Azobisisobutyronitrile Research Articles

Molecularly imprinted polymer-based microspheres for selective extraction of hemoglobin from blood serum

In this study, a highly selective molecularly imprinted microsphere (Hb-MAFol-Nd(III)-MIP) was prepared with ion-chelate approach for the extraction of hemoglobin (Hb) from blood serum. The Hb-imprinted microspheres were synthesized by suspension polymerization. For this purpose, Hb, N-methacryloylamino folic acid-Nd(III) (MAFol-Nd(III)), ethtylene glycol dimethacrylate (EDMA) and azobisisobutyronitrile (AIBN) were used as the template, complex functional monomer, cross-linker and initiator, respectively. Imprinted and NIP microspheres were characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). The binding efficiency of the template on both MIP and NIP was optimized with respect to various parameters including pH, contact time, and hemoglobin concentration. As a result, the maximum binding capacity was observed to be as 361 mg g−1 at the pH value 7.0. For selectivity study, myoglobin (Mb), cytochrome c (Cyt) and lysozyme (Lys) were chosen as competitive proteins. The prepared imprinted microspheres exhibited high selectivity toward template based on the selectivity coefficients (k). The extraction of Hb from spiked blood serum sample was performed with excellent success. From the correlation coefficients, isotherm study indicated that the adsorption of Hb by MIP fit a Langmuir model.

Fabrication of selective electrochemical sensor for the detection of folic acid in spinach, wheat and tablets using functionalized graphene-oxide based molecular imprinted polymer

A novel cost-effective sensor material was developed from modified graphene oxide based molecular imprinted polymer (GO-MIP) for the detection of folic acid (FA). This GO-MIP was obtained through several processes including functionalization, polymerization and template molecule introduction/removal during the synthesizing process. Firstly, graphene oxide (GO) was prepared by modified Hummers method which undergoes hydroxyl functionalization to form GO–OH. It further undergoes surface modification with allyl bromide in presence of sodium hydroxide (NaOH) and dimethyl sulfoxide (DMSO) to form vinylated GO–OH (GO–O–CH=CH2). The GO–O–CH=CH2 subjected to further molecular imprinting process with methacrylic acid (MAA) as the monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linker, azobisisobutyronitrile (AIBN) as the initiator and FA as the template molecule. The different preparatory stages of materials were characterized by FTIR, XRD and SEM techniques to understand the formation. The obtained GO–MIP was used as an active material for FA sensing. The pH studies were carried out using cyclic voltameteric measurement and maximum current is obtained at pH 4.0. The proposed GO-MIP based electrode showed excellent electrocatalytic activity toward FA detection at optimized conditions. The limit of detection obtained in the present study is 1.0 nM. The results obtained from the real time usability of electrodes in wheat flour, tablet and spinach are well with commercially available FA monitors. The results endorse the promising application of GO-MIP toward superior FA sensing with long-term stability.

Fabrication of a Molecularly-Imprinted-Polymer-Based Graphene Oxide Nanocomposite for Electrochemical Sensing of New Psychoactive Substances

As new psychoactive substances (commonly known as "the third generation drugs") have characteristics such as short-term emergence, rapid updating, and great social harmfulness, there is a large gap in the development of their detection methods. Herein, graphite oxide (GO) was first prepared and immobilized with a reversible addition-fragmentation chain transfer (RAFT) agent, then a new psychoactive substance (4-MEC) was chosen as a template, and then the surface RAFT polymerization of methacrylamide (MAAM) was carried out by using azobisisobutyronitrile (AIBN) as an initiator and divinylbenzene (DVB) as a cross-linker. After the removal of the embedded template, graphene oxide modified by molecularly imprinted polymers (GO-MIPs) was finally obtained. Owing to the specific imprinted cavities for 4-MEC, the satisfactory selectivity and stability of the GO-MIP nanocomposite have been demonstrated. The GO-MIP nanocomposite was then used to fabricate the electrochemical sensor, which displayed a high selectivity in detecting 4-MEC over a linear concentration range between 5 and 60 μg mL-1 with a detection limit of 0.438 μg mL-1. As a result, the GO-MIPs sensor developed an accurate, efficient, convenient, and sensitive method for public security departments to detect illicit drugs and new psychoactive substances.

Synthesis and Characterization of MIPs for Selective Removal of Textile Dye Acid Black-234 from Wastewater Sample

Herein, a molecularly imprinted polymer (MIP) was prepared using bulk polymerization and applied to wastewater to aid the adsorption of targeted template molecules using ethylene glycol dimethacrylate (EGDMA), methacrylic acid (MAA), acid black-234 (AB-234), 2,2'-azobisisobutyronitrile (AIBN), and methanol as a cross linker, functional monomer, template, initiator, and porogenic solvent, respectively. For a non-molecularly imprinted polymer (NIP), the same procedure was followed but without adding a template. Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and a surface area analyzer were used to determine the surface functional groups, morphology and specific surface area of the MIP and NIP. At pH 5, the AB-234 adsorption capability of the MIP was higher (94%) than the NIP (31%). The adsorption isotherm data of the MIP correlated very well with the Langmuir adsorption model with Qm 82, 83 and 100 mg/g at 283 K, 298 K, and 313 K, respectively. The adsorption process followed pseudo-second-order kinetics. The imprinted factor (IF) and Kd value of the MIP were 5.13 and 0.53, respectively. Thermodynamic studies show that AB-234 dye adsorption on the MIP and NIP was spontaneous and endothermic. The MIP proved to be the best selective adsorbent for AB-234, even in the presence of dyes with similar and different structures than the NIP.

Study of modified PVDF membranes with high-capacity adsorption features using Quantum mechanics, Monte Carlo, and Molecular Dynamics Simulations

Petrochemical wastewater should be appropriately handled to avoid pollution in natural water. A current research field in this area is to use super hydrophilic membranes with simultaneous superoleophobicity for separating emulsified oil from water. In this study, molecular simulations approaches such as molecular dynamics (MD), Monte Carlo (MC), and quantum mechanics (QM) simulations were used to scrutinize the behavior of adsorption capacities of neat and modified PVDF membranes. For this, PVDF grafted with N-isopropylacrylamide (NIPAAm), azobisisobutyronitrile (AIBN) and also blended with different weight percentages of poly[oligo(ethylene glycol) methacrylate] (PEGMA)-g-1-butyl-3-vinyl imidazolium bromide (BVIm-Br) (PEGMA-co-BVIm-Br) copolymer, as a super hydrophilic agent, to create different membranes compositions. It has been demonstrated in QM simulations that the PVDF-(PEGMA-co-BVIm-Br)-Water-oil configurations facilitate electron transfer more effectively than the other configurations. This makes PVDF-(PEGMA-co-BVIm-Br) a suitable adsorbent for water compared to the neat PVDF. Moreover, the adsorption energy of adsorbates on the membranes with different compositions as adsorbents was estimated using the MC method via Adsorption Locator of Materials Studio (MS) software. Based on the results from the MC simulations, more water molecules were adsorbed into the membrane structure when the hydrophilic agent (PEGMA-co-BVIm-Br) was added to it, which indicates a greater degree of hydrophilicity. Finally, MD simulations were employed to consider the hydrophilic agent effect (PEGMA-co-BVIm-Br) on the physicochemical properties of the membrane structures, such as X-ray diffraction (XRD) pattern, glass transition temperature (Tg), cohesive energy density (CED), fractional free volume (FFV), solubility parameters (δ), and mechanical properties.

Effect of cross-linking agents on the adsorption of histamine on molecularly imprinted polyacrylamide

The ability of molecularly imprinted polymers (MIPs) prepared with flexible cross-linking agents for selective uptake of guest molecules is investigated. New polyacrylamide polymers had been synthesized for histamine (HA) extraction using solid supports based on MIPs immobilized on silica surface (SiO2). The MIPs were prepared via radical polymerization in acetonitrile and in the presence of azobisisobutyronitrile (AIBN) as initiator, using HA as a target molecule, acrylamide as a functional monomer and several cross-linking agents having alkyl spacers of various lengths: N,N′-methylenebisacrylamide (BA1), N,N′-ethylenebisacrylamide (BA2), N,N’-(butane-1,4-diyl)-bis(2-methacrylamide) (BA4) and N,N’-(hexane-1,6-diyl)-bis(2-methacrylamide) (BA6). All the prepared MIPs have a strong absorption capacity of HA compared to non-imprinted polyacrylamide (NIPs). MIP4 made with the BA4 cross-linker shows a higher selectivity for adsorption of HA than MIPs made with BA1, BA2 and BA6. Thus, the imprinting factor for adsorption from a 5 ppm HA solution was 2.5 for MIP4 against 1.4 to 1.6 for MIP1, MIP2 and MIP6. Langmuir–Volmer and Volmer models of the adsorption isotherms of MIPs and NIPs accurately fit the experimental data. They provide the characteristic parameters of the adsorption thermodynamic of the materials. The higher performance of MIP4 for selective adsorption of HA is mainly coming from a higher density of molecular imprints (1.4 μmol m−2 against 0.13–0.15 μmol m−2 for MIP1 and MIP2 and 0.4 μmol m−2 for MIP6) than a higher affinity of HA for the molecular imprints. The selectivity with respect to the tyramine and melamine interfering molecules is also higher for MIP4. As the main outcome, some moderate flexibility of the material is advantageous. Such flexibility allows for a reversible healing and re-opening of the molecular imprints as the HA guest is removed and back-adsorbed.

Renewable Polymers Derived from Limonene

Renewable natural and synthetic basic substances can be used to produce biodegradable polymers. Several methods of the polymerization of terpene limonene have been evaluated. The polymerization methods evaluated are radical polymerization, cationic polymerization and thiol-ene polymerization. The free-radical polymerization of limonene with azobisisobutyronitrile (AIBN) as an initiator was carried out. The cationic polymerization of limonene was carried out using AlCl3 as a catalyst. The copolymerization of limonene with mercaptoethanol, 2-mercaptoethyl ether without an initiator and with an AIBN initiator was studied and it was also shown that polymerization can proceed spontaneously. The resulting compounds were investigated by NMR and FTIR spectroscopy. The values of the molecular weight characteristics of the samples obtained are presented, such as: number-average molecular weight, hydrodynamic radius and characteristic viscosity, depending on the method of production. The coefficients α (molecular shape) in the Mark–Kuhn–Houwink equation are determined according to the established values of the characteristic viscosity. According to the values obtained, the AC molecules in solution have parameters α 0.14 to 0.26, which corresponds to a good solvent and the molecular shape-dense coil.

Synthesis and Characterization of Poly(methyl methacrylate-co-vinyl triethoxysilane) Prepared by Free Radical Polymerization

The copolymerization of methyl methacrylate (MMA) with vinyl triethoxysilane (VTES) was carried out in ethyl cellosolve at 70 ℃ using azobisisobutyronitrile (AIBN) as a free radical initiator. The prepared copolymer was purified and then analysed by FT-IR, NMR, TGA and SEM analyses. FT-IR along with NMR confirm the successful preparation of the copolymer. The prepared copolymer shows better thermal stability than poly(methyl methacrylate). A morphological study was also carried out by SEM analysis. SEM micrographs show that the copolymer surface gets roughened and becomes porous on copolymerization.

Synthesis, Characterization, Optical and Thermal Properties of P(NVC-co-BZMA) Copolymer and Its ZnO Composites

Recent studies have paid particular attention to polymer-nanoparticle composite materials considering they have a number of interesting properties, which include optical, thermal, electrical, and others (Reyna-Gonzalez et al., 2009; Yakuphanoglu et al., 2010). In this study, a free radical polymerization process was used to create a copolymer of N-vinylcarbazole (NVC) and benzyl methacrylate (BZMA) at 25–75 mol% each. The procedure was conducted at 70°C with azobisisobutyronitrile (AIBN) acting as the initiator. Nano zinc oxide powders were then added to composites at three different ratios of 5%, 10%, and 15% weight of the copolymer. In order to better understand the structures of the P(NVC-co-BZMA) and its composites, FT-IR, 1H NMR, and UV spectroscopic techniques were also implemented. The optical characteristics of both the pure copolymer and its composites were examined. In the visible region, the composite containing 15% nano ZnO had the highest optical absorbance value. Additionally, the thermal behaviours of the composites and copolymers were analysed.

Insight into thermo-mechanical enhancement of polymer nanocomposites coated microsand proppants for hydraulic fracturing

The present work reports the fabrication of ultra-high strength microsand proppants (100 mesh) through a polymer nanocomposite dual coating approach and gives insight into their thermo-mechanical reinforcements. The dual coating can be of 3D-cross-linked poly(styrene-methyl methacrylate)/divinylbenzene) (PS-PMMA/DVB) porous network and thermally cross-linked epoxy with graphene nanosheets. The inner layer of PS-PMMA/DVB was prepared using bulk polymerization of styrene (S) and methyl methacrylate (MMA) at 70 °C with a free radical initiator azobisisobutyronitrile (AIBN). The outer layer was prepared by mixing epoxy resin, a cross-linker, and commercial graphene (CG) followed by thermally curing the mixture. The dual-coated microsand proppants exhibited enhanced mechanical characteristics of elastic modulus (E) as high as 7.78 GPa, hardness (H) of 0.35 GPa, and fracture toughness (Kc) of 3.19 MPa m1/2 along with largely improved thermal properties. Moreover, the dual-coated microsand proppants exhibit a very high-stress resistance up to 14000 psi, and to the best of our knowledge, this is the highest stress resistance value attained for the modified sand-based proppants so far.

In-Capillary Photodeposition of Glyphosate-Containing Polyacrylamide Nanometer-Thick Films.

The present research reports on in-water, site-specific photodeposition of glyphosate (GLP)-containing polyacrylamide (PAA-GLP) nanometer-thick films (nanofilms) on an inner surface of fused silica (fused quartz) microcapillaries presilanized with trimethoxy(octen-7-yl)silane (TMOS). TMOS was chosen because of the vinyl group presence in its structure, enabling its participation in the (UV light)-activated free-radical polymerization (UV-FRP) after its immobilization on a fused silica surface. The photodeposition was conducted in an aqueous (H2O/ACN; 3:1, v/v) solution, using UV-FRP (λ = 365 nm) of the acrylamide (AA) functional monomer, the N,N'-methylenebis(acrylamide) (BAA) cross-linking monomer, GLP, and the azobisisobutyronitrile (AIBN) UV-FRP initiator. Acetonitrile (ACN) was used as the porogen and the solvent to dissolve monomers and GLP. Because of the micrometric diameters of microcapillaries, the silanization and photodeposition procedures were first optimized on fused silica slides. The introduction of TMOS, as well as the formation of PAA and PAA-GLP nanofilms, was determined using atomic force microscopy (AFM), scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) spectroscopy, and confocal micro-Raman spectroscopy. Particularly, AFM and SEM-EDX measurements determined nanofilms' thickness and GLP content, respectively, whereas in-depth confocal (micro-Raman spectroscopy)-assisted imaging of PAA- and PAA-GLP-coated microcapillary inner surfaces confirmed the successful photodeposition. Moreover, we examined the GLP impact on polymer gelation by monitoring hydration in a hydrogel and a dried powder PAA-GLP. Our study demonstrated the usefulness of the in-capillary micro-Raman spectroscopy imaging and in-depth profiling of GLP-encapsulated PAA nanofilms. In the future, our simple and inexpensive procedure will enable the fabrication of polymer-based microfluidic chemosensors or adsorptive-separating devices for GLP detection, determination, and degradation.

Studies on the Regioselective Rearrangement of Azanorbornanic Aminyl Radicals into 2,8-Diazabicyclo[3.2.1]oct-2-ene Systems.

Aminyl radicals are nitrogen-centered radicals of interest in synthetic strategies involving C-N bond formation due to their high reactivity. These intermediate radicals are generated by the reaction of an organic azide with tributyltin hydride (Bu3SnH) in the presence of substoichiometric amounts of azobisisobutyronitrile (AIBN). In this work, we report the regioselective rearrangement of azanorbornanic ([2.2.1]azabicyclic) aminyl radicals into 2,8-diazabicyclo[3.2.1]oct-2-ene systems. With the aim to establish the structural requirements for this ring expansion, we have studied the effect of different bridgehead atoms of the [2.2.1]bicyclic system and the presence of an alkyl substituent at C4. Attempts to perform this ring expansion on a monocyclic analogue have been also explored to evaluate the influence of the bicyclic skeleton on the rearrangement. A detailed mechanistic proposal supported by computational studies is reported.

Physico-chemical elucidation of the mechanism involved in optical lithography: Micro-fabrication of 2D and 3D platforms

Direct laser lithography has attracted much attention as a convenient micro-fabrication method to develop rapid, free-form, and low-cost microstructures. In this work, different microdevices were fabricated using a home-made two-photon excitation microscope and a commercial negative UV photoresin. The mechanism involved during the fabrication of the devices as well as the effects of the irradiation intensity and removal time on micro-patterns was investigated by optical microscopy. For the characterization of the microstructures, scanning electron microscopy, atomic force microscopy, Nuclear Magnetic Resonance (1H-NMR), and Fourier transform infrared spectroscopy were used. High-resolution optical characterization shows an enormous uniformity and high reproducibility of fabricated platforms in two and three dimensions. These results prompted us to propose a different mechanism not compatible with a polymerization reaction as the triggering mechanism for the interaction between light and the photoresin. We demonstrate the coexistence of an allylic photo-induced reaction with a photo-induced polymerization effect during the fabrication process. We studied the influence of these mechanisms by fabricating micro-patterns in two conditions, with and without the presence of a polymerization initiator [azobisisobutyronitrile (AIBN)], which boots the polymerization reaction. Even though the two mechanisms are present during the fabrication process, the polymerization is dominant in the presence of a photo-initiator as AIBN. Finally, we discuss the applications of our microdevices as suitable platforms for industry and biomedical applications.

Ophthalmic Hydrogel Contact Lens Material Containing Magnesium Oxide Nanoparticles and 3-(Trifluoromethyl)styrene for Biomedical Application.

This research was conducted for the synthesis and application of ophthalmic lens materials with improved oxygen permeability and durability. Polyvinylpyrrolidone (PVP), N-vinyl-2-pyrrolidone (NVP), 3-(trifluoromethyl)styrene (3-TFMSt), and magnesium oxide nanoparticles were used as additives for the basic combination of 2-hydroxyethyl methacrylate (HEMA). Additionally, the materials were copolymerized with ethylene glycol dimethacrylate (EGDMA) as the cross-linking agent and azobisisobutyronitrile (AIBN) as the initiator. The addition of magnesium oxide nanoparticles was found to increase the tensile strength from 0.0631 to 0.0842 kgf/mm2. Copolymerization with a small amount of 3-TFMSt of about 1% increased the tensile strength to 0.1506 kgf/mm2 and the oxygen permeability from 6.00 to 9.64 (cm2/s)∙(mLO2/mL·mmHg)∙10-11. The contact lens material produced using N-vinyl-2-pyrrolidone and magnesium oxide nanoparticles as additives satisfied the basic physical properties required for hydrogel contact lenses and is expected to be used usefully as a material for fabricating high-performance hydrogel lenses.

Modification of Cotton Fabric with Molecularly Imprinted Polymer-Coated Carbon Dots as a Sensor for 17 α-methyltestosterone.

Molecularly imprinted polymers@ethylenediamine-modified carbon dots grafted on cotton fabrics (MIPs@EDA-CDs/CF) and smartphone-based fluorescence image analysis were proposed and used for the first time for the detection of 17 α-methyltestosterone (MT). The EDA-CDs were synthesized and grafted on cotton fabric before coating with the MIPs. The MIPs were synthesized using the MT as a template molecule, methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a cross-linker, and azobisisobutyronitrile (AIBN) as an initiator. The MIPs@EDA-CDs/CF were characterized using FTIR, SEM-EDS, and RGB fluorescence imaging. The fluorescence images were also taken using a smartphone and the ImageJ program was used for RGB measurement. The Δ red intensity was linearly proportional to MT concentration in the range of 100 to 1000 μg/L (R2 = 0.999) with a detection limit of 44.4 μg/L and quantification limit of 134 μg/L. The MIPs@EDA-CDs/CF could be stored at 4 °C for a few weeks and could be reused twice. The proposed method could apply for the specific determination of MT in water and sediment samples along with satisfactory recoveries of 96-104% and an acceptable relative standard deviation of 1-6% at the ppb level.

Thermoresponsive and antibacterial two-dimensional polyglycerol-interlocked-polynipam for targeted drug delivery.

Two-dimensional polymeric networks are a new class of polymers with interesting physicochemical and biological properties. They promise a wide range of future biomedical applications including pathogen interactions, drug delivery, bioimaging, photothermal, and photodynamic therapy, owing to their unique features, such as high surface area and multivalent interactions at nano-biointerfaces. In this work, a thermosensitive two-dimensional polymeric network consisting poly(N-isopropylacrylamide) (pNIPAM) chains that are mechanically interlocked by a polyglycerol platform was synthesized and used for bacteria incapacitation. Two-dimensional hyperbranched polyglycerol (2D-hPG) was synthesized by a graphene-assisted strategy and used for encapsulation of azobisisobutyronitrile (AIBN). Radical polymerization of N-isopropylacrylamide by encapsulated AIBN resulted in thermoresponsive platforms with ~ 500 nm lateral size and 20–50 nm thickness. Due to its porous structure, 2D-PNPG was able to efficiently load antibiotics, such as tetracycline (TC) and amoxicillin (AMX). The rate of release of antibiotics from 2D-PNPG and the antibacterial activity of the system correlated with the variation of temperature as a result of the thermosensitivity of 2D-PNPG. This study shows that two-dimensional polymers are efficient platforms for future biomedical applications including drug delivery and bacteria incapacitation.Graphical abstract Thermoresponsive two-dimensional nanomaterials with the ability of loading therapeutic agents and antibacterial activity are synthesized and characterized.

In Ukrainian

The purpose of the work is synthesis of new organomineral composites by in situ immobilization and adsorption of poly[8-methacroyloxy-quinoline] on the surface of vermiculite and study of sorption properties of cations Cu(II), Pb(II) and Fe(III). In situ immobilization of poly [8-oxyquinolinemethacrylate] on the surface of vermiculite was carried out by initiated radical polymerization of 8 oxyquinoline methacrylate using 2,2′-azobisisobutyronitrile (AIBN) as a dinitrile initiator in the presence of vermiculite. To obtain the composite by adsorption of poly[8-oxyquinolinemethacrylate] on the surface of vermiculite, the polymer was synthesized in advance, then dissolved in tetrahydrofuran and adsorbed on vermiculite. The fact of immobilization of poly[8-oxyquinolinemethacrylate] on the surface of vermiculite was confirmed by comparative analysis of the IR spectra of the source mineral and relative composites. The regularities of thermal decomposition of immobilized polymer were studied by thermogravimetric analysis combined with mass spectrometry. Using the results of low-temperature adsorption-desorption of nitrogen and scanning electron microscopy, changes in the morphology of the vermiculite surface after immobilization of poly[8-oxyquinolinemethacrylate] by the selected methods are shown. The sorption characteristics of the synthesized composites with respect to Cu(II), Pb(II) and Fe(III) ions were examined in static mode. The polymer with oxyquinoline groups immobilized on the surface of vermiculite showed sorption activity against those metal ions with which 8-oxyquinoline forms stable complexes, the sorption capacity relative to cations Cu(II) is doubled after in situ immobilization of poly [8-oxyquinoline methacrylate] on the surface of vermiculite and increases almost 3 times after adsorption of this polymer. For Pb(ІІ) ions this effect is lower: after in situ immobilization of [8-methacroyloxy-quinoline] sorption capacity increases by one-third and as the result, the increasing of adsorption of this polymer is insignificant and is within the experimental accuracy.

Catalyst- and Stabilizer-Free Rational Synthesis of Ionic Polymer Nanoparticles in One Step for Oil/Water Separation Membranes.

Ionic polymer nanoparticles (IPNs) were synthesized in one pot by quaternization precipitation polymerization (QPP) as a novel polymerization technique. QPP eliminated the usage of high-cost ionic monomers and reduced the number of steps for the preparation of IPN. The monomers 2-(dimethylamino)ethyl methacrylate (DMAEMA) and 4-vinylbenzyl chloride (VBC) polymerized in the presence of azobisisobutyronitrile (AIBN) and underwent quaternization simultaneously, which yielded ionic poly(DMAEMA-co-VBC) nanoparticles in one step with the size of 50-80 nm without any stabilizer and catalyst. Similarly, 4-vinylpyridine (VP) and VBC polymerized in the presence of AIBN and underwent quaternization simultaneously, which yielded ionic poly(VP-co-VBC) nanoparticles in one step with the size of 70-90 nm without any stabilizer and catalyst. The as-synthesized IPN was further utilized for the fabrication of hydrophilic nanocomposite ultrafiltration membranes for oil/water separation. Fabricated hybrid membranes were characterized and studied for oil rejection properties. It exhibited an oil rejection of >96% with a pure water permeability of 219 L/m2 h bar.

Softwood impregnation by MMA monomer using supercritical CO2

Supercritical carbon dioxide (scCO2) was employed to impregnate MMA monomer into five different types of softwood, i.e., spruce, cedar, western pine, eastern pine and costal hemlock, followed by in-situ polymerization initiated by azobisisobutyronitrile (AIBN) in scCO2. The operational conditions were investigated at scCO2 temperatures of 50 and 55 °C, pressures of 14, 21 and 28 MPa and equilibrium time from 12 to 72 h. 55 °C, 28 MPa, and 48 h were considered as the optimal experimental conditions. Microscopy analysis showed that the formed PMMA was distributed within the porous wood matrix thoroughly and evenly. Material properties including water resistance, dimensional stability, hardness, and thermal stability were significantly improved after the impregnation of PMMA into the wood structure. The supercritical CO2 process shows great promise as a novel and green technique for polymer impregnation of wood to achieve improved properties for next generation construction and architectural products.

A green miniaturized QuEChERS based on an electrospun nanofibrous polymeric deep eutectic solvent coupled to gas chromatography-mass spectrometry for analysis of multiclass pesticide residues in cereal flour samples

A new polymeric deep eutectic solvent (DES) composed of poly (2-hydroxyethyl methacrylate):1-tetradecanol ([PHEMA]:[TD]) was prepared through thermally-induced free-radical polymerization using azobisisobutyronitrile (AIBN) as initiator. The [PHEMA]:[TD] DES was mixed with polyamide 6 (PA6) and electrospun into a composite fibrous scaffold for the first time. The PA6/[HEMA]:[TD] nanofibers were characterized by ATR-FTIR, SEM, BET, and BJH techniques and applied as a sorbent in the micro-solid phase extraction (µSPE) step of pesticide residues from cereal flour samples. The analyses were carried out with the GC–MS technique. The effect of sorbent mass, desorption solvent (kind and volume), pH, and ionic strength was investigated to establish the optimal conditions. Besides, the factors influencing the performance of the electrospinning process, such as electrospinning voltage, polymer solution feed rate, syringe needle tip-to-collector distance, and electrospinning duration, were also optimized. Matrix-matched calibration curves showed good linearity (r2 = 0.9803–0.9984) in the concentration range of 0.016–250 μg kg−1. The obtained limits of quantification (0.016–1.805 μg kg−1) were lower than the maximum residue levels (MRLs) established by the European Union and the Food and Agriculture Organization (0.01–0.05 mg kg−1) for the pesticide residues in cereal samples. The intra-day and inter-day precision based on relative standard deviation (RSD) were obtained as 1.1–5.8% and 2.4–8.5%, respectively. The method was applied to the detection of multiclass pesticide residues in maize, rice, wheat, and pastry flour samples, and the obtained relative recoveries were in the range of 71–118% (RSD%<7.5). Finally, the procedure greenness was evaluated based on Complex Green Analytical Procedure Index (Complex GAPI) and the Analytical Eco-Scale (AEC) approaches. This paper also suggests the first application of green hydrophobic PA6/[PHEMA]:[TD] electrospun nanofibers as sorbent for analyzing pesticides in different cereal samples.