Monomer Concentration Research Articles

A Theoretical Investigation of the Polyaddition of an AB2+A2+B4 Monomer Mixture.

Hyperbranched polymers (HBPs) are widely applied nowadays as functional materials for biomedicine needs, nonlinear optics, organic semiconductors, etc. One of the effective and promising ways to synthesize HBPs is a polyaddition of AB2+A2+B4 monomers that is generated in the A2+CB2, AA'+B3, A2+B'B2, and A2+C2+B3 systems or using other approaches. It is clear that all the foundational features of HBPs that are manufactured by a polyaddition reaction are defined by the component composition of the monomer mixture. For this reason, we have designed a structural kinetic model of AB2+A2+B4 monomer mixture polyaddition which makes it possible to predict the impact of the monomer mixture's composition on the molecular weight characteristics of hyperbranched polymers (number average (DPn) and weight average (DPw) degree of polymerization), as well as the degree of branching (DB) and gel point (pg). The suggested model also considers the possibility of a positive or negative substitution effect during polyaddition. The change in the macromolecule parameters of HBPs formed by polyaddition of AB2+A2+B4 monomers is described as an infinite system of kinetic equations. The solution for the equation system was found using the method of generating functions. The impact of both the component's composition and the substitution effect during the polyaddition of AB2+A2+B4 monomers on structural and molecular weight HBP characteristics was investigated. The suggested model is fairly versatile; it makes it possible to describe every possible case of polyaddition with various monomer combinations, such as A2+AB2, AB2+B4, AB2, or A2+B4. The influence of each monomer type on the main characteristics of hyperbranched polymers that are obtained by the polyaddition of AB2+A2+B4 monomers has been investigated. Based on the results obtained, an empirical formula was proposed to estimate the pg = pA during the polyaddition of an AB2+A2+B4 monomer mixture: pg = pA = (-0.53([B]0/[A]0)1/2 + 0.78)υAB2 + (1/3)1/2([B]0/[A]0)1/2, where (1/3)1/2([B]0/[A]0)1/2 is the Flory equation for the A2+B4 polyaddition, [A]0 and [B]0 are the A and B group concentration from A2 and B4, respectively, and υAB2 is the mole fraction of the AB2 monomer in the mixture. The equation obtained allows us to accurately predict the pg value, with an AB2 monomer content of up to 80%.

Effect of Synthesis Temperature on Adsorbent Performance of Blending Anionic and Cationic Gels in Divalent Metal Ions Adsorption

In this study, the anionic and cationic gels were synthesized separately using copolymerization between N-isopropylacrylamide (NIPAM) and acrylic acid or chitosan through a polymerization reaction using N,N'-methylenebisacrylamide (MBAA) as a cross-linker with various monomer concentrations and synthesis temperature. The anionic and cationic gels were blended to minimize inter-intra particle association and to improve the adsorption ability. The FTIR analysis found that the synthesis of the NIPAM-co-acrylic acid and NIPAM-co-chitosan gels was successfully carried out, indicating no presence of a vinyl group in the functional group. The result showed that the ion adsorption amount of Pb2+ ions blending gels increased significantly, almost twice compared to the adsorption before blending. The adsorption amount of Pb2+ ions increased with increasing the gel synthesis temperature. The adsorption amount follows the order of Pb2+ > Fe2+ > Ni2+. The adsorption amount of Pb2+ tends to decrease with increasing sedimentation volume. The higher the synthesis temperature, the larger the porous diameter formed. These results demonstrate that blending gel of NIPAM-co-chitosan and NIPAM-co-acrylic acid is a feasible alternative for removing heavy metal ions owing to its good adsorption performance.

Preparation of Low-Molecular-Weight Polyacrylamide as the Delayed Crosslinking Plugging Agent for Drilling Fluid.

Deep wells and ultra-deep wells often encounter cracks, karst caves, and other developed strata, which can lead to leakage during drilling. Conventional bridge slurry plugging technology is prone to leaking due to the poor plugging effect of the plugging agent. The gel plugging agent possesses characteristics of flexible plugging and adaptive matching of formation leakage channels. It can fill cracks or caves and enhance the pressure-bearing capacity of the formation. A controllable crosslinking plugging agent based on low-molecular-weight polyacrylamide was studied. Polyacrylamide with different molecular weights is synthesized from acrylamide and an initiator. A crosslinking time-controllable polymer is synthesized from low-molecular-weight polyacrylamide by adding crosslinking agent and retarder. The low-molecular-weight polyacrylamide plugging agent has low viscosity before gelation and good fluidity in the wellbore. After being configured on the ground, it is transported by pipeline and sent underground to reach the thickening condition. The gel solution rapidly solidifies, and its strength improves after high-temperature crosslinking. The synthesis conditions of the polymer were as follows: a monomer concentration of 9%, initiator 3.5%, synthesis temperature of 65 °C, and hydrogen peroxide initiator. The optimal formula of the gel plugging agent is as follows: a polymer concentration of 6%, a crosslinking agent concentration of 1%, and a retarder concentration of 8%. The generated polymer molecular structure contains amide groups. This crosslinking time-controllable plugging agent based on low-molecular-weight polyacrylamide has stable rheology, and its temperature resistance can reach 150 °C. At 150 °C, the gelation time can be controlled by adjusting the concentration of retarder, and the longest can reach 4 h. The plugging efficiency of the gel plugging agent is more than 95%. With the increase in seam width, the pressure of the gel plugging agent gradually decreases.

The Effects of Excipients on Freeze-dried Monoclonal Antibody Formulation Degradation and Sub-Visible Particle Formation during Shaking.

We previously reported an unexpected phenomenon that shaking stress could cause more protein degradation in freeze-dried monoclonal antibody (mAb) formulations than liquid ones (J Pharm Sci, 2022, 2134). The main purposes of the present study were to investigate the effects of shaking stress on protein degradation and sub-visible particle (SbVP) formation in freeze-dried mAb formulations, and to analyze the factors influencing protein degradation during production and transportation. The aggregation behavior of mAb-X formulations during production and transportation was simulated by shaking at a rate of 300rpm at 25°C for 24h. The contents of particles and monomers were analyzed by micro-flow imaging, dynamic light scattering, size exclusion chromatography, and ultraviolet - visible (UV-Vis) spectroscopy to compare the protective effects of excipients on the aggregation of mAb-X. Shaking stress could cause protein degradation in freeze-dried mAb-X formulations, while surfactant, appropriate pH, polyol mannitol, and high protein concentration could impact SbVP generation. Water content had little effect on freeze-dried protein degradation during shaking, as far as the water content was controlled in the acceptable range as recommended by mainstream pharmacopoeias (i.e., less than 3%). Shaking stress can reduce the physical stability of freeze-dried mAb formulations, and the addition of surfactants, polyol mannitol, and a high protein concentration have protective effects against the degradation of model mAb formulations induced by shaking stress. The experimental results provide new insight for the development of freeze-dried mAb formulations.

Synthesizing cationic polymers and tuning their properties for microalgae harvesting

This study reports a facile technique to synthesize and tune the cationic polymer, poly(3-acrylamidopropyl)trimethylammonium chloride (PAPTAC), in terms of molecular weight and surface change for harvesting three microalgae species (Scenedesmus sp., P.purpureum, and C. vulgaris). The PAPTAC polymer was synthesised by UV-induced free-radical polymerisation. Polymer tuning was demonstrated by regulating the monomer concentration (60 to 360 mg/mL) and UV power (36 and 60 W) for polymerisation. The obtained PAPTAC polymer was evaluated for harvesting three different microalgae species and compared to a commercially available polymer. The highest flocculation efficiency for Scenedesmus sp. and P. purpureum was observed at a dosage of 25 mg-polymer/g of dry biomass by using PAPTAC-90, resulting in higher flocculation efficiency than the commercial polymer. Results in this study show evidence of effective neutralisation of the negative charge surface of microalgae cells by the produced cationic PAPTAC polymer and polymer bridging for effective flocculation. The obtained PAPTAC polymer was less effective for harvesting C. vulgaris, possibly due to other factors such as cell morphology and composition of extracellular polymeric substances of at the cell membrane that may also influence harvesting performance.

Free radical graft polymerization of hydroxyethyl methacrylate and acrylic acid on polyetherimide membrane surface via redox system to improve anti-fouling and oil resistance performance

In this paper, a new scheme of graft polymerization of acrylic acid (AA) and hydroxyethyl methacrylate (HEMA) initiated by the generation of free radicals in a redox system was used to modify the surface of polyetherimide (PEI) membranes and to improve the antifouling and oil resistance properties. Various physicochemical characterization techniques (ATR-FTIR, XPS, TG, SEM, AFM, etc.) confirmed the successful grafting of hydrophilic monomers onto the PEI membrane surface. Further, the effects of different monomer concentrations on graft density, permeation separation, contamination resistance, and mechanical properties were investigated. Both PEI-g-PAA and PEI-g-PHEMA showed better hydrophilicity (WCA decreased from 60° in PEI to 33° and 45°, respectively), efficient separation (75–84%) in oil-containing wastewater filtration tests with methyl tert-butyl ether (MTBE) and petroleum ether with a slight decrease in mechanical strength. In addition, bovine serum albumin (BSA) and MTBE were selected as contaminants to examine the antifouling properties. Compared to the flux recovery rate (FRR) of 75% for the original PEI membranes, the grafted membranes almost wholly recovered the permeate flux with a simple backwash of ultrapure water. In summary, the results of the above study suggest the development of a novel and simple preparation strategy for surface grafting modification of PEI membranes, which will facilitate the subsequent research of PEI materials in membrane development, and the resulting grafted membranes will be of developmental and exploratory value in the field of oil and water treatment.

Extracellular Matrix Stiffness Induces Mitochondrial Morphological Heterogeneity via AMPK Activation

To investigate the mechanical responses of mitochondrial morphology to extracellular matrix stiffness in human mesenchymal stem cells (hMSCs) and the role of AMP-activated protein kinase (AMPK) in the regulation of mitochondrial mechanoresponses. Two polyacrylamide (PAAm) hydrogels, a soft one with a Young's modulus of 1 kPa and a stiff one of 20 kPa, were prepared by changing the monomer concentrations of acrylamide and bis-acrylamide. Then, hMSCs were cultured on the soft and stiff PAAm hydrogels and changes in mitochondrial morphology were observed using a laser confocal microscope. Western blot was performed to determine the expression and activation of AMPK, a protein associated with mitochondrial homeostasis. Furthermore, the activation of AMPK was regulated on the soft and stiff matrixes by AMPK activator A-769662 and the inhibitor Compound C, respectively, to observe the morphological changes of mitochondria. The morphology of the mitochondria in hMSCs showed heterogeneity when there was a change in gel stiffness. On the 1 kPa soft matrix, 74% mitochondria exhibited a dense, elongated filamentous network structure, while on the 20 kPa stiff matrix, up to 63.3% mitochondria were fragmented or punctate and were sparsely distributed. Western blot results revealed that the phosphorylated AMPK (p-AMPK)/AMPK ratio on the stiff matrix was 1.6 times as high as that on the soft one. Immunofluorescence assay results revealed that the expression of p-AMPK was elevated on the hard matrix and showed nuclear localization, which indicated that the activation of intracellular AMPK increased continuously along with the increase in extracellular matrix stiffness. When the hMSCs on the soft matrix were treated with A-769662, an AMPK activator, the mitochondria transitioned from a filamentous network morphology to a fragmented morphology, with the ratio of filamentous network decreasing from 74% to 9.5%. Additionally, AMPK inhibition with Compound C promoted mitochondrial fusion on the stiff matrix and significantly reduced the generation of punctate mitochondria. Extracellular matrix stiffness regulates mitochondrial morphology in hMSCs through the activation of AMPK. Stiff matrix promotes the AMPK activation, resulting in mitochondrial fission and the subsequent fragmentation of mitochondria. The impact of matrix stiffness on mitochondrial morphology can be reversed by altering the level of AMPK phosphorylation.

Insights on the chlorine resistance of polyester composite nanofiltration membranes

The use of chlorine as a pretreatment of water treatment and desalination processes causes a loss in performance and lifespan of the membranes usually employed in these processes. Polyester (PE) membranes have been proposed as an alternative due to the absence of amidic hydrogen; however, fabricating PE composite membranes with equivalent performance and high tolerance towards chlorine has proven challenging. In this work, we evaluate the effects of monomer concentration and blends, proton scavenger, surfactant concentration, reaction time and temperature on interfacial polymerization (IP) of trimesoyl chloride and resorcinol. Reaction temperature was the most crucial factor to achieve a PE coating film with high crosslinking degree (XD), high divalent rejection and excellent chlorine tolerance. The resorcinol membrane showed a Na2SO4 rejection of >90 % before and after 6000 ppmh-Cl2 at pH 7. XPS analysis showed that chlorination of PE membranes resulted in loss of CC bonds and increase in C–C and C–O bonds. At high crosslinking degrees, the changes caused by chlorine were minimal. Based on the characterization and the performance of the chlorinated membranes, ring chlorination followed by ring hydrolysis is the proposed mechanism for degradation of lower XD membranes.

Dual-responsive silicone films loaded with silver particles for potential biomedical applications

Silicone is one of the most widely used polymers in biomedicine because of its versatile use in medical products; it can be modified to improve their properties with potential use in biomedicine. In this research, silicone films were modified by a one-step grafting reaction of N-isopropylacrylamide (NIPAAm) and acrylic acid (AAc) initiated by azobisisobutyronitrile (AIBN) and gamma radiation from a Co-60 source. Variables such as temperature, solvent, reaction time, monomer concentration, dose, and amount of AIBN were studied to determine its influence on the graft. The modified films were characterized by infrared spectroscopy (FTIR-ATR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM-EDS), mechanical tests, and physicochemical studies to determine critical pH and Lower Critical Solution Temperature (LCST). Given the incorporation of the monomers, the synthesis and loading of Ag particles was carried out, through a reaction in water without reducing agents. Finally, the antimicrobial activity of the films synthesized by both methods and loaded with silver was evaluated against S. aureus and E. coli bacteria confirming their in vitro effectiveness.Silicone, acrylic acid, N-isopropylacrylamide, grafting, gamma radiation, silver particles.

Synthesis of Vinyl-Containing Polydimethylsiloxane in An Active Medium.

This research deals with the synthesis of copoly(methylvinyl)(dimethyl)siloxanes by the copolycondensation of dimethyldiethoxy- and methylvinyldimethoxysilane in an active medium, followed by thermal condensation in a vacuum. We achieved a range of copolymers exhibiting finely tuned molecular weights spanning between 1500 and 20,000 with regulated functional methylvinylsiloxane units. Analysis of the microstructure showed that the copolymerization predominantly formed products demonstrating a random distribution of units (R~1). However, an increase in the content of vinyl-containing monomers increases the R parameter, indicating an enhanced tendency towards alternating linkages within the copolymer matrix.

Surface functionalization of synthesized sodium alginate from brown algae for maximizing the yield of re-refined used lubricating oil using extraction-flocculation–an environment-friendly approach

This study aims at efficient, economically feasible, and environmentally friendly regeneration of waste lubricant by surface-functionalized bio flocculant via extractive-flocculative technique for maximization of yield. Further, optimization has also been escalated for designing the optimal process parameters (such as reaction time, solvent to waste oil ratio, and bio-flocculant concentration) for enhancing the quality and cost effectiveness of the regenerated product. FTIR, SEM, and TGA analysis were used to characterize the synthesized bio-flocculant. GC-MS, FTIR, and NMR analysis were used to characterize the chemical composition, chemical nature, and functional group of virgin, used, and re-refined lubricant. Experimental findings showed that a grafting efficacy of 76% can be achieved with optimal conditions of reaction temperature of 70 °C, irradiation time of 6 min, 2.5 wt. % monomer concentration and 800 W microwave radiation. Maximum yield of 94% can be obtained with optimal process constraints such as reaction time of 60 min, refining temperature of 80 °C, the ratio of solvent and waste oil of 3:1 g/g and 1 g/kg of solvent flocculant dosage, grafting % of 76. Fuel characterization studies reveal that the fuel characteristics of re-refined lubricant are analogous to those of fresh oil.

Effect of Ethanol Addition on some Properties of Self-Polymerized Acrylic Resins

Background: Self-polymerized acrylic resins are widely utilized in dentistry. A higher residual monomer content is seen after polymerization of denture base resins. The literature showed that the ethanol solvent could rise the leaching of residual monomer from the polymer. The purpose of the current research was to investigate the influence of ethanol addition on hardness and roughness of acrylic resins. Materials and Methods: Sixty acrylic resin specimens were prepared and were divided into 2 main sets due to the kind of test used (surface hardness and surface roughness). There were three groups according to the ethanol concentrations. The first group was the control specimens with no ethanol, the second group was loaded with 10 ml of ethanol; and the third group was loaded with 15 ml of ethanol. The acrylic specimens were measured using the Shore A Durometer hardness and the surface roughness tester. Results: showed that the addition of ethanol significantly decrease the surface hardness of acrylic resins. The results indicated that there are significant differences between groups (P< 0.0010). However, no significant differences between 10ml and 15 ml groups (P>0.05). For surface roughness test, no significant differences were found among the studied groups (P>0.05). Conclusions: The addition of ethanol to self-polymerized acrylic resins would significantly decrease the hardness and increases the surface roughness of acrylic resins

Effect of Ethanol Addition on some Properties of Self-Polymerized Acrylic Resins

Background: Self-polymerized acrylic resins are widely utilized in dentistry. A higher residual monomer content is seen after polymerization of denture base resins. The literature showed that the ethanol solvent could rise the leaching of residual monomer from the polymer. The purpose of the current research was to investigate the influence of ethanol addition on hardness and roughness of acrylic resins. Materials and Methods: Sixty acrylic resin specimens were prepared and were divided into 2 main sets due to the kind of test used (surface hardness and surface roughness). There were three groups according to the ethanol concentrations. The first group was the control specimens with no ethanol, the second group was loaded with 10 ml of ethanol; and the third group was loaded with 15 ml of ethanol. The acrylic specimens were measured using the Shore A Durometer hardness and the surface roughness tester. Results: showed that the addition of ethanol significantly decrease the surface hardness of acrylic resins. The results indicated that there are significant differences between groups (P< 0.0010). However, no significant differences between 10ml and 15 ml groups (P>0.05). For surface roughness test, no significant differences were found among the studied groups (P>0.05). Conclusions: The addition of ethanol to self-polymerized acrylic resins would significantly decrease the hardness and increases the surface roughness of acrylic resins

Hybridization of PPy/C toward high capacity and stability for sodium-ion batteries

Hybrid composites are widely regarded as the most promising choice for anode material in sodium-ion batteries. However, integrating high capacity and excellent cyclic stability into composites remains challenging. This work demonstrates a thin-liquid-layer polymerization approach to fabricate an integrated porous polypyrrole/carbon composite (PPy/C) for a high-performance sodium storage anode. By adjusting the monomer concentration reasonably and combining with heterostructure engineering, the optimized PPy/C was used as the anode for sodium-ion batteries, achieving rapid electrochemical kinetics and satisfactory reversible capacity. The reaction mechanism between PPy and Na+ in the Faraday reaction was revealed by ex-situ electrochemical impedance spectroscopy (EIS). DFT calculations illustrate that the synergistic effect between porous carbon and PPy can regulate the electron transfer mode around Na atoms, which contributes to anchoring Na in the PPy/C composite structure. Moreover, the PPy/C offers an ultrahigh capacity of 552 mA h g−1 at 0.1 A g−1 and a capacity retention rate of 86.5 % after 200 cycles. A full cell assembled with PPy/C and Na3V2(PO4)3 demonstrates a high energy density of 243.1 W h kg–1 at 125 W kg−1 power density. This work would offer valuable thought for advancing the practical application of conductive polymer/carbon composites.

Agglomeration behavior and mechanism of polybutadiene latex by nanocomposite emulsion particles

Polymer agglomeration method is an efficient way to enlarge the particle size of polybutadiene latex (PBL). However, thus far, the particle size of polymer agglomerating agent and agglomerated PBL could not been accurately regulated, and there is a lack of investigation of agglomeration mechanism. Herein, an efficient way for regulating the particle size of the agglomerating agent and PBL was proposed. It was found that the particle size of agglomerating agents can be obtained in the range of 69 nm to 143 nm by adjusting the monomer content and the amount of α-methacrylic acid in the emulsion polymerization process. Then, the effects of different agglomeration parameters on the particle size of agglomerated PBL were investigated, including the amount, the α-MAA content and the particle size of agglomerating agent, agglomeration temperature and agglomeration time. The results indicated that the particle size of agglomerated PBL first increased and then decreased to a stable state with the increase of the amount of agglomerating agent. This phenomenon was quite different from the results of existing studies, which show that the particle size of agglomerated PBL gradually increases with the increase of the amount of agglomerating agent. According to the investigation of agglomeration process of PBL, the PBL agglomeration mechanism of dispersion-adsorption-coalescence-shrinkage was proposed. This study not only provides theoretical support for the PBL polymer agglomeration process, but also provides a practical way to increase acrylonitrile–butadiene–styrene (ABS) production efficiency.

Adsorption of Cu (II) ions from aquatic environment using pre-irradiated Ethylene Tetrafluoroethylene Film

Although copper (Cu) is a very beneficial metal, having too much of it in the body can cause lung issues, severe anemia, nausea, and vomiting. In order to extract Cu (II) ions from aqueous solution, an adsorbent was constructed in this study employing pre-irradiation grafted Ethylene tetrafluoroethylene (ETFE) film. The grafting method was used to binary monomers of sodium styrene sulfonate (SSS) and acrylic acid (AA), where NaCl served as an additive. The grafted polymer was also subjected to studies of tensile strength, water uptake, surface area extension, Scanning Electron Microscopy (SEM), and Fourier Transform Infrared spectroscopy (FTIR). The adsorption of Cu (II) was investigated with respect to pH, starting metal ion concentrations, contact time, monomer concentrations, and temperature. With 50 kGy of radiation dose, 4% NaCl, and 30% of monomer solution (SSS:AA = 1:2) in water generated the highest graft yield of 470%. The maximum adsorption capacity (412 mg g−1) was discovered with an initial concentration of 2500 mg L−1, a pH of 4.86, and a contact time of 24 h at room temperature (25 ℃). A monolayer adsorption was recommended by the good linking between experimental data and the Langmuir Isotherm Model. The kinetic adsorption data closely fitted with the pseudo-second-order reaction. Due to its increased adsorption capacity and reusability, the synthesized new grafted polymer can be considered an efficient adsorbent for Cu (II) removal from wastewater.

Multifunctional Poly(3,4-ethylenedioxythiophene)/Crystalline Nanofibrous Cellulose Composites for Eco-Friendly and Sustainable Electronics.

Nanocellulose constitutes promising resources for next-generation electronics, particularly when incorporated with conductive polymers due to their abundance, renewability, processability, biodegradability, flexibility, and mechanical performance. In this study, electrically conducting cellulose nanofibers were fabricated through in situ chemical polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT) on the surface of sulfuric acid-treated cellulose nanofibers (SACN). The utilization of highly crystalline SACN extracted from tunicate yielded synergistic effects in PEDOT polymerization for achieving a highly conductive and molecularly uniform coating. Polymerization parameters, such as monomer concentration, molar ratio with oxidants, and temperature, were systematically investigated. High electrical conductivity of up to 57.8 S cm-1 was obtained without utilizing the classical polystyrenesulfonate dopant. The resulting nanocomposite demonstrates the unique advantages of both electrically conductive PEDOT and mechanically robust high-crystalline cellulose nanofibers. As a proof-of-applicational concept, an electrical circuit was drawn with SACN-PEDOT as the conductive ink on flexible paper using a simple commercial extrusion-based printer. Furthermore, the flame-retardant property of SACN-PEDOT was demonstrated owing to the high crystallinity of SACN, effective char formation, and high conductivity of PEDOT. The multifunctional SACN-PEDOT developed in this study shows great promise to be employed in versatile applications as a low-cost, ecofriendly, flexible, and sustainable electrically conductive material.

Tailoring morphology for improved dispersibility of hydrophilic silica nanoparticles to fabricate thin-film nanocomposite membranes

Improving the dispersibility of nanomaterials is a promising approach to enhance the performance of thin-film nanocomposite (TFN) membranes. In this study, hydrophilic nonporous, mesoporous, and dendritic mesoporous silica nanoparticles (NSNs, MSNs, and DMSNs) with a uniform particle size were utilized as aqueous phase additives to prepare TFN membranes through in-situ polymerization. The electrostatic adsorption of nanoparticles increased the concentration of amine monomers on the surface of the polysulfone (PSF) substrate. In collaboration with the steric hindrance effect, nanoparticles restricted the diffusion of piperazine (PIP) into the organic phase to polymerize with the acyl chloride monomers. Compared to TFC-0, the TFN membranes exhibited a rougher surface with increased negative charge and had more channels that facilitated the transportation of water molecules. Among the nanoparticles, DMSNs exhibited excellent dispersibility, ensuring their uniform distribution within the polyamide (PA) matrix. Furthermore, DMSNs possessed an open central-radial pore structure, offering more efficient channels for water molecules to cross the membrane. Therefore, a highly crosslinked, defect-free, and hydrophilic PA layer of TFN-DMSNs was achieved. In the performance characterization, TFN-DMSNs demonstrated a high water/salt permselectivity (A/B) of up to 32.25 bar−1, and exhibited good resistance to acidic/alkaline environments as well as foulants during the operation. This study proposes a novel approach to prepare advanced TFN membranes by optimizing the morphological structure of nanoparticles.

Targeted elimination of molybdenum ions from a leaching solution with the ability of radiated grafting GMA-PAN nanofibers

In this study, electrospun polyacrylonitrile nanofibers were effectively functionalized for enhanced molybdenum ion adsorption through a multi-step approach. Initially, glycidyl methacrylate was grafted onto the nanofibers via irradiation-induced grafting polymerization, followed by chemical modification with various amino groups, with triethylamine identified as the optimal modifier. The impacts of key synthesis parameters and reaction conditions on grafting level and adsorption capacity were thoroughly investigated, with a focus on achieving maximum efficiency. The resulting nanofibers were characterized using FTIR, SEM, and BET techniques, confirming the successful modification and structural features conducive to adsorption. Furthermore, a comprehensive experimental design, incorporating a central composite design, yielded optimal conditions for molybdenum adsorption, with key parameters including monomer concentration, irradiation dose, adsorbent mass, initial concentration, time, pH, temperature, and amine concentration. The adsorption kinetics were effectively described by the pseudo-second-order model, while the Langmuir isotherm model provided valuable insight into the adsorption behavior. Impressively, the adsorbent exhibited exceptional adsorption efficiency, surpassing 98% even after six adsorption–desorption cycles using 0.5 M HCl. Thermodynamic analysis revealed the exothermic nature of the adsorption process, along with decreased entropy and overall spontaneity, underlining the favorable conditions for molybdenum adsorption. Notably, the synthesized adsorbent demonstrated notable selectivity for molybdenum and achieved an impressive adsorption capacity of 109.79 mg/g, highlighting its potential for practical applications in molybdenum removal from aqueous solutions.

Preparation and characterizations of antibacterial poly(methyl methacrylate) bone cement via copolymerization with a quaternary ammonium monomer of dimethylaminotriclosan methacrylate

Poly (methyl methacrylate) (PMMA) bone cement relies on the loaded antibiotic to realize the antibacterial purpose. But the exothermic behavior during setting often makes temperature-sensitive antibiotics inactivated. It is necessary to develop new material candidates to replace antibiotics. In this study, a new quaternary ammonium methacrylate (QAM) monomer called dimethylaminetriclosan methacrylate (DMATCM) was designed by the quaternization between 2-(Dimethylamino)ethyl methacrylate and triclosan, then employed as the modifier to explore the feasibility of equipping bone cement with antibacterial activity, and to investigate the variations on the physical and biological performances brought by the substitution ratio of DMATCM to MMA. Results showed that DMATCM opened its C=C bonding to participate in the MMA polymerization, and the quaternary ammonium group helped it to perform broad-spectrum antibacterial property against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. With an increased substitution ratio of DMATCM to MMA, the glass transition temperatures, the maximum exothermic temperatures, and the contact angles of bone cements declined, but the residual monomer contents, the fluid uptakes, and the setting times under Vical indentation increased. Long-term soaking made almost no changes to the weight loss and the mechanical properties of DMATCM-modified cements with lower substitution ratios of 0∼20%, and the activation rather enhanced the strengths of uncured AMBC-4 and AMBC-5 samples. Owing to more DMATCM exposed on the cement surface, the inhibition ring diameter produced by modified cement was improved to a maximum of 28.09 mm, and MC3T3-E1 cells performed the cell viabilities all beyond 70% and healthy adhesion after 72 h co-culturing. Taking all measured properties and ISO standards into account, the antibacterial bone cement under the ratio of 10% performed better, besides its good bactericidal effect, the other properties satisfied the requirements for clinical application.