表面交联的三元共聚高吸水树脂的合成及其性能研究

以丙烯酸、丙烯酰胺及丙烯磺酸钠为单体,采用水溶液聚合法制得三元共聚高吸水树脂(SAP1),用乙二醇二环氧甘油醚与氯化铝作交联剂,对SAP1进行表面交联处理得高吸水树脂SAP2。SAP2在加压下吸盐水率高,凝胶颗粒表面干爽且易分散。考察了引发温度、丙烯酸中和度、交联剂、引发剂、丙烯酰胺及丙烯磺酸钠的用量对常压下吸盐水率的影响。同时还考察了乙二醇二环氧甘油醚与无机盐用量对常压及加压下吸盐水率的影响。     

Modified suspension‐PVC particles as absorbents of ortho‐dichlorobenzene from water

Modified porous PVC particles are studied as absorbents of o‐dichlorobenzene (DCB), from water. The modified particles were produced by an in‐situ stabilizer‐free polymerization/crosslinking of a monomer/crosslinker/peroxide solution absorbed within commercial porous suspension‐type PVC particles. The modifying monomers used include styrene with divinyl benzene (DVB) as a crosslinking comonomer, methyl methacrylate (MMA), butyl acrylate (BA), or ethylhexyl acrylate (EHA) with ethylene glycol dimethacrylate (EGDMA) as a crosslinking comonomer. The effect of the nature of the monomers, morphology, porosity, surface area and composition of the modified PVC particles on DCB absorption was studied. Batch experiments (absorption rate and isotherms) were used to screen the PVC absorbents on the basis of absorption rate and absorption capacity. Continuous absorption column experiments were conducted to study the parameters characterizing the absorption process. Both the unmodified and modified PVC particles absorb DCB from water. The PBA and PEHA‐modified PVC particles approach equilibrium capacity faster and have greater absorption capacity than neat PVC, PS‐modified PVC and PMMA‐modified PVC particles. The absorption characteristics are influenced by the modifying polymer's T_g. The rubbery nature of PBA and PEHA yields better absorption in spite of the significantly lower surface area and porosity obtained in the modified PVC particles. Thus, indicating that fast adsorption followed by bulk absorption of DCB is taking place. A clear influence of the crosslinking effect was not established. The continuous absorption experiments were found more efficient than the batch absorption experiments. Copyright © 2003 John Wiley & Sons, Ltd.     

Superabsorbent polymer with improved permeability and absorption rate using hollow glass microspheres

Itaconic acid-vinyl sulfonic acid based super absorbent polymer (SAP) was synthesized by aqueous solution polymerization using ammonium persulfate as the initiator, tetra (ethylene glycol) diacrylate as the internal crosslinking agent, and sodium hydroxide as the neutralizing agent. Surface-crosslinking was introduced to improve the low absorbency under load of the itaconic acid-based SAP. Hollow glass microspheres were added during surface-crosslinking to improve the absorption properties and permeability of the SAP. Hollow glass microspheres increased the specific surface area of SAP and acted as an incompressible filler resulting in the improvement of gel strength and the relief of gel blocking by preventing adhesion between SAP particles. The surface-crosslinked SAP with 2 wt% hollow glass microspheres showed the highest permeability and absorbency under load. The absorption rate of the synthesized material was also increased.     

均相条件下甲壳素基高吸水树脂的制备及性能研究

利用冻融循环处理破坏甲壳素致密的晶体结构和氢键相互作用,使甲壳素溶解在8 wt%NaOH/4wt%urea水溶液中,制备了碱-甲壳素均相溶液.采用静态溶液聚合法,以过硫酸铵(APS)为引发剂、甲叉双丙烯酰胺(MBA)为交联剂,在均相条件下制备了甲壳素接枝聚丙烯酸钠高吸水树脂.研究了丙烯酸、NaOH、MBA和APS用量以及反应温度和时间对产物吸水性能和得率的影响.在最优化条件下制备的树脂的最大吸蒸馏水、自来水、生理盐水和人工尿液倍率分别可达1251,455,84和77 g.g-1.采用FTIR和XRD对合成的树脂进行初步结构表征,证明反应过程中甲壳素与丙烯酸发生了接枝共聚反应,而不是甲壳素与聚丙烯酸钠的简单物理共混.     

Preparation and swelling properties of hydrolysis-resistant superabsorbent composite based on acrylic acid and sodium bentonite

Abstract

A novel hydrolysis-resistant superabsorbent composite was prepared via the solution polymerization based on acrylic acid (AA) and sodium bentonite (SBT) as monomers, tetraallylammonium bromine (TAAB) as crosslinker and ammonium persulfate (APS) as initiator. The mechanism of polymerization and the structure of the superabsorbent polymer (SAP) were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (X-ray), and scanning electron microscopy (SEM). The reaction conditions such as different mass ratios of APS to AA, TAAB to AA, SBT to AA, neutralization degree of AA were optimized by orthogonal experiment, and the influence of each reaction condition on the capacity of water absorption at 150?°C was investigated via single-factor controlled experiment. The hydrolysis resistance and swelling kinetics of the SAP were studied in different solutions at 150?°C. Compared to traditional SAPs, the SAP synthesized with TAAB as crosslinker performed a more excellent hydrolysis resistance and water absorbency capacity at high temperatures. The water absorbency in distilled water or 0.1?mol L^?1 NaCl solution could reach 392.6 and 145.2?g g^?1at 150?°C, respectively. The SAP maintaining high swelling capacity in the pH range of 5–9 indicated its wide application values in the acidic or alkaline environment at high temperature. In addition, the SAP exhibited good reusability which could still retain about 73% of its initial water absorbency after reswelling six times at 150?°C.     

Loading characteristics and chemical stability of headgroup‐functionalized poly(ethylene glycol)‐lipid ligand tethers on polypropylene capillary‐channeled polymer fibers

Polypropylene capillary‐channeled polymer fibers have been modified by adsorption of headgroup‐functionalized poly(ethylene glycol)‐lipids to generate a species‐specific stationary phase. In order to study ligand binding characteristics, a fluorescein‐labeled poly(ethylene glycol)‐lipid was used as a model system. Breakthrough curves and frontal analysis were employed to characterize the surface loading characteristics across a range of lipid concentrations and mobile phase flow rates. Efficient mass transfer and fluid transport yield a linear adsorption isotherm up to the maximum loading concentration of 3 mg/mL, at a linear velocity of 57.1 mm/s. Under these conditions, the dynamic binding capacity was found to be 1.52 mg/g of fiber support. Variation of the linear velocity from 8.6 to 57.1 mm/s showed only small changes in breakthrough volume. The maximum capacity of 1.8 mg/g is found under conditions of a load velocity of 34.2 mm/s and a concentration of 3 mg/mL lipid. Exposure of the lipid modified fibers to several challenge solvents reveals a chemically robust system, with only 50% acetonitrile and hexanes able to disrupt the lipid adsorption. The straightforward capillary‐channeled polymer fiber surface modification with headgroup‐functionalized lipids provides both a diverse yet practically robust ligand tethering system.     

Control of various morphological changes of poly(meth)acrylate microspheres and their swelling degrees by SPG emulsification

Crosslinked poly(meth)acrylate polymers with a variety of morphologies were synthesized with two steps. In the first step, a microporous glass membrane (Shirasu Porous Glass, SPG) was employed to prepare uniform emulsion droplets by applying an adequate pressure to the monomer phase, which was composed of the ADVN initiator, solvent of toluene or heptane or their mixture, and a mixture of (meth)acrylate monomers. The droplets were formed continuously through the membrane and suspended in the aqueous solution, which contained a PVA‐127 suspending agent, SLS emulsifier, and NaNO₂ inhibitor to suppress the nucleation of secondary particles. SPG pore sizes of 0.90, 5.25, and 9.25 μm were used. Then the emulsion droplets were polymerized at 343 K with a rotation rate 160 rpm for 24 h. The (meth)acrylate monomers 2‐ethylhexyl acrylate (2‐EHA), 2‐ethylhexyl methacrylate (2‐EHMA), cyclohexyl acrylate (CHA), methyl methacrylate (MMA), lauryl acrylate (LA), and lauryl methacrylate (LMA) were used in this research. The influences of the ratios of the monomer and crosslinking agent EGDMA, the amount of diluents, the monomer type on the polymer particle morphology, the swelling degree, and the polymer particle size were investigated. It was found that an increase in the concentrations of EGDMA and heptane resulted in higher coarse porous spheres and smaller polymer particle sizes. A coefficient with a variation close to 10%, or a standard deviation of about 4, was obtained. The capacity of these spheres as solvent absorption materials was examined. The highest swelling degrees of heptane and toluene were obtained when LA was employed as the monomer with 30% (by weight) of EGDMA and 70% (by weight) of heptane as an inert solvent. The highest capacity of the solvent absorption was obtained when using a polymer particle size of 4.81 μm, as prepared by SPG pore size 0.9 μm. The polymer particles were able to absorb aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, and a mix of aliphatic hydrocarbon solvents and aromatic hydrocarbon solvents, such as toluene and heptane. The capacity of solvent absorption for the aromatic hydrocarbon solvents was higher than for the aliphatic hydrocarbon solvents. In addition, the particles did not rupture or collapse after absorption in solvents. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4038–4056, 2000     

Synthesis of Biodegradable Hydrogel by Radical Ring‐Opening Polymerization of 2‐Methylene‐1,3,6‐Trioxocane

2‐Methylene‐1,3,6‐trioxocane (MTC), maleic anhydride (MA), and poly(ethylene glycol diacrylate) 400 (PEGD) or divinyl adipate (DVA) were terpolymerized in the presence of a radical initiator. Though the obtained gels did not absorb deionized water, the gels could absorb deionized water and saline after hydrolyzing the MA carboxylate anhydride functionality. The absorbing ratios of deionized water and saline were high. The biodegradability of the hydrogels after hydrolysis was found to be good by a biochemical oxygen demand (BOD)‐tester using soil.     

Preparation of the thermosensitive metal ion imprinted polymer in supercritical carbon dioxide: application in the selective recognition of copper (II)

The temperature‐sensitive Cu(II) ion imprinted polymer (Cu(II)‐MIIP) materials were prepared via precipitation polymerization methods in supercritical carbon dioxide (scCO₂) by using methanol as cosolvent. In the polymerization process, the polymerization mixture consists of copper ion, N‐isopropylacrylamide (functional monomer), ethylene glycol dimethacrylate (crosslinker), and 2,2′‐azobisisobutyronitrile (initiator). Non‐imprinted polymer particles were similarly prepared in the same way except for the presence of copper ion in the polymerization reaction. In this study, the characteristic of swelling/shrinking for Cu(II)‐MIIP in response to the change in temperature was investigated by scanning electron microscopy and photograph of swelling/shrinking for Cu(II)‐MIIP in deionized water. The above‐synthesized polymer particles were characterized by using Fourier transform infrared, thermo‐gravimetric analysis, and X‐ray diffraction techniques. Furthermore, the complete removal of the copper metal ion from the CuP was confirmed by atomic absorption spectroscopy. The selectivity adsorption of polymer materials was investigated from dilute aqueous solutions, and it was found to have an imprinting efficiency of 2.13 for Zn and Co ions. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and application of a nanoporous ion‐imprinted polymer for the separation and preconcentration of trace amounts of vanadium from food samples before determination by electrothermal atomic absorption spectrometry

A vanadium ion‐imprinted polymer was synthesized in the presence of V(V) and N‐benzoyl‐N‐phenyl hydroxyl amine using 4‐vinyl pyridine as the monomer, ethylene glycol dimethacrylate as the cross linker and 2,2’‐azobis(isobutyronitrile) as the initiator. The imprinted V(V) ions were completely removed by leaching the polymer with 5 mol/L nitric acid, and the polymer structure was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The ion‐imprinted polymer was used as the sorbent in the development of the solid‐phase extraction method for V(V) prior to its determination by electrothermal atomic absorption spectrometry. The maximum sorption capacity for V(V) ions was 26.7 mg/g at pH 4.0. Under the optimum conditions, for a sample volume of 150.0 mL, an enrichment factor of 289.0 and a detection limit of 6.4 ng/L were obtained. The developed method was successfully applied to the determination of vanadium in parsley, zucchini, black tea, rice, and water samples.     

高吸水性树脂

高吸水性树脂,可以吸收其本身重量的几百倍水。将水溶性高分子如羧甲基纤维素、聚丙烯酸钠盐或聚乙烯醇进行轻微的交联可以得到。由于其高吸水性、在压力下的高保水性和高增稠性,被广泛应用于纸尿布、生理巾、土壤保水剂、工业脱水剂、增稠剂等。     

Particle monolayer formation at the air–water interface by silica particle with well‐defined grafted polymer

Particle monolayer formation at the air–water interface by polymer‐grafted colloidal silica was investigated. Methyl methacrylate (MMA) was polymerized from initiative bromide groups at colloidal silica surface by atom transfer radical polymerization. We obtained polymer‐grafted silica particle (SiO₂‐PMMA) with relative narrow polydispersity of PMMA. For the polymer‐grafted particle with high graft density, particle monolayer formation was confirmed by π‐A isotherm measurement and SEM observation. Interparticle distance was controllable by surface pressure. Furthermore, grafted polymer chains were suggested to be fairly extended at the air–water interface. However, for the polymer‐grafted particle with low graft density, monolayer structure on substrate showed aggregation and voids. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2789–2797, 2006     

Synthesis and characterization of surface‐initiated polymer brushes on silicon substrates by reversible addition fragmentation chain transfer polymerization

Polymer brushes were prepared by using the reversible addition fragmentation chain transfer (RAFT) technique. The silicon substrates (Si (111) surface) were modified with ethyl xanthate groups which were introduced by the treatment of Si (111) surface with sodium ethyl xanthate. The polymer brushes were then prepared under RAFT conditions from the Si (111) wafer. Its “living” characteristics were determined by a series of characterizations including gel permeation chromatography (GPC), ellipsometry, and contact angle measurements. The results showed a well‐defined graft layer consisting of polymer brushes with low‐polydispersity could be prepared directly on Si (111)‐X surface (where X represents an ethyl xanthate groups). The structure of the polymer brushes was characterized and confirmed with the surface sensitive techniques such as X‐ray photoelectron spectroscopy (XPS) and scanning probe microscopy (SPM). Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of Molecularly Imprinted Polymer for Removal of Effective Impurity (Benzhydrol) from Diphenhydramine Hydrochloride Drug

The present study describes the synthesis and preliminary testing of molecularly imprinted polymers (MIPs) as scavenger resins for removal of the genotoxic impurities (GTI) benzhydrol from active pharmaceutical ingredients (API). A new molecularly imprinted polymer was synthesized using benzhydrol (template molecule), methacrylic acid (functional monomer), ethylene glycol dimethacrylate (cross‐linker), 2,2′‐azobisisobutironitril (intiator) and chloroform (porogenic solvent). To compare the performance of this polymer, a control polymer or non‐imprinted polymer (NIP) was prepared under the same conditions without the use of template molecule. The synthesized polymers were characterized by FT‐IR spectroscopy. Selectivity of the molecularly imprinted polymer for absorption benzhydrol impurities through adsorption experiments reviews and the results were compared with the adsorption of impurities by NIP. Various parameters were optimized such as time, pH, type of eluent for elution of impurities from polymer, concentration of sample and saturation of polymer. The proposed method was applied for removal of benzhydrol from Diphenhydramine hydrochloride syrup and passing it through the MIPs led to the quantitative removal of benzhydrol.     

Novel itaconic acid-based superabsorbent polymer with improved gel strength and salt resistance using 2-acrylamido-2-methyl-1-propanesulfonic acid

The synthesis of novel superabsorbent polymers (SAPs) based on itaconic acid (IA) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) is described for application in personal hygiene products such as disposable diapers. The AMPS is introduced to improve the low absorption performance of the existing IA-based SAPs. The salt-resistant properties of AMPS are shown to improve the absorption performance of SAP with respect to aqueous salt solutions. Further, the high ionization constant of the sulfonic acid group of AMPS contributes to the increase of the centrifugation retention capacity (CRC) of the SAP. Meanwhile, the amide group of AMPS improves the gel strength of the SAP by forming hydrogen bonds between the polymer chains. This increase in gel strength is demonstrated by the enhanced absorbency under load (AUL) and rheological analysis. The degree of neutralization affect the absorption properties of SAP, and the SAP exhibits maximum CRC and AUL of 57.3 and 14.4 g/g at 60% neutralization, respectively. As a crosslinking agent content increased, AUL increased but CRC significantly decreased. Additionally, soil pH evaluation confirms that SAP do not cause soil acidification.     

高吸水性树脂的吸水机理

高吸水性树脂是三度空间网络聚合物，是高分子电介质。在高分子网络链上嵌有可电离的离子对，遇水形成离子网络。该树脂能吸收自身重量几百倍至几千倍的水，且保水性好，即使在压力下，水也不从中溢出。其吸水机理可用Ｆｌｏｒｙ－Ｈｕｇｇｉｎｓ热力学公式来解释。     

Managing polymer surface structure using surface active block copolymers in block copolymer mixtures

Surface coatings were prepared from semifluorinated monodendron surface‐active block copolymers (SABC) and a thermoplastic elastomer (TPE) [poly(styrene‐b‐ethylene butylene‐b‐styrene)] by either spin‐casting a bilayer structure or by blending. The surface of these coatings was characterized by contact angle measurements, scanning force microscopy (SFM) and near‐edge X‐ray absorption fine structure (NEXAFS) methods. Both bilayers and blends resulted in very low energy surfaces under the right processing conditions and the liquid crystallinity of the semifluorinated monodendrons gave rise to temporally stable, non‐reconstructing surfaces in water. However for small thicknesses of the SABC top layer or for low SABC content blends, SFM shows islands of the fluorinated block of the SABC and incomplete surface coverage of the TPE, an observation confirmed by NEXAFS analysis. Very high water contact angles were produced by even modest amounts of SABC in either case but to achieve low contact angle hysteresis, it was necessary to produce uniform surface coverage by the SABC. Such uniform coverage can be accomplished by spin casting a top layer of SABC as thin as 60 nm in the bilayer case but at least 10 wt% SABC in TPE combined with drop casting of a hot solutions is needed for the blends to achieve equivalent surface structure and properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 411–420, 2004     

NMR investigation of the nature of water in disposable incontinence pads containing superabsorbent polymers and fluffed wood pulp

The use of nuclear magnetic resonance to make quantitative measurements of the absorption processes occurring in the constituent materials of disposable incontinence pads was investigated. Modern incontinence pads often have a layered structure with the absorbent layer principally consisting of superabsorbent polymer (SAP) grains distributed in fluffed wood pulp. T ₂-weighted and magnetisation transfer contrast (MTC) measurements were made using samples of SAP, fluffed wood pulp, and a mixture of 50% SAP and 50% fluffed wood pulp following the addition of water and NaCl solutions. The T ₂-weighted signal always decreased on mixing the liquid and material samples, with SAP showing the smallest magnitude of signal decline. The MTC change was minimal for SAP, but increased for the other samples. The small changes in the T ₂-weighted signals and the MTC observed when adding water to SAP indicate that water is not principally being tightly bound by the polymer. The absorption time-course was further evaluated by acquiring proton-density-weighted 1D profiles after the addition of water to the samples. In SAP, the fitted time constant was comparable to the activation energy measured by other methods. The relaxation times both declined on mixing the liquids with samples of SAP and fluffed wood pulp. The reduction in spin–spin relaxation is sufficient to account for the T ₂-weighted signal changes.     

Small molecule adsorption on to polyester capillary‐channeled polymer fibers: Frontal analysis of naphthalene and naphthol (naphthalene and naphthol adsorption on capillary‐channeled polymer fibers)

Frontal analysis was carried out employing poly(ethylene‐terephthalate) capillary‐channeled polymer fibers as the stationary phase for the immobilization of low‐molecular‐weight polycyclic aromatic hydrocarbon compounds (naphthol and naphthalene) from 2% methanol/water solutions. The effects of several experimental parameters on the frontal profile, the breakthrough volume, and the equilibrium parameters were determined for each solute. The amount adsorbed at exhaustion of naphthalene and naphthol was also compared. The kinetics and thermodynamics were maintained at relatively fast flow rates/linear velocities (～6–18 mm/s). Comparisons of dynamic capacity revealed that naphthalene was more retained than naphthol, in most situations more than five times that of the naphthol adsorption. This increase in capacity is most likely due to the multilayering of naphthalene on the surface of the fibers through π–π interactions between the solute and the fiber surface and successive layering of solute molecules. The extent of layering is a function of the flow, with faster flow rates (and subsequent shear forces) reducing the extent of adsorbate–adsorbate interactions. Although the overall loading capacity of the capillary‐channeled polymer fibers is far below porous phases, there are a number of attractive attributes that support further development.     

Fabrication of superhydrophobic sponge with hierarchical structure and application for oil/water separation

Oil/water separation polyurethane sponge with hierarchically structured surface similar to the chemical/topological structures of lotus leaf has been successfully developed by combining mussel-inspired one-step copolymerization approach. The chemical structure, surface topography, and surface wettability of the sponge were characterized by FTIR, SEM, and contact angle experiments, respectively. The results showed that as-prepared sponge exhibited high oil absorption rate because of the expansion in oil and collapse in water of the polymer molecular brushes. Meanwhile, it also possessed high absorption capacity (20 times of the self-weight), high oil retention (93.7%), and good recyclability. It had excellent potential in practical applications.