Solution Polymerization Method Research Articles

Synthesis, investigation of temperature and salt resistant polyacrylamide microspheres used for deep sealing and profile control and function strengthening mechanism

AbstractBased on the requirements of deep sealing and profile control for the excellent temperature and salt resistance on polyacrylamide microspheres, the Poly‐AM/AMPS was prepared depends on aqueous solution polymerization method to improving oil and gas recovery efficiency in low‐permeability and heterogeneous reservoirs resulted by water channeling. The key technical parameters were established through single‐factor experimental methods, and the chemical structure was studied by infrared spectrum analysis (FTIR), energy spectrum analysis, and x‐ray diffraction analysis, and then the thermal stability was investigated depends on the thermogravimetric (TG) and differential thermogravimetric (DTG) distribution curves, moreover, the particle size and distribution, microstructure, and surface morphology were further studied. As a result, the results confirmed that the molecular structure of Poly‐AM/AMPS meets the expected design, and the quality retention rate at 800°C is 17.4%, the median particle size of Poly‐AM/AMPS particles is 35.88 μm, and the particle size distribution range is about 1.94–497.8 μm. Further, the Poly‐AM/AMPS was modified by maleic anhydride, sodium styrenesulfonate, and dimethyl diallyl ammonium chloride through conventional functional strengthening and modification, modified by nano‐SiO2, GO, and S‐CaCO3 through nano‐functional strengthening and modification. Additionally, the functional strengthening and modification mechanism was studied depends on the FTIR, TG, and DTG methods.

-COOH & -OH Condensation Reaction Utilization for Biomass FDCA-based Polyesters.

A green and sustainable -COOH & -OH condensation solution polymerization method was hereby reported for FDCA-based polyesters to avoid discoloration and toxic solvents. First, taking poly(ethylene 2,5-furandicarboxylate) (PEF) as the representative of FDCA-based polyester, enabling good white appearance PEF with Mn =6.51×103 g mol-1 from FDCA and ethylene glycol in green solvent γ-valerolactone (GVL), catalyzed by 4-dimethylaminopyridine (DMAP) and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC). Additionally, the molecular weight of PEF was rapidly improved (Mn >2.5×104 g mol-1 ) via remelting polycondensation within minutes, with the dispersity still kept relatively low dispersity (Đ<1.40). Importantly, the -COOH & -OH condensation solution polymerization method was successfully applied for the synthesis of various FDCA-based polyesters, including diols with varying carbon chain lengths (3 to 11 carbons) and cycloalkyl diols, especially the applicability of this method to diols containing C=C double bonds, which was found to exhibit low heat resistance. Lastly, assisting with 13 C labeled 1,4-succinic acid and in-situ 13 C-NMR, an in-depth study of the possible catalytic mechanism was proposed, by which, EDC activated FDCA, and then DMAP catalyzed it with diol to yield macromolecular chain of polyester. Overall, the results provided a green and sustainable strategy for the synthesis of FDCA-based polyesters.

The Development of Anti-Salt Fluid Loss Additive for Cement-Metakaolin Slurry with Semi-Saturated/Saturated Saline Water: The Application of Maleic Anhydride

Conventional fluid loss additives have difficultly controlling the water loss of cement–metakaolin slurry with semi-saturated brine cement slurry and limiting it to less than 50 mL (30 min)−1. This paper describes the development of an anti-salt fluid loss additive for metakaolin–cement systems. This study adopted the aqueous solution polymerization method; selected four kinds of monomers, namely 2-Acrylamido-2-methylpropane sulfonic acid (AMPS), N,N-Dimethylacrylamide (DMAA), acrylamide (AM), and methyl acrylate (MA); and performed a single-factor experiment on the proportion of monomer, reaction temperature, initiator dosage, and developed fluid loss additive, which has a high salt tolerance and temperature tolerance. This fluid loss additive can resist salt until saturation, and it can control fluid loss in 24 mL·(30 min)−1 when its dosage is 2%. The fluid loss additive can achieve the effect of fluid loss reduction by increasing the filtrate viscosity, forming a flexible elastic adsorption layer via adsorption, and blocking mud cake pores.

Efficacious adsorption of divalent nickel ions over sodium alginate-g-poly(acrylamide)/hydrolyzed Luffa cylindrica-CoFe2O4 bionanocomposite hydrogel

Existing Ni2+ heavy metal ions in an aqueous medium are highly hazardous for living organisms and humans. Therefore, designing low-cost adsorbents with enhanced effectiveness is essential for removing nickel ions to safeguard public health. In this study, a novel green nanocomposite hydrogel was synthesized through the free radical solution and bulk polymerization method, and its capability to remove divalent nickel ions from aqueous media was examined. The bionanocomposite hydrogel named as SA-g-poly(AAm)/HL-CoFe2O4 was produced by grafting polyacrylamide (AAm) onto sodium alginate (SA) in the presence of a magnetic composite recognized as HL-CoFe2O4, where HL represents hydrolyzed Luffa Cylindrica. By employing FT-IR, XRD, VSM, SEM, EDX-Map, BET, DLS, HPLC, and TGA techniques, morphological evaluation and characterization of the adsorbents were carried out. The performance of the adsorption process was studied under varying operational conditions including pH, temperature, contact duration, initial concentration of pollutant ions, and adsorbent dosage. HPLC analysis proved the non-toxic structure of the bionanocomposite hydrogel. The number of unreacted acrylamide monomers within the hydrogel matrix was measured at 20.82 mg/kg. The optimum conditions was discovered to be pH = 6, room temperature, adsorbent dosage of 1 of g.L−1, initial Ni2+ concentration of 10 mg.L−1, and contact time of 100 min, and the maximum adsorption efficiency at optimal state was calculated as 70.09, 90.25, and 93.83 % for SA-g-poly (AAm), SA-g-poly(AAm)/HL, and SA-g-poly(AAm)/HL-CoFe2O4 samples, respectively. Langmuir isotherm model was in good agreement with the experimental data and the maximum adsorption capacity of SA-g-poly(AAm), SA-g-poly(AAm)/HL, and SA-g-poly(AAm)/HL-CoFe2O4 samples was calculated to be 31.37, 43.15, and 45.19 mg.g−1, respectively. The adsorption process, according to kinetic studies, follows a pseudo-second-order kinetic model. Investigations on thermodynamics also demonstrated that the process is exothermic and spontaneous. Exploring the interference effect of co-existing ions showed that the adsorption efficiency has decreased with concentration enhancement of Ca2+ and Na+ cations in aqueous medium. Furthermore, the adsorption/desorption assessments revealed that after 8 consecutive cycles, there had been no noticeable decline in the adsorption effectiveness. Finally, actual wastewater treatment outcomes demonstrated that the bionanocomposite hydrogel successfully removes heavy metal pollutants from shipbuilding industry effluent. Therefore, the findings revealed that the newly fabricated bionanocomposite hydrogel is an efficient, cost-effective, easy-separable, and green adsorbent that could be potentially utilized to remove divalent nickel ions from wastewater.

Scalable fabrication of textile-based planar-structured supercapacitors with excellent capacitive performance

The researchers have been engaged in the development of textile-based high-performance flexible energy storage devices. The conventional fabrics are transformed into electrode composites by uniformly depositing polypyrrole (PPy) coating onto them using a simple interfacial solution polymerization method. The traditional textiles encompass cellulose fabrics such as cotton and ramie, protein fabrics like silk and wool, as well as chemical fiber fabric including polyester, polyamide, and acrylon. The PPy can be effectively coated onto the surface of cellulose fibers and penetrate into their interior, resulting in significantly higher loading capacity on cotton and ramie fabrics compared to other types of fibers. The two fabric electrodes (cotton@PPy and ramie@PPy) have better capacitive properties, especially the areal capacitance of ramie@PPy reaches 2836 mF cm−2. The PPy-coated fabric is precisely divided into standardized interdigital electrodes of consistent dimensions through the utilization of laser cutting techniques. The fabrication of a planar supercapacitor can be achieved through the straightforward assembly of two interdigital electrodes. The planar supercapacitor based on ramie@PPy shows a maximum energy density of 8.21 μWh cm−2 at power density of 0.20 mW cm−2. After undergoing 5000 cycles, the device demonstrates a remarkable ability to retain 90 % of its initial capacitance. The assembled supercapacitors exhibit exceptional flexibility and practicality, enabling power supply to electronic devices when connected in series. The fabric-based flexible supercapacitor can be easily mass-produced, making it a promising candidate for flexible energy storage devices.

Development and Gelation Mechanism of Ultra-High-Temperature-Resistant Polymer Gel.

To expand the applicability of gel fracturing fluids in ultra-high-temperature reservoirs, a temperature-resistant polymer was synthesized using the solution polymerization method. Subsequently, an ultra-high-temperature-resistant polymer gel was formulated by incorporating an organic zirconium crosslinking agent. A comprehensive investigation was carried out to systematically study and evaluate the steady shear property, dynamic viscoelasticity, and temperature and shear resistance performance, as well as the core damage characteristics of the polymer gel. The obtained results demonstrate that the viscosity remained at 147 mPa·s at a temperature of 200 °C with a shear rate of 170 s-1. Compared with the significant 30.9% average core damage rate observed in the guanidine gum fracturing fluid, the core damage attributed to the polymer gel was substantially mitigated, measuring only 16.6%. Finally, the gelation mechanism of the polymer gel was scrutinized in conjunction with microscopic morphology analysis. We expect that this study will not only contribute to the effective development of deep and ultradeep oil and gas reservoirs but also furnish a theoretical foundation for practical field applications.

One-step preparation of double network phase change composite with GO for enhanced thermal management performance

We developed a novel functional material that combined porous structures with solidified phase change materials (PCMs). This material, known as a double network Polyethylene Glycol/Graphene Oxide/Polyacrylic Acid phase change aerogel (PGA), was synthesized by the one-step method of solution polymerization. Polyethylene glycol (PEG) was chosen as the PCM, while polyacrylic acid (PAA) and graphene oxide (GO) were used as the first and second networks. The double networks in PGA served to immobilize PEG through hydrogen-bonding interaction and interwining. As a result, the PGA exhibited excellent phase change performance, with a phase change enthalpy of 108.9 J/g and an impressive enthalpy efficiency of 93.1%. The PGA possesses a porosity of 34%, a specific surface area of 53 m2/g, an average pore diameter of 0.35 μm. The three-dimensional network skeleton, consisting of PEG, GO, and PAA, leveraged the GO to enhance phase change conductivity, while maintaining thermal insulation through a uniform mesh structure. Moreover, the PGA material demonstrates remarkable thermal stability even after 35 thermal cycles. When used to construct insulated cups, the PGA materials exhibited superior thermal insulation and phase change modulation compared to air laminated glass cups. This highlights its potential application in reducing energy consumption and increasing energy utilization efficiency.

Influence of Molecular Weight on the Enzymatic Degradation of PLA Isomer Blends by a Langmuir System.

Polylactides (PLAs) and lactide copolymers are biodegradable, compostable, and derived from renewable resources, offering a sustainable alternative to petroleum-based synthetic polymers owing to their advantages of comparable mechanical properties with commodity plastics and biodegradability. Their hydrolytic stability and thermal properties can affect their potential for long-lasting applications. However, stereocomplex crystallization is a robust method between isomer PLAs that allows significant amelioration in copolymer properties, such as thermal stability, mechanical properties, and biocompatibility, through substantial intermolecular interactions amid l-lactyl and d-lactyl sequences, which have been the key approach to initial degradation rate and further PLA applications. It was demonstrated that the essential parameters affecting stereocomplexation are the mixing ratio and the chain length of each unit sequence. This study deals with the molecular weight, one of the specific interactions between isomers of PLAs. A solution polymerization method was applied to control molecular weight and chain architecture. The stereocomplexation was monitored with DSC. It was confirmed that the lower molecular weight polymer showed a higher degradation rate, as a hydrolyzed fragment having a molecular weight below a certain length dissolves into the water. To systematically explore the critical contribution of molecular weights, the Langmuir system was used to observe the stereocomplexation effect and the overall degradation rate.

Microscopic molecular and experimental insights into multi-stage inhibition mechanisms of alkylated hydrate inhibitor

A deep understanding of the mechanism of hydrate inhibitors on hydrate formation is crucial for the development of efficient natural gas hydrate inhibitors. However, the current understanding of the inhibitory mechanism of hydrate inhibitors in the nucleation and formation processes is still very limited, which greatly hinders the development of new types of hydrate inhibitors. In this study, the solution polymerization method was employed to prepare poly (N-vinyl pyrrolidone-co-N,N-dimethyl acrylamide), as a new kinetic hydrate inhibitor. The inhibition properties were investigated by the constant cooling test and the step cooling test. Meanwhile, the multi-stage inhibition mechanisms of alkylated hydrate inhibitor were also revealed based on molecular simulations. The results of experiments and molecular simulations illustrate that the mechanism of the inhibitors varies at different stages. The inhibitors retard hydrate formation by reducing the solubility of methane molecules in water during the nucleation phase. However, during the formation phase, the hydrate inhibition is achieved by adsorption. In particular, the absorption of poly (vinyl pyrrolidone) on the surface of hydrate can be effectively improved by alkylation, and the interaction energy of poly (N-vinyl pyrrolidone-co-N,N-dimethyl acrylamide) with the hydrate nucleus was increased by 3.22 times compared to poly (vinyl pyrrolidone). It resulted in an increase in subcooling of 8.2 °C. Also, the effective induction time of poly (N-vinyl pyrrolidone-co-N,N-dimethyl acrylamide) at 8 °C was extended to 987 min. A molecular model for evaluating the interaction of inhibitors with hydrates is also successfully developed, which corresponds well to the experimental results. These results contribute to a better understanding of hydrate formation in drilling fluids and implications for developing new materials for high-performance hydrate drilling fluids.

Room temperature NH3 gas sensor based on PMMA/RGO/ZnO nanocomposite films fabricated by in-situ solution polymerization

Effective detection of ammonia gas is of great importance due to its detrimental effects on human health, environment, and ecosystem. High-performance composite gas sensors are vital in accomplishing this goal. Herein, we investigate the performance of an ammonia (NH3) gas sensor fabricated via dip-coating the silver interdigitated electrode for PMMA/RGO/ZnO (PRZ) nanocomposite solution with acetone as a solvent. The PRZ ternary nanocomposite was synthesized using the in-situ solution polymerization method and the resistive properties of the films assembled on the interdigitated electrode were analyzed, with respect to the fixed and varying ammonia gas concentrations, using LCR meter. When the sensor is operated in the controlled chamber containing ammonia gas at room temperature, the sensor responds rapidly to ammonia with a fast recovery of 13.02 s at a gas concentration of 350 ppm. The PRZ sensor exhibits high sensing percentage response (527%), excellent repeatability (four times), high sensitivity at low concentrations (less than 10 ppm), swift response and recovery times (1.94 s/13.02 s), and long-term stability (up to 90 days) with fluctuation of 3.2%, which signifies PRZ composite as a potential material for ammonia gas sensor. Aspects such as simplicity of the synthesis process and fabrication, excellent sensing performance, as well as fast response-recovery time at a particular gas concentration are noteworthy in this study. These features can be utilized for the detection of ammonia gas in chemical and biological fields.

Poly lauryl methacrylate modified superhydrophobic Fe foam, with excellent stability and magnetic oil/water separation ability

With the acceleration of the industrial process, oil-water separation is an urgent problem for oil spill accidents and wastewater treatments. Exploiting superhydrophobic materials applied in harsh environments and remote drives remains a significant challenge in solving oil moisture problems. An alternative strategy to solve this problem has been demonstrated by decorating poly lauryl methacrylate (LMA) on Fe foam via the solution polymerization method. The as-prepared Fe foam possesses good superhydrophobicity (>150°) under broad pH (1 < pH < 12) and a wide temperature range (−55°C-180 °C). Furthermore, outstanding separation efficiency (>99.1%), high cycle stability (>50 times), and high oil flux (63.7–114.6 kL m−2 h−1) against diverse oil/water mixtures can be realized under gravity. Interestingly, oil harvesting capacity above or beneath the water can be realized by remote magnetic driving as well.

Controlled Growing of Graphdiyne Film for Friction Reduction and Antiwear

Like the multilayered graphene which is the most widely used solid lubricant, graphdiyne (GDY) as a 2D material holds potential similar prospects but has been rarely researched so far. One reason is that growing a GDY film in a controllable manner on diverse material surfaces remains a great challenge. To address the issue, a catalytic pregrowth and solution polymerization method is developed to synthesize a GDY film on various substrates. It allows fine control over film structure and thickness. A macroscopic ultralow friction coefficient of 0.08 is obtained, and a relatively long life of more than 5 h under a high load of 1378 MPa is achieved. Molecular dynamics simulations together with the surface analysis demonstrate that the increased deformation degree and weakened relative motion between GDY layers contribute to the low friction. Especially, different from graphene, the friction of GDY exhibits a double increase and decrease in one period of λ ≈ 8-9 Å, and it is roughly equal to the distance between two adjacent alkyne bonds in the x direction, indicating GDY's structure and lattice play an important role in reducing friction.

Amine Infused Fly Ash Grafted Acrylic Acid/Acrylamide Hydrogel for Carbon Dioxide (CO2) Adsorption and Its Kinetic Analysis.

In most carbon dioxide (CO2) capture processes, chemical absorption using an amine solvent is widely used technology; however, the solvent is prone to solvent degradation and solvent loss which leads to the formation of corrosion. This paper investigates the adsorption performance of amine-infused hydrogels (AIFHs) to increase carbon dioxide (CO2) capture by leveraging the potency of amine absorption and adsorption properties of class F fly ash (FA). The solution polymerization method was used to synthesize the FA-grafted acrylic acid/acrylamide hydrogel (FA-AAc/AAm), which was then immersed in monoethanolamine (MEA) to form amine infused hydrogels (AIHs). The prepared FA-AAc/AAm showed dense matrices morphology with no obvious pore at the dry state but capable of capturing up to 0.71 mol/g CO2 at 0.5 wt% FA content, 2 bar pressure, 30 °C reaction temperature, 60 L/min flow rate, and 30 wt% MEA contents. Cumulative adsorption capacity was calculated and Pseudo-first order kinetic model was used to investigate the CO2 adsorption kinetic at different parameters. Remarkably, this FA-AAc/AAm hydrogel is also capable of absorbing liquid activator that was 1000% more than its original weight. FA-AAc/AAm can be used as an alternative AIHs that employ FA waste to capture CO2 and minimize the GHG impact on the environment.

Deformation Behavior of Single Carbon Fibers Impregnated with Polysulfone by Polymer Solution Method.

Tensile deformation behavior of continuous high-strength and high-modulus single carbon fibers impregnated with a polysulfone solution was investigated. The effect of the carbon fiber type, mass fraction of the polymer, and the loading rate on the tensile strength was studied. It was observed that, whereas for high-modulus carbon fibers the magnitude of tensile strength depends significantly on the loading rate, for high-strength carbon fibers, such dependence was nearly not observed. SEM study shows that at low loading rates, elementary filaments inside the impregnated fiber are able to align themselves along the load application axis because a thermoplastic matrix can flow under the tensile stresses' force. As a result, the fiber's strength properties can be realized more effectively in the thermoplastic-based composites than in the same composite with an epoxy matrix.

Mitigating the Toxic Effects of Chromium on Wheat (Triticum aestivum L.) Seed Germination and Seedling Growth by Using Biochar and Polymer-Modified Biochar in Contaminated Soil

The present study was conducted to investigate the potential influences of biochar in mitigating the phytotoxic effects of hexavalent chromium (CrVI) on the germination of wheat (Triticum aestivum L.). Biochar (JBC) was produced from Jujube (Ziziphus jujube L.) wood waste at three different pyrolysis temperatures (300 °C, 500 °C and 700 °C), which was later polymerized (JPBC) via the solution-polymerization method. Phytotoxicity of CrVI was induced to wheat seeds at variable CrVI application rates (5, 10, 20, 40 mg L−1). Applied CrVI concentrations confined the seed germination and seedling growth in order of: 5 &lt; 10 &lt; 20 &lt; 40 mg L−1. The application of JBCs (0.2 g per petri plate) resulted in a 150% increase in shoot length, while dry biomass was increased by 250% with JPBCs application. Uptake of CrVI was significantly lower in JBC-300 (7.74 μg/seedling) and JPBC-300 (1.13 μg/seedling) treatments, as compared to control (13.24 μg/seedling), at the highest stress level (40 mg L−1). Therefore, the findings of the current study showed that JBCs and JPBCs performed excellently in improving seedling growth while JPBCs performed more efficiently than pristine JBCs in mitigating CrVI phytotoxicity and availability.

Organocatalytic [2 + 2] Photopolymerization under Visible Light: Accessing Sustainable Polymers from Cinnamic Acids.

Herein, the successful development of a metal-free, solution [2 + 2] photopolymerization of natural cinnamic acid-derived bisolefinic monomers is reported, which is enabled by a strategy based on direct triplet state access via energy transfer catalysis. 2,2'-Methoxythioxanthone has been identified as an effective organic photocatalyst for the [2 + 2] photopolymerization in solution, which can be excited by visible light and activate the biscinnamate monomers via triplet energy transfer. This method features its metal-free conditions, visible light utilization, solution polymerization, and abundant biomass-based feedstock, as well as processable polymer products, which is different from the rigid, insoluble products obtained from solid-state photopolymerization. This solution polymerization method also shows a good compatibility to monomer structures; cinnamic acid-derived bisolefinic monomers with different linkers, including diamine, natural diol, and bisphenol, can all readily undergo [2 + 2] photopolymerization, and be transformed into colorless, sustainable polymers.

Effects of a novel hybrid polymer material on the hydro-mechanical behavior of subgrade silts considering freeze-thaw cycles

Freeze-thaw (FT) cycles are considered to be a potential threat to the hydro-mechanical behavior of subgrade soils in seasonal frozen regions. Enhancing the resistance of the soils to FT cycles therefore becomes a pressing problem that needs to be solved. This paper developed a durable polyacrylate intercalated bentonite superabsorbent polymer (BT-SAP) employing the solution polymerization method, which is a novel hybrid polymer material with the function of reducing the sensitivity of subgrade soils to FT cycles. To evaluate the effects of BT-SAPs on the hydro-mechanical behavior of subgrade silts experiencing FT cycles, the 3D pore structure, volumetric strain (εv), soil-water characteristic curve (SWCC), and resilient modulus (MR) of the soil modified with BT-SAPs were determined using a series of laboratory tests. Specimens with three BT-SAP contents (BC) compacted at their respective optimum moisture content and maximum dry density were first subjected to different numbers of FT cycles (NFT). Then, they were dried or wetted to specific moisture contents (w) before the determination of (i) SWCCs using the filter paper method and (ii) MR from cyclic triaxial tests. Finally, the 3D pore structure of specimens after FT cycles was measured by X-ray μ-CT. Experimental results show that the viscous and micro-swelling effects of the generated BT-SAP-water-gels can inhibit the emergence and development of larger pores and cracks inside the soil after FT cycles. The addition of BT-SAPs significantly reduces the sensitivity of the soil's volume and water retention capacity to FT cycles. The MR decreases with NFT but increases with BC. The important finding is that an optimal BT-SAP content of 0.25% was determined suitable for fine-grained subgrade soils. In addition, an artificial neural network (ANN) model was developed using 1200 sets of the MR measurements obtained in this study and well predicts the MR considering several factors such as BC, NFT, w, dry density, and stress levels. This study provides useful guidelines for the application of BT-SAP materials in subgrade engineering in seasonal frozen regions.

Aloe vera Rind Valorization to Improve the Swelling Capacity of Commercial Acrylic Hydrogels

Acrylic hydrogels have been used in agriculture to increase the availability of water in the soil; cause faster plant growth and increase plant survival to water stress; allow controlled release of fertilizers; and, therefore, increase crop yields. On the other hand, Aloe vera gel production generates a large amount of solid waste as cuticles, which is currently underutilized despite that it is a good source of cellulose nanofibers that could be used to improve the swelling capacity of commercial acrylic hydrogels. In this work, both morphology (SEM) and particle size (TEM) of the cellulose nanofibers obtained from A. vera cuticles by the acid hydrolysis method combined with ultrasound were analyzed; as well as the presence of functional groups (FITR) and thermal stability (TGA). Then, acrylic hydrogels were synthesized by the solution polymerization method, and nanofibers were added to these hydrogels at different concentrations (0% w w−1, 3% w w−1, 5% w w−1, and 10% w w−1). These concentrations had a nonlinear relationship with the swelling capacity, and the hydrogel reinforced at 3% cellulose nanofiber was chosen as the best formulation in this work, as this one improved the swelling capacity of hydrogels at equilibrium (476 g H2O g hydrogel−1) compared to the hydrogel without nanofiber (310 g H2O g hydrogel−1), while hydrogels with 10% nanofiber had a similar swelling capacity to the non-reinforced hydrogel (295 H2O g hydrogel−1). Therefore, cellulose-based superabsorbent hydrogels with potential application in agriculture were developed in this work.

Structural Modifications of Sodium Polyacrylate-Polyacrylamide to Enhance Its Water Absorption Rate

Superabsorbent polymers (SAPs) can absorb a large amount of water and find broad applications in various industries. There are many reports on the synthesis and structural modification techniques to improve the water absorption property of SAPs. However, we see few studies on the comparison and integration of these techniques. In this study, three structurally modified SAPs were synthesized and are evaluated for the effects of surface cross-linking, foaming, and the integration of the two modifications to improve the absorption rate and capacity of a conventional SAP. First, sodium polyacrylate-polyacrylamide was prepared as the base polymer by the aqueous solution polymerization method. Second, the base polymer was modified with surface cross-linking to enhance absorption, and a surface cross-linked SAP was obtained. Third, the base polymer was modified with foaming to obtain a foamed SAP. Lastly, the foamed SAP was modified further with surface cross-linking to obtain a foamed and surface cross-linked SAP. In comparison with the base polymer, the three synthesized SAPs were evaluated for their absorption performance. Results show that their absorption performance could be improved by the three modification processes. Specifically, the surface cross-linked SAP had the best absorption capacity under load, the foamed SAP had the highest absorption capacity of 1954 g/g, and the foamed and surface cross-linked SAP had the fastest absorption rate with an initial swelling rate of Kis = 21.94.

Synthesis and Evaluation of Finasteride-Loaded HPMC-Based Nanogels for Transdermal Delivery: A Versatile Nanoscopic Platform.

Herein, we report nanogels comprising diverse feed ratio of polymer hydroxypropyl methylcellulose (HPMC), monomer acrylic acid (AA), and cross-linker methylene bisacrylamide (MBA) fabricated for transdermal delivery of finasteride (FIN). Free radical solution polymerization method with subsequent condensation was employed for the synthesis using ammonium per sulfate (APS) and sodium hydrogen sulfite (SHS) as initiators. Carbopol-940 gel (CG) was formulated as assisting platform to deliver FIN nanogels transdermally. Developed formulations were evaluated by several in vitro, ex vivo, and in vivo parameters such as particle size and charge distribution analysis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffractogram (XRD), rheological testing, in vitro swelling and drug release, and ex vivo skin permeation, irritation, and toxicity assessment. The results endorsed the nanogel formation (117.3 ± 29.113 nm), and the impact of synthesizing method was signified by high yield of nanogels (≈91%). Efficient response for in vitro swelling and FIN release was revealed at pH 5.5 and 7.4. Skin irritation and toxicity assessment ensured the biocompatibility of prepared nanocomposites. On the basis of the results obtained, it can be concluded that the developed nanogels were stable with excellent drug permeation profile across skin.