Influence of the Molecular Character and Degree of Crosslinking on the Interaction of Crosslinked Polyacrylamide-Supported Amines with Cu(Ii) Ions

Abstract

Amino groups were incorporated into polyacrylamides with 2?20 mol% of crosslinking agents by transamidation with ethylenediamine. Divinylbenzene, N,Nv′-methylene-bis-acrylamide, and tetraethyleneglycol diacrylate were used as the crosslinking agents. The complexation of these resins, which contain ligand functions in different macromolecular structural environments, was investigated with Cu(II) ions. The Cu(II) uptake of these different resins was correlated with the molecular character and degree of crosslinking in the polymer matrix. The time course and kinetics of complexation depend on the nature of the crosslinking agent in the polymer matrix. The swelling behavior of the uncomplexed and complexed resins, structural characteristics, and thermal decomposition behavior were followed by IR, EPR, and thermal analysis. The swelling characteristics of the complexed resins are lower than those of the uncomplexed resins. Complexation resulted in shifting of the IR absorptions. The EPR parameters depend on the nature of crosslinking and are in agreement with the distorted tetragonal geometry of the Cu(II) complexes. The thermal decomposition behavior also depends on the nature and the degree of crosslinking in the polymer matrix.     

单一化学交联与物理化学复合交联高吸油树脂的比较

提出在单一化学交联吸油树脂中引入物理交联的设想，并采用悬浮聚合法了单一化学交联和物理－化学复合交联的聚丙烯酸酯系高吸油树脂，对两种不同树脂的吸油速率，低亲油性单体树脂的吸油性能，最佳单体配比以及化学交联剂含量的影响进行了比较，结果表明物理交联的引入加快了树脂的吸油速率，提高低亲油性单体树脂的吸油能力，并且还使最佳单体配比中低亲油性单体含量增加，同时表明部分物理交联吸油树脂有一最佳化学交联剂含量区。     

甲基丙烯酸甲酯和二乙烯苯对苯乙烯共聚合的影响

以甲基丙烯酸甲酯(MMA)、苯乙烯(St)和二乙烯苯(DVB)三元共聚体系为研究对象,采用气相色谱法研究了体系中MMA和DVB浓度对聚苯乙烯型树脂交联的影响。结果表明:MMA加速St和DVB的聚合速率,其中对St的加速作用又明显大于对DVB的。随MMA含量的增加,聚苯乙烯型树脂交联不均匀的情况得以明显改善,而增加体系中DVB的含量,DVB与St、MMA反应速率的差异变大,树脂交联不均匀的情况变严重。     

Investigations on the adsorbents for uremic middle molecular toxins (Ⅱ)——Influences of crosslinking agent chain length on the adsorption capacities of crosslinked chitosan adsorbents

Chitosan resins, which clinically served as adsorbents in hemoperfusion therapy, were prepared with reversed-phase suspension methodology using three differently structured crosslinking agents, methanal, glyoxal and glutaraldehyde. And the glyoxal and glutaraldehyde crosslinked chitosan resins were reduced with NaBH4 afterwards. By analyzing the results from FTIR and SEM, it was found that the reduction treatment to the adsorbents efficiently improved the chemical stability of these chitosan resins, and the shifts in crosslinking agents exerted influences over the morphologies of the adsorbents obviously. After being put to use in the adsorption tests upon some model uremic middle molecular toxins and BSA in vitro, all three adsorbents demonstrated a fairly realistic adsorption capability to the model toxins but little to BSA. And the adsorption process reached the equilibrium in a clinically qualified short time. But the adsorption capacities of these adsorbents to the model toxins were quite different. It     

Thermosetting characteristics of some new polymethylol epoxy resins

Several new polymethylol epoxy resins have been synthesised in a one pot reaction system and characterised. The new resins are derived from epichlorohydrine, formaldehyde and several aromatic phenols: phenol, biphenylol, bisphenol-A, bisphenol-S, sulphone, and DDT. The rate of crosslinking has been studied at different temperatures (120–180°C) by determining the amount of H₂O evolved from the crosslinking reaction using a DuPont moisture evolution analyser; the activation energy of setting has been determined from Arrhenius plots. The results are 57.1, 50.0, 42.9, 75.2, 11.3 and 74.3 kJ mol⁻¹ for resins I–VI respectively. The set resins show good thermal stability and are resistant toward chemicals and solvents; these resins also set catalytically at room temperature.     

丙烯酸酯类吸油树脂的合成与性能研究

以丙烯酸酯、甲基丙烯酸酯为主要单体,二丙烯酸丁二醇酯为交联剂,过氧化二苯甲酰为引发剂,采用悬浮聚合方法,合成聚丙烯酸酯类高吸油树脂.研究了分散剂、引发剂、交联剂用量及单体配比等因素对树脂吸油性能的影响.结果表明,分散剂用量为单体质量的0.12%,引发剂用量为1.0%,交联剂用量为1.5%时树脂的吸油能力最佳,吸甲苯倍率可达15倍,吸汽油倍率可达10倍,吸机油倍率可达近9倍.     

聚α-乙烯基吡啶大孔树脂的合成及其对胆红素的清除

本文合成了交联聚α-乙烯基吡啶珠状树脂,对树脂的交联度及致孔剂等因素进行了探索。实验结果表明:交联度在10％、致孔剂用量为200％时,可获得高比表面积的树脂。聚α-乙烯基吡啶珠状树脂对胆红素的清除率可达91％。但共血液相容性较差,对血液中白细胞及血小板的破坏达50％。使用时需包膜。     

Investigations on the adsorbents for uremic middle molecular toxins (II)

Chitosan resins, which clinically served as adsorbents in hemo perfusion therapy, were prepared with reversed-phase suspension methodology using three differently structured crosslinking agents, methanal, glyoxal and glutaraldehyde. And the glyoxal and glutaraldehyde crosslinked chitosan resins were reduced with NaBH₄ afterwards. By analyzing the results from FTIR and SEM, it was found that the reduction treatment to the adsorbents efficiently improved the chemical stability of these chitosan resins, and the shifts in crosslinking agents exerted influences over the morphologies of the adsorbents obviously. After being put to use in the adsorption tests upon some model uremic middle molecular toxins and BSA in vitro, all three adsorbents demonstrated a fairly realistic adsorption capability to the model toxins but little to BSA. And the adsorption process reached the equilibrium in a clinically qualified short time. But the adsorption capacities of these adsorbents to the model toxins were quite different. It had been found that with the growing of fatty chain length of crosslinking agent, these adsorbents showed a gradually increased adsorption capacity to the model toxins, and the glutaraldehyde crosslinked chitosan resin behaved best.     

Characterization of Plukenetia volubilis L. fatty acid-based alkyd resins

Fatty acid-based alkyd resins prepared with different amounts of glycerol and pentaerythritol were characterized. Sacha inchi oil and linseed oil (comparative purposes) were used as fatty acids’ sources. FT-IR and ¹H NMR spectroscopy were done for alkyd structural verification. Alkyd resins were evaluated through physico-chemical (colour, density, viscosity) and thermal characterization. Film coating performance (drying, hardness, chemical resistance) was also studied. The oxidative crosslinking time tendency was corroborated by the quartz crystal microbalance (QCM) technique. Alkyd resins obtained with fatty acids from sacha inchi and linseed oils had similar properties. Results indicated that lighter resins can be obtained from sacha inchi oil, whereas pentaerythritol increases viscosity and thermal stability, and retards drying time of fatty-acid based alkyd resins.     

Investigations on the Crosslinking Reactions of Melamine Resins in the Presence of Wood

Summary. The crosslinking behavior of MFRs (melamine formaldehyde resins) in the presence of wood was investigated. The influence of various factors (wood content, resin structure, etc.) on the crosslinking temperature of the resins was examined using DMTA and DSC/TGA. Fully methylated MFRs turned out to be more stable in the presence of wood than partially methylated MFRs. A dependence of the crosslinking temperature on the wood content was found. Model reactions with wood components demonstrated, that cellulose, hemicelluloses, and lignin affect the crosslinking temperature to different extends, whereas hemicelluloses (xylan) showed the strongest effect. Solvents, especially water, led to a further decrease of the crosslinking temperature of wood/MFR compounds.     

Investigations on the Crosslinking Reactions of Melamine Resins in the Presence of Wood

The crosslinking behavior of MFRs (melamine formaldehyde resins) in the presence of wood was investigated. The influence of various factors (wood content, resin structure, etc.) on the crosslinking temperature of the resins was examined using DMTA and DSC/TGA. Fully methylated MFRs turned out to be more stable in the presence of wood than partially methylated MFRs. A dependence of the crosslinking temperature on the wood content was found. Model reactions with wood components demonstrated, that cellulose, hemicelluloses, and lignin affect the crosslinking temperature to different extends, whereas hemicelluloses (xylan) showed the strongest effect. Solvents, especially water, led to a further decrease of the crosslinking temperature of wood/MFR compounds.     

Facile synthesis of hypercrosslinked resin via photochlorination of p-xylene and succedent alkylation polymerization

A combination of photochlorination of p-xylene and succedent Friedel-Crafts alkylation polymerization was firstly used in the preparation of the hypercrosslinked adsorptive resin.The data of GC-MS and GC showed that a series of chlorizates were produced when p-xylene was photochlorinated.Hypercrosslinked resins could be synthesized by copolymerization,self-polymerization of chlorizates or post crosslinking reaction.The chemical structure and micromorphology of the porous resins were characterized by BET,FT-IR,SEM and elementary analysis(EA).The results showed that the novel adsorptive resins possess high BET surface near to 1038 m~2/g and large pore volumes range from 0.5 to 1.2 cm~3/g.     

Curing kinetics of liquid-crystalline epoxy resins

By endcapping mesogenic rigid rod molecules with reactive epoxy groups a novel class of liquid-crystalline thermoset has been obtained. In fact is has been shown that the nematic molecular arrangement is sustained over the crosslinking reaction of liquid-crystalline epoxy resins when the curing reaction is carried out in the thermal stability range of the liquid-crystalline phase. Calorimetric analysis was used in characterizing the isothermal cure. An unsophisticated model is proposed for evaluating the activation energies of the crosslinking reaction. For liquid-crystalline epoxy resins lower activation energies result with respect to the cure reactions for non liquid-crystalline epoxy resins.     

HIGH INDEX OPTICAL MATERIALS PREPARED BY COPOLYMERIZATION OF NOVEL BIFUNCTIONAL THIOMETHACRYLATES

Optical materials, such as ophthalmic lens, are thermosetting resins, which require crosslinking agents. An optical resin, having a high refractive index, is usually produced by radical copolymerization in which high index crosslinking monomers are significantly important. We provide here the resins prepared by radical polymerization of novel bifunctional thiomethacrylates as high index crosslinkers.     

Novel flame‐retardant thermosets: Diglycidyl ether of bisphenol A as a curing agent of boron‐containing phenolic resins

Boron‐containing novolac resins were synthesized by the modification of a commercial novolac resin with different contents of bis(benzo‐1,3,2‐dioxaborolanyl)oxide. These novolac resins were crosslinked with diglycidyl ether of bisphenol A (DGEBA), and their thermal, thermodynamomechanical, and flame‐retardant properties were evaluated. The boron‐containing novolac resins were less thermally stable than the unmodified novolac resin. Their modification degree and DGEBA content were related to the crosslinking density of the materials. The boron‐containing novolac resins generated boric acid at high temperatures and gave an intumescent char that slowed down the degradation and prevented it from being total. They also showed good flame‐retardant properties. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1701–1710, 2006     

聚甲基丙烯酸羟乙酯树脂对胆红素的吸附研究

本文通过水相悬浮聚合制备了大孔交联聚甲基丙烯酸羟乙酯（PHEMA）树脂，研究了PHEMA树脂以及用乙醇胺功能基化后的PHEMA树脂对胆红素的吸附性能。结果表明，PHEMA树脂对胆红素的吸附性能受树脂孔结构，吸附温度，离子强度以及溶液中白蛋白的影响。该类吸附剂对胆红素有良好的吸附性能，其中用乙醇胺功能基化的树脂表现出更好的吸附能力。     

Development of new hydrophilic polymer supports based on dimethylacrylamide

A survey of the development of hydrophilic resins based on dimethylacrylamide (DMA) is presented. It describes the preparation of DMA-based resins by suspension copolymerization of DMA and acrylamide-based crosslinking and functional monomers. Swellability data for a number of DMA-based resins are tabulated, demonstrating that the resins swell to approximately the same extent in dichloromethane as they do in water, methanol, dimethylformamide or dimethylsulphoxide, but they swell only slightly or not at all in tetrahydrofuran. Typical chemical reactions employed for quantitative estimation or derivatization of resin-bound functional groups, including those involving intra-resin crosslinking, are discussed. The development of composite polymer supports, in which the DMA-based polymer is supported on kieselguhr particles or an amphiphilic ion exchange polymer is supported on DMA-based resin beads, is also covered briefly.     

Synthesis and characterization of bismaleimides from epoxy resins

Novel bismaleimides (BMIs) were prepared from functional monomaleimides and diglycidyl ether of bisphenol A (DGEBA) and some of them were shown to have good processibility and improved water resistance while retaining characteristic thermal stability of polyimide. Functional monomaleimides were synthesized via the condensation reaction of maleic anhydride with either aminobenzoic acid or aminophenol. Crosslinking reaction of thus obtained BMIs was carried out with or without catalyst at the temperature range of 100–250°C. The type of the functional group species and their position in monomaleimides significantly affected the crosslinking behavior of the resulting BMIs and the thermal property of their crosslinked products. BMIs with meta linkage, obtained from meta monomaleimides, exhibited much faster thermal crosslinking behavior than corresponding para BMIs. When the molecular weight of BMI was larger, the crosslinking density became smaller and T_g was lower as expected, while the viscosity started to increase at a higher temperature. Glass transition temperatures of the crosslinked resins were in the range of 160–250°C and these resins showed excellent thermal stability up to 370°C.     

Development of novel flame‐retardant thermosets based on boron‐modified phenol–formaldehyde resins

Boron‐containing novolac resins were prepared through the modification of a commercial novolac resin with different contents of bis(benzo‐1,3,2‐dioxaborolanyl) oxide. Their thermal and flame‐retardant properties were measured. Then, they were crosslinked with hexamethylenetetramine, and their thermal, thermodynamomechanical, and flame‐retardant properties were evaluated. Their modification degree was related to the segmental motion of the materials. The crosslinking of the boron‐modified novolac resins with hexamethylenetetramine was slower and not as extensive as that of commercial novolac resins because the nitrogen from intermediate species coordinated with boron. The thermal degradation of the boron‐containing novolac resins generated boric acid at high temperatures and gave an intumescent char that slowed the degradation and prevented it from being complete. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3503–3512, 2006     

采用重复互贯聚合用废弃白球末合成凝胶型阳离子交换树脂的研究

采用重复互贯聚合工艺将废弃白球末加入单体－交联剂－引发剂体系中充分溶胀，再按照常规悬浮聚合和磺化反应工艺合成凝胶型阳离子交换树脂，结果显示，细粒度白球的交联度在4％－7％，单体吸收比为100％，采用盐水滴加工艺保证单体在白球中的均匀扩散和吸收，所合成的阳树脂的各项性能指标均国家标准，这种重复互贯聚合白球与相同交联度的普通白球比较，具有较高的磺化反应活性，较高的交联度，湿真密度，湿视密度和较高的交换容量。