Influence des solvants sur la copolymérisation de l'acrylamide avec l'acrylonitrile

The copolymerization of acrylamide with acrylonitrile was investigated in various solvents, which can be put into three groups according to their influence on molecular associations; (1) solvents autoassociated by hydrogen- bonds (acetic acid, methanol, water, dimethylformamide); (2) polar solvents which can associate with the NH group of acrylamide (acetonitrile, dioxane, acetone); (3) inert solvents (toluene, benzene, hexane). The reaction kinetics and the compositions of the copolymers are different for each group of solvents. The composition of copolymers formed in solvents of group 1 vary widely, depend- ing on the solvent. Copolymers formed in all solvents of group 2 have the same composition which is that of copolymers formed in bulk. The amount of acrylamide is highest in copolymers formed in inert solvents of group 3. Such parameters as the degree of conversion, the reaction temperature, the mode of initiation and the extent of dilution only slightly affect the composition of copolymers. Homopolymerizations of acrylamide and acrylonitrile were investigated in all solvent used.The results suggest that the effects of solvents on the copolymerization of acrylamide with acrylonitrile are consequences of the various modes of molecular association of acrylamide. The solvents affect the equilibrium between auto- association of acrylamide and its association with solvent and thereby affect the reactivity of the monomer.     

Preparation of hydrophobically-modified acrylamide copolymers using poly(ethylene imine) as a photoinitiator and its performance evaluation in Bohai oilfield

This paper presents copolymers of acrylamide, N,N-dimethyl-N-vinylnonadecan-1-ammonium chloride and N-(2,4-dimethylpentan-2-yl) acrylamide synthesized by photopolymerization using modified poly(ethylene imine) as initiator in water. These hydrophobically modified acrylamide copolymers were dissolved in the brine that was used in enhanced oil recovery in Bohai oilfield. It was found that when the content of N-(2,4-dimethylpentan-2-yl) acrylamide and N,N-dimethyl-N-vinylnonadecan-1-ammonium chloride were 0.1 mol % and 0.3 mol %, respectively, the resulting polymer could meet the demand of solution time and the polymer mechanical shear stability required in Bohai oilfield. The solution properties of synthesized copolymers were compared with the hydrophobically modified polymer currently used in enhanced oil recovery in Bohai oilfield.     

Synthesis of poly(styrene-graft-ethylene oxide) by ethoxylation of amide group containing styrene copolymers

Graft copolymers containing poly(ethylene oxide) side chains on a polystyrene backbone have been synthesized. Styrene copolymers synthesized by free radical mechanism and containing between 5 and 15 mol % acrylamide or methacrylamide were used as backbones. The amide groups in the copolymers were ionized by using potassium tert-butoxide or potassium naphthalene, and grafting was achieved by utilizing the amide anions as initiator sites for the polymerization of ethylene oxide in 2-ethoxyethyl ether at 65°C. The graft copolymers were characterized with respect to molecular weight and composition using elemental analysis, NMR, gel permeation chromatography, IR, and viscosity measurements. The size of the side chains were between 600 and 2000 g/mol. GPC results from a hydrolyzed graft copolymer sample suggest a narrow size distribution for the poly(ethylene oxide) grafts. Solution properties of the graft copolymers were investigated in different toluene/methanol mixtures. The intrinsic viscosities of the graft copolymers were found to depend primarily on the poly(ethylene oxide) content rather than the graft density or the poly(ethylene oxide) chain length. © 1993 John Wiley & Sons, Inc.     

Water-soluble copolymers. XXV. Ion-binding studies of N-substituted acrylamide copolymers using potentiometric and spectroscopic methods

Spectroscopic and potentiometric methods have been used to study the ionic properties of several N-substituted acrylamide copolymers that display unusual ion-binding character. The ionic groups and the amide groups (both on the same repeating unit and on adjacent acrylamide units) in the copolymers are found to chelate calcium ions. The stabilizing effect of this amide chelation is found to be dependent on copolymer composition. A model is proposed to explain the unusual binding behavior of the acrylamide polymers. This involves the formation of an intramonomer chelate or one with neighboring acrylamide units that prevent precipitation of the polymers.     

甜菜碱型两性离子聚合物P(AM-DMAPAAS)的盐溶液性质

将丙烯酰胺丙基二甲基胺（DMAPAA）和1,3-丙基磺内酯,在55 ℃下反应20 h,合成了3-（丙烯酰胺丙基二甲胺基）丙磺酸盐（DMAPAAS）,将其在盐溶液中与丙烯酰胺（AM）单体进行自由基共聚合反应,获得净电荷为零的磺基甜菜碱型两性离子共聚物P(AM-DMAPAAS);对该两性离子共聚物进行了表征和溶解性评价。 研究结果表明,共聚物在NaCl溶液中的粘度比在纯水中的大,在Mg2+和Ca2+盐溶液中的粘度更大,且随着溶液浓度的增大而增大,表现出明显的反聚电解质溶液性质。 升高相同温度,两性离子共聚物的粘度保留率是普通聚丙烯酰胺的1.4倍。     

Preparation and properties of two-component hydrogels based on 2-acrylamido-2-methylpropane sulphonic acid

Xerogels comprising 2-acrylamido-2-methylpropane sulphonic acid (AMPS) and acrylic acid as well as AMPS and acrylamide crosslinked with hexafunctional crosslinking agent have been prepared by catalytic initiation polymerization to complete conversion. Different percentages of hexafunctional crosslinker, 1,1,1-trimethylolpropane trimethacrylate, were used to prepare crosslinked copolymers having different degree of crosslink densities. The crosslinked copolymers were swollen in water to equilibrium. The volume fraction of polymer, the swelling capacity and the equilibrium water content were obtained. Low conversion polymerization was used to determine the reactivity ratios of both monomer pairs. Fourier transform spectroscopy was utilized to measure the molar ratio of copolymers constituents. © 1998 John Wiley & Sons, Ltd.     

Morphogenetic control of calcite crystal growth in sulfonic acid based hydrogels

In this paper the mineralization of CaCO(3) in various hydrogel matrices is presented. Sulfonic acid based hydrogels were prepared by introduction of sulfonate-containing monomers into a polyacrylamide network. The sulfonate content of polyacrylamide-co-vinylsulfonate and polyacrylamide-co-allylsulfonate decreases during elution of the copolymers in demineralized water, indicating insufficient linking of the sulfonate-bearing monomers within the hydrogel. In contrast to this, acrylamidomethylpropanesulfonate (AMPS) effectively copolymerizes with acrylamide (AAm) monomers. To study the influence of spatial arrangement of ionic functional groups within hydrogel networks on the mineralization of CaCO(3), AMPS copolymers with different degrees of AMPS cross-linking were synthesized. For the mineralization experiments the copolymers were placed into a double-diffusion arrangement. Calcite as the thermodynamically stable modification of CaCO(3) was obtained with a particular morphology. The pseudocubic habitus resembles aggregates obtained by mineralization in pure polyacrylamide. However, closer examination of the aggregates by scanning electron microscopy (SEM) shows that the crystal growth in the AMPS copolymers is different from that observed in polyacrylamide. Whereas the morphology of the calcite aggregates could be fine-tuned by using copolymers with different sulfonate content, the spatial distribution of the ionic functional groups alters the course of crystallization. Calcium ions are locally accumulated due to the heterogeneous distribution of functional sulfonate groups within the copolymer network. Thereby the nucleation of calcite is triggered, resulting in enhanced mineralization.     

Shear rheology of anionic and zwitterionic modified polyacrylamides

Two groups of copolymers were synthesized from high molecular weight polyacrylamides. One group of copolymers consisted of sulfonated, anionic copolymers (PAM-S) of acrylamide with the sodium salt of 2-acryloamido-2-methyl-1-propane sulfonic acid, and the other consisted of zwitterionic copolymers (PAM-Z) of acrylamide with a sulfobetaine methacrylate monomer. The shear rheology of aqueous solutions of the copolymers and their mixtures was studied experimentally. Solutions of both copolymers exhibit shear thinning behavior in the range of concentrations explored. Solutions of mixtures of two copolymers (PAM-Z and PAM-S) exhibited a slight viscosity synergy at high relative contents of PAM-S. Addition of a relatively high concentration of an electrolyte (0.3 M NaCl) induces decreases in viscosity due to coil contraction and eliminates the synergy of the mixtures. Mixtures of the zwitterionic copolymer and a cationic surfactant, cetyl trimethylammonium p-toluene sulfonate (CTAT), were also studied. These solutions exhibit a strong synergistic effect at low-shear rates when the surfactant forms wormlike micelles. In addition, oscillatory shear measurements demonstrate that PAM-Z/CTAT mixtures are significantly more elastic than CTAT solutions, which indicates that PAM-Z is effective in promoting micelle entanglements, as reflected by the increase in relaxation time with PAM-Z content.     

Fluorocarbon- containing hydrophobically modified poly(N-isopropylacrylamide)

A fluorocarbon-modified poly(N-isopropylacrylamide) has been synthesized by copolymerization of N-isopropyl acrylamide with a small amount of acrylate or methacrylate containing a perfluoroalkyl group. It was found that the hydrophilicity of macromolecular backbone is an important factor to the solution properties of the copolymers and that hydrophobic association between fluorocarbon groups is stronger than that between the corresponding hydrocarbon analogies. The viscosity of some of the copolymer solutions was very sensitive to temperature. It was dilatant at higher fluorocarbon comonomer content ( > 0.20-1.0 mol%) and was Newtonian at very low fluorocarbon comonomer content (0.03-0.2 mol% ) . Evidence for hydrophobic association of the fluorocarbon groups was obtained from the effects of adding Nad and surfactants on the solution viscosity. The LC-ST properties of these copolymers were studied by DSC method and this was also found to be consistent with hydrophobic association between the fluorocarbo     

丙烯酰胺和表面活性大单体共聚物的合成及其性能研究

首先合成表面活性大分子单体丙烯酸聚氧乙烯（２３）－十二烷基酯（ＡＡ－ＰＯＥＬＥ）,再通过与丙烯酰胺共聚合的方法得到在水溶性聚合物聚丙烯酰胺分子结构中引入疏水基团的共聚物改性ＰＡＭ。因ＡＡ－ＯＰＥＬＥ单体具有表面活性,所以共聚合时无需添加乳化剂。当改性ＰＡＭ中疏水基团含量为１．１０ｍｏｌ％时,其水溶液表现出独特的流变性和增稠性,着重讨论了改性ＰＡＭ作为乳胶增稠剂的性能。     

THERMOPROCESSIBLE HYDROGELS. I. SYNTHESIS AND PROPERTIES OF POLYACRYLAMIDES WITH PERFLUOROALKYL SIDE CHAINS

ABSTRACT

Copolymers composed of acrylamide (AM), N,N-dimethylacrylamide (DMAM), N-isopropylacrylamide (NIPAM) and 2-(N-ethyl-perfluorooctanesulfonamido) acrylamide (FOSA) were synthesized by free radical polymerization. The chemical structure of the resulting polymers was characterized with NMR spectroscopy and thermal properties were measured by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). ¹H-NMR spectra of the copolymers of NIPAM with FOSA showed that FOSA was incorporated quantitatively. The glass transition temperature (T_g) of the copolymers and the terpolymers decreased with increasing FOSA content. The T_gs, however, were higher than predicted for a random copolymer by the Fox equation, which was attributed to microphase separation of the hydrophobic, fluorinated species. Copolymers of AM and FOSA became discolored above 180°C due to formation of cyclic imide and nitrile moieties through cyclization or dehydration of amide groups. The equilibrium water sorption of the copolymers decreased with increasing FOSA content, but increasing FOSA suppressed the water desorption kinetics. Water sorption and thermal stability were improved by terpolymerization of AM, NIPAM, DMAM and FOSA.     

Temperature responsive methacrylamide polymers with antibacterial activity

<正>A new methacrylamide monomer,hexylamine methacrylamide(MAHA),was synthesized and used in polymerizations.The homopolymer of MAHA and its copolymers were synthesized by free radical polymerization techniques with N-isopropyl acrylamide(NIPAAm) in two different compositions.The quaternization of the homopolymer and copolymers were carried out using 1-bromopropane.The copolymers with NIPAAm and a low MAHA content showed temperature-responsive behavior in an aqueous environment.The lower critical solution temperatures(LCSTs) of these polymers varied between 32℃and 44℃.The LCSTs of quaternized copolymers were higher than those of neutral copolymers because they were more hydrophilic.The obtained homopolymers and copolymers were tested for antibacterial activities against S.aureus and E.coli.The quaternized water-soluble copolymers showed antibacterial activities against S.aureus.The quaternization resulted in the synthesis of both antibacterial and temperature-responsive copolymers.     

Effect of synthesis conditions on molecular characteristics of acrylamide copolymers with acrylic acid,carriers of cationic biologically active substances

Methods of molecular hydrodynamics and optics were used to study properties of aqueous solutions of acrylamide copolymers with acrylic acid. Dependences of the molecular characteristics of the copolymers on their synthesis conditions were determined and conditions were found in which the process of radical copolymerization of acrylamide with acrylic acid yields water-soluble carboxyl-containing acrylamide copolymers with molecular masses not exceeding 4×10⁴ Da.     

Water-Soluble Copolymers. II. Synthesis and Characterization of Model Dextran-g-Acrylamides by Ce(lV)/HNO3-lnduced Initiation

In order to develop polymers useful as mobility control agents in enhanced oil recovery processes, water-soluble acrylamide grafted polysaccharide copolymers have been synthesized in water at 25° C using a ceric ammonium nitrate/nitric acid system. The effects of varying concentrations of ceric ion, monomer, and substrate on conversion, graft length, and molecular structure of the reaction products have been examined. The crude reaction products were purified by fractional precipitation and then were analyzed for nitrogen content using a micro-Kjeldahl method. The chemical structures of the graft copolymers were studied by selective hydrolysis of the carbohydrate backbones. Intrinsic viscosity and grafting length data were used to predict solution behavior of the graft copolymers prepared under controlled conditions. Aqueous size exclusion and viscosity studies showed direct correlations between hydrodynamic volume and length of the polyacrylamide side-chain grafts.     

New associative EHEC‐g‐PAam copolymers: Their syntheses,characterization, and rheological behavior

The syntheses and rheological behavior of ethyl hydroxyethyl cellulose (EHEC)‐based graft‐copolymers were studied. Copolymers were prepared by grafting EHEC with acrylamide (Aam) via reversible addition fragmentation chain transfer (RAFT) polymerization. Hydroxyl groups of EHEC were esterified with a carboxylic acid functional chain transfer agent (CTA) to prepare EHEC‐macroCTAs with different degrees of substitution. EHEC‐macroCTAs were characterized by ATR‐FTIR, ¹³C NMR, and SEC, and elemental analysis was used to quantify the degree of CTA substitution. EHEC‐macroCTAs with different degrees of substitution were copolymerized with acrylamide by “grafting from” technique. Formation of new cellulose‐based copolymers was comprehensively confirmed by ¹H NMR, ATR‐FTIR, and SEC measurements. Further, the associations of EHEC‐g‐PAam copolymers in water were studied at various concentrations and temperatures by means of UV–vis spectroscopy, fluorescence spectroscopy, and rheological measurements. The results indicate that copolymers have both intra and intermolecular association in water depending on the amount of grafts. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1869–1879, 2009     

水溶性疏水缔合型聚(丙烯酰胺-丙烯酸十六酯)溶液性质的研究

采用沉淀聚合法制备水溶性的丙烯酰胺－丙烯酸十六疏水缔合型共聚物,研究了共聚物水溶液的性质及其影响因素。随着疏水基团含量增加,共聚物在纯水中及NaCl溶液中的特性粘数[η]均减小,疏水基团临界缔合浓度降低。共聚物溶液浓度高于监界缔合浓度时,溶液表现粘度急剧增加,表明溶液中分子间缔合大量形成。     

Copolymerization of vinyl monomers with irradiated acrylamide crystals

Liquid vinyl monomers (styrene and methyl methacrylate) were copolymerized with γ-irradiated acrylamide in a two-phase system. The products obtained were mainly diblock copolymers of acrylamide and the vinyl monomer used, but small amounts of homopolymers were also formed. The effects of radiation dose, copolymerization temperature, initial molar ratio of monomers, crystal size of acrylamide, mode of irradiation, and the existence of a solvent were investigated. In addition to the conventional methods, the reaction was studied by electron spin resonance spectroscopy. A mechanism was proposed and a kinetic rate equation was established for this copolymerization. Characterization of the copolymers was made by physical and mechanical testing.     

甲基丙烯酸乙基联吡啶共聚物的电化学性能研究

本文通过先共聚、后季铵化于共聚物侧链上接入单封端联吡啶的方法,合成了三种含有不同第二共聚单体的侧链型甲基丙烯酸乙基联吡啶共聚物P(BrEMA-M_2-EV),其中M_2=AM,MMA,ST。循环伏安曲线和紫外-可见光谱的测定结果表明:活性中心的含量及不同第二共聚单体对联吡啶共聚物的电化学活性和稳定性有比较显著的影响,但不影响其光谱性质。三种联吡啶共聚物均能可逆地显示黄棕色浅紫色兰紫色的三色互变。     

Kinetic aspects of flocculation of bentonite clay in the presence of anionic and cationic acrylamide copolymers

The flocculation kinetics in aqueous-salt medium in the presence of anionic and cationic high-molecular-weight random acrylamide copolymers was studied in the hindered sedimentation mode, with a suspension of bentonite clay as example. The influence exerted on the flocculation parameters by the concentration and order of addition of ionic acrylamide copolymers taken in various combinations was analyzed.     

Preparation and properties of alkylated poly(styrene-graft-ethylene oxide)

Poly(styrene-graft-ethylene oxide), having alkyl chains (C₁₂ or C₁₈) on the polystyrene main chain or on the poly(ethylene oxide) (PEO) side chains, were synthesized. The main chain was alkylated by first ionizing amide groups in a styrene/acrylamide copolymer with tert-butoxide, and then using the amide anions as sites for reactions with 1-bromoalkanes. An excess of amide anions was used in the reaction, and the remaining anions were subsequently utilized as initiator sites for the anionic polymerization of ethylene oxide (EO). Synthesis of poly(styrene-graft-ethylene oxide) with alkylated side chains was accomplished by polymerization of EO onto the ionized styrene/acrylamide copolymer, followed by an alkylation of the terminal alkoxide anions with 1-bromoalkanes. The alkylated graft copolymers were structurally characterized by using elemental analysis, ¹H NMR, GPC, and IR spectroscopy. DSC analysis showed that only graft copolymers with PEO contents exceeding about 50 wt % and side chain crystallinities comparable to those of homo-PEO. Main chain alkylated graft copolymers generally had higher crystalinities, as compared to nonalkylated and side chain alkylated samples. The graft copolymers absorbed water corresponding to one water molecule per EO unit at low PEO contents. The water absorption increased progressively at PEO contents above 30 wt % for main chain alkylated samples and above 50 wt % for non-alkylated samples. © 1995 John Wiley & Sons, Inc.