Poly Acrylic Acid Research Articles

Shear Bond Strength of Orthodontic Brackets Bonded with Thermo-Cured Glass-Based Materials-An In Vitro Study.

The results of orthodontic therapy largely depend, among other factors, on the preparation of the tooth enamel itself and the choice of material used to bond orthodontic brackets. The aim of this in vitro study was to determine the shear bond strength (SBS) and adhesive remnant index (ARI) score of thermo-cured glass-ionomers on different pretreated enamel, in comparison with the commonly used composite cement. Three commercially available nano-ionomer or highly viscous glass-ionomer cements (EQUIA Forte® Fil, EQUIA Fil, Ketac Universal) and two types of compo-sites (Heliosit Orthodontic, ConTec Go!) were investigated in this study. The research involved two hundred human premolars. The teeth were cleaned and polished, then randomly divided into five groups according to the enamel preparation method and the type of material. The enamel was treated in three different ways: polyacrylic acid, phosphoric acid, 5% NaOCl + etching with phosphoric acid, and a control group without treatment. Glass-ionomer cement was thermo-cured with heat from a polymerization unit during setting. Statistical analysis was performed using a Chi-square test and one-way ANOVA for independent samples. Spearman's Rho correlation coefficient was used to examine the relationship. Regardless of the material type, the results indicated that the weakest bond between the bracket and tooth enamel was found in samples without enamel pretreatment. The majority of the materials stayed on the brackets in samples without enamel preparation, according to ARI scores. The study's findings demonstrated that the strength of the adhesion between the bracket and enamel is greatly influenced by enamel etching and glass-ionomer thermo-curing. Clinical investigations would be required to validate the outcomes.

Precisely Prelithiated Polyacrylic Acid Binder Improving Electrochemical Performance of Micron‐Sized Silicon Anodes for Lithium‐Ion Batteries

AbstractSilicon, serving as an anode material of Li‐ion batteries, offers a theoretical capacity significantly higher than graphite, but its practical application is hindered by poor conductivity, low lithium ion diffusivity, and severe volumetric expansion. Here, a simple and eco‐friendly methodology is proposed to synthesize precisely prelithiated polyacrylic acid binder, optimizing the interface between the binder and micron Si particles. The incorporation of these binders not only mitigates the detrimental effects of volumetric expansion but also enhances mechanical strength, and ionic conductivity of the anode, significantly improving the initial Coulombic efficiency (ICE), cycling stability, and rate performance of micron‐sized Si anodes. This study not only highlights the potential of prelithiated binders in overcoming the limitations of micron‐sized Si anodes but also sets a new benchmark for the development of high‐capacity, eco‐friendly Li‐ion batteries.

In situ and post-synthesis polymer stabilization of ferromagnetic nanoparticles synthesized by a membrane or conventional reactor

Membrane reactors have been proven to be effective in producing nanoparticles with reduced polydispersity indices. Recently, our group has incorporated this technology into the synthesis of ferromagnetic nanoparticles. In the initial phase, we conducted post-synthesis stabilization experiments to assess the performance of various polymeric agents. Polyacrylic acid (PAA) was chosen because of its notable affinity for the functional groups on the nanoparticle surface. Subsequently, in situ stabilization experiments were conducted using a membrane reactor, with variations in PAA addition flow rates ranging from 0.33 to 1.5 mL/min and maturation times in an ultrasonic bath ranging from 0.5 to 2 h. The samples were characterized in terms of their hydrodynamic diameter, polydispersity, and Z-potential. Notably, the smallest particle size was achieved at the intermediate point with a PAA flow rate of 0.66 mL/min. However, the influence of maturation time did not follow a predictable pattern; the most favorable characteristics, based on the analyzed variables, were observed at 1.5 and 2 h.

A Universal Strategy for Constructing Hydrogel Assemblies Enabled by PAA Hydrogel Adhesive.

Hydrogel is a significant type of building block for constructing macroscopic assemblies, the construction of which usually entails the incorporation of supramolecular groups. However, supramolecular group recognition is specific and only suitable for assembling two particular modified hydrogels, but not a versatile strategy. Herein, a universal strategy without modification process is proposed using polyacrylic acid (PAA) hydrogel as the adhesive layer to assemble different kinds of hydrogels. Furthermore, hydrogel assemblies with various shapes and multi-stimuli responsiveness are constructed by assembling different stimuli-responsive hydrogels with PAA hydrogel. Therefore, hydrogel assemblies are able to complete bending motions upon applying corresponding stimuli. This strategy provides a universal approach for constructing hydrogel assemblies, and also shows the potential for developing soft robots with versatile functions.

Mineral scaling and organic fouling in electrodialytic crystallization

The management of hypersaline brine is a critical challenge to achieving a circular water economy. Traditional brine treatment technologies mainly rely on thermal evaporation, which requires intensive energy, cost, and/or areal footprint. Electrodialytic crystallization (EDC) has been recently developed as a novel process that enables brine crystallization without evaporation. However, the potential effects of mineral scaling and organic fouling on the performance of EDC have not been revealed. In this study, we systematically investigated mineral scaling and organic fouling in EDC. We demonstrate that the ion transport and crystallization efficiencies of EDC are generally unaffected by a variety of mineral scalants and organic foulants, despite an increase of energy consumption in the presence of humic acid. Further, EDC is shown to be less susceptible to gypsum scaling than RO, mainly due to the difference in concentration polarization between these two membrane processes. To mitigate gypsum scaling in an assumptive EDC-RO treatment train towards zero liquid discharge (ZLD), polyacrylic acid (PAA) is employed as an antiscalant that prevents gypsum scaling in RO while not adversely affecting EDC performance at relatively low concentration. Our study unravels the behaviors of EDC when treating feedwater with high scaling and fouling potentials, providing valuable insights for understanding mineral scaling and organic fouling when applying an ED-based technology for hypersaline brine treatment towards ZLD.

Adhesive and conductive hydrogels based on poly(acrylic acid) composites for application as flexible biosensors

A PAA (polyacrylic acid)-based nanocomposite hydrogel (CASM) reinforced with sodium carboxymethyl cellulose (CMC-Na), organo-montmorillonite (OMMT), and sodium lignosulfonate (SLS) was prepared using free radical polymerization. In this work, CMC-Na was utilized to enhance the viscosity of the system, while the electrostatic interaction between CMC-Na and OMMT facilitated the uniform dispersion of OMMT within the matrix. Additionally, SLS aided in the dispersion of the components, reducing the interaction forces between particles in the hydrogel, thereby improving its flexibility and extensibility. The results demonstrated that the synergistic effects of CMC-Na, OMMT, and SLS led to a hydrogel with a tensile strength of up to 74.5 KPa, a tensile strain exceeding 3600 %, and certain shape memory properties. Furthermore, the incorporation of SLS, which provides phenolic hydroxyl and sulfonic groups, significantly enhanced the adhesive properties of the hydrogel, achieving a peel strength of up to 1200 N/m on aluminum. The sulfonic groups also facilitated ion transport, resulting in excellent electrical conductivity (9.82 mS/cm) and strain sensitivity (GF=4.36). This approach of improving hydrogel properties through the incorporation of inorganic particles and cross-linked structures offers a novel strategy for the multifunctional modification of hydrogels.

PH-responsive size- and charge-selective block copolymer membrane for the separation of small proteins

Blue-light-induced RAFT polymerization was utilized to synthesize poly(N,N-dimethylacrylamide)–block–polystyrene (PDMA–b–PS) diblock copolymers to obtain 40 g per batch for membrane fabrication. Using a combination of self-assembly and non-solvent induced phase separation (SNIPS), larger isoporous membranes (≈ 0.5 m · 0.3 m) were fabricated with pore diameters of ≈ 25 nm in the dry state and around 4 nm in the wet state. These membranes were post-modified with hydrochloric acid to impart negatively charged, pH-responsive poly(acrylic acid)–block–polystyrene (PAA–b–PS) membranes. While all proteins like cytochrome C, insulin, lysozyme, myoglobin, and ovalbumin were fully rejected by the pristine PDMA–b–PS membrane, the PAA–b–PS membrane demonstrated selective rejection based on protein size and charge, effectively rejecting the proteins with a hydrodynamic radius Rh ≥ 1.9 nm. The PAA–b–PS membrane showed a real selectivity of 4.1 for the positively charged protein cytochrome C compared to the similarly sized, but negatively charged insulin, as well as a real selectivity of 16.1 towards the negatively charged ovalbumin. This illustrates the size- and charge-selective characteristics of the PAA–b–PS membrane for protein separation.

Development of a Biopolymer-Based Anti-Fog Coating with Sealing Properties for Applications in the Food Packaging Sector.

The quest for sustainable and functional food packaging materials has led researchers to explore biopolymers such as pullulan, which has emerged as a notable candidate for its excellent film-forming and anti-fogging properties. This study introduces an innovative anti-fog coating by combining pullulan with poly (acrylic acid sodium salt) to enhance the display of packaged food in high humidity environments without impairing the sealing performance of the packaging material-two critical factors in preserving food quality and consumers' acceptance. The research focused on varying the ratios of pullulan to poly (acrylic acid sodium salt) and investigating the performance of this formulation as an anti-fog coating on bioriented polypropylene (BOPP). Contact angle analysis showed a significant improvement in BOPP wettability after coating deposition, with water contact angle values ranging from ~60° to ~17° for formulations consisting only of poly (acrylic acid sodium salt) (P0) or pullulan (P100), respectively. Furthermore, seal strength evaluations demonstrated acceptable performance, with the optimal formulation (P50) achieving the highest sealing force (~2.7 N/2.5 cm) at higher temperatures (130 °C). These results highlight the exceptional potential of a pullulan-based coating as an alternative to conventional packaging materials, significantly enhancing anti-fogging performance.

Peptide direct growth on poly(acrylic acid)/poly(vinyl alcohol) electrospun fibers coated with branched poly(ethylenimine): A solid-phase approach for scaffolds biofunctionalization

Due to their resemblance to the fibrillar structure of the extracellular matrix, electrospun nanofibrous meshes are currently used as porous and mechanically stable scaffolds for cell culture. In this study, we propose an innovative methodology for growing peptide sequences directly onto the surface of electrospun nanofibers. To achieve this, electrospun fibers were produced from a poly(acrylic acid)/poly(vinyl alcohol) blend that was thermally crosslinked and subjected to a covalent coating of branched poly(ethylenimine). The exposed amino functionalities on the fiber surface were then used for the direct solid-phase synthesis of the RGD peptide sequence. In contrast to established strategies, mainly involving the grafting of pre-synthesized peptides onto the polymer chains before electrospinning or onto the nanofibers surface, this method allows for the concurrent synthesis and anchoring of peptides to the substrate, with potential applications in combinatorial chemistry. The incorporation of this integrin-binding motive significantly enhanced the nanofibers' ability to capture human cervical carcinoma (HeLa) cells, selected as a proof of concept to assess the functionalities of the developed material.

Laser‐Induced Nucleation of Acetaminophen through the Addition of Insoluble Impurities and Acidic Polymers

AbstractThis study investigates the crystallization of acetaminophen (ACET) in ultrapure water and a 10 wt.% aqueous polyacrylic acid (PAA) solution using non‐photochemical laser‐induced nucleation (NPLIN) for the first time. Using a 532 nm nanosecond laser, two distinct crystal morphologies—rhombic and tetragonal plate‐like—are formed in both solvents after adding impurities. Notably, the PAA solution showed a reduced number of crystals and slower growth rates compared to ultrapure water, suggesting that the acidic polymer modulates crystal growth. Interestingly, crystals are not induced by the laser without impurities. However, impurities like copper phthalocyanine (CuPc) or boron carbide (CB4) enabled successful NPLIN, with CB4 showing higher nucleation efficiency than CuPc. The study also explores how laser power affects nucleation probability and identifies potential laser energy thresholds. Experimental data on ACET crystal sizes over time are fitted to derived equations, which accurately represented trends and predicted results. The nanoparticle heating mechanism and the role of acidic polymers in affecting nucleation probability and growth rate are discussed, along with potential mechanisms for changes in crystal morphology.

A bioadhesive pacing lead for atraumatic cardiac monitoring and stimulation in rodent and porcine models.

Current clinically used electronic implants, including cardiac pacing leads for epicardial monitoring and stimulation of the heart, rely on surgical suturing or direct insertion of electrodes to the heart tissue. These approaches can cause tissue trauma during the implantation and retrieval of the pacing leads, with the potential for bleeding, tissue damage, and device failure. Here, we report a bioadhesive pacing lead that can directly interface with cardiac tissue through physical and covalent interactions to support minimally invasive adhesive implantation and gentle on-demand removal of the device with a detachment solution. We developed 3D-printable bioadhesive materials for customized fabrication of the device by graft-polymerizing polyacrylic acid on hydrophilic polyurethane and mixing with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to obtain electrical conductivity. The bioadhesive construct exhibited mechanical properties similar to cardiac tissue and strong tissue adhesion, supporting stable electrical interfacing. Infusion of a detachment solution to cleave physical and covalent cross-links between the adhesive interface and the tissue allowed retrieval of the bioadhesive pacing leads in rat and porcine models without apparent tissue damage. Continuous and reliable cardiac monitoring and pacing of rodent and porcine hearts were demonstrated for 2 weeks with consistent capture threshold and sensing amplitude, in contrast to a commercially available alternative. Pacing and continuous telemetric monitoring were achieved in a porcine model. These findings may offer a promising platform for adhesive bioelectronic devices for cardiac monitoring and treatment.

Stimuli-responsive drug release of polyacrylic acid-coated silica–titania hollow nanoparticles

Inorganic hollow nanoparticles have received a great deal of attention as nanocarriers for drug delivery system, but it is still challenging to control the drug release time and achieve high drug delivery efficiency. In this study, we intend to build a controllable smart drug delivery system that delivers drugs to a desired location for a desired time using a stimulus-responsive material. Polyacrylic acid (PAA), a pH-responsive material, is coated on the silica–titania hollow nanoparticles (HNPs) to acquire stimulus-responsive material for controlled drug release.

Evaluation of mechanical properties and potential environmental applications of biomimetic mineralized composites

With the growing emphasis on environmental protection, there has been extensive research on new green cementitious materials suitable for different conditions. This study focuses on the influence of key environmental factors on proposed biomimetic mineralized composites (BMC) using polyacrylic acid (PAA) as a modifier, based on the biomimetic chemistry induced carbonate precipitation (BCICP) method. The environmental factors examined include the cementing matrices type, the magnesium ions concentration, and the cementing solution pH. The samples treated under various conditions were evaluated for their unconfined compressive strength (UCS) and calcium carbonate content, and their microstructure was characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results demonstrate that the BMC treatment could achieve high-strength cementation for both Toyoura sand and Fujian quartz sand, with a more pronounced enhancement observed for Toyoura sand. Magnesium ions reduce the cementation effect, and they cannot fully replace calcium ions in participating in the cementation process. Moreover, the cementing solution pH significantly influences the cementation effect, with the best acid-base condition for PAA to modify BMC sand samples found at a pH of 11.5. Overall, the BMC exhibits high performance under various environmental conditions. These findings could provide valuable insights into the influence of environmental factors and the potential applications of BMC in diverse environments.

The corrosion resistance and anti-bacterial performance of polyelectrolyte-embedded Ca-P coating loaded with ciprofloxacin on magnesium alloy

Polyacrylic acid (PAA) is utilized as the template for the hydrothermal fabrication of Ca-P coatings on biodegradable magnesium (Mg) alloys, and ciprofloxacin (CIP) is also adopted for the coating's anti-bacterial performance. The coating's composition and structure are characterized. The anti-bacterial performance of the coating is evaluated using plate counting method against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The corrosion rates of different samples are measured by electrochemical polarization, electrochemical impedance spectroscopy (EIS), and hydrogen evolution (HE) experiments. The long-term release behavior of the loaded antibiotics is analyzed through UV–vis. The results show that the obtained coating would display corrosion protection, anti-bacterial effect, and acceptable adhesive force, verifying that this drug-loaded coating effectively overcomes the limitations of Mg alloys in the biological environment. The biocompatibility of the coating is also characterized using the CCK-8 method. Finally, the role of the PAA in the structural transformation of the coating is explained based on the molecular dynamics (MD) simulation and this method seems to open a new pathway for understanding the reconstructing effect of the templates inside a hydrothermally synthesized coating.

Effect of Polymer Architecture and Acidic Group Density on the Degree of Salt Formation in Amorphous Solid Dispersions.

Recent work has shown that an amorphous drug-polymer salt can be highly stable against crystallization under hot and humid storage conditions (e.g., 40 °C/75% RH) and provide fast release and that these advantages depend on the degree of salt formation. Here, we investigate the salt formation between the basic drug lumefantrine (LMF) and several acidic polymers: poly(acrylic acid) (PAA), hypromellose phthalate (HPMCP), hypromellose acetate succinate (HPMCAS), cellulose acetate phthalate (CAP), Eudragit L100, and Eudragit L100-55. Salt formation was performed by "slurry synthesis" where dry components were mixed at room temperature in the presence of a small quantity of an organic solvent, which was subsequently removed. This method achieved more complete salt formation than the conventional methods of hot-melt extrusion and rotary evaporation. The acidic group density of a polymer was determined by nonaqueous titration in the same solvent used for slurry synthesis; the degree of LMF protonation was determined by X-ray photoelectron spectroscopy. The polymers studied show very different abilities to protonate LMF when compared at a common drug loading, following the order PAA > (HPMCP ∼ CAP ∼ L100 ∼ L100-55) > HPMCAS, but the difference largely disappears when the degree of protonation is plotted against the concentration of the available acidic groups for reaction. This indicates that the extent of salt formation is mainly controlled by the acidic group density and is less sensitive to the polymer architecture. Our results are relevant for selecting the optimal polymer to control the degree of ionization in amorphous solid dispersions.

Benzoyl peroxide encapsulation in poly(urea‐formaldehyde) microcapsules for use in dental materials

AbstractNew self‐healing resin composites with tertiary amine microcapsules enhance the mechanical performance of dental restorations. However, a higher concentration of dibenzoyl peroxide (BPO) must be added to the composite to react with the core material when the microcapsules rupture, reducing the shelf life of dental materials due to their reactivity. As a result, one approach to reducing the amount of BPO dissolved in dental resin is to microencapsulate it. Thus, this manuscript described the encapsulation of BPO in poly(urea‐formaldehyde) (PUF) microcapsules (MC) and investigated its effect on the flexural strength of BisGMA/TEGDMA composites. To synthesize hollow MC, poly(acrylic acid) (PAA) was tested as a continuous phase viscosity modifier. The MC were then infiltrated with BPO dissolved in linseed oil as core materials. PAA in continuous phase increased MC diameter due to improved air bubble stability. BPO dissolved in linseed oil was successfully infiltrated into empty PUF MC, causing the MC shell wall to expand. The dental resin had adequate adhesion to the PUF shell, which ruptured under induced stress. Thus, the MC filled with BPO as a healing agent has the potential to reduce the amount of BPO that is typically dissolved in the monomeric phase of dental materials, which can increase the shelf life of self‐healing dental materials.Highlights The reactivity of dibenzoyl peroxide (BPO) affects resin stability in dental materials. When combined with tertiary amines, BPO acts as a healing agent in self‐healing composite materials. BPO dissolved in linseed oil can be infiltrated in PUF microcapsules and increase its size. Hollow microcapsules synthesized in a more viscous continuous phase have a larger diameter. Microencapsulated BPO is released during stress stimuli in dental resin.

The crosslinking and decrosslinking of fluorinated diblock copolymer from RAFT emulsion polymerization toward surface anti‐icing

AbstractHere, we demonstrate disulfide‐crosslinked polyfluoroacrylate AB block copolymer films with excellent anti‐icing properties. The fluorinated latexes of AB block copolymers were synthesized via two‐step reversible addition‐fragmentation chain‐transfer (RAFT) emulsion polymerization using polyacrylic acid and its sodium salts as the hydrophilic A‐block, and polyhexafluorobutyl acrylate as the hydrophobic B‐block. Diacetone acrylamide was copolymerized in different blocks as a crosslinking anchor. A disulfide‐containing compound dithiodipropionic acid dihydrazide was chosen as the crosslinking agent to form disulfide‐crosslinked fluorinated films to enhance the mechanical properties, surface properties, swelling properties, and anti‐icing properties of the films. It has proved that the crosslinking site has a great impact on the film formation process which in turn affects the film performance. The B‐block crosslinked films showed better resistance to water while the A‐block crosslinked films were more organic solution resistant. The A‐block crosslinked films also possessed better anti‐icing properties due to the high F/O value. Furthermore, decrosslinking experiments were conducted using a reductant tris(2‐carboxyethyl)phosphine hydrochloride to break the disulfide bond. The recycling rate of the B‐block crosslinked films could reach >90% while the recycling rate of the A‐block crosslinked films reached >75%.

3D Printed Silk Fibroin‐Based Hydrogels with Tunable Adhesion and Stretchability for Wearable Sensing

AbstractHydrogel‐based wearable strain sensors have recently gained considerable interest due to their promising applications in real‐time health monitoring and motion detection. However, achieving integrated high‐stretchability, self‐adhesiveness, and long‐term water‐retaining property simultaneously in hydrogel systems remains a big challenge, which limits their applications in wearable electronics. Herein, a multifunctional hydrogel material designed is proposed for wearable strain sensors that can be manufactured by digital light processing (DLP) 3D printing technology. By tailoring the composition of chemically cross‐linked networks (ploy(acrylamide)/poly(acrylic acid)/poly(ethylene glycol) diacrylate), physically cross‐linked networks (ploy(acrylamide)/poly(acrylic acid)/poly(ethylene glycol) diacrylate/silk fibroin/glycerol/water) and microstructures on the surface, the 3D printed hydrogel exhibits promising superior and adjustable mechanical properties, tunable adhesion and good water‐retaining property simultaneously. In addition, through adding conductive ions, high ionic conductivity can also be achieved for stretchable sensing applications. Based on these integrated multifunctionalities, the 3D printed hydrogel is suitable for wearable strain sensors to detect various body motions. This work provides a prospect for 3D printable hydrogel systems with broad applications in wearable electronics.

Electromagnetic shielding materials of highly conductive PVA/PAA/hydrogel cross-linked with MXene

MXene-based materials that effectively deal with harmful electromagnetic waves are attracting more and more attention. In this paper, MXene hydrogels with good properties were prepared using polyvinyl alcohol (PVA) and polyacrylic acid (PAA) to construct a three-dimensional framework for hydrogels, and then adding homemade MXene materials to take advantage of their excellent properties, which resulted in the formation of an electrically conductive framework. The study shows that MXene-10 has a tensile strength of 0.29 MPa and an electrical conductivity of 156.24 S/mm. In addition, electromagnetic shielding (EMI) of 33.6 dB can be achieved when the MXene hydrogel is only 2 mm.

Mechanistic aspect of copper selenide as an electrocatalyst for the detection of hydrogen peroxide in gaseous phase

The electrocatalytic properties of copper selenide for hydrogen peroxide detection in a gas phase were investigated using cyclic and square-wave voltammetry. Copper selenide demonstrated significant electrocatalytic activity towards hydrogen peroxide oxidation in a basic medium containing polyacrylic acid as a gas-absorbing polyelectrolyte. Experimental data were corroborated by a brief theoretical analysis and simulations based on a two-electron irreversible electrode mechanism of a dissolved redox couple. The voltammetric response of a conventional glassy carbon electrode modified with copper selenide showed a linear correlation with hydrogen peroxide concentration over a range of 3.0 × 10−5 to 1.0 × 10−3 mol L−1 in solution.Practical application of this method for gaseous hydrogen peroxide detection was explored using screen-printed electrodes (SPE) coated with a thin film of polyacrylic acid containing medium, with copper selenide serving as a modifier of the working electrode. The detectable concentration range of gaseous hydrogen peroxide using the modified SPE spanned picomolar concentrations. The statistical parameters of the calibration line in terms of LOQ, LOD and R2 are 4.1 × 10−6, 1.2 × 10−6 mol L−1, and 0.996, which correspond very closely to the gas concentrations of 6.1 × 10−12 to 6.1 × 10−11 mol L−1.