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     

Molecularly imprinted PVC beads for the recognition of proteins

Ultrathin films of molecularly imprinted polymer (MIP) were prepared by photoiniferter on PVC beads for the selective uptake of lysozyme, taken as a model protein. Acrylamide was selected as the functional monomer and N,N‐methylenebisacrylamide as the crosslinking agent. The copolymerization process was confined to the surface of the PVC beads grafted with diethyldithiocarbamate iniferter initiator in the presence of lysozyme. After extraction of lysozyme from the shell of the PVC‐MIP beads, the latter were then used as artificial receptors for the rebinding of lysozyme. The sequential steps of the modification of PVC beads were monitored by XPS, infrared and Raman spectroscopies. The imprinting step was found to be essential as the PVC‐MIP beads could recognize lysozyme but not the non‐imprinted beads (PVC‐NIP). The binding properties of PVC‐MIP beads were determined using UV spectroscopy from adsorption isotherms of lysozyme, cytochrome, and myoglobin. The imprinted beads were found to be highly selective toward lysozyme over the competitive proteins. This work shows the interest of photoiniferter as an efficient mean for the design of molecularly imprinted polymer beads for rapid, selective removal of proteins. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43694.     

Estimation of phase diagrams for copolymer‐diluent systems in thermally induced phase separation

The binary interaction model was introduced to estimate phase diagrams of copolymer‐diluent systems in thermally induced phase separation. The crystallization curves and cloud points of poly(ethylene‐co‐vinyl alcohol) (EVOH) with 1,4‐butanediol, EVOH/1,3‐propanediol, and EVOH/glycerol were calculated and compared with experimental value or literature data. Fair agreement was obtained. To confirm the importance of incorporating intramolecular interactions, calculations with and without the consideration of intramolecular interactions were performed and compared. It was found that better results can be obtained if intramolecular interaction was introduced. The reason for the small differences between the calculated value and the experimental data of the liquid–liquid phase separation is discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

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     

Synthesis of poly(vinyl butyral)s in homogeneous phase and their thermal properties

The condensation reaction of butyraldehyde (BA) with poly(vinyl alcohol) (PVA) to give poly(vinyl butyral) (PVB) was studied in detail using N‐methyl‐2‐pyrrolidone (NMP) as solvent for PVA and PVBs. PVBs having various degrees of acetalization were obtained. The acetalization reaction under a variety of conditions gave at best a polymer with 97% acetalization. The extent of modification and the structure of the polymer, i.e., the ratio of acetal units from meso and racemic dyads of PVA, were determined by ¹H‐NMR. The acetalization degree was reflected in the solubility of PVB; all products were soluble in NMP. PVBs were characterized by IR spectroscopy and ¹H and ¹³C‐NMR. The glass transition temperatures of PVBs, determined by DSC, increased as vinyl alcohol units increased and displayed a positive departure from linearity. Thermal degradation of PVBs was studied using differential thermal analysis (DTA) and thermogravimetry (TGA) under dynamic conditions in nitrogen. The content of hydroxyl groups had an effect on the thermal stability of PVBs; the thermal stability of PVBs decreased as vinyl alcohol units increased. The apparent activation energy of the decomposition was determined by the Kissinger and Flynn–Wall methods, which agree well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5007–5017, 2006     

Effect of some selective aromatic cosolutes on the main thermodynamic parameters of aqueous poly(n‐vinyl‐2‐pyrrolidone) solutions

Cloud‐point curves and theta temperatures have been determined for aqueous solutions of poly(N‐vinyl‐2‐pyrrolidone) at several concentrations for a variety of aromatic additives (benzoic acid, o‐ and p‐hydroxy benzoic acid, aniline, o‐ and p‐hydroxy aniline). The theta temperature of polymer is suppressed at lower temperatures depending on the chemical structure and the concentration of additives. The effectiveness, in decreasing order, of the cosolutes in reducing the temperature is: p‐hydroxy benzoic acid > o‐hydroxy benzoic acid > p‐hydroxy aniline > o‐hydroxy aniline ≈ benzoic acid > aniline. It is understood that changes in theta temperatures caused by the cosolute result from the changes taking place in the hydrophilic and hydrophobic interactions among polymer, solvent and polymer–solvent interactions from the added cosolute. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 507–510, 2000     

Effects of inorganic salts on the spectral behavior of poly(N‐vinyl‐2‐pyrrolidone) in aqueous solutions

Electronic spectral behavior of poly(N‐vinyl‐2‐pyrrolidone) (PVP) was determined in aqueous solutions including a variety of inorganic salts (phosphates, mono‐ and dihydrogen phosphates, sulfates, chlorides, nitrates, bisulfites, and persulfates) for several concentrations. The n → π* excitations are shifted to longer wavelengths depending on the nature and the concentration of salt. The resulting dependence of λ_max on the molar concentration can be expressed to show the increasing effect of anionic and cationic species in bathochromic shift. The increasing order of effectiveness of anions in shifting the λ_max is S₂O₈ ⁼ > S₂O₅ ⁼ > PO₄ ³⁻ > HPO₄ ²⁻ > SO₄ ²⁻ > H₂PO₄ ²⁻ > Cl⁻. The order for the cation is as Na⁺ ≈ K⁺ ≈ NH₄ ⁺ in the 0.1–0.6M concentration range and Na⁺ ≈ K⁺ > NH₄ ⁺ in > 0.6M aqueous solutions. The changes observed in λ_max by the salt were correlated with the changes occurring in the structure of water and the polymer–solvent interactions. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1434–1439, 2000     

A new approach for selective surface modification of fluoropolymers by remote plasmas

Ethylene‐co‐tetrafluoroethylene (ETFE) and poly (vinylidene fluoride) (PVDF) films were exposed to the remote Ar, H₂, and O₂ plasmas. The modified polymer surfaces were characterized by X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurement. The plasma exposure led to weight loss and changes in the chemical composition on the polymer surface. Selective surface modification of fluoropolymers introduces various functional groups without altering the bulk properties. The results may be summarized as follows: the remote hydrogen plasma was the most effective in alternation from C? F to C? H (abstraction of fluorine). On the other hand, the remote oxygen plasma was unfavorable to abstract fluorine atoms, but effective in dehydrogenation (abstraction of hydrogen). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1012–1020, 2004     

New coordination polymers. IV. Oxidation of poly(vinyl alcohol) by permanganate ion in alkaline solutions. kinetics and mechanism of decomposition of intermediate complex

The kinetics of decomposition of [PVA. Mn^VIO-] intermediate complex have been studied spectrophotometrically. A first-order dependence on the intermediate concentration was observed. The decomposition rate was found to be base-catalysed. The kinetic parameters have been evaluated and a mechanism consistent with the results obtained is discussed.     

Preparation and characterizaton of poly(dimethyl amino ethyl methacrylate) modified poly(vinyl alcohol) membrane by UV radiation for the permeation of 5‐fluorouracil

Poly(vinyl alcohol) was modified by UV radiation with dimethyl amino ethyl methacrylate (DMAEMA) monomer to get poly(dimethyl amino ethyl methacrylate) modified poly(vinyl alcohol) (PVADMAEMA) membrane. The PVADMAEMA membranes were characterized by Fourier transform infrared spectroscopy. The tensile strength and elongation of PVADMAEMA membranes were measured by Universal Testing Machine. The results of X‐ray diffraction (XRD) and differential scanning calorimetry (DSC) showed that (1) the crystalline area in PVADMAEMA decreased with increasing the content of poly(dimethyl amino ethyl methacrylate) in the membrane. (2) Only one glass transition temperature (T_g) was found for the various PVADMAEMA membranes. It means that poly(dimethyl amino ethyl methacrylate) and PVA are compatible in PVADMAEMA membrane. (3)The T_g of the membrane is reduced with increasing the content of poly(dimethyl amino ethyl methacrylate) in the membrane. The water content on the PVADMAEMA membranes was determined. It was found that the water content on the PVADMAEMA membrane increased with increasing the content of poly(dimethyl amino ethyl methacrylate). The changes of properties enhanced the permeability of 5‐Fluorouracil (5‐Fu) through the PVADMAEMA membranes. A linear relationship between the permeability and the weight percent of poly(dimethyl amino ethyl methacrylate) in the PVADMAEMA membrane is found. It is expressed as P (cm/s) = (9.6 ± 0.4) × 10^?5 + (8.8 ± 0.6) × 10^?5 W _x , where P is the permeability of 5‐Fu through the membrane and W_x is the weight percent of poly(dimethyl amino ethyl methacrylate) in the PVADMAEMA membrane. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Biodegradable membranes for the controlled release of progesterone. 1. Characterization of membrane morphologies coagulated from PLGA/progesterone/DMF solutions

Biodegradable membranes containing progesterone as a drug were prepared from ternary, poly(d,l‐lactide‐co‐glycolide)/progesterone/dimethylformamide, solutions. The homogeneous solutions, after cast on glass plates, were solidified to result in a solid membrane structure by three different solvent‐removal processes: solvent evaporation under vacuum, solvent extraction via immersion into the nonsolvent bath, or vapor exposure at high humidity condition. Impregnation characteristics of progesterone in the prepared membranes varied significantly, depending on the removal processes used. When a cast solution was solidified by exposure at the environment of 70% relative humidity, progesterone was separated from a membrane structure with the morphology of flake‐like shapes, and thermal analysis of the prepared membrane showed the clear, endothermic peak of the drug. Vitrification of a cast solution by solvent evaporation under vacuum induces both the uniform drug dispersion in the polymer matrix, with the drug forming spherical structures, and the strong interaction between the drug and the matrix, as identified by a broadened melting endotherm of the drug. When coagulated at thermodynamic nonequilibrium conditions through rapid exchange between dimethyformamide and water, the cast solution film results in a membrane structure consisting of the drug distributed nonuniformly in the polymer matrix. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 60–67, 2000     

Mechanism of the droplet formation and stabilization in the aqueous two‐phase polymerization of acrylamide

Aqueous two‐phase polymerization of acrylamide has been carried out in an aqueous solution of poly(ethylene glycol) initiated by ammonium persulfate. The chemical composition of the product was characterized by FTIR, and the droplet size distribution in the initial stage of the polymerization was followed by dynamic light scattering. On the basis of the evolution of polyacrylamide aqueous droplets size distribution and morphology at every stage, a new mechanism of droplet formation was proposed. The experimental phenomenon that the small droplets always existed in the process of polymerization and some irregular shape droplets were formed in the product of aqueous two phase polymerization could be successfully explained by the new mechanism. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

New coordination polymers. III: Oxidation of poly(vinyl alcohol) by permanganate ion in alkaline solutions. Kinetics and mechanism of formation of intermediate complex with a spectrophotometric detection of manganate(vi) transient species

The kinetics of formation of the [PVA. Mn^VIO] intermediate complex have been measured by the conventional spectrophotometric technique. The rate of formation of the complex was found to be given by the expression d[Complex]/dt = k₁[MnO-₄][PVA^?]. The results showed that the rate of formation is dependent on the base concentration. A first-order reaction in permanganate and fractional order with respect to the poly(vinyl alcohol) (PVA) concentration were observed. The activation parameters have been evaluated and a tentative reaction mechanism has been suggested.     

Adsorption of surfactant by hydrophobically modified poly[2‐(diethylamino)ethylmethacrylate‐co‐N‐vinyl‐2‐pyrrolidone/octadecyl acrylate)] hydrogels and effect of surfactant adsorption on the volume phase transition

Hydrophobically modified poly[2‐(diethylamino)ethylmethacrylate‐co‐N‐vinyl‐2‐pyrrolidone/octadecyl acrylate) [P(DEAEMA‐co‐NVP/OA)] hydrogels were synthesized by free‐radical crosslinking copolymerization of 2‐(diethylamino)ethylmethacrylate (DEAEMA), N‐vinyl‐2‐pyrrolidone (NVP) with different amounts of hydrophobic comonomer octadecyl acrylate (OA) in tert‐butanol with ethylene glycole dimethacrylate (EGDMA) as a crosslinker. The swelling equilibrium of the hydrogels was investigated as a function of temperature and hydrophobic comonomer content in aqueous solutions of the anionic surfactant sodium dodecyl sulfate (SDS) and the cationic surfactant dodecyltrimethylammonium bromide (DTAB). The results indicated that the swelling behavior and temperature sensitivity of the hydrogels were affected by the type and concentration of surfactant solutions. Additionally, the amount of the adsorbed SDS and DTAB molecules onto the hydrogels was determined by fluorescence measurements. An increase of OA content in the hydrogel caused an increase in the amount of adsorbed surfactant molecules in both media. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3771–3775, 2007     

A mucoadhesive polymer prepared by template polymerization of acrylic acid in the presence of poly(vinyl alcohol) for mucosal drug delivery

The interpolymer complexes composed of PVA and PAA were prepared by template polymerization of acrylic acid in the presence of PVA with different molecular weights and degrees of saponification. The carbonyl absorption band of the PAA in the PAA/PVA interpolymer complexes was shifted to a lower wavenumber due to H‐bonding between the carboxyl group of PAA and the hydroxyl group of PVA. The swelling ratio and the degree of dissolution of the PVA/PAA interpolymer complexes were dependent on the pH of the medium, the molecular weight, and the degree of saponification of the PVA. The release rate of a model drug, lidocaine, from the complexes decreased with increasing degree of saponification of the PVA due to the lower swelling degree of the complex. The adhesive force of the PVA/PAA interpolymer complexes with a plastic plate (poly propylene) was stronger than that of the commercial Carbopol 971P. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 327–331, 2004     

Pervaporation behavior of PVA membrane containing β‐cyclodextrin for separating xylene isomeric mixtures

To evaluate molecular recognition function of β‐cyclodextrin to xylene isomers, β‐CD polymer of branching chain extension (β‐CD‐EGDE) was synthesized by crosslinking β‐CD with ethylene glycol diglycidyl ether (EGDE). The pervaporation blend membranes of β‐CD‐EGDE/PVA were prepared by casting an aqueous solution of PVA and β‐CD polymer mixture, and the membranes were used for separation of p‐/m‐ and p‐/o‐xylene mixtures. It was observed that the pristine PVA membrane almost had no selectivity for xylene isomer mixtures. The PVA membrane incorporating β‐CD polymer had molecular recognition function, which selectively facilitated the transport of the xylene isomers. To ascertain pervaporation behavior, the sorption and desorption processes of the membrane in xylenes were investigated. The sorption result showed that the complex formation constant between β‐CDs and xylenes played a key role in swelling behavior. There was a significant difference between diffusion coefficients D and D⁰, calculated from the sorption and desorption measurements, respectively, indicating that the diffusivity selectivity in desorption stage may have remarkable effect on the total selectivity during pervaporation process. © 2012 American Institute of Chemical Engineers AIChE J, 59: 604–612, 2013     

Synthesis and characterization of novel poly(γ‐benzyl‐L‐glutamate) derivatives tailored for the preparation of nanoparticles of pharmaceutical interest

Four poly(γ‐benzyl‐L ‐glutamate) (PBLG) derivatives bearing at one end specific groups were synthesized by ring‐opening polymerization of the corresponding γ‐benzyl‐L ‐glutamate N‐carboxyanhydride using different amine‐terminated initiators. These moieties were chosen to introduce, on demand, specific functionalities in nanoparticles of pharmaceutical interest. The PBLG and PBLG derivatives were characterized by ¹H NMR, viscosimetry, Fourier transform infrared spectroscopy and differential scanning calorimetry. Nanoparticles smaller than 100 nm in diameter could be easily prepared from these PBLG derivatives by slight modification of a known nanoprecipitation technique. Copyright © 2006 Society of Chemical Industry     

Telechelic polymers by living and controlled/living polymerization methods

Telechelic polymers, defined as macromolecules that contain two reactive end groups, are used as cross-linkers, chain extenders, and important building blocks for various macromolecular structures, including block and graft copolymers, star, hyperbranched or dendritic polymers. This review article describes the general techniques for the preparation of telechelic polymers by living and controlled/living polymerization methods; namely atom transfer radical polymerization, nitroxide mediated radical polymerization, reversible addition-fragmentation chain transfer polymerization, iniferters, iodine transfer polymerization, cobalt mediated radical polymerization, organotellurium-, organostibine-, organobismuthine-mediated living radical polymerization, living anionic polymerization, living cationic polymerization, and ring opening metathesis polymerization. The efficient click reactions for the synthesis of telechelic polymers are also presented.     

A novel approach using differential scanning calorimetry to investigate the dissolved state in aqueous solutions of polymers used for papermaking

The size and conformations of dissolved polymer molecules of polyethylene glycol (PEG) in 5% aqueous solutions were examined through the use of differential scanning calorimetry (DSC). As long as the freezable bound water is considered to be the water enclosed by the entangled polymer chains in the solution, the appearance of the characteristics of a polymer begins to occur at a degree of polymerization (DP) between 11 and 21 and is largely completed at a DP of about 50. Assuming that the peak temperature of the DSC curve for the freezable bound water indicates the size of the entangled molecular coil, the lowering of the peak temperature with a decrease of molecular weight (MW) suggests a decrease in the size of the entangled molecular coil. The linear relationship between the peak temperature and the reciprocal of the number‐average MW suggests melting point depression as a plausible mechanism for the peak temperature lowering. Mixing of two polymers with different MWs—and thus, entangled molecular coils of different sizes—causes a kind of polymer–polymer interaction and the coil sizes change as follows. If the difference in the values of the two MWs is large, the sizes of the entangled molecular coil of each MW are brought closer to each other. The extent of approach is roughly proportional to the mixing ratio. If the difference in the values of the two MWs is not large, the original entangled molecular coils disappear and a single molecular coil of intermediate size appears instead. The size of the single intermediate molecular coil varies roughly according to the simple mixing law for the values of the two MWs. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2798–2807, 2003