Showing papers on "Acrylic acid published in 2022"

Micro‐Gel Ensembles for Accelerated Healing of Chronic Wound via pH Regulation

Abstract: The pH value in the wound milieu plays a key role in cellular processes and cell cycle processes involved in the process of wound healing. Here, a microfluidic assembly technique is employed to fabricate micro‐gel ensembles that can precisely tune the pH value of wound surface and accelerate wound healing. The micro‐gel ensembles consist of poly (hydroxypropyl acrylate‐co‐acrylic acid)‐magnesium ions (poly‐(HPA‐co‐AA)‐Mg2+) gel and carboxymethyl chitosan (CMCS) gel, which can release and absorb hydrogen ion (H+) separately at different stages of healing in response to the evolution of wound microenvironment. By regulating the wound pH to affect the proliferation and migration of cell on the wound and the activity of various biological factors in the wound, the physiological processes are greatly facilitated which results in much accelerated healing of chronic wound. This work presents an effective strategy in designing wound healing materials with vast potentials for chronic wound management.

Hydrochar-embedded carboxymethyl cellulose-g-poly(acrylic acid) hydrogel as stable soil water retention and nutrient release agent for plant growth

Abstract: The cellulose-based hydrogel has been widely applied for soil water retention and nutrient release agents for several decades. Embedding the inorganic materials into hydrogels is an excellent strategy to improve the inherent limits of the cellulose-based hydrogel. Notably, municipal sludge-derived hydrochar (HC) has reduced the environmental burden and offered a potential hydrogel carrier to control water-retention and nutrient-release. However, the above function for plant growth of hydrochar-embedded carboxymethyl cellulose-g-poly(acrylic acid) (CMC-g-PAA/HC) is unknown, and relevant reports are lacking. This study investigated the water retention, nutrient release behavior, and effect of germination and plant growth of CMC-g-PAA/HC hydrogel. Characterization results showed that HC was successfully incorporated into CMC-g-PAA/HC with 6.0% higher thermostability, 7.2–21.0% lower swelling ratio (SR) in water, and substantial SR in phosphate solution (P-solution). The water loss rate of CMC-g-PAA/HC in P-solution or water owned a more significant temperature response (7.9–15.0 folds) than CMC-g-PAA (8.2–10.0 folds). Moreover, 4.0% higher n value and more 18.5% released P for CMC-g-PAA/HC were also observed. These phenomena were due to restricting the polymer chains movement and the water molecules diffusion inside the hydrogels with HC. Phytotoxicity assessments showed that HC in CMC-g-PAA/HC could effectively alleviate the inhibition effects on rape germination retained with 78.3% germination vigor and 80.0% germination ratio, even dramatically improved plant growth to 28 d. The results of this study demonstrated a new route for developing eco-friendly CMC-g-PAA/HC hydrogel, advantageous as a water retention agent and nutrient carrier in arid and semiarid regions.

A Multilevel Buffered Binder Network for High-Performance Silicon Anodes

Abstract: Developing “ideal” binders to achieve ultrahigh area-capacity stable silicon (Si) anodes remains a significant challenge. Herein, a self-healing binder with a multilevel buffered structure is designed to alleviate the structural damage and performance degradation caused by extreme volume deformation of Si. In this multilevel configuration, employing the coexistence strategy of dynamic supramolecular interactions and rigid covalent bonds, the dopamine-grafted poly(acrylic acid) (PAA-DA) possesses abundant hydrogen bonds and strong viscoelasticity, which facilitates the dynamic reconstruction of the entire network. Moreover, the hydroxyl groups on the polyethylene glycol (PVA) form a strong covalent bond network with the carboxyl groups in PAA-DA under thermal polymerization conditions to ensure the integrity of the electrode structure. At 4 A g–1, the resulting Si electrode retains 1974.1 mAh g–1 after 500 cycles. This binder design strategy with dynamic repair and stable network structure gives specific inspiration for developing high-energy-density batteries.

Safranin-O cationic dye removal from wastewater using carboxymethyl cellulose-grafted-poly(acrylic acid-co-itaconic acid) nanocomposite hydrogel.

Abstract: Copolymer of acrylic acid (AA) and itaconic acid (IA) grafted onto sodium carboxymethyl cellulose hydrogel (CMC-g-poly (AA-co-IA)) was successfully synthesized as an adsorbent to remove safranin-O from wastewater. The swelling and removal efficiencies of CMC-g-poly (AA-co-IA) were enhanced by increasing IA/AA molar ratio as well as by incorporation of montmorillonite clay nano-sheets (MMT). The surface area of MMT, CMC-g-poly (AA-co-IA), and CMC-g-poly (AA-co-IA) samples was 15.632, 0.61452, and 0.66584 m2/g, respectively, indicating the effectiveness of MMT nano-sheets in improving hydrogel surface area. The maximum removal efficiency of CMC-g-poly (AA-co-IA)/MMT under optimum conditions i.e., pH of 8, initial concentration of 10 mg/L, adsorbent dose of 2 g/L, and contact time of 40 min was ascertained 99.78% using a response surface methodology-central composite design (RSM-CCD). Pseudo-second-order and Langmuir models giving the maximum monolayer adsorption capacity of 18.5185 mg/g and 19.1205 mg/g for CMC-g-poly (AA-co-IA) and CMC-g-poly (AA-co-IA)/MMT samples, respectively are the best-fitted models for kinetic and equilibrium data. Thermodynamically, safranin-O decontamination was spontaneous, exothermic, and entropy decreasing. Moreover, ad (de)sorption behavior study showed that CMC-g-poly (AA-co-IA)/MMT performance was not changed after multiple recovery steps. Therefore, CMC-g-poly (AA-co-IA)/MMT was considered as a highly potential adsorbent for safranin-O removal from wastewater.

Smart Magnetic Nanocarriers for Multi-Stimuli On-Demand Drug Delivery

Abstract: In this study, we report the realization of drug-loaded smart magnetic nanocarriers constituted by superparamagnetic iron oxide nanoparticles encapsulated in a dual pH- and temperature-responsive poly (N-vinylcaprolactam-co-acrylic acid) copolymer to achieve highly controlled drug release and localized magnetic hyperthermia. The magnetic core was constituted by flower-like magnetite nanoparticles with a size of 16.4 nm prepared by the polyol approach, with good saturation magnetization and a high specific absorption rate. The core was encapsulated in poly (N-vinylcaprolactam-co-acrylic acid) obtaining magnetic nanocarriers that revealed reversible hydration/dehydration transition at the acidic condition and/or at temperatures above physiological body temperature, which can be triggered by magnetic hyperthermia. The efficacy of the system was proved by loading doxorubicin with very high encapsulation efficiency (>96.0%) at neutral pH. The double pH- and temperature-responsive nature of the magnetic nanocarriers facilitated a burst, almost complete release of the drug at acidic pH under hyperthermia conditions, while a negligible amount of doxorubicin was released at physiological body temperature at neutral pH, confirming that in addition to pH variation, drug release can be improved by hyperthermia treatment. These results suggest this multi-stimuli-sensitive nanoplatform is a promising candidate for remote-controlled drug release in combination with magnetic hyperthermia for cancer treatment.

Biomimetic Gradient Hydrogel Actuators with Ultrafast Thermo-Responsiveness and High Strength.

Abstract: Most current hydrogel actuators suffer from either poor mechanical properties or limited responsiveness. Also, the widely used thermo-responsive poly-(N-isopropylacrylamide) (PNIPAM) homopolymer hydrogels have a slow response rate. Thus, it remains a challenge to fabricate thermo-responsive hydrogel actuators with both excellent mechanical and responsive properties. Herein, ultrafast thermo-responsive VSNPs-P(NIPAM-co-AA) hydrogels containing multivalent vinyl functionalized silica nanoparticles (VSNPs) are fabricated. The ultrafast thermo-responsiveness is due to the mobile polymer chains grafted from the surfaces of the VSNPs, which can facilitate hydrophobic aggregation, inducing the phase transition and generating water transport channels for quick water expulsion. In addition, the copolymerization of NIPAM with acrylic acid (AA) decreases the transition temperature of the thermo-responsive PNIPAM-based hydrogels, contributing to ultrafast thermo-responsive shrinking behavior with a large volume change of as high as 72.5%. Moreover, inspired by nature, intelligent hydrogel actuators with gradient structure can be facilely prepared through self-healing between the ultrafast thermo-responsive VSNPs-P(NIPAM-co-AA) hydrogel layers and high-strength VSNPs-PAA-Fe3+ multibond network (MBN) hydrogel layers. The obtained well-integrated gradient hydrogel actuators show ultrafast thermo-responsive performance within only 9 s in 60 °C water, as well as high strength, and can be used for more practical applications as intelligent soft actuators or artificial robots.

Fabrication of adhesive hydrogels based on poly (acrylic acid) and modified hyaluronic acid

Abstract: Hydrogel wound dressings with good flexibility and adhesiveness to resist deformation during wound movement are urgently needed in clinical application. In this work, the hydrogels based on poly (acrylic acid) and N-hydroxysuccinimide grafted hyaluronic acid (PAA/HA-NHS) with good elasticity and adhesiveness were prepared by chemical cross-linking and hydrogen bonding. The elastic and adhesive properties within the PAA hydrogels could reach a balance by adjusting the concentration of potassium persulfate (KPS) and N, N'-methylenebisacrylamide (MBA). Subsequently, HA-NHS was incorporated into the PAA hydrogel system. The mechanical test revealed that the elongation at break and interfacial toughness of the PAA/HA-NHS hydrogels could reach 265.79 ± 21.93% and 52.88 ± 3.51 J/m2, respectively. In addition, the hydrogels possess a connected porous network and well water absorption ability (with porosity of 51.90 ± 0.11% and swelling ratio in wet state of 122.17 ± 2.78%). In vitro experiment demonstrates that the PAA/HA-NHS hydrogels exhibit nontoxic and cell in-adhesive properties. The PAA/HA-NHS hydrogels could cover the wound spots directly, stretch with the skin movement and gently remove from the wound tissue due to the suitable adhesiveness and poor cell adhesion. In conclusion, the PAA/HA-NHS hydrogels show great application value in the field of wound dressing.

Synthesis and Characterization of Acrylamide/Acrylic Acid Co-Polymers and Glutaraldehyde Crosslinked pH-Sensitive Hydrogels.

Abstract: This project aims to synthesize and characterize the pH-sensitive controlled release of 5-fluorouracil (5-FU) loaded hydrogels (5-FULH) by polymerization of acrylamide (AM) and acrylic acid (AA) in the presence of glutaraldehyde (GA) as a crosslinker with ammonium persulphate as an initiator. The formulation's code is named according to acrylamide (A1, A2, A3), acrylic acid (B1, B2, B3) and glutaraldehyde (C1, C2, C3). The optimized formulations were exposed to various physicochemical tests, namely swelling, diffusion, porosity, sol gel analysis, and attenuated total reflection-Fourier transform infrared (ATR-FTIR). These 5-FULH were subjected to kinetic models for drug release data. The 5-FU were shown to be soluble in distilled water and phosphate buffer media at pH 7.4, and sparingly soluble in an acidic media at pH 1.2. The ATR-FTIR data confirmed that the 5-FU have no interaction with other ingredients. The lowest dynamic (0.98 ± 0.04% to 1.90 ± 0.03%; 1.65 ± 0.01% to 6.88 ± 0.03%) and equilibrium swelling (1.85 ± 0.01% to 6.68 ± 0.03%; 10.12 ± 0.02% to 27.89 ± 0.03%) of formulations was observed at pH 1.2, whereas the higher dynamic (4.33 ± 0.04% to 10.21 ± 0.01%) and equilibrium swelling (22.25 ± 0.03% to 55.48 ± 0.04%) was recorded at pH 7.4. These findings clearly indicated that the synthesized 5-FULH have potential swelling characteristics in pH 6.8 that will enhance the drug's release in the same pH medium. The porosity values of formulated 5-FULH range from 34% to 62% with different weight ratios of AM, AA, and GA. The gel fractions data showed variations ranging from 74 ± 0.4% (A1) to 94 ± 0.2% (B3). However, formulation A1 reported the highest 24 ± 0.1% and B3 the lowest 09 ± 0.3% sol fractions rate among the formulations. Around 20% drug release from the 5-FULH was found at 1 h in an acidic media (pH1.2), whereas >65% of drug release (pH7.4) was observed at around 25 h. These findings concluded that GA crosslinked 5-FU loaded AM and AA based hydrogels would be a potential pH-sensitive oral controlled colon drug delivery carrier.

Highly Elastic and Polar Block Polymer Binder Enabling Accommodation of Volume Change and Confinement of Polysulfide for High-Performance Lithium–Sulfur Batteries

Abstract: Lithium polysulfide (LiPS) shuttling and sulfur volume change causing degradation of electrodes have hindered the practical application of lithium–sulfur batteries. Here, a highly elastic and polar block polymer binder, poly(acrylic acid)-b-((poly(n-butyl acrylate)-co-poly(2,2,3,4,4,4-hexafluorobutyl acrylate))-b-poly(acrylic acid) (PAA-b-(PnBA-co-PHFBA)-b-PAA), was designed and synthesized to both accommodate sulfur volume change and confine LiPSs. The rigid–soft modulated triblock polymer combined the traditional polar binder PAA, low glass-temperature PnBA, and high-polarity PHFBA. The resultant binder can not only adjust the striking volume expansion and inhibit disintegration of a pure sulfur cathode but also strongly anchor LiPSs. The cycle stability and rate performance of lithium–sulfur batteries were significantly improved after being incorporated with the multifunctional binder. Besides, abundant F atoms can enhance ionic conductivity to improve electrochemical reaction of the sulfur cathode. This work offers a feasible and effective strategy for designing an efficient multifunctional binder toward building next-generation high energy density lithium–sulfur batteries.

Ultrastrong Poly(2‐Oxazoline)/Poly(Acrylic Acid) Double‐Network Hydrogels with Cartilage‐Like Mechanical Properties

Abstract: The exceptional stiffness and toughness of double‐network hydrogels (DNHs) offer the possibility to mimic even complex biomaterials, such as cartilage. The latter has a limited regenerative capacity and thus needs to be substituted with an artificial material. DNHs composed of cross‐linked poly(2‐oxazoline)s (POx) and poly(acrylic acid) (PAA) are synthesized by free radical polymerization in a two‐step process. The resulting DNHs are stabilized by hydrogen bridges even at pH 7.4 (physiological PBS buffer) due to the pKa‐shifting effect of POx on PAA. DNHs based on poly(2‐methyl‐2‐oxazoline), which have a water content (WC) of around 66 wt% and are not cytotoxic, show biomechanical properties that match those of cartilage in terms of WC, stiffness, toughness, coefficient of friction, compression in body relevant stress conditions and viscoelastic behavior. This material also has high strength in PBS pH 7.4 and in egg white as synovial liquid substitute. In particular, a compression strength of up to 60 MPa makes this material superior.