Acrylic Acid Research Articles

3D Printing of Aqueous Two-Phase Systems with Linear and Bottlebrush Polyelectrolytes.

We formed core-shell-like polyelectrolyte complexes (PECs) from an anionic bottlebrush polymer with poly (acrylic acid) side chains with a cationic linear poly (allylamine hydrochloride). By varying the pH, the number of side chains of the polyanionic BB polymers (Nbb), the charge density of the polyelectrolytes, and the salt concentration, the phase separation behavior and salt resistance of the complexes could be tuned by the conformation of the BBs. By combining the linear/bottlebrush polyelectrolyte complexation with all-liquid 3D printing, flow-through tubular constructs were produced that showed selective transport across the PEC membrane comprising the walls of the tubules. These tubular constructs afford a new platform for flow-through delivery systems.

3D Printing of Aqueous Two‐Phase Systems with Linear and Bottlebrush Polyelectrolytes

We formed core‐shell‐like polyelectrolyte complexes (PECs) from an anionic bottlebrush polymer with poly (acrylic acid) side chains with a cationic linear poly (allylamine hydrochloride). By varying the pH, the number of side chains of the polyanionic BB polymers (Nbb), the charge density of the polyelectrolytes, and the salt concentration, the phase separation behavior and salt resistance of the complexes could be tuned by the conformation of the BBs. By combining the linear/bottlebrush polyelectrolyte complexation with all‐liquid 3D printing, flow‐through tubular constructs were produced that showed selective transport across the PEC membrane comprising the walls of the tubules. These tubular constructs afford a new platform for flow‐through delivery systems.

Preparation of a functional monomer containing polymerisable double bonds and chain transfer sulfhydryl groups

ABSTRACT Methacrylate functional monomers containing polymerisable double bonds and sulphhydryl group were synthesised using (methyl) hydroxyethyl (propyl) acrylate and mercaptopropionic acid as precursors with benzene (toluene, ethyl acetate, ether) as solvent and aqueous agent, p-toluene sulphonic acid as catalyst, hydroquinone as polymerisation inhibitor. The yield of methacrylate functional monomers was more than 90%. The structure and purity of methacrylate functional monomers was characterised by proton nuclear magnetic resonance (1H-NMR) and liquid chromatography–mass spectrometry (LC-MS). The precursor material source is of low cost and widely available, and the product did not need to be purified by a special method, which means that it can be directly used for the synthesis of vinyl branched polymer. Therefore, the price of vinyl branched polymer can be greatly reduced and the application range of vinyl branched polymer can be greatly expanded.

Deorphanizing solute carriers in Saccharomyces cerevisiae for secondary uptake of xenobiotic compounds

The exchange of small molecules between the cell and the environment happens through transporter proteins. Besides nutrients and native metabolic products, xenobiotic molecules are also transported, however it is not well understood which transporters are involved. In this study, by combining exo-metabolome screening in yeast with transporter characterization in Xenopus oocytes, we mapped the activity of 30 yeast transporters toward six small non-toxic substrates. Firstly, using LC–MS, we determined 385 compounds from a chemical library that were imported and exported by S. cerevisiae. Of the 385 compounds transported by yeast, we selected six compounds (viz. sn-glycero-3-phosphocholine, 2,5-furandicarboxylic acid, 2-methylpyrazine, cefadroxil, acrylic acid, 2-benzoxazolol) for characterization against 30 S. cerevisiae xenobiotic transport proteins expressed in Xenopus oocytes. The compounds were selected to represent a diverse set of chemicals with a broad interest in applied microbiology. Twenty transporters showed activity toward one or more of the compounds. The tested transporter proteins were mostly promiscuous in equilibrative transport (i.e., facilitated diffusion). The compounds 2,5-furandicarboxylic acid, 2-methylpyrazine, cefadroxil, and sn-glycero-3-phosphocholine were transported equilibratively by transporters that could transport up to three of the compounds. In contrast, the compounds acrylic acid and 2-benzoxazolol, were strictly transported by dedicated transporters. The prevalence of promiscuous equilibrative transporters of non-native substrates has significant implications for strain development in biotechnology and offers an explanation as to why transporter engineering has been a challenge in metabolic engineering. The method described here can be generally applied to study the transport of other small non-toxic molecules. The yeast transporter library is available at AddGene (ID 79999).

Synthesis and characterization of novel D‐mannitol based hydrogel: Swelling and adsorption behavior of heavy metal ion studies

AbstractA highly efficient hydrogel derived from D‐Mannitol xanthate has been successfully synthesized using a free‐radical solution copolymerization technique. An equimolar mixture of acrylonitrile (AN) and acrylic acid (AA) has been reacted with D‐Mannitol xanthate (DMX) under inert atmosphere. Three distinct grades of D‐Mannitol xanthate‐based hydrogels viz. DMXHGs‐1, DMXHGs‐2, and DMXHGs‐3, were prepared. Extensive analyses were conducted on the hydrogels using various methods such as UV, FT‐IR, SEM, XRD, GPC, TGA and ΔpHPZC. The maximum swelling ratio of DMXHGs‐3 was found to be 52122%, 50434% and 48576% for 24 h with water retention ratio of 80.98%, 78.64% and 79.22% for 30 h in distilled, tap and gray water respectively. These findings indicate the DMXHGs‐3 hydrogel has remarkable swelling and water retention capacity. Comprehensive investigations were carried out to evaluate the hydrogel's remarkable adsorption capacity to act as an adsorbent for effectively removing hazardous metal ions. The highest removal percentages of 95.5% and 94.4% and maximum adsorption capacities of 523.56 mg g−1 and 462.96 mg g−1 were observed with DMXHGs‐3 hydrogel for Cu2+ and Co2+ ions, respectively. Metal ion removal experiments were conducted by varying several parameters including dosage, pH, temperature, concentration, and time. The quantification of Cu2+ and Co2+ was accomplished using UV–visible spectroscopy. Present studies demonstrate the suitability of D‐mannitol xanthate‐based hydrogels for the efficient removal of toxic metal ions from wastewater.

Anti-adipogenesis effect of indole-3-acrylic acid on human preadipocytes and HFD-induced zebrafish.

Obesity, defined as excessive or abnormal body fat accumulation, which could significantly increase the risk of cardiovascular disease, type 2 diabetes mellitus (T2DM) diseases and seriously affect people's quality of life. More than 2 billion people are overweight, and the incidence of obesity is increasing rapidly worldwide, it has become a widely concerned public health issue in the world. Diverse evidence show that active metabolites are involved in the pathophysiological processes of obesity. However, whether the downstream catabolite of tryptophan, 3-indole acrylic acid (IA), is involved in obesity remains unclear. We collected the samples of serum from peripheral blood of obesity and health controls, and liquid chromatography-mass spectrometry (LC-MS) was performed to identify the plasma levels of IA. Additionally, we verified the potential benefits of IA on human preadipocytes and HFD- induced zebrafish by cell viability assay, flow cytometry assay, Oil red O staining, total cholesterol (T-CHO), triglyceride (TG) and nonesterified free fatty acids (NEFA) measurements and Nile Red staining. RNA-Seq, functional analysis and western blot revealed the mechanisms underlying the function of IA. We found that the content of IA in peripheral blood serum of overweight people was significantly lower than that of normal people. In addition, supplementation with IA in zebrafish larvae induced by a high fat diet (HFD) dramatically reduced HFD induced lipid accumulation. IA had no effect on proliferation and apoptosis of preadipocytes, but significantly inhibited adipogenesis of preadipocytes by down-regulate CEBPα and PPARγ. RNA-Seq and functional analysis revealed that IA regulated the adipogenesis of preadipocytes through stimulate the phosphorylation of STAT1. Taken together, IA has been identified as a potent metabolite for the prevention or treatment of obesity.

A Silver Nanoparticle‐Embedded Tamarind Kernel Gum/Poly (Sodium Acrylate) Nanocomposite for Sustainable Release of Doxycycline

AbstractThe current work describes an eco‐friendly novel synthesis of silver (Ag) nanoparticles (NPs)/Tamarind kernel gum (TKG)/Poly (sodium acrylate) (PSA) nanocomposite without the use of any toxic materials. It is a one‐step route synthesis of silver nanocomposite hydrogel in which TKG and PSA are cross‐linked using methylene bisacrylamide (MBA) cross‐linker. The developed hydrogels were characterized using XRD, FTIR, UV‐visible, FE‐SEM, and TEM techniques. Doxycycline (dox) was chosen as a model drug for release studies using TKG/PSA and Ag/TKG/PSA nanocomposite. The observation is that Ag NP/TKG/PSA nanocomposite showed a pH‐dependent swelling which is higher at pH 7.4 than at pH 1.2. Similarly, the cumulative drug release percentage (CDR %) using silver nanocomposite is higher at pH 7.4 than at pH 1.2. Also, the presence of Ag NPs decreased the swelling ratio (SR) of TKG/PSA hydrogel, which controls the rate of release of the dox drug. In addition, the dox release kinetics were studied using the Korsmeyer‐Peppas and Higuchi model. It has been found that drug release data was fitted in the Korsmeyer‐Peppas model with a higher value of regression coefficient (R2). Thus, Ag/TKG/PSA nanocomposite showed satisfactory results for sustainable release of doxycycline drug.

Antifreezing, Antidrying, and Conductive Hydrogels for Electronic Skin Applications at Ultralow Temperatures.

Although conductive hydrogel-based flexible electronic devices have superb flexibility and high conductivities, they tend to malfunction in dry or frigid areas. Herein, an ultralow-temperature tolerant, antidrying, and conductive composite hydrogel is designed for electronic skin applications on the basis of the synergy of double-cross-linked polymer networks, Hofmeister effect, and electrostatic interaction and fabricated by in situ free radical polymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid and acrylic acid in the presence of poly(vinyl alcohol) and conductive MXene sheets, followed by impregnation with LiCl. Thanks to the synergy of LiCl and the charged polar terminal groups of the synthesized polymers, the composite hydrogel can not only bear an ultralow temperature of -80 °C without freezing but also maintain its original mass. Meanwhile, the resultant hydrogel possesses satisfactory self-regeneration ability benefiting from the moisturizing effect of LiCl. The conductive network of MXene sheets greatly improves the ionic conductivity of the hydrogel at low temperatures, exhibiting an ionic conductivity of 1.4 S m-1 at -80 °C. Furthermore, the electronic skin assembled by the multifunctional hydrogel is efficient in monitoring human motions at -80 °C. The antifreezing and antidrying features along with favorable ionic conductivity, high tensile strength, and outstanding flexibility make the composite hydrogel promising for applications in frigid and dry regions.

Kilogram scale facile synthesis and systematic characterization of a Gd-macrochelate as T1-weighted magnetic resonance imaging contrast agent

To overcome the problems of commercial magnetic resonance imaging (MRI) contrast agents (CAs) (i.e., small molecule Gd chelates), we have proposed a new concept of Gd macrochelates based on the coordination of Gd3+ and macromolecules, e.g., poly(acrylic acid) (PAA). To further decrease the r2/r1 ratio of the reported Gd macrochelates that is an important factor for T1 imaging, in this study, a superior macromolecule hydrolyzed polymaleic anhydride (HPMA) was found to coordinate Gd3+. The synthesis conditions were optimized and the generated Gd-HPMA macrochelate was systematically characterized. The obtained Gd-HPMA29 synthesized in a 100 L of reactor has a r1 value of 16.35 mM−1 s−1 and r2/r1 ratio of 2.05 at 7.0 T, a high Gd yield of 92.7% and a high product weight (1074 g), which demonstrates the feasibility of kilogram scale facile synthesis. After optimization of excipients and sterilization at a high temperature, the obtained Gd-HPMA30 formulation has a pH value of 7.97, osmolality of 691 mOsmol/kg water, density of 1.145 g/mL, and viscosity of 2.2 cP at 20 ℃ or 1.8 cP at 37 ℃, which meet all specifications and physicochemical criteria for clinical injections indicating the immense potential for clinical applications.Graphical

Mussel-Inspired Self-Adhesive and Tough Hydrogels for Effectively Cooling Solar Cells and Thermoelectric Generators.

Adhesive hydrogel-based evaporative cooling, which necessitates no electricity input, holds promise for reducing energy consumption in thermal management. Herein, inspired by the surface attachment of mussel adhesive proteins via abundant dynamic covalent bonds and noncovalent interactions, we propose a facile strategy to fabricate a self-adhesive cooling hydrogel (Li-AA-TA-PAM) using a copolymer of acrylamide (AM) and acrylic acid (AA) as the primary framework. The monomers formed hydrogen bonds between their carboxyl and amide groups, while tannic acid (TA), rich in catechol groups, enhances the adhesion of the hydrogel through hydrogen bonding. The hydrogel demonstrated strong adhesion to various material surfaces, including plastic, ceramic, glass, and metal. Even under high-speed rotation, it still maintains robust adhesion. The adhesion strength of the Li-AA-TA-PAM hydrogel to aluminum foil reached an impressive value of 296.875 kPa. Interestingly, the excellent contact caused by robust adhesion accelerates heat transfer, resulting in a rapid cooling performance, which mimics the perspiration of mammals. Lithium bromide (LiBr) with hydroactively sorptive sites is introduced to enhance sorption kinetics, thereby extending the effective cooling period. Consequently, the operation temperature of commercial polycrystalline silicon solar cells was reduced by 16 °C under an illumination of 1 kW m-2, and the corresponding efficiency of energy conversion was increased by 1.14%, thereby enhancing the output properties and life span of solar cells. The strategy demonstrates the potential for refrigeration applications using viscous gels.

Inhibiting Pathological Calcium Phosphate Mineralization: Implications for Disease Progression.

Pathological calcifications, especially calcium phosphate microcalcifications (MCs), appear in most early breast cancer lesions, and their formation correlates with more aggressive tumors and a poorer prognosis. Hydroxyapatite (HA) is a key MC component that crystallizes in the tumor microenvironment. It is often associated with malignant breast cancer lesions and can trigger tumorigenesis in vitro. Here, we investigate the impact of additives on HA crystallization and inhibition, and how precancerous breast cells respond to minerals that are deposited in the presence of these additives. We show that nonstoichiometric HA spontaneously crystallizes in a solution simulating the tumor microenvironmental fluids and exhibits lump-like morphology similar to breast cancer MCs. In this system, the effectiveness of poly(aspartic acid) and poly(acrylic acid) (PAA) to inhibit HA is examined as a potential route to improve cancer prognosis. In the presence of additives, the formation of HA lumps is associated with the promotion or only minimal inhibition of mineralization, whereas the formation of amorphous calcium phosphate (ACP) lumps is followed by inhibition of mineralization. PAA emerges as a robust HA inhibitor by forming spherical ACP particles. When precancerous breast cells are exposed to various HA and ACP minerals, the most influential factors on cell proliferation are the mineral phase and whether the mineral is in the form of discrete particles or particle aggregates. The tumorigenic effects on cells, ranging from cytotoxicity and suppression of proliferation to triggering of proliferation, can be summarized as HA particles < HA aggregates < ACP particles < ACP aggregates. The cellular response to minerals can be attributed to a combination of factors, including mineral phase, crystallinity, morphology, surface texture, aggregation state, and surface potential. These findings have implications for understanding mineral-cell interactions within the tumor microenvironment and suggest that, in some cases, the byproducts of HA inhibition can contribute to disease progression more than HA itself.

Gamma radiation synthesis of hydroxyethyl cellulose/acrylic acid/CYANEX 471X hydrogel for silver ions capture from acidic nitrate medium

AbstractThe current novelty in this study is to recover silver ion with selective extractant such as cyanex 471X (triisobutylphosphine sulfide) through a clean and green method with high efficiency. Herein, a sustainable hydrogel (HEC/AAc/CX3) was fabricated from triisobutylphosphine sulfide, hydroxyethyl cellulose (HEC), and acrylic acid (AAc) using gamma irradiation polymerization and implanted for the sorption of silver Ag (I) ions from a nitrate acidic medium. Different techniques were employed for characterization of HEC/AAc/CX3 hydrogel such as FT-IR, SEM, XRD, and EDX, before and after the sorption process of Ag(I) ions. Gel content and swelling kinetics ratio of hydrogels at different irradiation doses (10, 20, 30, 40, and 50 kGy) were studied. The Fickian diffusion model results indicate that HEC/AAc/CX3 hydrogel is non-Fickian diffusion, which confirmed that the diffusion and relaxation rates are compatible and were selected for further sorption of Ag(I). The irradiated HEC/AAc/CX3 hydrogels, which contain 0.1 g of cyanex 471X, were employed for batch sorption of 100 mg/L Ag(I) from an acidic solution, and the suggested conditions were pH = 1, time = 60, and v/m = 0.05 L/g, which gives a sorption percentage of 75%. The values of thermodynamic parameters ΔH, ΔG, and ΔS were evaluated as—62.80 kJ/mol, 5 kJ/mol, and -227 J/mol, which indicate that the sorption system was exothermic and nonspontaneous in nature. The maximum adsorption capacity of irradiated HEC/AAc/CX3 for Ag(I) was found to be 12 mg. g−1 at 298 K. Furthermore, the maximum desorption percent of Ag ions from HEC/AAc/CX3 was found to be 70% and achieved with 0.5 M NH4SCN after one desorption cycle. The prepared hydrogel proved its selectivity towards silver ions with facile desorption steps and reusability cycles. Graphical Abstract

Long lifetimes white afterglow in slightly crosslinked polymer systems

Intrinsic polymer room-temperature phosphorescence (IPRTP) materials have attracted considerable attention for application in flexible electronics, information encryption, lighting displays, and other fields due to their excellent processabilities and luminescence properties. However, achieving multicolor long-lived luminescence, particularly white afterglow, in undoped polymers is challenging. Herein, we propose a strategy of covalently coupling different conjugated chromophores with poly(acrylic acid (AA)-AA-N-succinimide ester) (PAA-NHS) by a simple and rapid one-pot reaction to obtain pure polymers with long-lived RTPs of various colors. Among these polymers, the highest phosphorescence quantum yield of PAPHE reaches 14.7%. Furthermore, the afterglow colors of polymers can be modulated from blue to red by introducing three chromophores into them. Importantly, the acquired polymer TPAP-514 exhibits a white afterglow at room temperature with the chromaticity coordinates (0.33, 0.33) when the ratio of chromophores reaches a suitable value owing to the three-primary-color mechanism. Systematic studies prove that the emission comes from the superposition of different triplet excited states of the three components. Moreover, the potential applications of the obtained polymers in light-emitting diodes and dynamic anti-counterfeiting are explored. The proposed strategy provides a new idea for constructing intrinsic polymers with diverse white-light emission RTPs.

Evaluation of Various Types of Alginate Inks for Light-Mediated Extrusion 3D Printing.

Naturally derived biopolymers modifying or combining with other components are excellent candidates to promote the full potential of additive manufacturing in biomedicine, cosmetics, and the food industry. This work aims to develop new photo-cross-linkable alginate-based inks for extrusion 3D printing. Specifically, this work is focused on the effect of the addition of cross-linkers with different chemical structures (polyethylene glycol diacrylate (PEGDA), N,N'-methylenebisacrylamide (NMBA), and acrylic acid (AA)) in the potential printability and physical properties of methacrylated alginate (AlgMe) hydrogels. Although all inks showed maximum photo-curing conversions and gelation times less than 2 min, only those structures printed with the inks incorporating cross-linking agents with flexible and long chain structure (PEGDA and AA) displayed acceptable size accuracy (~0.4-0.5) and printing index (Pr ~1.00). The addition of these cross-linking agents leads to higher Young's moduli (from 1.6 to 2.0-2.6 KPa) in the hydrogels, and their different chemical structures results in variations in their mechanical and rheological properties. However, similar swelling ability (~15 swelling factor), degradability (~45 days 100% weight loss), and cytocompatibility (~100%) were assessed in all the systems, which is of great importance for the final applicability of these hydrogels.

Hepatocellular carcinoma biomarkers screening based on hydrogel photonic barcodes with tyramine deposition amplified ELISA

Hepatocellular carcinoma (HCC), as one of the most lethal cancers, significantly impacts human health. Attempts in this area tends to develop novel technologies with sensitive and multiplexed detection properties for early diagnosis. Here, we present novel hydrogel photonic crystal (PhC) barcodes with tyramine deposition amplified enzyme-linked immunosorbent assay (ELISA) for highly sensitive and multiplexed HCC biomarker screening. Because of the abundant amino groups of acrylic acid (AA) component, the constructed hydrogel PhC barcodes with inverse opal structure could facilitate the loading of antibody probes for subsequent detection of tumor markers. By integrating tyramine deposition amplified ELISA on the barcode, the detection signal of tumor markers has been enhanced. Based on these features, it is demonstrated that the hydrogel PhC barcodes with tyramine deposition amplified ELISA could realize highly sensitive and multiplexed detection of HCC-related biomarkers. It was found that this method is flexible, sensitive and accurate, suitable for multivariate analysis of low abundance tumor markers and future cancer diagnosis. These features make the newly developed PhC barcodes an innovation platform, which possesses tremendous potential for practical application of low abundance targets.

Room‐Temperature Phosphorescence Hydrogel with Multiple Color Based on Salt‐Induced Aggregation

AbstractOrganic photoluminescent materials with room‐temperature phosphorescence (RTP) are of great interest, yet achieving RTP in hydrogels faces challenges due to water‐quenching effects. In this study, a straightforward method is presented to achieve RTP hydrogel using a self‐healing and salt‐hardening hydrogel. The hydrogel is synthesized by polymerizing acrylic acid (AA) with diethylenetriamine (DETA) as the dynamic crosslinker. The poly(acrylic acid)/DETA hydrogel could achieve an afterglow lasting 1.6 s after soaking with NaBr solution. The salt‐enhanced hydrophobic aggregation of the hydrogel network promotes the clustering of carboxyl groups and oxygen atoms, resulting in a rigid environment that suppresses nonradioactive transitions and leads to the manifestation of RTP. Additionally, the dynamic association of AA‐DETA allows the freeze‐dried hydrogel powder to be blended with various hydrophobic dyes, leading to a remodelable hydrogel with delayed emission of multiple colors. In general, by combining salt‐hardening property with self‐healing property together, a RTP hydrogel platform that can be facilely loaded with various organic dyes is proposed.

Synthesis of acrylic acid from methyl lactate over calcium phosphate catalysts in a fixed bed reactor: time-on-stream behavior and kinetic analysis

Transformation of methyl lactate to acrylic acid was investigated over Ca3(PO4)2, Ca2(P2O7) and their mixture in the temperature range of 250-425 °C. The initial concentration of methyl lactate in water was varied from 2 wt% to neat methyl lactate. The results showed that these phosphate catalysts did not contain any measurable amounts of either acid sites or basic sites. The best catalyst was Ca3(PO4)2 giving 62% selectivity to acrylic acid at 75% conversion at 400 °C using GHSV of 95280 h−1 and 2 wt% methyl lactate in the initial feed. This catalyst exhibited larger surface area in comparison to Ca2(P2O7). Elemental analysis revealed that some Ca leaching occurred during reaction, while in case of Ca2(P2O7) the calcium leaching was 3.4 fold higher than observed for Ca3(PO4)2. Long-term results over Ca3(PO4)2 showed that extensive catalyst deactivation occurred during the first 11 h time-on-stream, after which the activity dropped only slightly. In addition to kinetic studies with different parameters, also, kinetic modeling was performed and the activation energies for formation of different products were determined over different catalysts.

Tunable H-bond effects enabled ionic conductive gels with high stretchability, transparency, self-adhesion and wide environmental tolerance for e-skin

It is a high demand but a great challenge to construct all-in-one ionic conductive hydrogels with excellent mechanical performances, transparency, self-adhesion, conductivity and environmental tolerance. Herein, a versatile gel platform was developed via a facile and rapid photopolymerization of acrylic acid (AA) in deep eutectic solvent (DES) with multiple roles simultaneously as water-free solvent, ionic conductor, regulator of hydrogen bond density. Benefiting from the formed crosslinking networks including covalently cross-linked polymer network and multiple dynamic interactions, the resultant PAA-DES gels exhibited high stretchability of 884.7 ± 4.9%, toughness of 31.2 ± 1.4 MJ/m3, fatigue resistance and recovery ability, transparency of 93%, self-adhesive strength of 472 kPa. Moreover, the inherent advantages of DES enabled the gels with good ionic conductivity (2.5 ± 0.2 mS/cm), wide working window and biocompatibility. The PAA-DES as self-adhesive ionic sensors not only possessed wide strain range (∼400%) and stability, but also displayed excellent humidity (30–80%), temperature (−40–60 °C), and sweat tolerance which could precisely and steadily discern and monitor human motions and weak physiological signals. Thus, this work not only provides a strategy to construct all-in-one ionic conductive gels with high elasticity, fatigue resilience, transparency, self-adhesion and wide environmental tolerance, but also exploits versatile platform for intelligent gel sensor and e-skin.

Effect of 2-acrylamide-2-methylpropane sulfonic acid on the early strength enhancement of calcium silicate hydrate seed

Nanomaterials are becoming widely used in cement to enhance the properties of cement-based materials. Artificially synthesized nano-C-S-H serves as a nucleation site for the hydration product C–S–H gel, facilitating its formation. This is deemed as an early strength agent to effectively promote cement hydration. Introducing comb-like polycarboxylate ether (PCE) during the synthesis of C–S–H can effectively reduce the size of C–S–H, resulting in better early strength effects. In this study, the acid-ether ratio of PCE is set at 6:1, and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) substitutes acrylic acid (AA) at varying molar ratios to obtain modified PCE. Calcium silicate hydrate seed-polycarboxylate ether (C-S-Hs-PCE) is synthesized using co-precipitation technique. This study investigated impacts of AMPS on the particle size of C-S-Hs-PCE and the early strength of cement-based materials using dynamic light scattering analysis, total organic carbon analyzer, X-ray diffraction analysis, low-field nuclear magnetic resonance, scanning electronic microscopy, isothermal calorimeter, and compressive strength testing. The results show that the C-S-Hs-PCE, synthesized at an AMPS to AA molar ratio of 5:95, turns out to possess a reduced particle size compared to use of PCE without AMPS. This is pivotal in promoting the hydration of the silicate phase and the formation of calcium hydroxide and C–S–H gel in the paste, and thereby reducing the total porosity while improving the early mechanical strength of the mortar, especially within first 24 h.

Preparation and anticorrosion performance of graphene composited waterborne coatings

Waterborne coatings are safe and environmentally friendly and widely used in automobile, construction and other fields. The low hardness of films formed by water-based anticorrosion coatings and their poor anticorrosion effect can be resulted from the addition of hydrophilic substances, which make it easy for water penetration. In this experiment, glycidyl methacrylate (GMA), butyl acrylate (BA), methyl methacrylate (MMA), and acrylic acid (AA) were used as the polymerization monomers to enhance the hardness, adhesion, and film-forming properties of the coatings by introducing the epoxy bond of GMA in the synthesis. The appropriate formula ratios for the waterborne coatings were determined by conditioning the content of wetting agent, thickener, levelling agent, defoamer, and modified acrylic-based resin. Based on this formula, suitable additive ratios of graphene were determined by condition experiments. When the addition ratio of graphene was 0.6wt% - 0.8wt%, the obtained coatings exhibited satisfactory hardness, film-forming properties, strong adhesion and anticorrosive properties. The results of salt spray tests and potentiodynamic polarization experiments verified that graphene in a certain proportion can effectively block the penetration of water, so that the coating presented excellent properties.