Preparation,rheological and drag reduction properties of hydrophobically associating polyacrylamide polymer

Hydrophobically associating polymer (HAMDP) was synthesized by using acrylamide, acrylic acid, 2-acrylamido-2-methylpropane sulfonic acid and dodecyl 2-methylacrylate as main monomers. Dynamic rheometer and self-made simulation evaluation apparatus were used to test the rheological and drag reduction properties of HAMDP. With the mass concentration increased, the apparent viscosity of HAMDP increased. The critical aggregation concentration was 2.29g/L. With the changement of the strain, the elastic modulus was larger than viscous modulus. With the increment of HAMDP, the area of thixotropic loop increased. Compared with commercial polyacrylamide, the drag reduction rate of HAMDP could be up to 62.38%.     

Studies on foam stability by the actions of hydrophobically modified polyacrylamides

Hydrophobically modified polyacrylamide (HMPAM), as a foam stabilizer, was prepared with a cationic surfomer, acrylamide and acrylic acid by free-radical polymerization in aqueous solution. The actions of HMPAM on foam stability have been investigated with the Waring blender method. The results showed the foam containing HMPAM was stabler than that contained polyacrylamide. Moreover, a linear relationship between the logarithm of the half decay time and polymer concentration was observed, and the slope reflects the polymer ability to stabilize the foam.     

高效液相色谱法测定聚合物水处理剂中残留的单体

建立了采用高效液相色谱测定聚环氧琥珀酸钠盐(PESA)、丙烯酸/马来酸酐二元共聚物(AA/MA)、聚丙烯酸盐(PAA)、水解聚马来酸钠盐(HPMA)、马来酸酐/丙烯酸/丙烯酸甲酯三元共聚物(MA/AA/MAc)5类聚合物水处理剂中残留单体的方法。以Agilent ZORBAX 300SB-C18柱(5 μm,150 mm×4.6 mm)为分析柱,柱温为30 ℃,流动相为0.01 mol/L KH2PO4溶液(用5%H3PO4调节pH为2.3)-甲醇(体积比为95∶5)进行等度洗脱,检测波长为210 nm,流速为0.6 mL/min,样品用流动相稀释过滤后直接进样分析,10 min内马来酸、富马酸及丙烯酸残留单体获得分离和定量。上述3种残留单体的检出限分别为0.5,0.5和0.2 mg/L,回收率为98.9%～103.7%,相对标准偏差为1.09%～1.69%,相关系数为0.9996～0.9999。实验结果表明,该法简便快速、灵敏可靠,适用于5类聚合物水处理剂中残留单体的测定。     

Effect of pH on the reactivity ratios in the copolymerization of acrylic acid and acrylamide

The content of acrylic acid and acrylamide in their copolymers can be controlled by changing pH. The reactivity ratio of acrylic acid decreases with increasing pH, while the reactivity ratio of acrylamide increases with increasing pH. At low pH values, acrylamide is present in its protonated form which causes its reactivity to be low whereas at high pH values the reactivity of acrylic acid is decreased owing to its dissociation. When the monomer and radical approach each other, the acrylate anion becomes the least reactive species because of its symmetrical charge distribution, like charge repulsion and barium ion screening effect. HMO calculations were performed for models of all monomers and polymer radicals involved in copolymerizations. The experimental results concerning the reactivity of acrylic acid and acrylamide in copolymerization and the observed reactivity ratios were discussed on the basis of HMO calculations and resonance and Coulomb electrostatic effects. The observed reactivity ratios were correlated with the calculated differences in resonance energies computed for the models of transition states involved in copolymerizations.     

聚丙烯腈的加压水解

定型纤维状或无定型的聚丙烯腈在高温压力下均可用水水解,且产物中含有酰胺、酰亚胺、羧酸铵盐,经减压干燥后,铵盐部分分解成羧酸,最后的平均相对组成为:羧酸∶铵盐∶酰胺∶酰亚胺≈13∶36∶18∶33。 在我们的反应条件下,聚丙烯腈产生严重的断链现象,分子量大为降低,特别是未经喷丝成型的浆块更严重。 用阳离子交换树脂交换之后再进行分析的方法,一方面避免了滴定两种不同羧基(游离羧基、铵盐的羧基)之间的干扰,同时亦避免了通常方法测定铵盐时酰胺的干扰,因而数据更为可靠。     

Determination of glyphosate and its biodegradation products by chromatographic methods

Conditions were selected for the separation of the herbicide glyphosate (N-(phosphonomethyl)glycine) and products of its microbiological utilization as N-acylated derivatives by ion-exchange liquid chromatography. The order of the elution of compounds on a Repro-Gel H column with UV detection correlates with their structures. The detection limits of the derivatives (wavelength 210 nm) are as follows (ng): glyphosate, 30; glycine and sarcosine, 20 and 43, respectively; aminomethylphosphonic acid, 45. The detection limit of methylphosphonic acid is 14 μg. Glyphosate and its biodegradation products were separated by thin-layer chromatography on plates with silica gel in the system isopropanol-5% aqueous ammonia solution (1: 1).     

Recovery of some metal ions using gamma-radiation induced grafted waste rubber powder

Waste rubber powder was grafted with different vinyl monomers by using gamma-radiation. The monomers used for grafting were acrylic acid, acrylamide and acrylonitrile. The sodium salt of grafted polyacrylic acid as well as the amidoxime derivative of grafted polycacrylonitrile were also obtained. Evaluation of the efficiency of the products obtained to the recovery of some metal ions such as cobalt and nickel as well as to phenol was carried out. It was found that the grafted waste rubber powder is able to recover cobalt and nickel ions from their corresponding salts depending on the type of monomers used. It was also found that phenol can be reasonably recovered by using rubber powder grafted with acrylamide and amidoxime derivative.     

疏水缔合聚丙烯酰胺的合成及溶液性能研究

水溶性疏水缔合聚合物是在聚合物亲水主链上引入极少量疏水基团(一般小于2ｍｏｌ%)而形成的一种新型水溶性聚合物[1]。由于这类聚合物具有独特的流变性能,因而备受学术界和工业界关注。目前已作为涂料增稠剂[2]和流变改性剂[3]得到了应用,而通过在部分水解聚丙烯酰胺(ＨＰＡＭ)的亲水主链上引入少量疏水单体而形成的疏水缔合聚丙烯酰胺(ＨＡＰＡＭ)则可望克服ＨＰＡＭ耐温、耐盐性差的缺陷[4]而作为新一代水溶性聚合物材料用于油气开采作业[5,6]。由于亲水单体和疏水单体的不相容性,通常通过在反应溶液中加入表面活性剂使亲水单体和疏水单体…     

PAAM高吸水树脂反相悬浮聚合

采用反相悬浮聚合法,通过部分中和丙烯酸与丙烯酰胺共聚制备了聚(丙烯酸-丙烯酰胺)(PAAM)高吸水树脂,讨论了聚合过程主要影响因素对其吸液性能的影响,并对其进行了FTIR、TGA测试,得到最佳的合成工艺配方:单体质量浓度为30%,中和度N为75%,丙烯酸与丙烯酰胺的摩尔比为7∶3,交联剂、引发剂和分散剂质量浓度分别为0.065%、0.7%和0.5%(相对于单体总质量),单体溶液的滴加速度为2～3mL/min,聚合温度和时间分别为70℃和1.5h。此时在蒸馏水、0.9%NaCl溶液%(wt)中最大吸水倍率分别为Qw=1300g/g、Qs=93g/g(Qw为蒸馏水中吸水倍率,Qs为0.9%NaCl溶液中的吸水倍率,下同),树脂在320℃之前都是比较稳定的,可以适应较高的使用温度。     

The adsorption of cationic and amphoteric copolymers on glass surfaces: zeta potential measurements,adsorption isotherm determination,and FT Raman characterization

The adsorption of cationic and amphoteric copolymers onto controlled pore glass (CPG) powders has been studied by measurement of the powder particle zeta (zeta) potential, by determination of the adsorption isotherm, and by FT Raman measurements of the polymer-coated powder. The cationic polymers consisted chiefly of homopolymers of dimethyldiallylammonium chloride (DMDAAC) or copolymers of DMDAAC and acrylamide. The amphoteric polymers studied included copolymers of DMDAAC and acrylic acid. The comonomer ratio was varied to explore the dependence of cationic charge density on the extent and effect of adsorption. Both types of polymers adsorb onto the anionic glass surface via an ion-exchange mechanism. Consequently, a correspondingly higher mass of a low-charge-density copolymer adsorbs than of a cationic homopolymer. The presence of the anionic portion in the amphoteric polymers does not significantly alter this picture. The zeta potential, however, reflects the overall nature of the polymer. Cationic polymers effectively neutralize the glass surface, while amphoteric polymers leave the zeta potential net negative. Adsorption isotherms, determined via the depletion technique using colloidal titration, were used to "calibrate" a FT Raman method. The latter was used to determined the amount of adsorbed polymer under solution conditions in which colloidal titration could not be performed.     

Fluorescence and viscometry study of complexation of poly(acrylic acid) with poly(acrylamide) and hydrolysed poly(acrylamide)

Interpolymer complexation of poly(acrylic acid) with poly(acrylamide) and hydrolysed poly(acrylamide) was studied by fluorescence spectroscopy and viscometry in dilute aqueous solutions. Changes in chain conformation and flexibility due to the interpolymer association are reflected in the intramolecular excimer fluorescence of pyrene groups covalently attached to the polymer chain. Both poly(acrylamide) and hydrolysed poly(acrylamide) form stable complexes with poly(acrylic acid) at low pH. The molecular weight of poly(acrylic acid) and solution properties such as pH and ionic strength were found to influence the stability and the structure of the complexes. In addition, the polymer solutions mixing time showed an effect on the mean stoichiometry of the complex. The intrinsic viscosity of the solutions of mixed polymers at low pH suggested a compact polymer structure for the complex.     

Molecularly imprinted solid-phase extraction sorbent for the clean-up of chlorinated phenoxyacids from aqueous samples.

A molecularly imprinted polymer (MIP) was synthesized using the herbicide 2,4,5-trichlorophenoxyacetic acid as a template, 4-vinylpyridine as an interacting monomer, ethylendimethacrylate as a cross-linker and a methanol-water mixture as a porogen. The binding properties and the selectivity of the polymer towards the template were investigated by frontal and zonal liquid chromatography. The polymer was used as a solid-phase extraction material for the clean-up of the template molecule and some related herbicides (2,4-dichlorophenoxyacetic acid, fenoprop, dichlorprop) from river water samples at a concentration level of ng/ml with quantitative recoveries comparable with those obtained with a traditional C18 reversed-phase column when analyzed by capillary electrophoresis. The results obtained show that the MIP-based approach to the solid-phase extraction is comparable with the more traditional solid-phase extraction with C18 reversed-phase columns in terms of recovery, but it is superior in terms of sample clean-up.     

Controllable preparation of magnetic polymer microspheres with different morphologies by miniemulsion polymerization

Magnetic poly(styrene-co-acrylic acid-co-acrylamide) microspheres were prepared by water-in-oil-in-water (W/O/W) miniemulsion polymerization of monomers in the presence of Fe3O4 nanoparticles. The copolymerizable monomers of acrylic acid and acrylamide were used not only to modify the surfaces of the microspheres with functional groups, but also to act as viscosity regulators to control the morphology and size of these microspheres. It was experimentally observed that the surfaces of these microspheres were functionalized with NH2 groups produced by copolymerization, the morphologies (sphere, ringlike, and one-hole) of the microspheres were controlled by the concentration of copolymerizable monomers, and all samples prepared were superparamagnetic. The possible mechanism of formation of these magnetic microspheres is also discussed.     

Photografting of polymers onto nanosized silica surface initiated by eosin moieties immobilized onto the surface

The photograft polymerization of various vinyl monomers onto nanosized silica surfaces was investigated. It was initiated by eosin moieties introduced onto the silica surface. The preparation of the silica with eosin moieties was achieved by the reaction of eosin with benzyl chloride groups on the silica surface.These were introduced by the reaction of surface silanol groups with 4‐(chloromethyl)phenyltrimethoxysilane in the presence of t‐butyl ammonium bromide as a phase‐transfer catalyst. The photopolymerization of various vinyl monomers, such as styrene, acrylamide, acrylic acid, and acrylonitrile was successfully initiated by eosin moieties on the silica surface in the presence of ascorbic acid as a reducing agent and by oxygen. The corresponding polymers were grafted from the silica surface. The grafting efficiency (percentage of grafted polymer to total polymer formed) in the photoinitiation system was much larger than that in the radical polymerization initiated by surface radicals; these radicals were formed by the thermal decomposition of azo groups introduced onto the silica surface. It was found that the polymer‐grafted silica gave stable dispersions in good solvents of grafted polymer and the wettability of the surfaces can be easily controlled by grafting of polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 600–606, 2005     

The polymerization of acrylic acid in the presence of copolymers containing interacting and non-interacting groups

There has been a kinetic examination of the polymerization of acrylic acid in dilute aqueous solution in the presence of copolymers of vinyl pyrrolidone with acrylamide or styrene. In general, the characteristics of the polymerizations are very similar to those found in the presence of polyvinyl pyrrolidone homopolymer, but the definite differences, taken in conjunction with gravimetric data on the polymer complexes, can be explained by the fact that acrylamide is hydrophilic while styrene is hydrophobic. The use of the copolymers has permitted an assessment of the effect of dilution of monomer adsorbed on the interacting polymer.     

超临界CO2在高分子合成与制备中的应用

介绍超临界二氧化碳流体作为介质在高分子合成与制备中的研究进展。文中表明，可在超临界二氧化碳中实施氟代单体的自由基溶液聚合、甲基丙烯酸甲酯的分散聚合、丙烯酸的沉淀聚合、丙烯酰胺的反相乳液聚合以及异丁基乙烯基醚的阳离子聚合等多种聚合反应，可用超临界二氧化碳溶胀聚合法制备梯度共混物。此外，超临界二氧化碳还可用于聚合物分级和聚合物微孔、微纤与微球材料的制备等，显示出超临界二氧化碳是一种对环境无污染且价廉的     

Copolymerization of acrylic acid amides with alkenyl halides

The binary radical copolymerization of acrylic acid amides (acrylamide and N-cyclohexen-1-ylacrylamide) with alkenyl halides (vinyl chloride, vinyl bromide, and allyl chloride) has been studied. The constants of relative activity of the monomers used are calculated. For the systems under investigation, the occurrence of dehydrochlorination of a polymer chain and protonation of a carbonyl group occur is confirmed. Allyl chloride shows the most pronounced tendency toward dehydrochlorination, while in the case of vinyl chloride, this tendency is the least distinct. The polymer-analogous transformations result in copolymers containing polyene fragments and units of ammonium or oxonium amide salts.     

Synthesis and Properties of Hydrophilic Copolymers Containing 5-Fluorouracil,Thymine, or Adenine

Hydrophilic copolymers containing 5-fluorouracil (5-FU), thymine, or adenine were prepared by the free-radical copolymerization of methacryloyl-type monomers containing them with water-soluble vinyl monomers such as acrylic acid, methacrylic acid, vinylpyrroli-done, acrylamide, and 4(5)-vinylimidazole with AIBN as initiator. Complex formation between the copolymers and RNA and between the copolymers having complementary nucleic acid bases in aqueous solution and a DMSO-ethylene glycol was studied by means of UV spectroscopy. These copolymers were found to release the N-hydroxyethyl derivatives of 5-FU, thymine, or adenine by hydrolysis of the ester of the polymer side chain under mild conditions. The effects of the kind of water-soluble comonomer, temperature, pH, and the imidazole group as catalyst on the hydrolysis of the ester are discussed.     

Hydrogel photonic sensor for the detection of 3-pyridinecarboxamide

Molecular imprinting is recognized as a powerful technique for preparing polymeric structures that contains tailor-made recognition sites for certain molecules. By combining a responsive hydrogel photonic crystal and molecular imprinting of 3-pyridinecarboxamide, polyacrylamide (PAM) imprinted photonic crystals (IPCs) with an inverse opal structure were prepared. They showed a rapid, recoverable, and selective response to 3-pyridinecarboxamide, which was detected by measuring the diffraction peak. The position of the diffraction peak could be tuned by copolymerizing acrylamide (AM) with acrylic acid (AA), by changing the ratio of AM to AA, by adding N,N'-methylene bisacrylamide to the monomers, or by imprinting molecules to monomers. More interestingly, the change in the Bragg diffraction of the IPCs can be directly converted into a readable optical signal that is visible to the naked eye without any labeling treatment.     

Deuterium Isotope Effect on the Phase Separation of Zipper‐Type Hydrogen‐Bonding Inter‐Polymer Complexes in Solution

We have investigated the deuterium isotope effect on phase separation in aqueous zipper‐type hydrogen‐bonding polymer solutions. The phase separation temperature of poly(acrylic acid)‐poly(acrylamide) in heavy water is about 16°C higher than that in water. This large isotope effect in the aqueous zipper‐type macromolecular system arises from the polymer‐polymer interaction due to cooperative hydrogen bonds in the polymer‐polymer complex.