Fabrication of pH‐responsive molecularly imprinted polyethersulfone particles for bisphenol‐A uptake

pH‐responsive molecularly imprinted particles were successfully fabricated by pore‐filling poly (acrylic acid) (PAA) gels into bisphenol‐A (BPA)‐imprinted polyethersulfone particles. The adsorbed BPA amount (or rate) decreased after filling the PAA gels both for the imprinted and nonimprinted particles. However, it was confirmed that changing the acidity of the solution reversibly controls the rebinding ability toward BPA and that the BPA uptake of the pore‐filled particles exhibited chemical valve behavior at a pH between 3 and 6. This finding can be attributed to the swelling of the PAA gels in the particles. The present methodology provides a simple way to prepare pH‐responsive molecularly imprinted materials and is expandable to the imprinting of other hydrophobic molecules, such as dibenzofuran. Also, the results of this work demonstrate the potential of stimuli‐responsive molecularly imprinted polymer materials as smart chemicals and as drug‐delivery systems. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Construction of a novel sensor based on electropolymerization of carmine for voltammetric determination of 4‐nitrophenol

4‐Nitrophenol (4‐NP) has been determined with voltammetric technique based on a novel sensor fabricated by electropolymerization of carmine on a glassy carbon electrode (GCE). An obvious reduction peak located at about ?0.700 V and a couple of redox peaks that were not well‐defined were observed in the potential range of ?1.00 to 0.600 V. Compared with its voltammetric behavior on a bare GCE, the reduction peak potential shifted positively and the peak current increased significantly. All experimental parameters were optimized and linear sweep voltammetry was proposed for its determination. In the optimal conditions, the reduction peak current was proportional to the 4‐NP concentration over the concentration range from 5.00 × 10^?8 to 1.00 × 10^?5 mol L^?1, and the detection limit was 1.00 × 10^?8 mol L^?1 after 200 s of accumulation. The high sensitivity and selectivity of the sensor was demonstrated by its practical application for the determination of trace amounts of 4‐NP in lake water. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3271–3277, 2007     

Preparation of a novel phthalimidomethylated polysulfone/unmodified polysulfone blend affinity membrane and applications for removal of p‐nitrophenol

A novel phthalimidomethyl polysulfone (PIPSf)/polysulfone(PSf) blend affinity membrane was prepared and applied for the removal of p‐nitrophenol from aqueous solutions. In this work, the chloromethylated polysulfone (CMPSf) was used to introduce phthalimido groups onto the polysulfone backbone by Gabriel reaction. The polymers can be easy to phthalimidomethylate to different degrees by control of the reaction temperature and time. Structures of the resulting polymers were confirmed by FT‐IR. The obtained polymers showed good solubility in dimethylformamide, dimethylacetamide and formed the affinity membrane blending with polysulfone at different blend compositions by the phase‐inversion method. Thus the properties of films were characterized with respect to water flux, pore size, and porosity. The surface and cross‐sectional views of the blend membranes were analyzed by scanning electron microscopy (SEM). The research on treatment of removal p‐nitrophenol was carried out by affinity membrane process. The adsorption capacity increased with increasing the initial concentration of p‐nitrophenol in aqueous solution, and the adsorption isotherm fitted the Freundlichmodel well. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Surface molecularly imprinted polymer microspheres based on nano‐TiO2 for selective recognition of kaempferol

The molecular imprinting technique is a new method for preparing molecularly imprinted polymers (MIPs) with specific molecular recognition sites for certain target molecules. In this study, a novel, facile preparation method was presented, called “seed precipitation polymerization,” for the synthesis of MIPs via surface imprinting and a support matrix. In the polymerization process, kaempferol was used as the template molecule, methacrylic acid as the functional monomer, nano‐TiO₂ as the support, azodiisobutyronitrile as the initiator, and ethylene glycol dimethacrylate as the crosslinker in acetonitrile solvent. The synthesized T‐MIP and MIP were analyzed by infrared spectroscopy and scanning electron microscopy. In addition, the obtained polymers were evaluated by adsorption isotherms and dynamic curves for their selective recognition properties for kaempferol. The results show that T‐MIP shows regular spherical particles; the adsorption dynamic curves of T‐MIP show that the adsorption capacity increases with time and reaches a maximum value and then finally reaches equilibrium, and the T‐MIP exhibits a higher affinity for kaempferol than does the MIP. The adsorption follows pseudo‐second‐order kinetics, the Freundlich adsorption equation fits the experimental data well, and there is strong evidence for multiple‐layer adsorption. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44888.     

Characterization of molecularly imprinted and nonimprinted polymer submicron particles specifically tailored for removal of trace 17β‐estradiol in water treatment

This study investigated the potential use of molecularly imprinted polymer (MIP) submicron particles for the selective removal of trace 17β‐estradiol (E2) in water treatment. Methacrylate‐based MIP submicron particles were synthesized, in a one‐step suspension polymerization procedure, using ethylene glycol dimethacrylate (EGDMA) as the cross‐linker. After template removal, the particles could be used as a smart material for specific binding of E2. The submicron size of MIP particles facilitated uniform dispersion in water for up to 17 days. These particles were meritorious in mass transfer behavior, allowing phase partitioning of E2 molecules in water during a short treatment time. After 1‐mL water samples of different E2 concentrations were treated with 20 mg of MIP particles for 2 min, recovery percentages as high as 97% ± 3% were achieved. The specific binding capacity of these MIP particles was determined to be 15 mg E2/g. Nonimprinted polymer nanoparticles were also evaluated for nonspecific binding of E2, using 0.5 mg in 1 mL of water, to attain 64% ± 3% efficiency in 3 min towards general water treatment. A simple capillary electrophoresis method was successfully developed for the characterization of MIP and NIP particles. Apparently the less negative the electrophoretic mobility, the higher binding efficiency and faster binding kinetics the particles would exhibit with E2 due to less hindered Brownian diffusion. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Oxidative degradation of 4‐nitrophenol in UV‐illuminated titania suspension

An internally‐irradiated annular photoreactor has been used to investigate the oxidative degradation of aqueous 4‐nitrophenol with titania as the photocatalyst. Reaction runs were performed over a 3‐h period and in practically all cases, complete degradation was possible within about 2 h. The kinetics was determined as a function of nitrophenol concentration, oxygen partial pressure, catalyst loading, pH, temperature and light intensity. The reaction was characterised by a relatively low activation energy of 7.83 kJ mol^?1 although transport intrusions were negligible. Rate decreased almost exponentially with pH while a quadratic (maximum) behaviour with respect to both oxygen pressure and nitrophenol concentration is symptomatic of self‐inhibition possibly due to the formation of intermediates which competitively adsorb on similar sites to the reactants. Increased catalyst dosage also improved the reaction rate although the possible effects of light scattering and solution opacity caused a drop at loadings higher than about 1.20 g dm^?3. Rate, however, has a linear dependency on light intensity, suggesting that hole–electron recombination processes were negligible at the conditions investigated. © 2001 Society of Chemical Industry     

Trace bensulfuron‐methyl analysis in tap water,soil, and soybean samples by a combination of molecularly imprinted stir bar sorption extraction and HPLC‐UV

A molecularly imprinted stir bar was prepared using bensulfuron‐methyl as the template molecule and methacrylic acid as the functional monomer. The imprinted and nonimprinted stir bars were characterized by scanning electron microscopy, nitrogen sorption porosimetry, thermogravimetric analysis, and differential scanning calorimetry. Extraction time, desorption time and pH value affecting extraction efficiency of the stir bar have been evaluated to achieve the selectively direct preconcentration of the template from aqueous samples. Competitive sorption experiments demonstrated that the imprinted stir bar gave high selectivity and imprinted effect on the template bensulfuron‐methyl compared to the nonimprinted stir bar. Based on S/N of 3, LOD was 0.83 nM. The method showed good recoveries and precision, 92.4% (RSD 1.5%, n = 3) for tap water spiked with 126 ng (100 mL sample), 84.6% (RSD 2.2%, n = 3) for soil spiked with 210 ng (100 g sample) and 73.7% (RSD 2.1%, n = 3) for soybean spiked with 250 ng (5 g sample), suggesting that the imprinted stir bar sorption extraction can be successfully applied to the preconcentration of bensulfuron‐methyl in real samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Cyclodextrin‐based molecularly imprinted polymers for the efficient recognition of pyrethroids in aqueous media

Recent years have witnessed growing applications of the molecular imprinting technique for the detection of pesticide residues in environmental and food samples. In this study, molecularly imprinted polymers (MIPs) for pyrethroids, a class of popular insecticides, were synthesized by the crosslinking of β‐cyclodextrin (β‐CD) with 1,6‐hexamethylene diisocyanate (HMDI) or toluene‐2,4‐diisocyanate (TDI) in dimethyl sulfoxide, with lambda‐cyhalothrin (LCT) as a model template. Equilibrium batch‐rebinding tests were operated in different aqueous solutions. The results indicate that MIP prepared with TDI (MIP–TDI) possessed a much greater binding activity to LCT than MIP based on HMDI (MIP–HMDI), and MIP–TDI displayed a remarkably specific binding to LCT (with an imprinting factor of around 3) in an acetonitrile/water (4:7 v/v) mixture. The adsorption of LCT by MIP–TDI reached equilibrium after 3 h; this demonstrated comparatively rapid adsorption kinetics. Also, MIP–TDI could be regenerated eight times at least; this implied that the robust β‐CD polymer has the potential for practical applications. Furthermore, a cross‐selectivity study indicated that the high adsorption of LCT and its analogues by MIP–TDI in aqueous media must have been ascribed to the cooperative effects of CD inclusion interaction and stereoshape memory. This study paved the way for the use of β‐CD as a functional monomer for preparing smart artificial receptors for the efficient recognition of pyrethroids under aqueous conditions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Kinetics of hydrogenation of 4‐chloro‐2‐nitrophenol catalyzed by Pt/carbon catalyst

Hydrogenation of 4‐chloro‐2‐nitrophenol (CNP) was carried out at moderate hydrogen pressures, 7–28 atm, and temperatures in the range 298–313 K using Pt/carbon and Pd/γ‐Al₂O₃ as catalysts in a stirred pressure reactor. Hydrogenation of CNP under the above conditions gave 4‐chloro‐2‐aminophenol (CAP). Dechlorination to form 2‐aminophenol and 2‐nitrophenol is observed when hydrogenation of CNP is carried out above 338 K, particularly with Pd/γ‐Al₂O₃ catalyst. Among the catalysts tested, 1%Pt/C was found to be an effective catalyst for the hydrogenation of CNP to form CAP, exclusively. To confirm the absence of gas–liquid mass transfer effects on the reaction, the effect of stirring speed (200–1000 rpm) and catalyst loading (0.02–0.16 g) on the initial reaction rate at maximum temperature 310 K and substrate concentration (0.25 mole) were thoroughly studied. The kinetics of hydrogenation of CNP carried out using 1%Pt/C indicated that the initial rates of hydrogenation had first order dependence with respect to substrate, catalyst and hydrogen pressure in the range of concentrations varied. From the Arrhenius plot of ln rate vs 1000/T, an apparent activation energy of 22 kJ mol^?1 was estimated. © 2001 Society of Chemical Industry     

The preparation of molecularly imprinted poly(o‐phenylenediamine) membranes for the specific O,O‐dimethyl‐α‐hydroxylphenyl phosphonate sensor and its characterization by AC impedance and cyclic voltammetry

A molecularly imprinted polymer (MIP) membrane for sensing O,O‐dimethyl‐α‐hydroxylphenyl phosphonate (DHP) has been prepared by electropolymerizing o‐phenylenediamine on the glassy carbon electrodes in the presence of DHP. Optimization studies with the aim to enhance insulating properties and response kinetics of the polymer membrane were carried out with respect to template molecular concentration, the monomers concentration, the polymer membrane thick and scan rate. Cyclic voltammetry and electrochemical impedance have been used to characterize the behavior of MIP polymer membrane. The capacitive measurements were also certified the imprinting effect of the polymer layers. The experimental results showed that DHP imprinted polymer has better recognition property for the template than that of a blank polymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2222–2227, 2006     

Synthesis of molecularly imprinted microspheres for recognition of trans‐aconitic acid

In the presence of a template molecule, trans‐aconitic acid and, using acetonitrile as solvent and dispersing medium, monodispersed microspheres with a diameter of 600–700 nm bearing molecularly imprinted binding sites were prepared by precipitation polymerization. It was found that the concentrations of template, monomer, and crosslinking agent as well as the chemical structure of the template greatly affect the polymer configuration. Microspheres are produced only when the concentration of the template molecule and the functional monomer are finely tuned. Comparison with the performance of a conventional imprinted polymer monolith showed that the imprinted microsphere had obvious advantages in specific binding to template molecule. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 542–547, 2004     

Preparation of pH and temperature dual‐sensitive molecularly imprinted polymers based on chitosan and N‐isopropylacrylamide for recognition of bovine serum albumin

pH and temperature dual‐sensitive protein imprinted microspheres with high absorption capacity have been successfully synthesized on the surface of SiO₂ using chitosan grafted N‐isopropylacrylamide (CS‐g‐NIPAM) as the pH and temperature sensitive monomer, with acrylamide as comonomer, N,N′‐methylenebisacrylamide as the crosslinking agent and bovine serum albumin (BSA) as the template protein. The pH and temperature dual‐sensitivity was also investigated. The results showed that the adsorption capacity and imprinting factor improved slowly with increasing incubation pH from 4.6 to 7.0, and then decreased sharply in alkaline conditions due to the reduction of non‐specific binding from electrostatic and hydrogen bonding interactions. Fourier transform infrared spectroscopy, thermogravimetric analysis and transmission electron microscopy were used to characterize the polymers. The as‐prepared SiO₂@BSA molecularly imprinted polymers were also found to have high adsorption capacity (119.88 mg g^?1) within 2 h, an excellent imprinting factor (α = 2.25), specific selectivity and good reusability. © 2019 Society of Chemical Industry     

Magnetic molecularly imprinted polymer nanoparticles coupled with high performance liquid chromatography for solid‐phase extraction of carvedilol in serum samples

Herein, we report a magnetic molecularly imprinted polymers (m‐MIPs) using Fe₃O₄ as a magnetic component, carvedilol as a template molecule for the solid‐phase extraction (MISPE) as the sample clean‐up technique combined with high‐performance liquid chromatography (HPLC) and for the controlled release of carvedilol at different pH values of 1.0 (simulated gastric fluid), 6.8 (simulated intestinal fluid), and 7.4 (simulated biological fluid). The adsorption kinetics was modeled with the pseudo‐first‐order and pseudo‐second‐order kinetics, and the adsorption isotherms were fitted with Langmuir and Freundlich models. The performance of the m‐MIPs for the controlled release of carvedilol was assessed and results indicated that the magnetic MIPs also have potential applications in controlled drug release. Furthermore, the m‐MIPs were applied to the extraction of carvedilol from human blood plasma samples. Carvedilol can be quantified by this method in the 2–350 μg L^?1 concentration range. The limit of detection and limit of quantification in plasma samples are 0.13 and 0.45 μg L^?1. The results from HPLC showed good precision (3.5% for 50.0 μg L^?1) and recoveries (between 85 and 93) using m‐MIP from human plasma samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41209.     

Transport selectivity of tribenuron‐methyl imprinted polymer nanowire membrane prepared using N,O‐bismethacryloyl ethanolamine as a functional crosslinking monomer

Using tribenuron‐methyl as a template and N,O‐bismethacryloyl ethanolamine as a functional crosslinking monomer, a molecularly imprinted nanowire membrane was prepared over an anodic alumina oxide membrane. The nanowire fabric of the imprinted membrane was established with a scanning electron microscope and a transmission electron microscope. However, the nonimprinted particulate membrane is formed in the absence of a template. Scatchard analysis showed that an equal class of binding sites were formed in the imprinted nanowire membrane and the dissociation constant and the maximum number of these binding sites were estimated to be 1.44 × 10⁻⁵ M and 22.7 µmol/g, respectively. The permeation experiments throughout the imprinted membrane and the nonimprinted one were carried out in a solution containing the template and its competitive analogs. These results demonstrated that the molecularly imprinted nanowire membrane exhibited higher transport selectivity for the template tribenuron‐methyl than its analogs, chlorimuron‐ethyl, thifensulfuron‐methyl and N‐(4‐bromophenylcarbamoyl)‐5‐chloro‐1H‐benzo[d]imidazole‐2‐carboxamide. But the nonimprinted granular membrane had no permselectivity for the four substrates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A pH‐controllable imprinted composite membrane for selective separation of podophyllotoxin and its analog

A molecularly imprinted composite membrane (MICM) with pH‐controllability and selectivity to podophyllotoxin (PPT) was prepared using a polyvinylidene fluoride (PVDF) microfiltration membrane as the support. The functional monomer is 1‐phenyl‐3‐methyl‐4‐methacryloyl‐5‐pyrazolone (PMMP), which is a new β‐diketone compound with enol/ketol tautomerization. In this study, imprinting parameters, including the amounts of functional monomer and cross‐linker, and immersion time of membrane in the imprinting solution, were optimized by equilibrium adsorption experiments. Pore structure and surface morphology of the optimal MICM (MICM₂) was characterized. Finally, competitive permeability of PPT in the presence of its analog 4′‐demethylpodophyllotoxin (DMEP) was measured under the drive of concentration difference. The results reveal that the surface morphology and pore structure of MICM₂ are structurally different from those of the control nonimprinted membrane. As a result, MICM₂ could efficiently recognize PPT in a complex system due to a better structural matching and the interaction between the functional groups of MICM₂ and PPT. However, the most interesting finding is its pH‐controllability. The membrane could switch the preference to either PPT or DMEP with the change of pH values in the sample solution. At pH values smaller than 8.4, it led to a faster transportation of PPT, while the situation reversed to DMEP at pH values greater than 8.4. This peculiar property would lead this imprinted membrane to have potential application in the separation and enrichment of PPT, and the new functional monomer PMMP exhibited an attractive application prospect in the functional material fields. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Graphene‐based molecularly imprinted polymer for separation and pre‐concentration of trace polycyclic aromatic hydrocarbons in environmental water samples

A composite of reduced graphene oxide and pyrene‐imprinted polymer was synthesized and employed as a solid phase for extraction of five selected polycyclic aromatic hydrocarbons (PAHs) from water samples. Gas chromatography‐time of flight/mass spectrometry was employed in the analysis of the extracts. The composite was prepared by a free radical polymerization of methacrylic acid and 4‐vinylpyridine as monomers and ethylene glycol dimethacrylate as a crosslinker. The adsorption studies were carried out through batch binding studies. The binding capacity for the imprinted and non‐imprinted composite was 101.83 and 68.21 µg g^?1, respectively. The adsorption followed the pseudo 2nd order and well fitted the Langmuir isotherm. Mean recoveries ranging from 73% to 105.4% for both spiked deionized water and environmental water samples were obtained when the imprinted composites were employed in solid phase extraction of the PAHs. The composites could be re‐used for five times without a significant loss in recoveries. The proposed method was employed for the analysis of spiked environmental water samples and did not show significant changes in the recoveries showing there were no matrix interferences. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45300.     

Rosin‐based molecularly imprinted polymers as the stationary phase in high‐performance liquid chromatography for selective separation of berberine hydrochloride

A novel method for the separation of berberine hydrochloride has been developed. Berberine hydrochloride molecularly imprinted polymers were prepared by suspension polymerization in the aqueous phase using berberine hydrochloride as the template, methyl acrylic acid as a functional monomer, and ethylene glycol maleic rosinate acrylate (which contains a phenanthrene ring skeleton) and ethylene glycol dimethacrylate as combinatorial crosslinkers. The imprinted polymers were successfully used as a selective stationary phase in high‐performance liquid chromatography. Separation performance of the chromatographic column was determined from the selectivity (evaluated by separation factor) and sorption selectivity (evaluated by imprinting factor) of the molecularly imprinted and non‐imprinted polymers towards the template. The optimum conditions to maximize separation and imprinting factors were investigated. Acetic acid–methanol solution (0.05% v/v) was selected as the optimum mobile phase, while 0.2 mL min^?1 was chosen as the optimized flow rate for selective separation of berberine hydrochloride. The highest imprinting and separation factors obtained were 1.924 and 18.52, respectively. Simultaneously, the chromatographic column backpressure was stable and showed good permeability. The chromatographic column was used to separate effectively template molecules from coptis root extract and other analogues. Such chromatographic columns with high selectivity can be used to selectively separate berberine hydrochloride from other compounds. © 2014 Society of Chemical Industry     

Selective molecularly imprinted polymer nanofiber sorbent for the extraction of bisphenol A in a water sample

Novel molecularly imprinted polymer nanofibers (MIP‐NFs) were prepared for the adsorption of bisphenol A (BPA) in a water sample using the sol–gel process and the electrospinning technique. The effects of a number of synthesis parameters on the adsorption efficiency were investigated. The successful removal of BPA from MIP‐NFs was studied using UV–visible spectroscopy. The prepared MIP‐NFs were characterized by Fourier transform infrared, field emission SEM, TEM and energy dispersive X‐ray analysis. The results showed that the required molar ratio of 3‐aminopropyltriethoxysilane (APTES) to BPA was 15:1, which indicates a good performance in the rebinding test. Likewise, the molar ratio of APTES:acid:water was 1:2:9. The nylon 6 polymer solution, with a concentration of 12 wt%, showed a maximum adsorption capacity for BPA due to a decrease in the nanofiber diameter and an increase in the accessible sites. Furthermore, the maximum adsorption capacity of BPA was achieved at pH 7. Concerning the binding of BPA on MIP‐NFs, the experimental data matched well with the pseudo‐second‐order kinetics data and the Sips isotherm model. The saturated binding capacity for MIP‐NFs was predicted to be 115.1 mg g^?1, which was more than twice as high as that for non‐imprinted polymer nanofibers (46.82 mg g^?1). The results obtained in this study confirmed that the prepared MIP‐NFs showed considerable binding specificity for BPA in comparison with similar structural compounds such as phenol, naphthol and Naphthol AS, in aqueous solution. The binding capacity of MIP‐NFs remained almost constant after five cycles of reuse. The real sample analysis indicated that MIP‐NFs could be utilized as a useful sorbent material for the extraction of BPA from a water sample.     

Grafting of molecularly imprinted polymers from the surface of Fe3O4 nanoparticles containing double bond via suspension polymerization in aqueous environment: A selective sorbent for theophylline

Molecularly imprinted polymers (MIPs) were grafted from the surface of Fe₃O₄ nanoparticles containing double bond via suspension polymerization in aqueous environment, and the leakage of Fe₃O₄ nanoparticles from MIPs was overcome in this study. The effect of different cross‐linker on adsorption capacity of the resultant magnetic MIPs was investigated using pure trimethylolpropane trimethacrylate (TRIM) or the mixture of TRIM and divinylbenzene (DVB) as cross‐linker. Both magnetic MIPs exhibited higher adsorption capacity for the template theophylline than the corresponding non‐imprinted polymer, and Freundlich model fitted reasonably well for theophylline adsorption on both magnetic MIPs. In addition, both magnetic MIPs exhibited good recognition properties for the template theophylline versus caffeine, and the selectivity of magnetic MIPs using pure TRIM as cross‐linker (mag‐MIP‐TRIM) was much higher than those using the mixture of TRIM and DVB as cross‐linker (mag‐MIP‐TRIM and DVB). The adsorption dynamics of theophylline on both magnetic MIPs fitted well with the first‐order kinetic model, but the adsorption equilibrium on mag‐MIP‐TRIM and DVB reached faster than that on mag‐MIP‐TRIM. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011