Search Results (47)

3,4-dimethylpyrazole (DMPZ), when used as a nitrification inhibitor, exhibits volatility, poor thermal stability, high production costs, and limited functionality restricted to nitrogen fixation. To address these limitations and introduce novel phosphorus-solubilizing and soil-loosening abilities, herein, a poly (acrylamide-co-acrylic acid)-encapsulated NI (P(AA-co-AM)-e-NI) is synthesized by incorporating linear P(AM-co-AA) macromolecular structures into NI systems. The P(AA-co-AM)-e-NI demonstrates an obvious phase transition from a glassy state to a rubbery state, with a glass transition temperature of ~150 °C. Only 5 wt% of the weight loss occurs at 220 °C, meeting the temperature requirements of the high-tower melt granulation process (≥165 °C). The DMPZ content in P(AA-co-AM)-e-NI is 1.067 wt%, representing a 120% increase compared to our previous products (0.484 wt%). P(AA-co-AM)-e-NI can effectively reduce the abundance of ammonia-oxidizing bacteria and prolong the duration during which nitrogen fertilizers exist in the form of ammonium nitrogen. It can also cooperatively enhance the conversion of insoluble phosphorus into soluble phosphorus in the presence of ammonium nitrogen (NH₄⁺-N). In addition, upon adding P(AA-co-AM)-e-NI into soils, soil bulk density and hardness decrease by 9.2% and 10.5%, respectively, and soil permeability increases by 10.5%, showing that it has a good soil-loosening ability and capacity to regulate the soil environment. Full article

The synthesis of poly(acrylic acid-co-acrylamide) was investigated to enhance its rheological properties. Syntheses were conducted in both aqueous and supercritical fluid media, with and without the incorporation of a novel star-shaped macromonomer. The macromonomer, synthesized from a Boltorn H30 core with PEGMA⁵⁰⁰ arms and modified to contain a single vinyl group, was copolymerized with acrylic acid and acrylamide. Comprehensive polymer characterization was performed using FTIR, NMR, and SEC-MALS-dRI techniques. Rheological assessments revealed that copolymers containing the star-shaped monomer exhibited significantly higher viscosities than those lacking the hyperbranched component, a result attributed to the inter- and intrachain interactions facilitated by the PEGMA⁵⁰⁰ arms. Additionally, purification studies demonstrated that dialysis was necessary to remove short-chain polymers, particularly for samples synthesized in supercritical media, to achieve optimal rheological performance. Polymers synthesized in a supercritical CO₂–ethyl acetate mixture exhibited higher viscosities compared to their water-synthesized counterparts. The integration of the novel star-shaped macromonomer into HPAM-like polymers offers substantial potential for enhanced oil recovery applications. Full article

Drug-loaded hydrogels are promising for modern medicine due to their physical modifiability. However, most hydrogels suffer from poor swelling, which limits their drug encapsulation and release capabilities. In this study, Poly (N-(2-hydroxyethyl) acrylamide-co-acrylic acid) (Poly (HEAA-co-AA)) hydrogels with high swelling properties are synthesized via free radical polymerization of neutralized acrylic monomers. The effects of the material ratio and acrylic acid neutralization degree on the swelling properties of hydrogels in water are investigated, and the swelling properties of hydrogels prepared with different monomer ratios in different pH buffer solutions are systematically studied. The results show that the swelling degree is sensitive to the monomer ratio and pH. The maximum equilibrium swelling degree of the hydrogels occurs at an HEAA to AA molar ratio of 2:2, with values of 11.36 g g⁻¹ at pH 1.68 and 112.79 g g⁻¹ at pH 9.18. Finally, the mechanical properties of PHA hydrogels under different HEAA/AA molar ratios are investigated, showing that the mechanical properties of PHA improved compared to those of PAA. The mechanical properties of the hydrogels are best and show good stability in rheological tests when the molar ratio of HEAA to AA is 2:2. This work has major potential applications in drug carrier systems. Full article

This work aims to investigate the synergistic effects of hybrid bio-fillers and compatibilizers on the properties of natural rubber composites. Rice husk silica (RSi) and hydroxyapatite (HA), derived from rice husk ash and seabass fish scales, respectively, were successfully prepared and used as bio-fillers. Poly(acrylic acid-co-acrylamide)-grafted deproteinized natural rubber (gDPNR) was synthesized via emulsion graft copolymerization, achieving a grafting efficiency and grafting percentage of 15.94 and 4.23%, respectively. The gDPNR was utilized as a compatibilizer in the preparation of natural rubber composites. The addition of hybrid bio-fillers at an RSi-to-HA ratio of 25:75 exhibited superior mechanical properties compared to composites containing a single filler. The incorporation of gDPNR improved filler dispersion and interfacial adhesion between the NR matrix and the bio-fillers, further enhancing the mechanical, thermal, and dielectric properties. The composite with hybrid bio-fillers and 10 phr of gDPNR exhibited the highest tensile strength, showing a 2.10-fold and 1.06-fold improvement over neat natural rubber composite and hybrid filler composite without compatibilizer, respectively. The presence of polar functional groups in gDPNR enhanced the dielectric constant of the natural rubber composites. These composites could have potential in sustainable industrial applications, including flexible electronics and eco-friendly devices. Full article

In this work, cellulose nanocrystals (CNCs) were obtained from the wood of Acacia farnesiana L. Willd (Huizache) via acid hydrolysis; then, they were used to reinforce polyacrylic acid–co-acrylamide (AAc/AAm) hydrogels synthesized in a solution process via in situ free radical photopolymerization. The nanomaterials were characterized using atomic force microscopy, dynamic light scattering (DLS), and the residual charge on the CNCs; the nanohydrogels were characterized using infrared spectroscopy, scanning electron microscopy, swelling kinetics, and Young’s modulus. Soluble-grade cellulose presented 94.6% α-cellulose, 0.5% β-cellulose, and 2.7% γ-cellulose, as well as a viscosity of 8.25 cp and a degree of polymerization (DP) of 706. The CNCs averaged 180 nm in length and 20 nm in width. In the nanohydrogels, it was observed that the swelling kinetic behavior followed the Schott kinetic model, at times lower than 500 h; after that, it became linear. The results show that the hydrogel swelling capacity depended on the crosslinking agent and CNC concentration, as well as the CNC chemical and morphological properties, rather than the CNC source. The hydrogels with CNCs exhibited a decreased swelling degree compared to the hydrogels without CNCs. Young’s modulus increased with CNC presence and depended on the concentration and characteristics of the CNC as a crosslinking agent. Full article

Herein, anionic (sodium dodecylbenzene sulfonate, SDBS) and cationic (cetyltrimethylammonium bromide, CTAB) surfactants are involved in the synthesis of a poly(acrylic acid-co-acrylamide) copolymer, p(AA-co-AM), containing nanoceria (CeO₂). The physicochemical and optical properties of CTAB-CeO₂@p(AA-co-AM) and SDBS-CeO₂@p(AA-co-AM) nanocomposites can be studied using different techniques. The physicochemical properties of nanoceria-immobilized p(AA-co-AM) are significantly developed when handled with SDBS. Compared to the CTAB-CeO₂@p(AA-co-AM) nanocomposite, SDBS-CeO₂@p(AA-co-AM) exhibits pronounced negatively charged mesoporous surfaces with Corel reef-like morphology. SDBS-CeO₂@p(AA-co-AM) contains ceria nano-cubes of ~30 nm size, evenly dispersed along a copolymeric moiety, displaying narrower energy bandgap. The photocatalytic efficiency of this nanocomposite is performed in activating persulfate-ions (PS) under visible light irradiation, yielding reactive oxygen species that effectively treat dye wastewater. Advanced SDBS-CeO₂@p(AA-co-AM)/PS/Vis photocatalytic oxidation system possesses ~100% methylene blue degradation efficiency within 2 h for five consecutive purification-cycles with thorough mineralization performance. Such superior photo-degradability consults efficacious synergistic combinations gathering the nanocomposite, persulphate-ions, and visible light radiation, yielding an escalated synergy-index value (SI = 6) with intensive generation of reactive-oxidizing species (SO₄^•−/h⁺ synergistic ratio 1:5.6). Including anionic-surfactant molecules in the synthesis of metal-containing copolymer nanocomposites is indispensably profitable in the future for the treatment of industrial wastewater. Full article

In this article, we report on the alginate heterografted by Poly(N-isopropyl acrylamide-co-N-tert-butyl acrylamide) and Poly(N-isopropyl acrylamide) (ALG-g-P(NIPAM86-co-NtBAM14)-g-PNIPAM) copolymer thermoresponsive hydrogel, reinforced by substituting part of the 5 wt% aqueous formulation by small amounts of Poly(acrylic acid)-g-P(boc-L-Lysine) (PAA-g-P(b-LL)) graft copolymer (up to 1 wt%). The resulting complex hydrogels were explored by oscillatory and steady-state shear rheology. The thermoresponsive profile of the formulations were affected remarkably by increasing the PAA-g-P(b-LL) component of the polymer blend. Especially, the sol-gel behavior altered to soft gel–strong gel behavior due to the formation of a semi-interpenetrating network based on the hydrophobic self-organization of the PAA-g-P(b-LL). In addition, the critical characteristics, namely T_{c,thermothickening} (temperature above which the viscosity increases steeply) and ΔT (transition temperature window), shifted and broadened to lower temperatures, respectively, due to the influence of the hydrophobic side chains P(b-LL) on the LCST of the PNIPAM-based grafted chains of the alginate. The effect of ionic strength was also examined, showing that this is another important factor affecting the thermoresponsiveness of the hydrogel. Again, the thermoresponsive profile of the hydrogel was changed significantly by the presence of salt. All the formulations showed self-healing capability and tolerance injectability, suitable for potential bioapplications in living bodies. Full article

This work aims to enhance natural rubber’s dielectric properties and antibacterial activity by incorporating silver nanoparticles and titanium dioxide. Deproteinized natural rubber (DPNR) was modified through the graft copolymerization of acrylic acid and acrylamide using N′, N′-Methylenebisacrylamide as a crosslinking agent, resulting in poly(acrylic acid-co-acrylamide)-modified, deproteinized natural rubber (MDPNR). This modification facilitated coordination with silver ions and interaction with titanium dioxide. Silver nanoparticles were generated under heat and pressure. Modified natural rubber composites containing silver nanoparticles and titanium dioxide (MDPNR/Ag-TiO₂) were prepared. Scanning electron microscopy (SEM) revealed well-distributed silver in the modified natural rubber matrix, while agglomeration of titanium dioxide was observed at a high loading. Both MDPNR and MDPNR/Ag-TiO₂ showed high thermal stability compared to DPNR. The MDPNR/Ag-TiO₂ composites exhibited higher Tg and lower tan δ, indicating higher stiffness due to the restriction of chain movement compared to that in MDPNR. DPNR exhibited a low dielectric constant, enhanced by poly(acrylic acid-co-acrylamide) modification and silver nanoparticle/titanium dioxide incorporation. Incorporating 0.5 phr of AgNO₃ and 2.5 phr of TiO₂ in the composites increased the dielectric constant by 1.33 times compared to that of MDPNR. MDPNR showed no antibacterial activity, while the MDPNR/Ag-TiO₂ composites exhibited promising antibacterial activity against Staphylococcus aureus and Escherichia coli. Full article

Nitrogen (N) losses from conventional N fertilizers contribute to environmental degradation and low N use efficiency. Highlighting the need for slow-release fertilizers (SRFs) to mitigate these problems, this study aims to develop slow-release N fertilizers using starch-grafted-poly[(acrylic acid)-co-acrylamide] based nanoclay polymer composites (NCPCs) and investigate their efficacy for slow N delivery in soil. Three types of NCPCs, NCPC(A) (poly [(acrylic acid)-co-acrylamide]), NCPC(W) (wheat starch-grafted-poly[(acrylic acid)-co-acrylamide), and NCPC(M) (maize starch-grafted-poly[(acrylic acid)-co-acrylamide) were prepared and characterized using FTIR spectroscopy and X-ray diffraction techniques. N-release behaviour of the products was assessed under two distinct soils, i.e., Assam (Typic Hapludults, pH 4.2) and Delhi (Typic Haplustepts, pH 7.9) soils. Additionally, the effects of varying soil moisture and temperature levels on N release were studied in the Assam soil. The N-release kinetics of the synthesized fertilizers were assessed using zero-order, first-order, Higuchi, and Korsmeyer−Peppas models. Degradability of the NCPCs was evaluated by measuring evolved CO₂–C under various soil conditions as an indicator of microbial degradation. The results indicated that NCPC fertilizers significantly slowed down the release of N compared to urea. According to the R² values obtained, it was evident that the first-order kinetic model most accurately describes the N release from both urea and NCPC-based N fertilizers in the studied soils. Among the formulations, NCPC(A) exhibited the lowest N release (42.94–53.76%), followed by NCPC(M) (51.05–61.70%), NCPC(W) (54.86–67.75%), and urea (74.33–84.27%) after 21 days of incubation. The rate of N release was lower in the Assam soil compared to the Delhi soil, with higher soil moisture and temperature levels accelerating the release. Starch addition improved the biodegradability of the NCPCs, with NCPC(W) showing the highest cumulative CO₂-C evolution (18.18–22.62 mg g⁻¹), followed by NCPC(M) (15.54–20.97 mg g⁻¹) and NCPC(A) (10.89–19.53 mg g⁻¹). In conclusion, NCPC-based slow-release fertilizers demonstrated a more gradual N release compared to conventional urea and the inclusion of starch enhanced their degradability in the soil, which confirms their potential for sustainable agricultural applications. However, soil properties and environmental factors influenced the N release and degradation rates of NCPCs. Full article

When encountering heavy oil reservoirs during drilling, due to the change in pressure difference inside the well, heavy oil will invade the drilling fluid, and drilling fluid will spill into the reservoir along the formation fractures, affecting the drilling process. A supramolecular polymer gel-based temporary plugging agent was prepared using acrylamide (AM), butyl acrylate (BA), and styrene (ST) as reacting monomers, N, N-methylenebisacrylamide (MBA) as a crosslinking agent, ammonium persulfate (APS) as an initiator, and poly(vinyl alcohol) (PVA) as a non-covalent component. A supermolecular polymer gel with a temperature tolerance of 120 °C and acid solubility of 90% was developed. The experimental results demonstrated that a mechanically robust, thermally stable supramolecular polymer gel was successfully synthesized through the copolymerization of AM, BA, and ST, as well as the in situ formation hydrogen bonding between poly (AM-co-BA-co-ST) and PVA, leading to a three-dimensional entangled structure. The gel-forming solution possessed excellent gelling performance even in the presence of a high content of salt and heavy oil, demonstrating superior resistance to salt and heavy oil under harsh reservoir conditions. High-temperature and high-pressure plugging displacement experiments proved that the supramolecular polymer gel exhibited high pressure-bearing capacity, and the blocking strength reached 5.96 MPa in a wedge-shaped fracture with a length of 30 cm. Furthermore, the dissolution rate of the supramolecular polymer gel was as high as 96.2% at 120 °C for 48 h under a 15% HCl solution condition. Full article

Attapulgite-hydroxyethyl cellulose-poly (acrylic acid-co-2-acrylamide-2-methylpropanesulfonic acid) (ATP-HEC-P(AA-co-AMPS)) in-concrete curing material was synthesized by aqueous solution polymerization using attapulgite (ATP) as an inorganic filler and hydroxyethyl cellulose (HEC) as a backbone. The effects of relevant factors such as ATP dosage, HEC dosage, degree of neutralization, initiator quality, and cross-linking agent quality on the water absorption characteristics of ATP-HEC-P (AA-co-AMPS) were investigated through expansion tests. The micro-morphology of ATP-HEC-P (AA-co-AMPS) was also comprehensively characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, a thermal analysis, and other applicable means. The results showed that the prepared ATP-HEC-P (AA-co-AMPS) had a strong water absorption and water retention capacity, with a water absorption multiplicity of 382 g/g in deionized water and 21.55% water retention capacity after being placed at room temperature for 7 d in a bare environment. Additionally, ATP-HEC-P (AA-co-AMPS) showed good performance for absorbing liquids within the pH range of 7–12. The material’s thermal stability and mechanical properties were also significantly improved after the addition of ATP. The preparation cost is low, the process is simple, and the material meets the requirements for concrete curing materials. Full article

In this particular study, a hydrogel known as SAP-1 was synthesized through the grafting of acrylic acid-co-acrylamide onto pullulan, resulting in the creation of Pul-g-Poly (acrylic acid-co-acrylamide). Additionally, a sponge hydrogel named SAP-2 was prepared by incorporating the surfactant sodium dodecyl benzene sulfonate (SDBS) into the hydrogel through free radical solution polymerization. To gain further insight into the composition and properties of the hydrogels, various techniques, such as Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance (1H NMR), atomic absorption spectroscopy, and field emission scanning electron microscopy (FE-SEM), were employed. Conversely, the absorption kinetics and the equilibrium capacities of the prepared hydrogels were investigated and analyzed. The outcomes of the investigation indicated that each of the synthesized hydrogels exhibited considerable efficacy as adsorbents for cadmium (II), copper (II), and nickel (II) ions. In particular, SAP-2 gel displayed a remarkable cadmium (II) ion absorption ability, with a rate of 190.72 mg/g. Following closely, SAP-1 gel demonstrated the ability to absorb cadmium (II) ions at a rate of 146.9 mg/g and copper (II) ions at a rate of 154 mg/g. Notably, SAP-2 hydrogel demonstrated the ability to repeat the adsorption–desorption cycles three times for cadmium (II) ions, resulting in absorption capacities of 190.72 mg/g, 100.43 mg/g, and 19.64 mg/g for the first, second, and third cycles, respectively. Thus, based on the abovementioned results, it can be concluded that all the synthesized hydrogels possess promising potential as suitable candidates for the adsorption and desorption of cadmium (II), copper (II), and nickel (II) ions. Full article

Bilayer hydrogel actuators, consisting of an actuating layer and a functional layer, show broad applications in areas such as soft robotics, artificial muscles, drug delivery and tissue engineering due to their inherent flexibility and responses to stimuli. However, to achieve the compatibility of good stimulus responses and high mechanical properties of bilayer hydrogel actuators is still a challenge. Herein, based on the double-network strategy and using the synchronous ultraviolet (UV) polymerization method, an upper critical solution temperature (UCST)-type bilayer hydrogel actuator was prepared, which consisted of a poly(acrylamide-co-acrylic acid)[MC] actuating layer and an agar/poly(N-hydroxyethyl acrylamide-co-methacrylic acid)[AHA] functional layer. The results showed that the tensile stress/strain of the bilayer hydrogel actuator was 1161.21 KPa/222.07%. In addition, the UCST of bilayer hydrogels was ~35 °C, allowing the bilayer hydrogel actuator to be curled into an “◎” shape, which could be unfolded when the temperature was 65 °C, but not at a temperature of 5 °C. Furthermore, hydrogel actuators of three different shapes were designed, namely “butterfly”, “cross” and “circle”, all of which demonstrated good actuating performances, showing the programmable potential of bilayer hydrogels. Overall, the bilayer hydrogels prepared using double-network and synchronous UV polymerization strategies realized the combination of high mechanical properties with an efficient temperature actuation, which provides a new method for the development of bilayer hydrogel actuators. Full article

The brittle behavior of poly(lactic acid) (PLA) and PLA composites with inorganic filler limits their applications; the addition of a toughening agent, such as a rubbery phase, was selected to transform the brittle to ductile behavior for versatility in various applications. This work aims to study the properties of PLA and PLA composite with filled nanosized hydroxyapatite (nHA) after adding modified natural rubber (MoNR), which acts as a toughening agent. MoNR refers to poly(acrylic acid-co-acrylamide)-grafted deproteinized natural rubber. nHA was prepared from fish scales. Its characteristics were investigated and was confirmed to be comparable to those of commercial grade. PLA-MoNR at various MoNR contents and PLA/nHA composites with/without MoNR were prepared by melt mixing. Their morphology, mechanical, and thermal properties were observed and investigated. Samples with MoNR added showed the dispersion of spherical particles, indicating incompatibility. However, the mechanical properties of PLA-MoNR, which had MoNR added at 10 phr, showed toughening behavior (increased impact strength by more than two times compared to that of neat PLA). The PLA/nHA composite with MoNR showed the same result. The addition of MoNR in the composite increased its impact strength by 1.27 times compared to the composite without MoNR. MoNR can be a stress concentrator, resulting in toughened PLA and PLA/nHA composite. Full article

Hydrogel polymer electrolytes (GPEs), as an important component of flexible energy storage devices, have gradually received wide attention compared with traditional liquid electrolytes due to their advantages of good mechanical, bending, and safety properties. In this paper, two cross-linked GPEs of poly(acrylic acid-co-acrylamide) or poly(acrylic acid-co-N-methylolacrylamide) with NaNO₃ aqueous solution (P(AA-co-AM)/NaNO₃ or P(AA-co-HAM)/NaNO₃) were successfully prepared using radical polymerization, respectively, using acrylic acid (AA) as the monomer, N-methylolacrylamide (HAM) or acrylamide (AM) as the comonomer, and N, N-methylenebisacrylamide (MBAA) as the cross-linking agent. We investigated the morphology, glass transition temperature (T_g), ionic conductivities, mechanical properties, and thermal stabilities of the two GPEs. By comparison, P(AA-co-HAM)/NaNO₃ GPE exhibits a higher ionic conductivity of 2.00 × 10⁻² S/cm, lower T_g of 152 °C, and appropriate mechanical properties, which are attributed to the hydrogen bonding between the -COOH and -OH, and moderate cross-linking. The flexible symmetrical supercapacitors were assembled with the two GPEs and two identical activated carbon electrodes, respectively. The results show that the flexible supercapacitor with P(AA-co-HAM)/NaNO₃ GPE shows good electrochemical performance with a specific capacitance of 63.9 F g⁻¹ at a current density of 0.2 A g⁻¹ and a capacitance retention of 89.4% after 3000 charge–discharge cycles. Our results provide a simple and practical design strategy of GPEs for flexible supercapacitors with wide application prospects. Full article