Groups Of PAA Research Articles

Construction of a Fluorescence/Phase-Change Dual-Mode Sensor Based on Carbon Dots/Poly(acrylic acid) for Highly Selective and Sensitive Detection of Ferric Ions.

Fe3+ is one of the crucial metal ions in biological systems, and its excess or deficiency in the body can trigger various diseases, posing a serious threat to human health. Moreover, improper handling or disposal of Fe3+ can lead to water pollution, thereby harming the environment. Therefore, the development of highly selective and sensitive Fe3+ detection probes is particularly urgent. In this paper, a dual-mode sensor based on sol-gel and fluorescence signal responses was developed for the visual detection of Fe3+. The visual sensing method based on the simultaneous response of Fe3+-triggered dual signals can minimize the interference from false-positive signals and enhance detection accuracy. The dual-mode sensor, denoted as PAA@CDs, was constructed by incorporating high-brightness (high fluorescence emission intensity) green-yellow carbon dots (CDs) into poly(acrylic acid) (PAA), which possesses a large number of carboxyl functional groups. Based on the interaction of Fe3+ with the surface functional groups of CDs, nonfluorescent complexes are formed, leading to nonradiative electron transfer, which induces fluorescence quenching and produces a fluorescence signal visible to the naked eye. Additionally, the interaction of Fe3+ with the carboxyl groups of PAA triggers the cross-linking of PAA, causing a sol-gel phase change signal. Consequently, the PAA@CDs exhibit a dual-response signal in Fe3+ detection. Based on the fluorescence method, the linear detection range of PAA@CDs for Fe3+ is 0.05-2.60 mM with a limit of detection (LOD) of 5.14 μM. Meanwhile, using the sol-gel method, the linear detection range is 0.02-2.20 mM, and the LOD is 42.5 μM. Furthermore, the PAA@CDs probes can be successfully applied to the detection of Fe3+ in real water samples, demonstrating their potential value in the analysis of real samples containing multiple ions.

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

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

Core-shell structured fiber as an iron ion self-reducible and self-anchorable Fenton catalyst for methylene blue high-efficient mineralization

The combination of GO decoration, PAA wet-spinning, Fe3+/Al3+ co-coordination with PANI coating was adopted to fabricate mechanically applicable core-shell structured fiber. Since GO could rely on its abundant oxygen-containing functional groups to interact with the carboxylic groups of PAA through hydrogen bonding and esterification crosslinking, GO decoration was expected to enhance the mechanical properties and water resistance of PAA matrix. Thanks to PANI-adjusted Fe3+/Fe2+ cycling, mass content of Fe2+ in PANI-coated fiber reached 0.08%, increasing by 242% compared to that of fibrous core. After the third cycle, Fe2+ mass content was 0.09% and higher than original content, and after 60 cycles, Fe2+ mass content was still as high as 0.09%; thus the resulting fiber could quickly catalyze H2O2 to mineralize 90% of MB during cyclic application. Due to strong PANI-induced iron ion-anchoring ability, iron ion leaching was only 0.36 mg/L during 60 cycles and less than 7% of that of fibrous core, so that the PANI-coated fiber could use its retained iron species to repeatedly decolorize MB at least 60 times. Since PANI shell could serve as an all-in-one locality to ensure Fe3+/Fe2+ cycling, pollutant mineralization, and iron ion anchoring, the fiber prepared herein presented its own superiority in treating dye wastewater.

Nanoarchitectonics and electrocatalytic properties of platinum nanoparticles in weak polyelectrolytes‐based multilayer thin films

AbstractIn this study, the electrocatalytic behavior of platinum (Pt) nanoparticles (NPs) in a novel multilayered thin film is investigated for proton exchange membrane fuel cells (PEMFC) applications. The multilayer thin films are assembled by the alternate deposition of branched polyethylenimine (BPEI) and poly(acrylic acid) (PAA) from aqueous solutions through a layer‐by‐layer (LbL) technique. Two extreme assembly pH conditions critically influence the films' physical and morphological characteristics, subsequently affecting their electrochemical behavior. Manipulation of the assembly pH modifies the charge density of the weak polyelectrolytes (BPEI and PAA), leading to variations in physical, structural, and electrochemical properties. The LbL thin films assembled at a pH of 9.5 for BPEI and 4.5 for PAA exhibit significantly greater thickness compared to the same film with all components deposited at pH 4.5. This is attributed to in‐and‐out diffusion of the partially charged polyelectrolytes with coiled polymeric conformation (BPEI at pH 9.5 and PAA at pH 4.5). As‐assembled LbL thin films are used as nanoreactors for the deposition of Pt NPs. The nanoscale control over polymeric conformation and charge density significantly influences electrocatalytic performance. 9.5BPEI/4.5PAA thin films exhibit higher electrocatalytic activity relative to 4.5BPEI/4.5PAA systems. This improved performance in 9.5BPEI/4.5PAA multilayers is ascribed to the fact that more carboxylic acid groups of PAA are coated in an exponentially grown behavior, which provides more active sites available for Pt NPs to be deposited. The multilayer thin films containing uniformly dispersed Pt NPs can be an attractive and advanced hybrid electrode material with great promise for the proton exchange membrane fuel cells.

Fabrication of poly(acrylic acid)/chitosan/linseed mucilage films: Thermal and mechanical properties

AbstractThe use of biodegradable polymers in the plastics industry has been increasing in recent years. The study of the chemical, physical, thermal, and mechanical properties of films based on biodegradable components is of interest to technologists because these properties determine their applicability for food packaging. In this work, films based on natural polymers such as linseed mucilage (LM) and chitosan (CH), as well as poly(acrylic acid) (PAA) were obtained through the casting method and using V‐50 as the initiator. The films were characterized through Fourier Transform Infrared spectroscopy, and thermogravimetric analysis, and their water absorption and swelling capacity, and thermal and mechanical properties were determined. Homogenous flexible, translucid, amber‐colored films, with low absorption and solubility in water were obtained. It was demonstrated through Fourier Transform Infrared analysis the chemical interaction between C–H, CO, and C–O chemical groups of LM, CH, and PAA. In addition, films showed high resistance to thermal decomposition between 125 and 425°C. The mechanical tests of tension allowed the composition of LM in the film, the behavior variates between a plastic and/or elastic material and with tensile strength (Rm) values between 10.8 and 16.4 MPa and elastic modulus (E) values between 56.2 and 169.2 GPa, we observed that at higher quantities of LM and thickness, both E and Rm tend to increase, while %EL decreases. This led us to conclude that the material transitioned from ductile and malleable to rigid and brittle. The films obtained with different ratios of LM/CH/PAA may exhibit a semi‐interpenetrating polymeric networking type morphology.Highlights Thermal and mechanical properties are of interest in food packaging materials. Water absorption can impact the packaged food. Films can be processed on existing machines for conventional plastics. Some conventional plastics could be replaced by these biodegradable films. Biodegradable films are of great interest to the industry of food packaging.

Longitudinal bond strength of a universal adhesive and chemical dentin characterization under different acid etching protocols.

This study aimed to analyze the longitudinal bond strength of a universal adhesive and chemically characterize the dentin substrate under different acid etching protocols. Dentin samples were etched with polyacrylic acid 25% (PAA) for 10 seconds (n=3) and phosphoric acid 32% (PA) for 15 seconds (n=3) and analyzed by Fourier transform infrared spectroscopy - attenuated total reflectance (FTIR-ATR) before and after treatment. For collagen degradation, samples (n=12) were divided into 3 groups: PAA, PA, and Deionized water (control), and analyzed by the quantity of solubilized type I collagen C-terminal cross-linked telopeptides and solubilized C-terminal peptide in relation to total protein concentration (ICTPtp and CTXtp) and by their ultimate tensile strength (UTS). For the adhesive interface analysis, dentin samples (n=72) were divided into 3 groups: PAA, PA, and Self-etch (SE), and subdivided into 2 groups: 24 h (baseline) and 1 year. The following tests were performed: microtensile bond strength (μTBS) (n=48), scanning electron microscopy (SEM) (n=12), and nanoleakage (n=12). The FTIR of PAA showed lower reduction of the peaks in the phosphate group when compared to PA. For ICTPtp, PA showed a significantly higher value. For CTXtp, PA and PAA groups failed to statically differ from each other. UTS was significantly lower for PA. For μTBS, storage time significantly affected bond strength. The results were unaffected by the etching protocol. For SEM, after 1 year, PA had little evidence of degradation in the upper third of the adhesive interface in comparison to the other groups. Nanoleakage showed no considerable silver impregnation after 1 year in the SE group. The use of PAA prior to a universal adhesive (when compared to PA) represents a less aggressive type of etching to dentin. However, self-etching still seems to be the best option for universal adhesive systems that have functional monomers in their composition.

A salt-free poly(acrylic acid) hydrogel electrolyte with self-released ions for quasi-solid-state electrochromic devices

The ionic conductivity of gel polymer electrolytes (GPEs) is usually provided by the added inorganic salt ions. Here, we report a salt-free poly(acrylic acid) (PAA) hydrogel electrolyte with an ionic conductivity of 3.7 × 10−3 S cm−1. The carboxylic groups of PAA can release free H+ ions to provide ionic conductivity, which not only simplifies the preparation of GPEs, but also benefits the fabrication of GPEs with high transparency (>95.6 % from 400 to 1000 nm). The as-prepared hydrogel electrolyte is assembled into an electrochromic (EC) device (ECD) by using Prussian blue/PAA GPE/hydrated tungsten trioxide. The fabricated ECD achieves a high optical modulation (72.7 %), fast responses (2.6 s for coloration and 2.2 s for bleaching), a high coloration efficiency (172.9 cm2 C−1) and good cycling stability (retaining 96.3 % of the original optical modulation after 1200 cycles). Moreover, the ECD has good energy storage properties, demonstrating a potential application for energy-storage smart windows.

Synergistic dopa-reinforced fluid hydrosol as highly efficient coal dust suppressant

A highly efficient coal dust suppressant with low initial viscosity and high adhesion-solidification properties was fabricated by reinforcing a polyacrylic acid hydrosol with dopa and glutathione (DG) redox system. The synthesis mechanism and dust suppression properties of the dust suppressant were investigated by ultraviolet–visible spectroscopy, high-performance liquid chromatography, and nuclear magnetic resonance spectroscopy experiments combined with density functional theory calculations. The polyacrylic acid hydrosol was synthesized by free radical polymerization with an optimal concentration ratio of 0.36 % ammonium persulfate to 9 % acrylic acid; the DG redox system presented a catechol-quinone dynamic equilibrium, and the dopa polymer reinforcing adhesion was synthesized by the reverse dismutation and polymerization of dopa and dopaquinone. Results revealed that the dust suppressant system formed a multiple hydrogen bonding cross-linking network, dominated by strong double hydrogen bonding interaction formed between the carboxyl groups of dopa polymer and polyacrylic acid, and synergized by hydrogen bonds between the carboxyl groups of glutathione and PAA, and between the hydroxyl and carboxyl groups of dopa and dopaquinone. Moreover, the − OH and − COOH groups in the dust suppressant system were more tightly bonded after dehydration and can form a mesh film to effectively adhere and solidify coal dust, and the coal crust film did not raise dust at 20.526 ± 0.083 m/s wind speed.

A common strategy to endow carboxyl group containing WPU with antibacterial, self-healing and recyclable functions

Waterborne polyurethanes (WPUs) are known for their eco-friendliness and adaptability in various industries. However, the quest for multifunctional materials has created a demand for WPUs with self-healing, recyclable, and antimicrobial properties. In this study, we introduce a universal approach to doping FeCl3 and poly(acrylic acid) (PAA) into carboxyl group containing WPUs that promotes dynamic coordination bonding between Fe3+ and -COO- groups of PAA and WPUs. WPU/Fe/PAA-5.5 with 5.5 wt % PAA stands out with excellent mechanical properties, strong self-healing capabilities and an impressive >90% antimicrobial rate. Importantly, these supramolecular films proved to be highly recyclable by facile hot-pressing, which can maintain good antimicrobial properties after multiple cycles. This research will shed light on the multifunctionalization of WPU.

Direct construction of strong, tough, conductive, and adhesive hydrogel bioelectronics enabled by salt-dissolved cellulose

Long-active mechanical toughness, conductivity, and adhesiveness are essential in the applications of hydrogel bioelectronics. Existing approaches usually integrate different functional materials into one system to endow hydrogels with desired properties, which tends to suffer from poor compatibility, cumbersome operations, and unsustainable processes, seriously limiting their real-world applications. Herein, we report a one-step strategy for directly constructing polyacrylic acid/cellulose (PAA/Cel) ionogels with a combination of strong, tough, conductive, and adhesive properties by adding ZnCl2-dissolved cellulose in a facile, efficient, and environmentally friendly manner. The introduction of salt-dissolved cellulose can simultaneously realize the all-round improvement of the ionogel in terms of mechanics, conductivity and adhesion. Particularly, for the PAA/Cel-20 % ionogel, it has a 3.3-fold higher compressive strength (18.8 MPa vs. 4.4 MPa), a 17.2-fold higher fracture toughness (154.0 kJ m−3 vs. 8.5 kJ m−3), a 5.5-fold higher interfacial toughness (247.3 J m−2 vs. 45.0 J m−2), a 4.0-fold higher shear strength (394.5 kPa vs. 78.6 kPa), and a 29.9-fold higher ionic conductivity (74.1 mS m−1 vs. 2.4 mS m−1) compared to the PAA hydrogel. These improved mechanical and adhesive behaviors are due to the synergistic enhancement effect of the compact hydrogen bonds formed between the carboxyl groups (–COOH) of PAA and the hydroxyl groups (–OH) of Cel, as well as the coordination interactions produced by Zn2+ and –COO− for PAA. The observed increase in ionic conductivity is attributed to the presence of abundant dissociated active ions including Zn2+ and Cl−. Our resulting ionogel enables electrophysiological signals to be reliably recorded with high signal-to-noise ratios when assembled as bioelectronics for use in monitoring body movements. The strategy presented here facilitates the development of high-performance adhesive ionogels and could go beyond for bioelectronics in medical monitoring systems.

Liquid Metal-Doped Conductive Hydrogel for Construction of Multifunctional Sensors.

Interest in wearable and stretchable multifunctional sensors has grown rapidly in recent years. The sensing elements must accurately detect external stimuli to expand their applicability as sensors. However, the sensor's self-healing and adhesion to a target object have been major challenges in developing such practical and versatile devices. In this study, we prepared a hydrogel (LM-SA-PAA) composed of liquid metal (LM), sodium alginate (SA), and poly(acrylic acid) (PAA) with ultrastretchable, excellent self-healing, self-adhesive, and high-sensitivity sensing capabilities that enable the conformal contact between the sensor and skin even during dynamic movements. The excellent self-healing performance of the hydrogel stems from its double cross-linked networks, including physical and chemical cross-linked networks. The physical cross-link formed by the ionic interaction between the carboxyl groups of PAA and gallium ions provide the hydrogel with reversible autonomous repair properties, whereas the covalent bond provides the hydrogel with a stable and strong chemical network. Alginate forms a microgel shell around LM nanoparticles via the coordination of its carboxyl groups with Ga ions. In addition to offering exceptional colloidal stability, the alginate shell has sufficient polar groups, ensuring that the hydrogel adheres to diverse substrates. Based on the efficient electrical pathway provided by the LM, the hydrogel exhibited strain sensitivity and enabled the detection of various human motions and electrocardiographic monitoring. The preparation method is simple and versatile and can be used for the low-cost fabrication of multifunctional sensors, which have broad application prospects in human-machine interface compatibility and medical monitoring.

Kök Kanal Tedavisinde Kullanılan Farklı İrrigasyon Solüsyonlarının Yüzey Gerilimlerinin Karşılaştırılması

Amaç: Bu çalışmanın amacı kök kanal tedavisinde kullanılan farklı irrigasyon solüsyonlarının yüzey gerilimi değerlerini karşılaştırmaktır. Gereç ve Yöntem: %5.25 NaOCl, %9 HEBP, %2 PAA, %17 EDTA, %5.25 NaOCl + %9 HEBP, %5.25 NaOCl + %2 PAA, %5.25 NaOCl + %17 EDTA solüsyonlarının yüzey gerilimi değerleri damla şekli analiz cihazı DSA30 (Kruss, Hamburg, Almanya) ile ölçüldü. Her irrigasyon solüsyonu için 10 ayrı ölçüm yapıldı. Veriler mj/m2 cinsinden kaydedildi. Grupların ortalama ve standart sapma değerleri, tek yönlü ANOVA ve Bonferroni ve Tukey Çoklu Karşılaştırma Testleri yapılarak istatistiksel olarak değerlendirildi. Bulgular: En yüksek yüzey gerilim değerini %5.25 NaOCl + %2 PAA solüsyonu, en düşük değeri %9 HEBP solüsyonu gösterdi. %5.25 NaOCl+ %2 PAA grubunun yüzey gerilimi, %5.25 NaOCl, %9 HEBP, %2 PAA, %5.25 NaOCl+ %9 HEBP gruplarından istatistiksel olarak daha yüksekti (p<0.05). %5.25 NaOCl, %9 HEBP, %2 PAA ve %5.25 NaOCl+ %9 HEBP grupları arasında istatistiksel açıdan herhangi bir fark bulunmadı (p>0.05). Sonuç: Test edilen irrigasyon solüsyonları arasında %9 HEBP solüsyonu en düşük yüzey gerilimine sahipti.

Effectiveness and implementation success of a co-produced physical activity referral scheme in Germany: study protocol of a pragmatic cluster randomised trial

BackgroundWhile effective physical activity referral schemes (PARSs) and related structures for promoting physical activity (PA) already exist in several countries, in Germany, PARSs have not yet been implemented systematically and nationwide. Through a co-production approach with relevant actors in the German healthcare system, a PARS was developed, and an implementation plan was created (e.g. financing). This study protocol aims to evaluate the developed PARS for people with non-communicable diseases (NCDs) in Germany regarding its potential effectiveness and implementation success.MethodsTo evaluate the effectiveness and implementation success of the PARS, we will apply a pragmatic cluster-randomised controlled trial (cRCT) in Hybrid II design by comparing two intervention groups (PARS vs PA advice [PAA]). The trial will take place in the Nürnberg metropolitan region, with 24 physician practices recruiting 567 people with NCDs. Both groups will receive brief PA advice from a physician to initially increase the participants’ motivation to change their activity level. Subsequently, the PARS group will be given individualised support from an exercise professional to increase their PA levels and be transferred to local exercise opportunities. In contrast, participants in the PAA group will receive only the brief PA advice as well as information and an overview of regional PA offerings to become more active at their own initiative. After 12 and 24 weeks, changes in moderate to vigorous PA and in physical activity-related health competence (movement competence, control competence, self-regulation competence) will be measured as primary outcomes. Secondary outcomes will include changes in quality of life. To measure implementation success, we refer to the RE-AIM framework and draw on patient documentation, interviews, focus groups and surveys of the participating actors (physicians, exercise professionals).DiscussionThrough a between-group comparison, we will investigate whether additional individual support by an exercise professional compared to brief PA advice alone leads to higher PA levels in people with NCDs. The acceptance and feasibility of both interventions in routine care in the German healthcare system will also be evaluated.Trial registrationClinicalTrials.gov, NCT04947787. Registered 01 June 2021.

Benzoxazine monomers grafted poly(acrylic acid) as novel organic additives with fluorescence and antibacterial properties

Novel additives with dual fluorescence and antibacterial properties derived from benzoxazine monomers and poly(acrylic acid) (PAA) were prepared. Three benzoxazine monomers containing a hydroxyl group (BZXs) synthesized via the Mannich reaction were used as organic fluorophores and subsequently reacted with PAA to obtain poly(acrylic acid)-grafted benzoxazines (PAA-g-BZXs) via esterification. The results from Fourier transform infrared (FTIR) spectroscopy and 1H nuclear magnetic resonance (NMR) showed that the BZXs were grafted onto the pendent groups of PAA only 25%. From UV-Vis, the maximum absorption wavelengths of PAA-g-BZXs were shown the same position of BZXs. By fluorescence spectroscopy, the excitation, emission, and fluorescence quantum yield of BZXs were found to be 375–480 nm, 550–585 nm, and 0.60, respectively. Meanwhile, PAA-g-BZXs showed the same excitation and emission wavelength positions around 360–485 nm and 500–585 nm, respectively. PAA-g-BZXs exhibited green emission light under a UV lamp due to the benzoxazine pendent groups. However, the fluorescence quantum yield of PAA-g-BZXs was decreased to be 0.40 BZXs due to only 25% of BZXs grafted on the pendent groups of PAA. Moreover, PAA-g-BZXs showed antibacterial activity against S. aureus and E. coli up to 100%. Only 1% by weight PAA-g-BZXs was an appropriate amount for the poly(lactic acid) (PLA) matrix to fabricate golden PLA/PAA-g-BZXs composite wires without adding any pigments since the obtained composite wires still showed a high optical performance by changing the color from gold under visible light to blue-green under UV irradiation.

Functional POSS based polyimide nanocomposite for enhanced structural, thermal, antifouling and antibacterial properties

Polyhedral oligomeric silsesquioxane (POSS) molecules are a combination of organic and inorganic hybrid nanocage structures (1–3 nm), which makes them ideal building blocks for the fabrication of functional nanostructured filler, and modify physico-chemical properties of polymeric nanocomposites. Herein, silver nanoparticles functionalized POSS nanofillers were incorporated in poly(pyromellitic dianhydride-co-4,4̍-oxydianiline) amic acid (PAA) matrix by in-situ chemical method followed by imidization for the fabrication of polyimide (PI) nanocomposite. Significant improvement in structural, thermal and wettability properties of functional Ag-POSS-PI nanocomposites were observed due to electrostatic, Van der Waals and hydrogen bonding interactions of functional Ag-POSS nanofiller with –NH2 and –COOH groups of PAA. The hydrophilicity of Ag-POSS-PI film increased (contact angle 79 ± 1.5°) as compared with neat PI (103 ± 1.8°). The antibacterial response using Ag-POSS-PI nanocomposite film against the E. coli bacterial colonies tended to decline with 64 × 106 CFU/mL as compared with neat PI film (1 × 108 CFU/mL) which is attributed to the antibacterial action of Ag NPs and amine groups of octaammonium POSS in PI. As-synthesized functional POSS based PI nanocomposite potentially finds their applications in aerospace, fire retardancy, microelectronics, environmental and biomedical fields.

Novel poly(amino acid)-type superplasticizers with enhanced dispersing performance for Portland cement doped with clay impurities

Poly(amino acid)-type macromolecules (PAAs), poly(ethylene glycol)-b-poly(aspartic acid) (PEG-PAAs), and poly(ethylene glycol)-b-poly(glutamic acid) (PEG-PGAs) were synthesized, and their states in aqueous solutions were studied. PEG-PAAs and PEG-PGAs were first used as novel polycarboxylate superplasticizers, and their dispersion and adsorption behaviors were investigated in cement slurries in the absence and presence of montmorillonite (MMT) clay. The results demonstrated that both PEG-PAAs and PEG-PGAs not only showed excellent water reducing and fluidity retention capabilities but also exhibited remarkable MMT clay tolerance. In contrast to the stretched molecular conformation of traditional polycarboxylate superplasticizers (PCEs), the hydrophobic main chain and the side methylene and ethylene linkers connected to the carboxylic groups of PAA and PGA segments resulted in self-assembly of the PEG-PAAs and PEG-PGAs in aqueous solutions, and the self-assembled nanosized aggregates exhibited relatively uniform spherical morphologies with average sizes of 30–100 nm. Carboxylic groups located on the periphery of the nanoaggregates acted as anchors and adsorbed on the surfaces of the cement particles. The nanoaggregates and the stretched hydrophilic PEG side chains, which jointly produced and enhanced the steric hindrance to prevent cement particle aggregation and hydration, resulted in notable dispersion capabilities. Total organic carbon (TOC), X-ray diffraction (XRD), and thermogravimetry–differential scanning calorimetry (TG-DSC) analyses revealed that the adsorption between the MMT clay and PAA nanoaggregates was surface adsorption (rather than interlayer adsorption), and this significant finding could be ascribed to the enlarged steric hindrance of the PAA nanoaggregates, which prevented the interlamination adsorption consumption of MMT clay to PAAs and revealed the outstanding clay insensitivity. This study provides a new perspective and strategy to design novel poly(amino acid)-type superplasticizers (PAAs) with excellent dispersion performances and improved clay tolerance.

A novel strategy for enhancing comprehensive properties of polyacrylate coating: Incorporation of highly dispersed zinc ions by using polyacrylic acid as carrier

The incorporation of metal ions into polyacrylate coating shows great potential in enhancing the performances of polyacrylate coatings, as well as providing additional functionalities. Herein, we developed a new type of water-soluble polyacrylic acid-Zn(II) composite (PAA-Zn) via the coordination of Zn2+ ions and carboxyl groups of PAA, which showed an extremely high stability in water in a wide range of pH (2–11). It was also facilely applied in polyacrylate latex (PL) as bifunctional additive to prepare high mechanical property, abrasion durable and antibacterial active coating. The PAA, acted as dispersing carrier of Zn2+ ions, and thus promoted uniform dispersion of Zn2+ ions in PL, while buffered the coordination between Zn2+ ions and PL. The as-prepared PL/PAA-Zn coating exhibited significantly improved tensile strength (11.45 MPa) and tear strength (21.01 kN/m) by 120% and 50% compared with those of pristine PL coating. Notably, abrasion durability was considerably enhanced in PL/PAA-Zn coating, showing the decreased mass loss by 36% when subjected to 2000 times of intensive abrasion with sandpaper (320 mesh) under 44 kPa. In addition, the PL/PAA-Zn coatings showed appreciable antibacterial activity against Gram-positive and Gram-negative bacteria. This work demonstrated a promising strategy for the uniform dispersion of metal ions in polyacrylate coatings for enhancing comprehensive properties.

Polyacrylonitrile/poly(acrylic acid) layer-by-layer superimposed composite nanofiber membrane with low iron ion leaching-out and stable methylene blue-removing performance

Membrane process is used to decontaminate dye wastewater. In the process of separation, the adsorbed and/or rejected dyes can greatly foul the membrane and negatively affect separation efficiency. Fenton oxidation can non-selectively mineralize dyes to prevent fouling the membrane. Therefore, this work focused on synthesizing the membrane coupled with Fenton catalyst for dye wastewater treatment. Polyacrylonitrile (PAN)/poly (acrylic acid) (PAA) composite nanofiber membrane was first prepared by layer-by-layer sequential electrospinning and then served as the substrate to load iron ions by the coordination of carboxyl groups of PAA with iron ions, after which a catalytic membrane was successfully prepared. During the application process, water would inevitably elute some iron ions from the catalytic membrane. In order to minimize the loss of iron ions, another PAA/PAN composite nanofiber membrane with the function of rejecting iron ions was then designed and superimposed onto the catalytic membrane using the adhesiveness of upper PAA layer. In this sense, the obtained composite membrane can stably catalyze H2O2 to effectively oxidize methylene blue (MB) due to low leaching-out of iron ions. The results showed that the iron ion loading ratio of PAN/PAA composite nanofiber membrane was increased by 167% compared to that of PAN nanofiber membrane, and the total iron ion elution ratios of PAN nanofiber membrane and PAN/PAA composite nanofiber membrane were 27 times and 6 times higher than that of superimposed composite membrane, respectively. As a result of high loading and low elution of iron ions, the superimposed composite membrane exhibited considerably stable efficiency for MB removal within 30 operation cycles, which reached up to 97.0%. Additionally, the superimposed composite membrane presented better mechanical property and more adjustable permeation flux than the control membranes, so that it would show a great potential for the application in the field of dye wastewater treatment.

Direct synthesis of substrate-independent nanoparticles for antibacterial application

In the present study, we designed a substrate-independent antimicrobial nanoparticle (SNP) via self-assembly of poly (acrylic acid) (PAA) and poly (diallyl dimethyl ammonium chloride) (PDDA). The prepared nanoparticle, with a cube structure, as revealed by scanning electron microscope (SEM), maintained structural integrity even after extensive washing. In addition, the SNP was endowed with substrate-independent adhesive affinity to various surfaces by carbodiimide reaction owing to the carboxyl group of PAA. The results of blood compatibility and cytocompatibility demonstrated that the SNP had a limited effect on blood coagulation and cell proliferation. The results of antibacterial tests indicated that the SNP exhibited significant inhibition ability for both gram-negative and gram-positive bacteria, reducing cell amount by 97.2% and 98.2% within 24 h for Escherichia coli and Staphylococcus aureus, respectively. The hemocompatibility and cytocompatibility were attributed to the introduction of carboxyl group, and the significantly antimicrobial property was ascribed to the introduction of PDDA. Furthermore, the SNP maintained outstanding long-term antimicrobial property. In general, it was believed that the designed SNP probably showed potential for applications in various biological and clinical fields.

Study on the Efficacy of Peracetic Acid Disinfectant (Type III) on Gastrointestinal Endoscopy Disinfection.

Purpose:The purpose of this study was to evaluate the disinfection efficacy of peracetic acid disinfectant (Type III) on gastrointestinal endoscopy.Methods:Endoscopes were disinfected, respectively, by 2% glutaraldehyde and peracetic acid disinfectant (Type III) according to the procedures stipulated by the 2016 version of “Regulation for cleaning and disinfection technique of flexible endoscope,” then samples were collected through biopsy channel at the specified steps. The bacterial count and pathogenic bacteria of these samples were detected, and hepatitis B virus surface antigen, hepatitis C virus antibody, and Treponemiapallidum antibody were detected by chemiluminescent microparticle immunoassay in peracetic acid disinfectant (Type III) group. The samples from the peracetic acid disinfectant (Type III) group were collected for 5 days continuously.Results:In total, 56 gastroscopes and 16 colonoscopes were disinfected by 2% glutaraldehyde (GA Group), 46 gastroscopes, and 15 colonoscopes were disinfected by peracetic acid disinfectant (Type Ⅲ) (PAA Group). After disinfection, the bacterial count was significantly reduced in the 2 groups (P<0.05). In terms of the qualified rate of gastroscopes and total qualified rate, the PAA Group was better than GA Group [the qualified rate of gastroscopes: 97.83% (45/46) vs. 92.86% (52/56), P>0.05; total qualified rate: 98.36% (60/61) vs. 94.44% (68/72), P>0.05], the qualified rate of colonoscopes in the 2 groups were both 100.00% (15/15, 16/16). After disinfecting by peracetic acid disinfectant (Type Ⅲ), hepatitis B virus surface antigen, anti-hepatitis C virus, and Treponemiapallidum antibody were negative. In term of colonies number detected for 5 days continuously, there was no significant difference at different collection steps (P>0.05).Conclusions:Peracetic acid disinfectant (Type III) can be well applied to clinical with meeting the standard of high-level disinfection for gastrointestinal endoscopy, and after disinfecting by peracetic acid disinfectant (Type III), there was no obvious bacterial residue in the biopsy channel.