Methacrylic Acid Monomer Research Articles

Multi-functional RAFT reagent to prepare fluorescent hyper-branched macromolecular probes for the detection of Fe3+ ions

Reversible addition-fragmentation chain transfer (RAFT) polymerization has the advantages of precise control, high yield, and narrow molecular weight distribution. These merits make it an ideal method for the preparation of hyper-branched fluorescent polymers (FL-HBPs). In this work, a multi-functional RAFT reagent (AVCT-NLP) was prepared for the synthesis of monodisperse FL-HBPs. Firstly, dithionate compound (CN1) containing a CC double bond was synthesized by the reaction of 4-nitrophenol with 1-(bromomethyl)-4-vinylbenzene. Subsequently, the NO2 group on CN1 was reduced to NH2, and the −Br on the 4-bromo-1,8-naphthalic anhydride was substituted to emit fluorescence. Finally, the fluorophore was introduced by the reaction of NH2 with the anhydride on the naphthalene ring to obtain AVCT-NLP which contains fluorophore, dithionate, and CC double bond in one molecule. AVCT-NLP was then used to synthesize the homopolymer (PAVCT-NLP) as both monomer and RAFT reagent. Moreover, PAVCT-NLP served as a macromolecular RAFT reagent, and hydrophilic monomer methacrylic acid (MAA) or 3-butene-1,2-diol were polymerized to obtain amphiphilic hyper-branched polymers (FL-AHBP-1, FL-AHBP-2). All the as-prepared macromolecules (PAVCT-NLP, FL-AHBP-1, and FL-AHBP-2) exhibited specific recognition and high sensitivity for Fe3+. The fluorescence quenching reached up to 74.4 %, with the limit of detection (LOD) as low as 1.82 nM. Additionally, the probe demonstrated pH stability and environmental adaptability. Due to the multi-functional structures of AVCT-NLP, it could be subjected to RAFT polymerization to obtain a monodisperse hyper-branched polymer. All polymers have a high fluorophore density and the polydispersity index (PDI) of the polymer is close to 1.00. This paper provided an effective approach for synthesizing polymer fluorescent probes with versatile structure and fluorescence properties in future applications.

Implementing magnetic molecularly imprinted solid phase extraction to analytical method for determination of 2-phenethylamine in cocoa powder and chocolate by LC-MS/MS system

The main aim of this study was to design, develop, and apply magnetic molecularly imprinted polymer (MMIP) during sample pretreatment before liquid chromatography tandem mass spectrometry (LC-MS/MS) 2-phenylethylamine determination in cocoa powder and chocolate samples. The morphology and structure of MMIP, obtained from methacrylic acid (monomer) and trimethylolpropane trimethacrylate (cross-linker) were characterized using scanning electron microscopy, nitrogen sorption analyses, infra-red spectroscopy, X-ray diffraction measurements, vibrating-sample magnetometry, and thermogravimetry analyses. The analyte adsorption mechanism on MMIP was studied using computational simulation. The magnetic solid phase extraction procedure on MMIP was optimized, resulting in a relative matrix effect of 6.2 % for cocoa powder and 2.8 % for chocolate. The LC-MS/MS quantified the 2-phenethylamine in eighteen cocoa powder and chocolate samples, showing a concentration range between 2.4 and 8.7 μg g−1.

Formulation and In Vitro Assessment of Polymeric pH-Responsive Nanogels of Chitosan for Sustained Delivery of Madecassoside.

Madecassoside, a triterpenoid saponin compound mainly isolated from the gotu kola herb (Centella asiatica), shows an extensive range of biological activities, including antiapoptotic, antioxidant, anti-inflammatory, moisturizing, neuroprotective, and wound healing effects. It has been highly used in the management of eczema, skin wounds, and other diseases. Due to poor oral bioavailability, membrane permeability, and intestinal absorption, the clinical application of the madecassoside is limited. Hence, a drug carrier system is needed that not only sustains the release of the madecassoside but also overcomes the drawbacks associated with its administration. Therefore, the authors prepared novel pH-responsive chitosan-based nanogels for the sustained release of madecassoside. Free radical polymerization technique was used for cross-linking of polymer chitosan and monomer methacrylic acid in the presence of cross-linker N',N'-methylene bis(acrylamide). The decrease in polymer crystallinity after polymerization and development of nanogels was demonstrated by XRD and FTIR analysis. The effects of nanogel contents on polymer volume, sol-gel analysis, swelling, drug loading, and release were investigated. Results indicated that high swelling and maximum release of the drug occurred at pH 7.4 compared to pH 1.2 and 4.6, indicating the excellent pH-sensitive nature of the engineered nanogels. High swelling and drug release were perceived with the integration of a high quantity of chitosan, while a decline was observed with the high integration of N',N'-methylene bis(acrylamide) and methacrylic acid contents. The same effects of nanogel contents were shown for drug loading too. Sol fraction was reduced, while gel fraction was enhanced by increasing the chitosan load, N',N'-methylene bis(acrylamide), and methacrylic acid. The Korsmeyer-Peppas model of kinetics was trailed by all nanogel formulations with non-Fickian diffusion. The results demonstrated that prepared nanogels can be employed for sustained release of the madecassoside.

Ion-Imprinted Polymer-Based Sensor for the Detection of Mercury Ions.

In this work, the development of a novel method for the detection of mercury (II) ions in wastewater using a mercury ion-imprinted polymer (IIP) combined with a quartz crystal microbalance (QCM) is described. The IIP was successfully synthesized via the polymerization of a of a novel fluorescein- and 2-aminophenol-functionalized methacrylic acid monomer, which was noted to have high binding affinity to mercury (II) ions. This polymer was subsequently coated on a QCM chip to create an IIP-QCM sensor. This sensor was established to have high selectivity and good sensitivity to mercury (II) ions, and had a limit of detection (LOD) of 14.17 ppb, a limit of quantification (LOQ) of 42.94 ppb, a signal-to-noise ratio (S/N) of 4.29, good repeatability, and a working range of 42.94 ppb to 2 ppm. The sensor was also able to analyze tap water and wastewater samples. The IIP-QCM is, therefore, promising as a highly selective, cost-effective, and rapid mercury ion sensor for applications involving the detection of mercury in wastewater.

Agar Graft Modification with Acrylic and Methacrylic Acid for the Preparation of pH-Sensitive Nanogels for 5-Fluorouracil Delivery.

Agar, a naturally occurring polysaccharide, has been modified by grafting it with acrylic (AcA) and methacrylic (McA) acid monomers, resulting in acrylic or methacrylic acid grafted polymer (AA-g-AcA or AA-g-McA) with pH-sensitive swelling behavior. Different ratios between agar, monomers, and initiator were applied. The synthesized grades of both new polymer series were characterized using FTIR spectroscopy, NMR, TGA, DSC, and XRD to ascertain the intended grafting. The percentage of grafting (% G), grafting efficiency (% GE), and % conversion (% C) were calculated, and models with optimal characteristics were further characterized. The swelling behavior of the newly synthesized polymers was studied over time and in solutions with different pH. These polymers were subsequently crosslinked with varying amounts of glutaraldehyde to obtain 5-fluorouracil-loaded nanogels. The optimal ratios of polymer, drug, and crosslinker resulted in nearly 80% loading efficiency. The performed physicochemical characterization (TEM and DLS) showed spherical nanogels with nanometer sizes (105.7-250 nm), negative zeta potentials, and narrow size distributions. According to FTIR analysis, 5-fluorouracil was physically incorporated. The swelling and release behavior of the prepared nanogels was pH-sensitive, favoring the delivery of the chemotherapeutic to tumor cells. The biocompatibility of the proposed nanocarrier was proven using an in vitro hemolysis assay.

Evaluation of deep eutectic solvents in the synthesis of molecularly imprinted fibers for the solid-phase microextraction of triazines in soil samples.

Nowadays, molecularly imprinted polymers (MIPs) are well established and are considered excellent materials for performing selective extractions. However, with the progressive implementation of the principles of green chemistry, it is necessary to find greener alternatives for both the synthesis and further use of MIPs in sample preparation. Accordingly, in the present work, different deep eutectic solvents (DES, both hydrophilic and hydrophobic), as an alternative to conventional organic solvents (i.e., toluene), were evaluated as porogens for the synthesis of imprinted fibers (monoliths), using fused silica capillaries as molds, for solid-phase microextraction (SPME). From this study, the polymer prepared with propazine (dummy template), methacrylic acid (monomer), ethylene glycol dimethacrylate (cross-linker), and a formic acid:L-menthol (1:1) DES (porogen) showed the best performance for selective rebinding of triazines. After optimization of the different variables involved in SPME, the new imprinted fibers were successfully applied to the extraction of target analytes (desisopropylatrazine, desethylatrazine, simazine, and atrazine) from soil sample extracts, providing relative recoveries ranging from 75.7 to 120.1%, reaching limits of detection within the range of 6.2-15.7ngg-1, depending upon the analyte.

Utilizing gamma radiation to induce polymerization of acrylonitrile/methacrylic acid on nonwoven fibers and its potential use in metal recovery

In this research, the focus was on creating new polymeric adsorbents through radiation-induced synthesis to effectively eliminate zinc from aqueous solutions in batch processes. The study explored the radiation-induced grafting method, a novel approach for producing polymer adsorbents, due to its advantages of process control and the absence of initiators. During the simultaneous irradiation process, acrylonitrile, methacrylic acid monomers, and phosphoric acid were grafted onto polypropylene nonwoven fiber as functional groups. To enhance zinc adsorption, the grafted polymers were modified with different amines, including diethylamine, triethylamine, ethanolamine, tributylamine, and tripropylamine. Among these, the modification with diethylamine exhibited the most promising results for zinc adsorption. After characterizing the adsorbent structure through SEM, FTIR, and TG analysis, the impact of various factors such as pH, contact time, adsorbent mass, and solution concentration on the adsorption process was investigated. Notably, under acidic conditions (pH=3) and an initial concentration of 40 ppm, a remarkable adsorption rate of over 98 % was achieved. To optimize the adsorption process, the response surface method (RSM) based on the central composite design was used to determine the ideal adsorption state. The Langmuir isotherm and the pseudo-second-order model yielded the best fit (R2=0.995) for describing the adsorption process and rate.

Green synthesis of Dextrin‐graft‐poly(allyl amine‐co‐methacrylic acid)/reduced graphene oxide composite and its application for dye and pesticide removal from the aqueous medium

AbstractA Dextrin‐graft‐poly(allyl amine‐co‐methacrylic acid)/reduced graphene oxide (DEXTGP/RGO) is synthesized through the grafting of a combination of allyl amine (AAM) and methacrylic acid (MAA) monomers onto the dextrin polysaccharide backbone by using the free radical copolymerization technique in an aqueous medium, with potassium peroxydisulfate serving as the initiator followed by the partial reduction of graphene oxide (GO). Various characterization techniques including FTIR, 1H/13C NMR, XRD, FESEM, EDAX, and BET analysis are utilized to characterize both the synthesized DEXTGP/RGO composite and graft copolymer. Investigations are conducted on multiple operational variables, including adsorption kinetics, isotherms, and thermodynamic parameters, for the adsorption of both MB and PL. Both intra‐particle diffusion kinetic model and pseudo‐second‐order kinetics are observed to follow for the adsorption of MB, while the Langmuir isotherm model provided a good fit for the equilibrium data. In contrast, the adsorption of PL displayed solely pseudo‐second‐order kinetics, while the equilibrium data shows good agreement with both the Langmuir and Dubinin‐Radushkevich isotherm models. Maximum adsorption capacity ( ) of the RGO composite is found to be 932.56 mg/g for MB and 311.63 mg/g for PL. The thermodynamic analysis revealed that the adsorption of dye and pesticide onto the RGO composite is a spontaneous process.

Design of multi-responsive and actuating microgels toward on-demand drug release.

Multifunctional colloidal microgels that exhibit stimuli-responsive behaviour and excellent biocompatibility have attracted particular attention for developing functional compartmentalized networks. Herein, a series of stimuli-responsive microgels (M0, M1, and M2) were designed through the copolymerization of di(ethylene glycol) methyl ether methacrylate (DEGMA) and methacrylic acid (MAA) monomers using hydroxy ethyl methacrylate-coupled azobenzene (HEMA-Az) and ethylene glycol dimetharylate (EGDMA) as crosslinkers. The behaviour of the microgels in response to temperature, pH, and light was thoroughly investigated using spectroscopic, microscopic, and light-scattering techniques. Interestingly, the microgels deswelled with an increase in temperature, decrease in pH, and under the irradiation of UV light. Such a reversible swelling/deswelling behaviour was exploited for microgel M2, which showed better photoactuation at pH 5 with a higher fluid pumping velocity. The actuating microgel M2 was optimized for loading the drug ciprofloxacin (Cf) to study its release at different temperature, pH, and light conditions. Microgel M2 exhibited photoresponsive Cf release at pH 5 and 37 °C, demonstrating its potential for application in on-demand drug release.

Preparation of molecularly imprinted polymer nanoparticles for selective adsorption of caffeine using dual-functionalized Ag2S quantum dots

Caffeine is the most abundant and widely consumed active medicinal compound, making it the most representative pollutant in the environment. This research involved synthesizing high-performance fluorescent HOOC-CC-functionalized Ag2S quantum dots (HOOC-QDs) measuring approximately 4.35 nm in size using the hydrothermal method. These QDs were then used to produce fluorescent molecularly imprinted polymer nanoparticles (MIP-Ag2S NPs) measuring 20.31 nm. The MIP-Ag2S NPs were created through a graft suspension copolymerization process involving methacrylic acid monomer, ethylene glycol dimethacrylate cross-linker, and caffeine template molecules. The polar carboxylic acid groups enhance the interaction with the template molecules, which is crucial for selectivity, and the -CC- groups aid in network formation. The MIP-Ag2S NPs emitted fluorescence at around 500 nm, which was significantly reduced after caffeine adsorption. The pH-sensitive MIP-Ag2S NPs had a maximum caffeine adsorption capacity of 488 mg/g at pH 6 and a maximum release of approximately 96% at pH 2.2. Additionally, repeated cycles of adsorption and desorption did not result in a significant loss of adsorption capacity. The HOOC-QDs can be used to prepare MIPs for extracting and recognizing pollutants and medicine in water and for controlled drug delivery systems.

Benzylfentanyl as a Surrogate Template for Fentanyl-Selective Imprinted Polymers.

The illicit use of fentanyl has led to hundreds of thousands of opioid-related deaths worldwide. Therefore, the detection of fentanyl by law enforcement and recreational users is of utmost importance. However, current detection methods are expensive, time-consuming, require special storage conditions, and necessitate complex instrumentation that is generally unportable and requires skilled personnel to operate. An alternative approach would be using molecularly imprinted polymers (MIPs) as the recognition component of a handheld sensor, testing strip, or color-based assay. In this work, a molecularly imprinted polymer was constructed using the functional monomer methacrylic acid (MAA) and the cross-linking monomer ethyleneglycol dimethacrylate (EGDMA), with benzylfentanyl (Bfen) as the template. The use of benzylfentanyl is advantageous because it closely mimics fentanyl's structure but does not cause any physiological narcotic effects. Important studies herein determined the optimum ratio of the template/functional monomer, with subsequent evaluations of selectivity of the MIP for the template and fentanyl versus the commonly encountered narcotics such as methamphetamine, cocaine, and heroin. The data obtained from the HPLC analysis showed that the Bfen-MIP was successful in selectively binding the template and actual fentanyl, better than other common narcotics.

Novel Hydrolytic Degradable Crosslinked Interpenetrating Polymeric Networks (IPNs): An Efficient Hybrid System to Manage the Controlled Release and Degradation of Misoprostol.

The goal of this study was to make pH-sensitive HPMC/Neocel C19-based interpenetrating polymeric networks (IPNs) that could be used to treat different diseases. An assembled novel carrier system was demonstrated in this study to achieve multiple functions such as drug protection and self-regulated release. Misoprostol (MPT) was incorporated as a model drug in hydroxyl-propyl-methylcellulose (HPMC)- and Neocel C19-based IPNs for controlled release. HPMC- and Neocel C19-based IPNs were fabricated through an aqueous polymerization method by utilizing the polymers HPMC and Neocel C19, the initiator ammonium peroxodisulfate (APS), the crosslinker methylenebisacrylamide (MBA), and the monomer methacrylic acid (MAA). An IPN based on these materials was created using an aqueous polymerization technique. Samples of IPN were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC), thermal analysis (TGA), and powder X-ray diffraction (PXRD). The effects of the pH levels 1.2 and 7.4 on these polymeric networks were also studied in vitro and through swelling experiments. We also performed in vivo studies on rabbits using commercial tablets and hydrogels. The thermal stability measured using TGA and DSC for the revised formulation was higher than that of the individual components. Crystallinity was low and amorphousness was high in the polymeric networks, as revealed using powder X-ray diffraction (PXRD). The results from the SEM analysis demonstrated that the surface of the polymeric networks is uneven and porous. Better swelling and in vitro results were achieved at a high pH (7.4), which endorses the pH-responsive characteristics of IPN. Drug release was also increased in 7.4 pH (80% in hours). The pharmacokinetic properties of the drugs showed improvement in our work with hydrogel. The tablet MRT was 13.17 h, which was decreased in the hydrogels, and its AUC was increased from 314.41 ng h/mL to 400.50 ng h/mL in hydrogels. The blood compatibility of the IPN hydrogel was measured using different weights (100 mg, 200 mg, 400 mg, and 600 mg; 5.34%, 12.51%, 20.23%, and 29.37%, respectively). As a result, IPN composed of HPMC and Neocel C19 was successfully synthesized, and it is now possible to use it for the controlled release of MPT.

Sуnthesis of terpene–methacrylic acid copolymers and their effect on the stability of inorganic dispersions in the presence of cationic surfactants

Copolymers of methacrylic acid and natural terpene monomers (α-pinene; β-pinene; ∆3-karene) with the molecular weight of (0.3–0.5)∙104 and a content of carboxyl groups of 14.5–16.3 % were synthesized. For the synthesized copolymers, hydrodynamic radius and the Kuhn segment, which characterizes flexibility of a polymer chain, were determined, as well as the Huggins constant in aqueous and saline solutions, and concentration regions for formation of supramolecular structures. In the presence of a cationic surfactant (benzetonium chloride, Hyamine), depending on the concentration of copolymers in the system, polymer-surfactant complexes were formed in soluble and insoluble forms. It has been shown that the effectiveness of the stabilizing action of soluble complexes with respect to an aqueous dispersion of calcium carbonate increases with an increase in the content of nonpolar groups in the polymer chain. A cationic surfactant (Hyamine) has been proposed as a precipitant in the method for the quantitative determination of carboxyl-containing polymers in aqueous and saline media.

Colloidal stability and rheological properties of bio-ferrofluids of polymer-coated single-core and multi-core nanoparticles

The polymethacrylic acid (PMAA)-coated magnetite nanoparticles with single and multi-cores were prepared by the emulsifier-free emulsion polymerization of methacrylic acid (MAA) monomers. X-ray diffraction analysis (XRD), Fourier transform infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM) were used to identify the nanoparticles and the polymer layer. The coated particles have spherical shapes. The single core diameter is 6.6 nm, and the multi-core diameter is 33.8 nm, with the number of cores in a particle of 131. The PMAA layer thickness is around 4 nm for both coated particles. This polymer layer enhances nanoparticles' dispersion ability while retaining their magnetic properties much higher than in other studies. The coated multi-core particles show excellent dispersion stability. The aggregation rate of these particles is hundreds of times lower than that of single-core particles. All the nanofluids exhibit shear-thinning behavior without and with an external magnetic field. The field-dependent viscosity agrees with the theory regarding the interaction parameter λ. However, the magneto-viscous of the magnetic fluids here are much smaller than comparable bio-ferrofluids.

Computational modelling analysis and synthesis of molecularly imprinted polymers (MIPs) with two functional monomers using bulk polymerization

Sulfamethoxazole (SMX) is a well-known antibiotic used for the treatment and prevention of diseases for dairy-producing animals. However, the overuse of antibiotics in milk-producing herd resulted in detectable traces in milk which can cause severe effect to human health and also pose a risk of antimicrobial resistance through milk consumption. Therefore, a simple and rapid detection method is required to monitor the level of SMX in milk. Molecularly imprinted polymer (MIP) is a synthetic recognition element producing structurally artificial recognition sites “cavities” in polymeric matrices which are complementary to SMX structure for rebinding purposes through a process known as molecular imprinting. This method allows the capture of SMX with high affinity and selectivity even in the presence of antibiotics with very similar molecular structures to SMX. Herein, this study aims to synthesize and characterize MIP with specific binding to SMX through computational predictions and experimental verification using two different functional monomers which are methacrylic acid (MAA) and acrylamide (AA). The docking analysis using PyRx – Virtual Screening Tool showed higher binding affinity for SMX-MAA compared to SMX-AA which were −2.0 and −1.7 kcal/mol, respectively. Smaller binding affinity values indicate a greater interaction between the MIP and the analyte. This modelling data was further validated through experimental study by synthesizing MIP using MAA and AA monomers which presented an imprinting factor (IF) of 1.46 and 0.98 in ultra-pure water (UPW), and 1.02 and 0.93 in phosphate buffer solution (PBS) media respectively. IF values in both mediums showed higher affinity for SMX-MAA compared to SMX-AA and in agreement with the predicted values from the docking analysis. All in all, MIP synthesized using MAA as the monomer can be used for selective detection of SMX as a recognition element in sensors. This method is simple, stable and relatively cheap compared to the conventional detection methods such as immunoassays, GC/MS and HPLC.

Computational approach to establish molecularly imprinted polymers interaction of functional monomer methacrylic acid and template norfloxacin

MIP is a potential method for fabricating polymeric materials with binding sites that have predetermined selectivity for a targeted analyte. The quality of the binding sites in MIP is directly influenced by monomer-template interaction strength. A computational approach is used to examine monomer-template interactions to obtain insight into the molecular level of imprinting polymer selectivity, regarding complex formation. In this work, five different monomers such as methyl methacrylic acid (MAA), methyl methacrylate (MMA), acrylonitrile (ACN), acrylamide (AA) and di-vinyl benzene (DVB) and their ratios with template have been screened. The geometry optimizations of the molecules were done using Amsterdam Modeling Suite (AMS) input program applying Amsterdam density function (ADF) module. The theoretical calculations were carried out exchange and correlation (XC) functional: RS: CAMY-B3LYP (Becke, 3-parameter, Lee–Yang–Parr) with basis set double zeta (DZ). The result showed the ratio of template to MAA was 1:3 for stable complex formation.

Methacrylic acid‐based amphiphilic block‐random copolymer stabilizers for emulsion polymerization

AbstractThe emulsion polymerization of styrene was investigated using polystyrene‐b‐[polystyrene‐r‐poly(methacrylic acid)] amphiphilic block‐random copolymers (BRCs) of different compositions as stabilizers. These stabilizers with molar masses <20,000 g/mol, which possess unique dispersion behaviour (i.e., self‐assembly with low aggregation numbers) when dissolved in aqueous medium at alkaline pH, were prepared by the nitroxide‐mediated bulk polymerization of styrene to achieve a desired molar mass followed by chain extension by batchwise addition of styrene and methacrylic acid monomers to obtain the stabilizing group. Emulsion polymerizations of styrene stabilized by these BRCs yielded stable latexes with particle diameters that range between 30 and 150 nm. When different concentrations of the stabilizer (2–3.5 mM) were utilized for emulsion polymerization of styrene, a similar novel emulsion polymerization mechanism observed previously by our group for the acrylic‐acid based amphiphilic BRCs was also seen, further validating the difference between this class of polymeric surfactants and conventional small molecule surfactants, block copolymers, or alkali soluble resins. The performance of methacrylic‐acid based BRCs was more efficient and yielded higher surface coverage of the polystyrene latexes when compared to the acrylic‐acid based BRCs as a result of the more hydrophobic nature of the former.

Effect of Methacrylic Acid Monomer on UV-Grafted Polyethersulfone Forward Osmosis Membrane

UV irradiation is one of the procedures that has been considered for membrane surface graft polymerization. It is commonly utilized for enhancing the wettability of polyethersulfone (PES) membranes. In this research study, the monomer methacrylic acid (MAA) was used for the UV grafting process of a commercial NF2 PES membrane for the preparation of a forward osmosis (FO) membrane. Three different monomer concentrations and three different UV irradiation times were considered. The intrinsic characteristics of both the surface-modified and pristine membranes were determined via a non-pressurized test method. Compared to the NF2 PES, the surface of the modified membranes was rendered more hydrophilic, as the measured water contact angle was reduced considerably from 65° to 32-58°. The membrane surface modification was also confirmed by the data collected from other techniques, such as atomic force microscopy (AFM), field emission-scanning electron microscope (FESEM) and Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Additionally, the modified membranes exhibited a greater water permeate flux (Jw) compared to the NF2 PES membrane. In this study, the water permeability (A), solute permeability (B) and structural parameter (S) were determined via a two-stage FO non-pressurized test method, changing the membrane orientation. Compared to the FO pressurized test, smaller S values were obtained with significantly high A and B values for the two non-pressurized tests. The adopted method in the current study is more adequate for determining the intrinsic characteristics of FO membranes.

Application of Molecular Imprinting for Creation of Highly Selective Sorbents for Extraction and Separation of Rare-Earth Elements.

The aim of the work is to study the effectiveness of a molecular imprinting technique application for the creation of highly selective macromolecular sorbents for selective sorption of light and heavy rare-earth metals (for example, samarium and gadolinium, respectively) with subsequent separation from each other. These sorbents seem to be promising due to the fact that only the target rare-earth metal will be sorbed owing to the fact that complementary cavities are formed during the synthesis of molecularly imprinted polymers. In other words, the advantage of the proposed macromolecules is the absence of accompanying sorption of metals with close chemical properties. Two types of molecularly imprinted polymers (MIP) were synthetized based on methacrylic acid (MAA) and 4-vinylpyridine (4VP) functional monomers. The sorption properties (extraction degree, exchange capacity) of the MIPs were studied. The impact of template removal cycle count (from 20 to 35) on the sorption effectivity was studied. Laboratory experiments on selective sorption and separation of samarium and gadolinium from a model solution were carried out.

Preparation of surface-modified electrode of copper(ii) oxide mixed with the molecularly imprinted polymer for enhancement of melamine detection with photoelectrochemical technique.

Melamine contamination in food and beverages affects short- and long-term health. In this work, enhanced sensitivity and selectivity in photoelectrochemical determination for melamine detection was achieved using copper(ii) oxide (CuO) combined with a molecularly imprinted polymer (MIP). A CuO nanomaterial was used to achieve MIP surface modification via co-precipitation synthesis. An MIP film was deposited by polymerizing the methacrylic acid monomer and a melamine template. The properties of the CuO nanomaterials, such as the surface morphology, chemical oxidation state, and crystalline structure, were characterized using field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction patterns (XRD), respectively. The diffuse reflection spectroscopy technique was applied to evaluate the optical properties of the CuO nanoparticles. The results indicated that the synthesized CuO nanomaterials had a monoclinic structure with an optical bandgap of 1.49 eV, which corresponds to absorbance in the visible light region. CPE electrodes with surface-modified CuO/MIP were measured using the photoelectrochemical techniques of cyclic voltammetry, differential pulse voltammetry (DPV), and amperometry. The modified CuO/MIP electrode for melamine detection in 7.4 pH PBS buffer solution exhibited a high sensitivity of 0.332 nA nM-1, with a linear range of 5.0-75.0 nM and a limit of detection of 2.45 nM. Moreover, real samples of various kinds of milk were applied to evaluate the sensing response of the prepared CuO/MIP electrode. The modified CuO/MIP electrodes could be reused seven times with good reproducibility and high selectivity for melamine detection.