly(acrylic acid) block and the formation of inter and intra chains hydrogen bonds. These were demonstrated by using small angle X-ray scattering (SAXS), quartz crystal microbalance with dissipation monitoring (QCM-D) and scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (STEM-EDX). In turn, the AuNPs are randomly spread all over the polymeric matrix, as demonstrated by field emission gun – scanning electron microscopy (FEG-SEM). A correlation analysis reveals the hSC density depends mostly on the initial concentration of AuNPs. These results can inspire the fabrication of more complex structures with multicomponent composition.

Boosting water flux and dye removal: Advanced composite membranes incorporating functionalized AC-PAA for wastewater treatment

This study addresses the challenge of enhancing dye removal and antifouling properties in wastewater treatment by developing a composite membrane incorporating poly(acrylic acid)-functionalized activated carbon (AC-PAA) into a polyethersulfone (PES) matrix. The activated carbon was functionalized using surface-initiated atom transfer radical polymerization (SI-ATRP), followed by hydrolysis to introduce hydrophilic poly(acrylic acid) chains. The AC-PAA composite was characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, and energy-dispersive X-ray analysis, confirming successful grafting and functionalization. Compared to pristine PES, the addition of 0.5 wt% AC-PAA led to significantly enhanced water flux (54 L/m2h vs. 30 L/m2h) and superior dye removal, achieving 63 % for methyl orange and 67 % for methylene blue at alkaline pH. Poly(acrylic acid) was selected for its carboxyl groups, which enhance adsorption capacity and antifouling characteristics. In addition to effective dye removal, the composite membranes demonstrated robust antifouling, with a flux recovery ratio of 72 %. Response surface methodology optimized parameters, confirming highest performance at pH 11 and 6 bar. This study highlights AC-PAA functionalized membranes as an efficient solution in wastewater treatment, advancing removal efficiency and antifouling capacity to address limitations in current membrane technology.

Kinetics and scale inhibition application studies towards bulk and RAFT copolymerization of maleic anhydride and acrylic acid

Poly(maleic anhydride) (PMA) is commonly reckoned as a better water scale inhibitor than poly(acrylic acid) (PAA) since each maleic anhydride unit can supply two carboxylic acid groups. However, pure PMA is difficult to achieve because the steric effect of its monomer MA. Herein, we synthesize copoly(MA-AA) copolymer by bulk polymerization method (bulk-copoly(MA-AA)), which avoids the use of any solvents which have to be removed afterwards. In addition, we also synthesize copoly(MA-AA) by reversible addition-fragmentation chain transfer (RAFT) polymerization method to afford RAFT-copoly(MA-AA) with low polydispersity index (PDI) less than 1.2, and the performance of RAFT-copoly(MA-AA) in water scale inhibition is more excellent relative to bulk-copoly(MA-AA). We also synthesize other copoly(MA-AA) copolymers by varying the molar ratio of MA to AA to study the polymerization mechanism. Through the static scale inhibition experiment, it is concluded that when the concentration of copoly(MA-AA) is 80 mg/L, the scale inhibition performance of RAFT-copoly(MA-AA) can reach 96.50 % which is the best among the control samples. It is also found that only 1:1 alternating copolymerization of MA and AA could be achieved as demonstrated by 1H nuclear magnetic resonance spectra of the copolymers, evidencing the strong steric hindrance of MA for its homo-polymerization.

Preparation, Swelling, and Drug Release Studies of Chitosan-based Hydrogels for Controlled Delivery of Buspirone Hydrochloride.

Buspirone is used for the management of depression and anxiety disorders. Due to its short half-life and low bioavailability, it requires multiple daily doses and is associated with some side effects. This study aimed to develop chitosan-based hydrogels as drug-controlled release carriers. The objective of this study is to prepare chitosan-based hydrogels as controlled release carriers in order to overcome the side effects of buspirone HCl and improve patients' compliance and their life quality. Polymer chitosan was polymerized with two monomers, acrylic acid and itaconic acid, to synthesize pH-sensitive hydrogel. The Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis were performed to confirm the structure formation and thermal stability. Water penetration capability and loading of the drug were performed by porosity and drug loading studies. The swelling and dissolution tests were performed to analyze the pH-sensitive nature of the developed hydrogels. FTIR, TGA, and DSC demonstrated that the chitosan-based hydrogels were successfully prepared. An increase in water penetration and drug loading into the hydrogel network was seen with the high incorporation of chitosan, acrylic acid, and itaconic acid. The swelling and dissolution studies revealed that prepared hydrogel offered the greatest swelling and drug release at a high pH of 7.4. The swelling and drug release from the hydrogel were affected by the concentrations of the incorporated contents. A controlled release of the drug was achieved by using chitosan-based hydrogel as a delivery carrier compared to commercial tablets of buspirone. The results showed that the developed chitosan-based hydrogel can be considered one of the most suitable drug carrier systems for the controlled delivery of buspirone.

Study on the preparation of a novel acrylic modified magnetic chitosan adsorbent and the adsorption behavior on Ga (III)

In the current study, a novel acrylic modified magnetic chitosan adsorbent (M- AA −CTS) was prepared, and then characterized using SEM, FTIR, and XPS. The preparation conditions, adsorption conditions, adsorption kinetics and thermodynamics were also studied. FTIR results indicate that acrylic acid is grafted onto the amino groups of chitosan in the form of poly acrylic acid and the amino groups are also crosslinked with glutaraldehyde. For the preparation process, the removal efficiency of Ga (III) ions is higher when the amount of acrylic acid is 3 mL, the reaction temperature is 308 K, the crosslinking time is 80 min, and the amount of glutaraldehyde is 0.6 mL. During the adsorption process, the higher adsorption capacity of Ga (III) ions can be achieved under the condition of the initial concentration of Ga (III) ions 50 mg/L, the adsorbent dose 0.05 g, the oscillation temperature 308 K and pH 3. The study on the adsorption kinetic indicates that the adsorption follows the pseudo-second-order kinetic model. The study on isotherm adsorption and thermodynamic indicates that the adsorption isotherm fits the Langmuir isotherm model better and the saturated adsorption capacity of Ga (III) ions on M−CTS−AA can reach 183.09 mg/g. Study on desorption and regeneration shows that after four cycles of desorption and reuse, the regeneration rate decreased from the initial 91.47 % to 73.3 %.

Rapid 3D printing of electro-active hydrogels

Electroactive hydrogels (EAH) have gained prominence for their unique ability to change shape or size under an electric field, finding applications in biosensors and soft actuators. This study focuses on a tunnelable EAH tailored for high-resolution 3D printing via the micro continuous liquid interface production (µCLIP) process. The resin formulations mainly involve acrylic acid (AA) and 4-hydroxybutyl acrylate (4-HBA). AA, with its carboxyl groups, introduces electroactuation, generating osmotic pressure in the hydrogel matrix. This results in swelling, inducing bending towards the cathode, accentuating the material’s responsiveness. In contrast, 4-HBA offers mechanical resilience, providing an elastic backbone, and ensuring the hydrogel’s applicability. Our results illustrate the hydrogel’s strength, flexibility, and bending capabilities across varied compositions and electric field strengths. Notably, the µCLIP process enabled the 3D printing of our EAH into sophisticated structures, like the lattice. The combination of AA’s electro-responsive traits with 4-HBA’s durability has birthed a material with vast practical implications. This study provides extended potential breakthroughs in soft robotics, wearable electronics, and medical devices, marking a significant stride in the realm of electroactive materials.

Charge regulated pH/NIR dual responsive nanoplatforms centered on cuproptosis for enhanced cancer theranostics

Multifunctional nanoplatforms capable of simultaneously executing multimodal therapy and imaging functions are of great potentials for cancer theranostics. We present an elegantly designed, easy-to-fabricate poly(acrylic acid)/mesoporous calcium phosphate/mesoporous copper phosphate nanosphere (PAA/mCaP/mCuP NS) with outstanding pH/NIR-sensitive multimodal-synergic anti-tumor effects. Optimal porous PAA NS scaffolds were prepared at room temperature by balancing the intra-PAA polymer and polymer-solvents Lennard-Jones potentials in a water:isopropyl alcohol (IPA) mix-solvent. Subsequent sponging of Ca2+ and Cu2+, and adsorption of PO43− to the PAA template were achieved through exquisite electrostatic interactions among ions and the ionizable PAA side-chain in an aqueous environment. This forms the basis for the tumor microenvironment pH-triggered release of Cu2+ to induce cuproptosis, as well as the photothermal effect originating from CuP, while Ca2+ can enhance the nanoplatform's biocompatibility and can damage mitochondria when overloaded. Lastly, PAA/mCaP/mCuP NSs still exhibit high drug loading efficiency for doxorubicin (DOX), enabling chemotherapy. Satisfactory anti-tumor effects of these modalities, along with their synergistic effects, were verified both in vitro and in vivo, with the NSs demonstrating good biodegradation in the latter. The fabricated NS itself holds great promise as an anti-tumor nanomedicine, and the thorough mechanical insights into NS formation may inspire the design of next-generation multifunctional nanoplatforms.

Paclitaxel Prodrug Enables Glutathione Depletion to Boost Cancer Treatment.

Herein, we constructed a paclitaxel (PTX) prodrug (PA) by conjugating PTX with acrylic acid as a cysteine-depleting agent. The as-synthesized PA can assemble with diacylphosphatidylethanolamine-PEG2000 to form stable nanoparticles (PA NPs). After endocytosis into cells, PA NPs can specifically react with cysteine and trigger release of PTX for chemotherapy. On the other hand, the depletion of cysteine can greatly downregulate the intracellular content of glutathione and lead to oxidative stress outburst-provoking ferroptosis. The released PTX can elicit antitumor immune response by inducing immunogenic cell death, thus promoting dendritic cells maturation and cascaded cytotoxic T lymphocytes activation, which not only produces a robust immunotherapy effect but also synergizes the ferroptosis therapy by inhibiting cysteine transport via the release of interferon-γ in the activated immune system. As a result, PA NPs exhibit favorable in vitro and in vivo antitumor performance with reduced systemic toxicity. Our work highlights the potential of simple molecular design of prodrugs for enhancing the therapeutic efficacy toward malignant cancer.

Synthesis and characterization of self-healable supramolecular hydrogel based on carboxymethyl cellulose for biomedical applications

Hydrogels have been widely used in biomedical fields including tissue engineering, drug delivery and cell delivery and 3D cell delivery due to abundant water content in their hydrophilic three-dimensional networks and having soft tissue similar to the human body. In recent years, supramolecular hydrogels (SHG) formed by the inclusion complex between polyethylene glycol (PEG) and macrocycles such as cyclodextrin (CD) have attracted much interest due to their excellent biocompatibility and great potential in biomedical. In this research, a carboxymethyl cellulose (CMC)-based graft copolymer was prepared by using acrylic acid (AA) and maleic anhydride functionalized β-CD (β-CD-MA) as comonomers and ammonium persulfate (APS) as initiator. Then, a self-healable supramolecular hydrogel was synthesized by formation of a host-guest inclusion complex between CMC-g-poly (AA-co-β-CD-MA) as host molecule and cytosine- and guanine-modified PEG as guest molecules. The prepared hydrogel was characterized by Scanning Electron Microscope (SEM), X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance spectroscopy (1H NMR). The thermal stability of hydrogel was also determined by thermal gravimetric (TGA) and differential scanning calorimetry (DSC) methods. In addition, the loading and release profiles of metformin hydrochloride (MH) drug as a model on hydrogel was investigated. The results indicated that the drug release from the hydrogel peaks around 360 min and aligns with the Ritger-Peppas model. The hydrogel's self-healing property was examined at ambient temperature and 37 °C. It showed 70 % healing in 1.5 h and completed recovery after 9 h.

The efficient metal- and halogen-free polymer catalyst for the intensification on CO2 cycloaddition

An environmentally friendly polymer catalyst (PAS) was synthesized via inverse emulsion polymerization using acrylic acid (AA) and 1-vinyl imidazole (VI) as monomers. The excellent catalytic activity of PAS was attributed to the synergistic effects of the carboxyl groups (-COOH) as hydrogen bond donors and N-heterocyclic carbene (NHCs) as electron donor, as well as the swelling properties of the polymer, which can enrich the substrate into the polymer network, increasing the contact between the substrate and active sites. Characterization results from thermogravimetric (TG) analysis and small-angle X-ray scattering (SAXS) showed that the excessive imidazole addition disrupted the polymer's chain-like structure, significantly reducing its swelling properties. And, the catalytic performance is influenced by both the amount of imidazole in PAS and the swelling properties of the polymer. Finally, the reaction mechanism of the CO2 cycloaddition reaction catalyzed by PAS was proposed and validated through density functional theory (DFT) calculations.

Complexes of polymeric acids and short polyamines as binary stimulus-sensitive systems

Stimulus-sensitive polymers are of great interest due to their unusual properties in solution and diverse applications. Copolymers with different groups (hydrophilic, hydrophobic and ionizable) are typical stimulus-sensitive polymers, and varying the copolymer composition allows the pH and thermal sensitivity to be adjusted for a particular application. We found that complexes of polymeric acids with short methylated polyamines having trimethylene insertions between amine groups exhibit stimulus-sensitive properties in aqueous media at moderate pH and temperature. The position of the lower critical temperature of the solution depends on the ratio of polyacid to polyamine and on the pH. The complex of poly(acrylic acid) and pentaamine was found to be electrosensitive: exposure to an electric field with reversible polarity (8 Hz) led to precipitation of the polymer. These binary stimulus-sensitive compositions consist of two simple substances and are a promising alternative to copolymer-based systems, since the adjustment of properties does not require the synthesis of new substances and expensive toxicological studies in the case of biomedical applications.

Optimizing the radiation synthesis and swelling of agar-based acrylate superabsorbent hydrogel for irrigation water conservation

This study reports the synthesis of novel agar/poly methacrylic acid/poly acrylic acid (AG/PMAc/PAc) superabsorbent hydrogels via gamma radiation and their subsequent urea modification to enhance swelling and water retention for agricultural applications. The superabsorbent hydrogels were prepared by irradiating aqueous mixtures of varying agar concentrations with methacrylic acid/acrylic acid (MAc/Ac) monomers, followed by urea treatment at different cycles and concentrations. The morphological characteristics and chemical structures were confirmed by SEM and FTIR, respectively. The maximum swelling occurred at 6 % agar and 1 % urea modification. Remarkably, the 1 % urea-modified hydrogel displayed a 41.1 % swelling increase and 236.4 % enhancement after the second modification cycle compared to unmodified samples. Water retention studies showed the modified hydrogel retained 53.2 % moisture after 14 days versus the complete drying of unmodified hydrogels. Soil application studies demonstrated the modified hydrogel increased moisture content by 177.3 % after 20 days, promoting better growth with 30 % more leaves and 38.9 % higher stem length in Vicia faba plants versus controls. This novel radiation-synthesized, urea-modified hydrogel with exceptional swelling and moisture retention capabilities shows promising potential for sustainable agricultural irrigation and crop productivity enhancement under water-deficit conditions.

Tough strippable hydrogel films based on acrylic acid/acrylamide/zirconyl chloride for surface radioactive decontamination at low temperatures

Strippable films are extensively utilised for the decontamination of radioactive surfaces because of their cost-effectiveness, ease of operation, and minimal liquid waste. However, traditional strippable detergents are formulated for use at normal ambient temperatures and typically lose their efficacy at low temperatures because of poor performance or excessively long film-forming time. In this study, we have developed an anti-freezing and sprayable AMZW detergent based on acrylic acid (AA), acrylamide (AM), zirconyl chloride octahydrate (ZrOCl2·8H2O), and water (H2O), which possesses a freezing point of approximately −34 ℃ due to the solvation interaction between Zr4+ and H2O. Even at temperatures as low as −25 ℃, the AMZW detergent can be easily sprayed using a conventional apparatus and rapidly cured into a strippable hydrogel film under irradiation by 365 nm UV LED light (LED@365 nm), household LED panel light, or sunlight. The coordination bond formed between Zr4+ and the carboxyl group of the polymer chain imparts excellent mechanical properties to the hydrogel while the carboxyl group can complex with uranyl nitrate hexahydrate (UO2(NO3)2·6H2O)—a radioactive simulant. As a result, the strippable hydrogel film demonstrates high tensile strength (6.1 ∼ 19.3 MPa), excellent flexibility (elongation of 90 ∼ 855 %), moderate peel strength (0.05 ∼ 3 N/cm, room temperature (RT)), and high decontamination efficiency (>91.6 % on stainless steel and glass; >81.3 % on concrete) over a wide range of temperatures (−25 ∼ 25 ℃). This work presents a novel approach for producing anti-freezing, fast-forming, flexible, and high-strength strippable hydrogel films for surface radioactive decontamination at low temperatures.