Co-functional Monomer Research Articles

Preparation of molecular imprinted microspheres based on inorganic–organic co-functional monomer for miniaturized solid-phase extraction of fluoroquinolones in milk

An inorganic-organic co-functional monomer, methacrylic acid-vinyltriethoxysilan (MAA-VTES) was designed for the synthesis of molecularly imprinted microspheres (MIMs). By virtue of the aqueous suspension polymerization and dummy template (pazufloxacin), the obtained MAA-VTES based MIMs exhibited good recognition and selectivity to fluoroquinolones (FQs), and were successfully applied as selective sorbents of a miniaturized home-made solid phase extraction device for the determination of ofloxacin (OFL), lomefloxacin (LOM) and ciprofloxacin (CIP) in milk samples. Under the optimum conditions of the miniaturized molecularly imprinted solid phase extraction (mini-MISPE) coupled with liquid chromatography-ultraviolet detector (LC-UV), good linearities were obtained for three FQs in a range of 0.2-20.0μgmL(-1) and the average recoveries at three spiked levels were ranged from 87.2% to 106.1% with the relative standard deviation (RSD) less than 5.4%. The presented co-functional monomer based mini-MISPE-LC-UV protocol introduced the rigidity and flexibility of inorganic silicon materials, exhibited excellent extraction performance towards targets, and could be potentially applied to the determination of FQs in milk samples.

Methyl parathion imprinted polymer nanoshell coated on the magnetic nanocore for selective recognition and fast adsorption and separation in soils

Core–shell magnetic methyl parathion (MP) imprinted polymers (Fe3O4@MPIPs) were fabricated by a layer-by-layer self-assembly process. In order to take full advantage of the synergistic effect of hydrogen-binding interactions and π–π accumulation between host and guest for molecular recognition, methacrylic acid and 4-vinyl pyridine were chosen as co-functional monomers and their optimal proportion were investigated. The core–shell and crystalline structure, morphology and magnetic properties of Fe3O4@MPIPs were characterized. The MP-imprinted nanoshell was almost uniform and about 100nm thick. Binding experiments demonstrated that Fe3O4@MPIPs possessed excellent binding properties, including high adsorption capacity and specific recognition, as well as fast adsorption kinetics and a fast phase separation rate. The equilibration adsorption capacity reached up to 9.1mg/g, which was 12 times higher than that of magnetic non-imprinted polymers, while adsorption reached equilibrium within 5min at a concentration of 0.2mmol/L. Furthermore, Fe3O4@MPIPs successfully provided selective separation and removal of MP in soils with a recovery and detection limit of 81.1–87.0% and 5.2ng/g, respectively.

Ionic liquids modified dummy molecularly imprinted microspheres as solid phase extraction materials for the determination of clenbuterol and clorprenaline in urine

New ionic liquid modified dummy molecularly imprinted microspheres (DMIMs) were synthesized by aqueous suspension polymerization using phenylephrine as dummy template and 1-allyl-3-ethylimidazolium bromide as co-functional monomer. The obtained DMIMs were characterized by Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM), and empolyed as the special sorbent of solid-phase extraction for isolation of clenbuterol (CLB) and clorprenaline (CLP) from urine sample. The results indicated that the ionic liquid modified polymers were monodispersed microspheres and had high selectivity and adsorbability to CLB and CLP, and the matrix interferences could be efficiently eliminated from the samples. Meanwhile, the effect of template leakage of DMIMs on quantitative analysis was avoided. Compared with other commercial sorbents (HLB, PCX, C18 and SCX), the DMIMs exhibited higher affinity and purification ability to CLP and CLB. Under the optimized conditions, good linearity was observed in a range of 0.90–400μgL−1 (r2=0.9999) with LOD of 0.19 and 0.070μgL−1 for CLP and CLB, respectively. The recoveries at three spiked levels were ranged from 93.3% to 106% with RSD≤5.6% (n=3).

Determination of sulfamethoxazole in milk using molecularly imprinted polymer monolith microextraction coupled to HPLC

We report on a new method for the selective extraction of the antibiotic sulfamethoxazole (SMO) in milk that is making use of a molecularly imprinted polymer (MIP) monolith as the sorbent. The monolith was synthesized in the tip of a micropipette using SMO as the template and a combination of acrylamide and 4-vinylpyridine as the co-functional monomers. The monolith was connected to syringes in different sizes and used for microextraction without any other treatment and showed high selectivity and enrichment ability for SMO. It was applied to the selective extraction and sensitive determination of SMO in milk. The linear range is from 5–600 μg L−1, the correlation coefficient (r2) is 0.9984, and the detection limit (at S/N = 3) is 1 μg L−1. Recoveries range from 93.6 to 101.7 %, with relative standard deviations of <6.1 %.

Daidzein-imprinted membranes using co-functional monomers

Daidzein-imprinted poly(methacrylamide-co-acrylic acid) composite membranes with different ratios of methacrylamide (MAM) versus acrylic acid (AA) were prepared via UV initiated photo-copolymerization on the commercial filter paper with ethylene glycol dimethacrylate (EGDMA) as cross-linker and mixed cellulose ester as agglutinant. Infra-red (IR) spectroscopy and scanning electron microscope (SEM) were used to visualize the surface of the membranes. Binding and recognising properties of the imprinted composite membranes to daidzein and its analogues genistein were evaluated by static adsorption experiment. It was found that the daidzein-imprinted membranes showed high selectivity to daidzein, with the highest selectivity when the composite membrane with the ratio of MAM vs AA as 4:1. The results suggested that the molecularly imprinted composite membranes were potentially useful for daidzein enrichment.

Sulfonamide imprinted polymers using co-functional monomers

Molecular imprinted polymers (MIPs) prepared using combination of acrylamide (ACM) and 4-vinylpyridine (4-Vpy) as co-functional monomers exhibited efficient recognition properties in both organic and aqueous media as HPLC stationary phase. The results indicate that amide and pyridine groups in functional monomers formed strong hydrogen-bonding interaction with the template molecule, and specific recognition sites were created within the polymer matrix during the imprinting process. When sulfamethoxazole (SMO) was used as template, a MIP prepared in a polar organic solvent (acetonitrile) using the combination of ACM and 4-Vpy showed better recognition of template than the polymer prepared in the same solvent using the combination of acidic monomer (methacrylic acid) and basic monomer 4-Vpy. On the contrary, when sulfamethazine (SMZ) was used as template, a MIP prepared using the combination of methacrylic acid (MAA) and 4-Vpy showed better recognition of template than the polymer prepared using the combination of ACM and 4-Vpy. Our results indicate that in organic media the degree of retention of the sample molecules on the imprinted polymers was controlled by the hydrogen-bonding interaction between the sample molecules and the polymer, while in aqueous media it was determined to a considerable extent by hydrophobic interactions. In both media the shape, size and the electronic structure of the template molecule were all-important factors in the recognition process.

Polyimide Films from Vapor Deposition: Toward High Strength, NIF Capsules

The focus of recent efforts at LLNL has been to demonstrate that vapor deposition processing is a suitable technique to form polyimide films with sufficient strength for current National Ignition Facility target specifications. Production of polyimide films with controlled stoichiometry was accomplished by: 1) depositing a novel co-functional monomer and 2) matching the vapor pressure of each monomer in PMDA/ODA co-depositions. The sublimation and deposition rate for the monomers was determined over a range of temperatures. Polyimide films with thicknesses up to 30 μm were fabricated. Composition, structure and strength were assessed using FTIR, SEM and biaxial burst testing. The best films had a tensile strength of approximately 100 MPa. A qualitative relationship between the stoichiometry and tensile strength of the film was demonstrated. Thin films (∼3.5 μm) were typically smooth with an rms of 1.5 nm.