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PVDF membrane has strong hydrophobicity and low anti-pollution performance, greatly limiting its practical application. These drawbacks have been successfully overcome by designing and then preparing a membrane with a semi-interpenetrating polymer (semi-IPN) of PVDF/poly(acrylic acid) (PAA) as the membrane matrix, TiO2 nanoparticles as functional components and F127 as pore-forming agent. The semi-IPN was prepared by copolymerizing acrylic acid with N,N methyl acrylamide in the presence of PVDF, and the TiO2 gel nanoparticles were in situ formed in the membrane-forming process. The properties of the composite membrane were significantly affected by the semi-IPN, F127 and TiO2. By adjusting the membrane structure with the semi-IPN, F127 and TiO2 nanoparticles, we prepared a composite membrane with a water contact angle of 40o, a BSA rejection ratio of 87.5% and a water flux of 802.5 L/m2/h/bar. After a simple UV irradiation, the water flux of this composite membrane rose to 1030 L/m2/h/bar, without any rejection decline. The membrane contaminated by humic acid could recover the water flux up to above 95.3% of its original value by a single UV irradiation, showing a very good antifouling performance. In addition, the composite membrane also exhibited a very strong pollution resistance and separation performance for bovine serum albumin and oil-water emulsion. All in all, based on the synergy of the semi-IPN and the evenly dispersed TiO2 nanoparticles, the prepared composite membrane exhibited excellent comprehensive properties and demonstrated a great potential for various separation applications.

The design of heterogeneous catalysts is challenged by the complexity of materials and processes that govern reactivity and by the fact that the number of good catalysts is very small in comparison to the number of possible materials. Here, we show how the subgroup-discovery (SGD) artificial-intelligence approach can be applied to an experimental plus theoretical data set to identify constraints on key physicochemical parameters, the so-called SG rules, which exclusively describe materials and reaction conditions with outstanding catalytic performance. By using high-throughput experimentation, 120 SiO2-supported catalysts containing ruthenium, tungsten, and phosphorus were synthesized and tested in the catalytic oxidation of propylene. As candidate descriptive parameters, the temperature and 10 parameters related to the composition and chemical nature of the catalyst materials, derived from calculated free-atom properties, were offered. The temperature, the phosphorus content, and the composition-weighted electronegativity are identified as key parameters describing high yields toward the value-added oxygenate products acrolein and acrylic acid. The SG rules not only reflect the underlying processes particularly associated with high performance but also guide the design of more complex catalysts containing up to five elements in their composition.

Responsive photonic crystals have attracted much attention due to their strong capability to manipulate the propagation of light in the visible region, but it is still a big challenge to invisibility and mechanical stability. Here, the novel Poly(ether sulfone)/Poly(acrylic acid) inverse opal photonic crystals, which have high mechanical stability and can release visible patterns after wetting with water, are discussed. The Poly(ether sulfone)/Poly(acrylic acid) inverse opal photonic crystals are also responsive to the concentration of ethanol, and the structural color response times increase with increasing ethanol concentration. This design uses the selective infiltration, hydrogen bonding and capillary action of solvent to realize the spectral diversity of reflectance. Owing to the high polarity and hydrogen bonding ability of carboxyl groups, water molecules are adsorbed easily by the poly(acrylic acid) gel. Subsequently, the encrypted information is decrypted due to the redshift of the structural color. Because of its lower polarity and hydrogen bonding ability relative to water, ethanol can impede the absorption of solvent by gel. Therefore, the ethanol concentration can be identified based on the structural color response time. Furthermore, reliable information decryption methods make Poly(ether sulfone)/Poly(acrylic acid) inverse opal photonic crystals potentially uesful as trusted encryption devices.

Multifunctional hydrogels with transparency, ultraviolet (UV)-blocking, stretchable, self-healing, adhesive, antioxidant and antibacterial properties are promising materials for biomedical and relevant applications. However, preparation of these hydrogels at ambient environment without stimuli is still a challenge. Here, a series of hydrogels possessing ultrashort gelation time (~30 s) at room or cold temperature were fabricated based on self-catalytic Fe3+/Tannic acid-cellulose nanofiber (Fe3+/TA-CNF). Fe3+/TA-CNF formed stable redox pairs to activate ammonium persulfate (initiator), generating abundant free radicals to trigger the ultrafast polymerization of acrylic acid (AA). To improve the antibacterial ability of hydrogel, a bilayer hydrogel composite (NF@HG) composed of tetracycline hydrochloride (TH)-loaded electrospun nanofibers and hydrogel layer was fabricated via a mild casting method. The NF@HG exhibited enhanced antibacterial ability and the sustained release of TH can provide long-term antibacterial activity. Besides, cell viability results demonstrated that NF@HG was non-cytotoxic. Taken together, this strategy based on self-catalytic Fe3+/TA-CNF system may inspire new aspects on fast and economical preparation of multifunctional hydrogels or composites, which have attractive industrial applications for biomedical materials.

Strain-sensitive and conductive hydrogels have attracted extensive research interest due to their potential applications in various fields, such as healthcare monitoring, human–machine interfaces and soft robots. However, low electrical signal transmission and poor tensile properties still limit the application of flexible sensing hydrogels in large amplitude and high frequency motion. In this study, a novel ionic liquid segmental polyelectrolyte hydrogel consisting of acrylic acid (AAc), 1-vinyl-3-butylimidazolium bromide (VBIMBr) and aluminum ion (Al3+) was prepared by molecular design and polymer synthesis. The cationic groups and amphiphilicity of ionic liquid chain segments effectively improve the tensile behavior of the polyelectrolyte hydrogel, with a maximum tensile strength of 0.16 MPa and a maximum breaking strain of 604%. The introduction of ionic liquid segments increased the current carrying concentration of polyelectrolyte hydrogel, and the conductivity reached the initial 4.8 times (12.5 S/m), which is a necessary condition for detecting various amplitude and high frequency limb movements. The flexible electronic sensor prepared by this polyelectrolyte hydrogel efficiently detects the movement of different parts of the human body stably and sensitively, even in extreme environment (−20 °C). These outstanding advantages demonstrate the great potential of this hydrogel in healthcare monitoring and wearable flexible strain sensors.

Gel electrolytes based on poly(acrylic acid) and poly(ethylene glycol)diacrylate (PAA-PEGDA-Ca2+) loaded with Ca2+ ions were successfully prepared using gamma irradiation. The use of radiation provides benefits, such as solventless preparation without byproducts. The obtained gel fraction, porosity, and swelling ratio were in the range of 60–90%, 11–60%, and 4–12 g/g, respectively. Fourier transform infrared spectroscopy confirmed the successful crosslinking between PAA and PEGDA. Crystallinity remained unaffected by the incorporation of Ca2+ ions. The thermal decomposition of the gels started at 200°C. The morphology was reported to have a spherical shape. 0.36-0.74 wt.% of Ca2+ was uniformly distributed on the gel electrolyte surface. In the presence of Ca2+ ions, the ionic conductivity of the gels improved by ∼2 times, whereas compressive strength slightly dropped to the range of 6–12 MPa. Graphical abstract Download : Download high-res image (122KB) Download : Download full-size image

A novel CaCO3 nanoparticle modification method by a styrene-acrylic polymer emulsion (SAPE) was introduced. The self-made SAPE was sprayed into the nano-CaCO3 slurry system, and SAPE chains were encapsulated onto the CaCO3 nanoparticle surface. The modified CaCO3 nanoparticle mechanism was discussed. Fourier transform infrared spectroscopy confirmed that the SAPE chain was anchored on the nano-CaCO3 surface by the reaction of the SAPE carboxyl group with the hydroxyl group on the CaCO3. The effect of acrylic acid (AA) amount on the activation degree and oil absorption of CaCO3/SAPE composite nanoparticles was investigated. The amount of AA was 2%, and the activation degree and oil absorption of the product were optimal. The estimated grafting efficiency of the CaCO3/SAPE composite nanoparticles was 90.5% when the amount of acrylamide (AAM) was 1.5%. Scanning electron microscopy showed that the CaCO3 nanoparticles could be dispersed uniformly in polypropylene (PP) film and formed a closed integration by SAPE-modified CaCO3. The styrene-acrylic polymer chains that were grafted on the CaCO3 nanoparticle surface could improve the compatibility between the CaCO3 nanoparticles and PP matrix. The PP composite film with modified CaCO3 nanoparticles had a higher tensile strength than that of pure CaCO3 nanoparticles, which can improve the mechanical properties of the PP material.

To address the rising challenges in self-controlled tandem processes, a catalytic reactor with two reversely-responsive layers was fabricated, for which the two layers acted as the carriers of two different-type active sites so as to achieve the adjustable catalytic ability. This first layer was a shape-memory copolymer consisting of 2-acrylamido-2-methylpropane sulfonic acid and 1-heptene. Given the “frozen” domains in the copolymer at low temperatures, the channel of the substrate became closed. At middle temperatures, the channel of the substrate became open as a result of the activation of the copolymer. The second layer was a copolymer embedding Ag nanoparticles made of polymeric 2-(trifluoromethyl) acrylic acid and 2-vinylpyridine. This layer showed the “closed” channel at low temperatures due to the electrostatic interactions between the two polymeric components, which inhibited the entry of reactants. At higher temperatures, as the polymeric interactions at this layer were broken, the channel in this layer became open for the reactants. In combination with the contained acidic sites and catalytic Ag nanoparticles sites in the two layers, which were individually responsible for catalytic hydrolysis and reduction, the reactor did not show substantive catalytic ability at low temperatures due to the closed channels in both the two layers. At middle temperatures, the reactor ran with simple hydrolysis due to the open channel in the first layer which contained acidic sites. At higher temperatures, the reactor ran with tandem catalytic processes because of the open channels in the two layers. Hence, the design of the dual-responsive catalytic reactor acquired the non-tandem/tandem self-controlled catalytic ability.

A superabsorbent hydrogel (SAH) composite from starch and polyacrylic acid p(St/AAc) was prepared by free radical polymerization in the presence of potassium persulfate initiator. The effects of two polymer composition on gel fraction, swelling, and water retention have been investigated. It was found that swelling was extremely sensitive to the acrylic acid contents; it increased with the decrease of acrylic acid content. Moreover, the hydrogel samples showed an excellent water retention capability. The swelling kinetics and water diffusion mechanism in distilled water were also discussed in order to choose appropriate SAH functioning as soil conditioner of sunflower under drought stress. A pot experiment was carried out to study the ameliorative role of SAH application on sunflower (Helianthus annuus L. Var Sakha) plants grown under drought stress. Growth parameters, content of photosynthetic pigments, total proline and phenol, and antioxidant enzymes were determined. The shoot and root length increased up to 49.84% and 5.35% rather than in the absence of SAH. Growth parameters and photosynthetic pigments of sunflower plants grown under drought in the absence of SAH were reduced. Hydrogel application enriched the photosynthetic pigment. Besides, it also decreased the harmful impacts of drought on sunflower plants. The results herein demonstrated that the hydrogel decreased the proline, total phenols, catalase, peroxidase, and polyphenol oxidase content. The findings of this study indicate that the use of hydrogel can be considered as an unconventional and novel tool in the mitigation of drought stress.

It is desirable to fabricate an antifatigue gel for skin-mimicking sensors on the demand of long-term durability in practical usage. Here, we developed a physically cross-linked eutectogel based on a poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) binary polymer skeleton and a deep eutectic solvent (DES). In this eutectogel, uniformly distributed PVA crystalline domains acted as stable physical cross-linkers, and high-density hydrogen bonds possessed great reversibility. Such a polymer network structure was expected to endow this eutectogel with excellent mechanical strength, stretchability, and a self-recovery ability. Specifically, this eutectogel exhibited a superior tensile strength of 2.6 MPa, a fracture strain of 680%, and a fracture toughness of 8.39 MJ m-3. In cyclic stretching/releasing tests with a fixed strain of 100%, this eutectogel could recover its mechanical properties within a 600 s resting time. Based on this self-recoverable eutectogel, a reliable flexible sensor was fabricated, which possessed good sensitivity and stability over a wide strain range (1-300%). More importantly, the flexile sensor was able to maintain a highly repeatable response signal during 1000 consecutive stretching/releasing cycles, showing outstanding long-term durability. Given the excellent sensing performance, this eutectogel has promising potential in wearable electronics, human-machine systems, and soft robotics.

The rheological properties of the gel-like material, the monomer of which is a crosslinked and modified 2-propenamide of acrylic acid, were determined by relaxation rheometry methods. The values of its elastic modulus and modulus of losses and complex viscosity depending on: deforming stress and its frequency are determined; relative deformation; temperature in the range (20-100) ° C and the regularities of these dependences are noted. It is established that: 1) the dependence of the modulus of elasticity (G'); modulus of loss (G'') and complex viscosity from: relative deformation; voltage; temperature; frequencies indicate that in the linear scale they change according to nonlinear dependencies, and in the transition to the logarithmic scale contain plateau-like areas; 2) analytical dependences of the above parameters on stress, strain rate and temperature are complex and difficult to establish; 3) in the range (20-80) ° C and relative deformations (10-100)% hydrogel has a virtually unchanged value of the modulus (G ') ten times greater than the modulus (G' '), whichdetermines the uniqueness of its rheological and biophysical properties ; 4) in the region (20-80) ° C hydrogel in terms of modulus of elasticity and tangent of the angle of loss is close to a completely elastic body; 5) when the frequency of the deforming voltage is more than 15.8 Hz and the relative deformation ≥100%, the gel is brittlely deformed; while the modulus of its elasticity decreases abruptly and the modulus of losses increases rapidly with increasing frequency of the deforming stress. 6) the dependence of the elastic-viscosity characteristics of the samples washed and unwashed in saline gel in the temperature range (20-80) ° C differ little and indicate that the equilibrium structure of the hydrogel 2-propenamide acrylic acid belongs to the typical colloidal dispersed structure of gelatinous substances.

An aqueous Zn-MnO2 battery with high energy density and good cyclability has been successfully developed with use of an ‘oversaturated gel electrolyte’ (OSGE) prepared by cost-effective acetates and poly(acrylic acid) at 75°C. The electrochemical stability window of the OSGE was extended to 3.45 V at room temperature and was able to maintain this window in temperatures up to 80°C. The ionic conductivity of the OSGE was 3.74 × 10−3 S•cm−1 at room temperature. Molecular dynamics simulation was employed to investigate the contacted cation solvation sheath and could be used to account for the excellent stability of the acetate OSGE. On utilisation of the electrolyte, a high reversibility was demonstrated at room temperature, with 600-hour stripping/plating on Zn metal electrodes and no formation of dendrites. The Zn-MnO2 battery successfully operated for 2000 cycles under an over-charge working voltage (2.0 V). This study not only overcomes the limitation associated with the solubility of salts, but also provides a feasible route for developing a highly stable aqueous Zn-MnO2 battery.

Lumefantrine (LMF), a high-mobility and easy-to-crystallize WHO drug for treating malaria, can form an amorphous salt with poly(acrylic acid) (PAA) that is remarkably stable against crystallization at high humidity and temperature and has fast dissolution rate. The amorphous salt up to 75% drug loading was synthesized under a mild slurry condition easily implemented in basic facilities for global health. Salt formation was confirmed by IR spectroscopy and the much elevated glass transition temperature. At 50% drug loading, the amorphous salt resists crystallization for at least 18 months under the highly stressful condition of 40 °C and 75% RH. In contrast, the dispersion containing neutral LMF in PVP fully crystallized in 4 d and the dispersion in HPMCAS, a weak polyelectrolyte of lower charge density than PAA, crystallized by 50% in 7 d. The amorphous salt at 50% drug loading showed much faster dissolution than crystalline LMF: In SGF, the area under the curve (AUC) was 30 times larger within the gastric emptying time (4 h); in FaSSIF, the enhancement was even larger – by 200 times. Nanodroplets were detected during the dissolution in SGF, possibly accounting for the apparent enhancement of dissolution rate. The LMF-PAA example as a challenging case, along with the previously reported clofazimine-PAA, demonstrates the general utility of amorphous drug–polymer salts to achieve high stability under tropical conditions and enhanced dissolution and bioavailability.

In this study, the impact of particle form of the Cannabis indica plant biofibers and the fiber’s surface tailoring on the physical, thermal, dielectric, and mechanical properties of unsaturated polyester composite specimens manufactured utilizing nonconventional materials were investigated. The mechanical properties such as compressive, flexural, and tensile strengths of the composite specimens were noticed to increase after functionalization of biofiber with acrylic acid and maximum enhancement was found at 20% of biofiber sacking. The physical characterization was concentrated on the assurance of the dielectric constant, dielectric strength, dielectric loss, moisture absorption, chemical resistance, percentage of swelling, limiting oxygen index, and biodegradation of polymer composites under red soil. An increase in dielectric strength from 28 to 29 kV, limiting oxygen index values from 19% to 23%, and moisture/water absorption behavior was noted for resulted bio-composites after surface tailoring of biofiber. To assess the deterioration of the polymeric materials with the temperature, differential scanning calorimetric and the thermogravimetric tests were carried out and enhancement in thermal stability was noted after fortification of polyester composites with functionalized biofiber.

As one of the most sustainable resources, wood has been widely used in the fields of construction, decoration, flooring and furniture. The emergence of transparent wood further expands the application fields of wood to solar cells, luminescent magnetic switches, artificial electronic skins and stress sensors. However, most of the transparent woods reported are obtained by impregnating resins such as polymethylmethacrylate (PMMA), epoxy resin (EP) and polyvinylpyrrolidone (PVP). Here, we demonstrated a flexible transparent wood prepared based on a deep eutectic solvent composed of acrylic acid and choline chloride. The light-absorbing chromophore group of natural wood was removed by the sodium chlorite delignification method to obtain the treated wood template, then the deep eutectic solvent was infiltrated into the wood template, and the final transparent wood was obtained by photo-initiated polymerization. This transparent wood has excellent stretchability (maximum tensile strain up to 73.9%), flexibility and tensile resilience. Moreover, this transparent wood also has good electrical conductivity and temperature sensing properties. The electrical signal of transparent wood has very favorable stability and repeatability in multiple heating–cooling cycles, indicating its great potential as a temperature sensor.

In this research, high-performance epoxy acrylate (EA) coating formulations that contain various acrylate-modified diepoxy siloxane (DESA) intermediates were synthesized and characterized. Firstly, diepoxy siloxane (DES) intermediates, which have varying chain lengths (Mw = 370–3300 Da), were modified by acrylic acid via the ring-opening reaction oxirane group. DESA intermediates were then used in the preparation of ultraviolet (UV)-curable EA formulations. EA was also synthesized via acrylic acid modification of a commercial bisphenol-A-based epoxy resin, used as the standard formulation. EA-based UV-curable formulas were applied on substrates and then cured by UV irradiation for investigating the coating performances. Subsequently, performances of the UV-cured coatings were evaluated by the various test techniques, such as hardness, gloss, cross-cut adhesion force scratch resistance, contact angle, yellowing resistance, abrasion resistance, chemical resistance, and color measurement. The effect of DESA variety on the formations was examined compared to both themselves and the standard formulation. The results showed that the varying amounts and chain lengths of DESA influenced UV-curable coatings’ properties; particularly, the scratch resistance, contact angle, and yellowing resistance significantly enhanced with the increasing chain length of DESA. High-performance UV-curable EA formulations could be produced with the scratch resistance of 4 N, the contact angle of 95°, and high yellowing resistance (ΔE = 0.35).

Effective control of monomer diffusion and reaction rate is the key to achieving a controlled interfacial polymerization (IP) and a high-performance nanofiltration (NF) membrane. Herein, an integration of multirole regulations was synchronously realized using poly(acrylic acid) (PAA) as an active additive in a piperazine (PIP) aqueous phase. Thanks to synergistic interactions, including hydrogen bonding, electrostatic interaction, and covalent bonding between PAA and PIP molecules, together with the increased viscosity of the solution, PIP diffusion was rationally controlled. Moreover, interfacial polycondensation was also restrained via the modestly reduced pH of the aqueous solution. These contribute to the formation of a thinner, looser, more hydrophilic, and higher negatively charged PAA-decorated polyamide selective layer with a unique nanostrand-nodule morphology. The harvested NF-PAA/PIP membrane showed an ∼70% rise in water permeability (up to 23.5 L·m-2·h-1·bar-1) while retaining high Na2SO4 and dye rejections. Furthermore, the optimized NF-PAA/PIP membrane presented a superior fouling resistance capability for typical pollutants, as well as long-term stability during successive filtration. Thus, this work offers a straightforward and impactful approach to regulating IP and promoting NF membrane properties.

This article takes a step forward in understanding the mechanisms involved during the preparation and performance of cross-linked high-drug-loading (HDL) amorphous solid dispersions (ASDs). Specifically, ASDs, having 90 wt % poorly water-soluble drug indomethacin (IND), were prepared via in situ thermal cross-linking of poly(acrylic acid) (PAA) and poly(vinyl alcohol) (PVA) and thoroughly evaluated in terms of physical stability and in vitro supersaturation. Results showed that HDL ASDs having excellent active pharmaceutical ingredient (API) amorphous stability and prolonged in vitro supersaturation were prepared by fine tuning the cross-linking procedure. Unraveling of the processes involved during ASD's formation shed light on the significant role of the cross-linking conditions (i.e., temperature and time), the physicochemical properties of the API, and the hydrolysis level of the cross-linker as key factors in modulating ASD's stability. In-depth analysis of the prepared systems revealed the (1) reduction of API's molecular motions within the cross-linked polymeric networks (through API's strong spatial confinement), (2) the structural changes in the prepared cross-linked matrices (induced by the high API drug loading), and (3) the tuning of the cross-linking density via utilization of low-hydrolyzed PVA as the major mechanisms responsible for ASD's exceptional performance. Complementary analysis by means of molecular dynamics simulations also highlighted the vital role of strong drug-polymer intermolecular interactions evolving among the ASD components. Overall, the impression of the complexity of in situ cross-linked ASDs has been reinforced with the excessive variation of parameters investigated in the current study, offering thus insights up to the submolecular level to lay the groundwork and foundations for the comprehensive assessment of a new emerging class of HDL amorphous API formulations.

PAA/nHAp was synthesized by solvent casting method and characterized by different techniques. nHAp was homogeneously dispersed in nano-sized in PAA matrix. The thermal properties and glass transiti...

In this study, it was investigated experimentally the influence of various solvents (distilled water and ethanol) on the solution properties, spinning performance, and fibre morphology of the electro spun Poly (acrylic acid) nanofibers. Firstly, polymer solutions were prepared at 5 wt % PAA with various solvent ratios of ethanol and distilled water. Then, solution properties such as viscosity, density, pH, conductivity, and surface tension were determined. The production of nanofiber samples was carried out by electrospinning under the optimum process parameters (voltage, distance between electrodes, feed rate, and atmospheric conditions). Finally, the morphological characterization of the nanofiber surface was carried out with SEM. According to the results, it was observed that conductivity, surface tension and the density of the solution increase as the ethanol ratio decreases. On the other hand, pH value increases as the ethanol ratio increases and, so, the acidic value of the solutions decreases. The viscosity increased until the ethanol/distilled water ratio was 50/50 and then decreased as the ethanol percentage decreased to under 50%. In addition, average fibre diameter decreases with ethanol ratio decreases. It is possible to say that solvent type affects solution properties, fibre morphology and spinning performance significantly. Generally, fine, uniform and bead free nanofibers could be electro spun and the PAA solution containing 70 wt % distilled water and 30 wt % ethanol was selected as the optimum in terms of fibre morphology, web quality and spinning performance.

Ionic liquid (IL)-decorated copolymers based on poly((ethylene glycol) methyl ether methacrylate)-co-(acrylic acid)-co-(1-vinyl-3-ethylimidazolium hexafluorophosphate) were prepared and used as bin...

Using N-isopropylacrylamide (NIPAM) and acrylic acid (AAc) as monomers, N,N′-methylenebisacrylamide (MBA) as a cross-linking agent, and molybdenum disulfide (MoS2) as functional particles, a P(NIPAM-co-AAc)/MoS2 composite hydrogel was prepared by free radical polymerization initiated by ultraviolet light. The results of Fourier transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy show that MoS2 has been successfully introduced into the P(NIPAM-co-AAc) system, and the obtained composite hydrogel has a porous network structure. Studies on the swelling property and dye adsorption performance show that the addition of MoS2 can increase the swelling ratio of P(NIPAM-co-AAc) hydrogels to a certain extent and can significantly improve the ability of the P(NIPAM-co-AAc) hydrogel to adsorb methylene blue (MB). The adsorption process of MB by the composite hydrogels conforms to the pseudo-second-order kinetics and the Langmuir isotherm adsorption models. The estimated equilibrium adsorption capacity (Qm) using the Langmuir isotherm model can reach 1258 mg/g, mainly due to the electrostatic interaction between the negatively charged groups −COO– and MoS2 particles on the network structure and the positively charged dye MB. The adsorption of MB by P(NIPAM-co-AAc)/MoS2 composite hydrogels depends on the temperature during adsorption. Compared with room temperature, a high temperature of 40 °C above the poly(N-isopropylacrylamide) (PNIPAM) phase transition temperature (∼32 °C) leads to a decreased adsorption capacity of the P(NIPAM-co-AAc)/MoS2 composite hydrogel for MB due to the enhanced hydrophobic properties of the network structure and the decrease of the swelling ratio. The prepared hydrogel material can be used as a good adsorbent for dyes, which is promising in wastewater treatment.

The fast development of Pickering emulsion systems inspires burgeoning demand on the universal synthesis platform for the surface modification of solid particle emulsifiers. In this work, a mild and convenient “visible light–mediated surface grafting through (VSGT)” strategy is proposed. Through the two-step strategy, silica nanoparticles (SNPs) were firstly modified by vinyl alkoxysilane and then used as the substrate for grafting homopolymer brushes via reversible addition-fragmentation chain transfer polymerization under the irradiation of a compact fluorescent lamp (CFL) light source. The whole process was proceeded at room temperature without tedious conditions and complex operations. Importantly, simply by changing the monomer types, hydrophilic acrylic polymer chains can all be grafted on SNP with controlled chain length and relatively uniform high surface densities including poly(acrylic acid) (PAA), poly(N,N-dimethylacrylamide) (PDMA), poly(N-isopropylacrylamide) (PNIPAM), and poly(diacetone acrylamide) (PDAAM). Through the synthesis platform, the interfacial performance of the surface-grafted nanoparticles exhibited as amendable working as Pickering emulsifiers in oil–water system, illustrated by the evolution of interfacial tensions and the inner structures of the corresponding Pickering emulsions. Moreover, the emulsion stabilized by SNP-g-PAA and SNP-g-PNIPAM showed pH and temperature triggered emulsification-demulsification behaviors, respectively, convincing the contribution of the surface grafted polymers and provide a feasible clue for the subtle design on the interfacial texture in advanced Pickering emulsions.

The thermal decomposition of polyethylene glycol fumarate–acrylic acid copolymer is investigated at different rates of heating. It is shown that increasing the rate of heating raises the temperature of the onset of decomposition. The kinetic parameters of decomposition are calculated using the integral Kissinger–Akahira–Sunose procedure. It is found that at different degrees of conversion, the activation energies are very close: E = 205–227 kJ/mol. The effect the composition of the copolymer has on the results from kinetic calculations is shown. The Coates–Redfern approach is used to determine the pre-exponential factor and the model of thermal decomposition. Calculated thermogravimetric curves are constructed and compared to experimental ones.

Swelling is one of the distinct properties and a significant parameter in the characterization of the crosslinked hydrogels. Swelling investigation at different temperatures was conducted for the produced hydrogel of chitosan grafted acrylamide/acrylic acid. Peleg’s model is a two parameters model, which can be used to describe the absorption of water or swelling. The data show that the swelling degree increases with temperature until it reaches 60°C, after which it decreases as the temperature rises higher. At RT, 30, 40, 60, and 80 °C, the swelling degree values of 1.4, 1.5,1.4, 2.3 and 0.7 g water/g dry hydrogel were observed after 8 hours. The applied models provided a good agreement with the experimental data with high values of the coefficient of determination (𝑅2). The observed F values and the standard error indicate the validity of the proposed model to describe the swelling of hydrogel at different temperatures. The swelling rate and swelling degree can be expressed using a 4th degree polynomial. It was concluded that the exponential association equation model represents swelling characteristics better than the others.

Based on the abundant and low-cost zinc-based acrylate resins, C/ZnO composites were fabricated via one-step carbonization at 700 °C in a N2 atmosphere for 2 h. Zinc-based acrylate resins, which were synthesized by free-radical polymerization of butyl acrylate (BA), acrylic acid (AA) and vinyl acetate (VAc) and dehydration condensation of Zn(OH)2, provided a common source for carbon and ZnO. These materials demonstrate enhanced electromagnetic wave absorption (EMWA) behavior with tunable microwave absorption bands at 2–18 GHz, which is related to the molar ratio (mol%) of Zn(OH)2 to acrylate monomers in zinc-based acrylate resins. Remarkably, the 0.11 mol% C/ZnO composite exhibits outstanding absorption properties: the minimum reflection loss (RLmin) at 16.7 wt% loading of −34.66 dB is observed at 3.0 mm and 10.32 GHz, and an RLmin of −24.83 dB is observed at a small thickness of 1.5 mm with an effective absorption bandwidth (EAB) of 3.61 GHz. Moreover, the EAB (RL ≤ −10 dB) from the C band to Ku band is achieved by simply adjusting the thickness of the absorbers, which are superior to the other hybrids of organic carbon and ZnO. These results provide a new strategy for the preparation of carbon-based composites containing metal oxides and their application in high-performance microwave absorption.

The aim of this study was to optimize the preparation method of polymethyl methacrylate (PMMA) denture base loaded with nano silver (NAg), to more effectively and safely impart sustainable antibacterial functions. NAg solution was synthetized and mixed with acrylic acid and methyl methyacrylate (MMA) monomer in order to prepare a new type of NAg solution (NS)/polymer methyl methacrylate denture base specimens (NS/PMMA). The surface morphology, mechanical strength, antimicrobial activity, anti-aging performance, cytotoxicity and biocompatibility of NS/PMMA denture base were evaluated in comparison with specimens fabricated using traditional NAg adding methods and NAg-free denture base. The aesthetic characteristics and mechanical strength of NS/PMMA denture base met the clinical application requirements. Meanwhile, NS/PMMA denture base showed better antibacterial activity, anti-aging properties, no cytotoxicity and displayed exceptional biocompatibility. NS/PMMA denture base thus has great potential for clinical application.

In this study, a quad acrylic copolymer composed of four monomers namely acrylic acid, methacrylic acid, butyl acrylate, and methyl methacrylate/cloisite30B(C30B) nanocomposites with different load...

Cr, Fe, Ce and W doped MoVTeNbO M2 phase catalysts were synthesized and used in the selective oxidation of propylene to acrylic acid (AA). Results show that the introduction of Cr, Fe, Ce and W substantially affects the physicochemical properties and catalytic performance of MoVTeNbO-based catalysts. Un-doped catalyst consists of M2 phase and TeO2, while Cr, Fe, Ce and W-doped catalysts are mainly composed of M2 and MoO3. It is indicated that doping of Cr, Fe, Ce and W can restrain the formation of TeO2, but favour the formation of MoO3. Un-doped, Cr and W-doped catalysts display irregular-shaped particles morphology, while Fe and Ce-doped catalysts display nanosheets morphology. In addition, the valence of superficial elements of catalysts changed greatly with the doping elements. For catalytic performance, in addition to Cr, the propylene conversion of the catalyst decreases obviously with doping of other elements, probably due to the drastically reduced specific surface area with doping of Fe, Ce and W. The existence of Cr and Ce can increase the selectivity to AA at all test temperatures (360–440 ℃), while Fe and W-doped catalysts only show higher selectivity than the un-doped one at high temperature of 420 and 440 ℃. It is illustrated that the catalysts with redox ability at relatively low temperature is more favorable for the selectivity to AA. Among them, Cr-doped catalyst shows the highest selectivity (85.3%) and yield (63.5%) of AA at test temperature of 380 ℃, which are 15.3 and 7.5% higher than that of un-doped catalyst, respectively. The M2 phase MoVTeNbO catalysts doped with Cr, Fe, Ce and W have been synthesized. It is demonstrated that the addition of Cr improves the stability of Te4+, and Cr-doped M2 phase shows excellent catalytic performance in the selective oxidation of propylene to acrylic acid.

Wearable solar radiation sensors based on ionic hydrogels are facilely prepared to simultaneously monitor the radiation dose for the production of vitamin D and the prevention of sunburn. Tetramethylethylenediamine (TEMED) is neutralized with acrylic acid (AA) to obtain tetramethylethylenediamine acrylate (TEMEDA), which is further polymerized with acrylamide by a free radical reaction. By simply adding MB or NR during the polymerization, the final obtained ionic hydrogels can indicate solar radiation. Due to the extent of discoloration, the discoloration speed of MB and NR is correlated to the radiation dose. This wearable sensor can indicate the solar radiation dose required by the human body to synthesize vitamin D through the discoloration of the ionized hydrogel of MB, whereas those with NR are able to illustrate the threshold of radiation dose that causes potential skin hurt. Therefore, the benefit and drawback of solar radiation can be well balanced by optimizing the exposure time to solar irradiation. In addition, polyurethane cross-linked with a thermoresponsive coating is used as band for this wearable sensor. Due to the hydrophilicity below its transition temperature, the cross-linked band possesses the easy cleaning capability of stains after the daily wear. Such type of wearable sensor can be broadly used for monitoring the solar radiation, especially in outdoor activities.

The volume change and shuttle effect of sulfur are detrimental to the stability and electrochemical performance of the sulfur cathode in lithium–sulfur (Li–S) batteries. In this study, a triple cro...

In this manuscript, self-healing nanocomposite hydrogels were successfully fabricated with nanocomposite materials based on functional cellulose nanocrystals (CNCs). CNCs were firstly extracted from microcrystalline cellulose by a typical and eco-friendly method with choline chloride and oxalic acid dihydrate as deep eutectic solvents. Well-defined poly(glycidyl methacrylate) (PGMA) was further grafted on the surface of CNCs by surface-initiated activator generated by electron transfer atom transfer radical polymerization. After ring-opening reaction of PGMA, CNCs@PGMA-OL nanocomposites with diol functional group were successfully obtained and further implanted into poly(acrylic acid)/guar gum-based self-healing hydrogels by multiple reversible weak interactions. These nanocomposite hydrogels display outstanding self-healing and mechanical strength properties, providing a facile strategy for the design and development CNC-based functional materials.

In this research, the MgO nanoparticles were incorporated into (acrylic acid /polyvinyl alcohol) PAA/PVA hydrogel by using gamma radiation technique at a dose rate of 1.9 kGy/k. The unique properties of MgO nanoparticles as structure, active surface properties, and stability make such nanoparticles have considerable potential as antimicrobial agents in food applications. In spite of known antibacterial activity of MgO NPs, the mechanism of metal oxide nanoparticle action on bacteria is complicated and not fully understood. The PAA/PVA system was mixed with various contents of MgO nanoparticles to prepare its MgO nanocomposite hydrogels. The morphology of the PAA/PVA copolymer hydrogels and their MgO nanocomposites hydrogels was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to prove the surface, bulk change, size, and the formation of MgO nanoparticles. TEM measurement estimated that the average particle size of prepared MgO NPs was 7.13 nm. The swelling properties of the various AAc hydrogels and its MgO nanocomposites hydrogels were also studied. The prepared acrylic acid copolymers and their MgO nanocomposites were examined for applicability as antibacterial material, and the results revealed that hydrogels and MgO nanocomposites hydrogels prepared in this study have higher antibacterial activity toward Staphylococus Aureus (S.a.) than Escherichia Coli (E. Coli). The discovery of novel and efficient nanocomposites may have a potential therapeutic role.

Loading and release behavior of a cationic dye, namely, safranine-T, through layer-by-layer (LbL) multilayered films of poly(diallyldimethylammonium chloride) (PDADMAC) and single/blend anionic polyelectrolytes (PEs), namely, poly(acrylic acid) (PAA), and poly(styrenesulfonate) (PSS), are described. The growths of PDADMAC/PSS-PAA multilayers and their safranine-T sorption behavior are monitored using the UV-Vis technique and discussed in terms of blend composition of anionic PEs and pH as well as their hydrophilicity and topography. The dye loading and desorption properties of the LbL films prepared from single/blend negatively charged PEs mainly depend on the interactions of PEs and safranine T. Strong interactions between PSS and safranine T result in a higher dye entrapping inside LbL films whereas either PAA-rich or single PAA-based LbL film exhibits larger dye desorption. A higher PSS content in the feed blend composition leads to an observable increase in theta(ave) and surface roughness whereas the use of PAA can yield a flatter surface due to its partially recomposed chain conformational structure at pH 11. Consequently, LbL multilayers obtained from single and blend polyanions can be considered as an encouraging material platform for the controlled release of charged species such as protein, drug, and dye. because of their tunable physicochemical and morphological properties as well as surface wettability.

Nowadays, hydrogels have been attracted a lot of interest due to their immense potential in different fields such as biomedicine and biotechnology. Biodegradable and biocompatible pH-sensitive chitosan-grafted polyacrylic acid (CTS-g-PAA) hydrogel was synthesized by grafting an acrylic acid monomer onto chitosan at the presence of methylene bisacrylamide as a cross-linking agent and ammonium persulphate as an initiator. FT-IR spectroscopy and scanning electron microscopy (SEM) were used to analyze the properties of the obtained hydrogel. The synthesized hydrogel is suitable for the delivery of many hydrophilic drugs or species. Using a multi-walled carbon nanotube modified-glassy carbon electrode (CNT-GCE), the loading and release conditions of Nile Blue (NB) as an electroactive compound were evaluated utilizing the differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The effect of various parameters on the electrochemical signal of NB was investigated, and the optimal conditions for the efficient performance of hydrogel to delivery of NB were obtained. The electrocatalytic current values show linear dependence to NB concentration in the range of 0.098 – 0.971 μM while the detection limit of this electrochemical platform was 12.3 nM. The unique proposed hydrogel with the electroactive NB has a broad range of possible applications in biosensors for signal enhancement and bioanalysis. Supplementary Information The online version contains supplementary material available at 10.1007/s10854-021-06939-7.

Chitosan graft poly(acrylic acid)/graphite oxide/attapulgite (CTS-g-PAA/GO/APT) composite hydrogel has been synthesized and used to remove rhodamine B (RB) and methyl orange (MO) from aqueous solutions through adsorption. The composite is characterized by infrared spectroscopy (IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The influence of adsorption conditions, i.e., the content of graphite oxide (GO) and attapulgite (ATP), the initial concentration of dye solutions, the adsorption time, ionic strength, pH values and dosage of the composite, on the adsorption capacities has been studied in detail. It is found that small amount of GO and ATP can improve the adsorption capacities of dyes significantly. Adsorption capacities of RB and MO onto CTS-g-PAA graft copolymer are 36.7 and 56.4 mg/g, respectively, while those onto CTS-g-PAA/GO/APT (GO 0.02 g, APT 0.05 g) composite hydrogel are 92.6 and 186.5 mg/g, respectively. Adsorption isotherms and thermodynamics are discussed. It indicates that the adsorption of RB is in accordance with both the Langmuir and R-P isotherm equations. However, that of MO meets the R-P equation. The adsorption of RB is spontaneous, while that of MO is not. Kinetic studies show that the adsorption of both RB and MO is in accordance with the Lagergren pseudo first-order kinetic model.