N，N-二甲基乙酰胺的合成进展与市场分析

N，N-二甲基乙酰胺是一种重要的精细化工中间体，其用途广泛。文章介绍了国内外N，N-二甲基乙酰胺的研究进展和生产方法，并展望了N，N-二甲基乙酰胺的市场应用领域和市场前景，从而针对性提出国内N，N-二甲基乙酰胺项目的发展前景和投资方向。     

Photochromic organic-inorganic polymer hybrids from spiropyran-modified poly(N,N-dimethylacrylamide)

Summary Photochromic organic-inorganic polymer hybrids were prepared by the sol-gel reaction of tetramethoxysilane (TMOS) in the presence of spiropyran-modified poly(N,N-dimethylacrylamide) 3. The obtained polymer hybrids were characterized by thermogravimetric analysis (TGA) and FT-IR, and photochromic behavior was followed by electronic absorption spectroscopy. Upon an irradiation of ultraviolet light, an absorption around 557 nm appeared in the visible region and the color of the hybrid turned to be violet. The effect of silica gel on the isomerization behavior seemed to be relatively small. Received: 8 November 1999/Revised version: 13 December 1999/Accepted: 15 December 1999     

Synthesis and characterisation of thermo-responsive poly(N,N′-diethylacrylamide) microgels

Poly(N,N-diethylacrylamide) microgels (diameter < 1000 nm) with narrow size distribution were synthesised by Surfactant-Free Emulsion Polymerisation at 70 °C in aqueous solution using potassium persulphate as initiator. The gels were characterised in comparison to the corresponding poly(N-isopropylacrylamide) microgels. They showed reversible collapse upon thermo-stimulation with a critical temperature between 28 and 30 °C, i.e. slightly below the critical temperature of the corresponding linear molecules. The average particle diameter as determined by electron microscopy decreased with increasing stirring rate adjusted during synthesis, although the effect was less straightforward for the poly(N,N-diethylacrylamide) microgels than for the poly(N-isopropylacrylamide) ones. In microgel preparations produced at the highest stirring speeds, the presence of small particles was observed, possibly a manifestation of residual ‘precursor particles’. A first characterisation of the biocompatibility of the gels was done by the WST-1 viability and the LDH cytotoxicity assays using the human breast cancer cell line MCF-7 (ATCC HTB-22) and a human T leukaemia cell line (Jurkat, ATCC TIB-125) as probes. No short-term effects (time span covered in the investigation <4 h) of the microgels on cell viability could be observed when the cell were incubated with the gels at 37 °C, i.e. above the critical temperature. At 22 °C and for microgel concentrations above 1 mg/mL some cytotoxicity was observed. In general the cytotoxicity was more pronounced for the poly(N-isopropylacrylamide) microgels than for the poly(N,N-diethylacrylamide) ones.     

N,N-二甲基乙酰胺的合成反应动力学

为了给N,N-二甲基乙酰胺的工业生产提供动力学支持,文章研究了二甲胺和冰醋酸直接缩合反应生成N,N-二甲基乙酰胺的本征动力学。在消除外扩散的影响下,考察了质量分数40%二甲胺与醋酸的摩尔比和反应温度对缩合反应的影响。测定和分析了在389.15,397.15,403.15,407.15,418.15 K下的动力学实验数据,利用数据处理软件进行拟合,得到N,N-二甲基乙酰胺的合成反应动力学方程,并通过了实验验证,为反应精馏的优化模拟提供了重要的基础数据。     

Synthesis of dendritic poly(arylene ether)s from a linear polymer core

Three generations of dendritic poly(arylene ether)s with terminal 4-fluorophenylthio- or 4-fluorophenylsulfonyl groups have been synthesized. A new relatively high molecular weight bisphenol containing two pendent 4-fluorophenylthio groups was converted to a poly(arylene ether sulfone) to act as the dendritic core. A divergent approach with an activation/condensation sequence was used. The pendent 4-fluorophenylthio groups in the base polymer were oxidized with H₂O₂ in formic acid to give 4-fluorophenylsulfonyl groups in which the fluoride groups are then activated toward nucleophilic displacement reactions. The condensation step involved the reaction of a phenol containing two pendent 4-fluorophenylthio groups with the activated core polymer in the presence of Cs₂CO₃. Reiteration of these steps gave the subsequent generations. The polymers have high thermal stabilities by TGA analysis (5% weight loss>500 °C).     

Synthesis and chelating properties of poly[(N,N-dicarboxymethyl)allylamine] derived from poly(allylamine)

Summary Poly[(N,N-dicarboxymethyl)allylamine] as a water-soluble polymeric chelating agent was prepared by carboxymethylation of poly(allylamine) (PAA) with chloroacetic acid or bromoacetic acid. The ¹H-NMR, IR, and elementary analyses showed that the iminodiacetic group was introduced quantitatively into the amino group of PAA. Chelating properties of this polymeric chelating agent toward Cu²⁺, Ni²⁺, Zn²⁺, and Ba²⁺ were examined by potentiometric titration.     

Synthesis and characterization of novel poly(amide-imide)s derived from N,N’-Bis(p-aminophenyl) terephthalamide

Summary An aromatic diamine monomer, N,N’-bis (p-aminophenyl) terephthalamide (PTP) was synthesized by employing sodium hydride as catalyst, 1,4-phenyleneamine (PDA) and dimethyl terephthalate (DMT) as starting materials. The structure of monomer was characterized by FT-IR, ¹H-NMR and elemental analysis. A series of new poly(amide-imide)s (PAIs) having inherent viscosities of 1.85–2.07 dL/g were synthesized from aromatic diamine PTP with various commercially available aromatic dianhydrides using a standard two-stage process with thermal imidization of poly(amic-acid) (PAA) films. The structure of polymers was respectively investigated by FT-IR. The WAXD patterns indicated an amorphous morphological structure of these polymers. All the new PAIs had good thermal stability with the glass transition temperature of 234–248 °C, the temperatures of 5% and 10% weight loss in nitrogen were in the range of 518–541 °C and 543–564 °C respectively. All PAIs were found to hold outstanding mechanical properties with the tensile strengths of 267.83–326.14 Mpa and Young’s modulus of 4.67–5.83 GPa.     

Synthesis of poly[2-(N,N-dimethyl)aminoethyl methacrylate-co-acrylonitrile]

Summary Radical copolymerization of 2-(N,N-dimethyl)aminoethyl methacrylate (1) and acrylonitrile (2) initiated by 2,2-azobis(2-methylpropionitrile) was carried out. The sequence distributions of the copolymers were investigated by ¹³C NMR spectroscopy. A terminal model was used to interpret the propagation process in the copolymerization. The monomer reactivity ratios in the bulk copolymerization at 45°C were evaluated as r₁=1.06 and r₂=0.07. Radical reactivity indices and frontier electron densities for 1 and 2 were calculated.     

Synthesis of star polymer poly(ethylene glycol)3–poly(N,N‐dimethyl acrylamide) and its application in protein resistance and separation

A star polymer composed of three poly(ethylene glycol) (PEG) arms and one poly(N,N‐dimethyl acrylamide) (PDMA) arm (PEG₃–PDMA) was synthesized by amidation and atom‐transfer radical polymerization. The structure of PEG₃–PDMA was confirmed by ¹H‐NMR and gel permeation chromatography results. The surface adsorption and protein‐resistance behaviors of the star polymer PEG₃–PDMA, diblock copolymer PEG–PDMA, and homopolymer PEG were investigated by a quartz crystal microbalance with dissipation. The results indicate that the PEG₃–PDMA coating could reduce protein adsorption to 13% at least, more effectively than the PEG–PDMA coating; this indicated that the protein‐resistance properties depended on the PEG chain density and surface coverage. If PEG₃–PDMA were to be used as the physical coating in capillary zone electrophoresis, it could yield a well‐suppressed eletroosmotic flow with greater stability and separate proteins with a lower relative standard deviration (RSD) of protein migration time and a higher separation efficiency than a bare fused‐silica capillary in a broad pH range. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Side reactions of phenylisocyanate in N,N-dimethylacetamide

Side reactions of isocyanate groups in N,N-dimethylacetamide (DMAC) were studied. Although 4,4′-diphenylmethane diisocyanate (MDI) in DMAC was stable and no changes occurred at 3°C, the isocyanate content decreased and a gel was finally formed at 40°C. Using phenyl isocyanate (PI) as a model compound of MDI, the identification of PI side-reaction products in DMAC were studied. From these experiments, the following five products were identified; (1) 1,3-diphenylurea (DPU), (2) 1,3-diphenyl-5-phenylcarbamyl-6-dimethylaminouracil (PUR), (3) 1,3,5-triphenylbiuret (TPB), (4) triphenyl-s-triazine-2,4,6-trione (TTT), and (5) 1,1-dimethyl-3-phenylurea (DMPU). Among these identified products, the novel side reaction product PUR, which was formed between PI and DMAC as solvent, was found along with TPB and TTT, which were already known to cause three-dimensional network formation.     

Synthesis and characterization of polypropylene-based polymer hybrids linking poly(methyl methacrylate) and poly(2-hydroxyethyl methacrylate)

Isotactic polypropylene-based polymer hybrids linking poly(methyl methacrylate) (PMMA) and poly(2-hydroxyethyl methacrylate) (PHEMA) were successfully synthesized by a graft copolymerization from maleic anhydride-modified polypropylene (PP-MAH). PP-MAH reacted with ethanolamine to produce a hydroxyl group containing polypropylene (PP-OH) and the thus obtained PP-OH was treated with 2-bromoisobutyryl bromide and converted to a 2-bromoisobutyryl group containing polypropylene (PP-Br). The metal-catalyzed radical polymerization of MMA with PP-Br was performed using a copper catalyst system in o-xylene solution at 100 °C to give the PP-based polymer hybrids linking PMMA segments (PP-PMMA hybrids). Thus obtained PP-PMMA hybrids demonstrated higher melting temperature than PP-Br and microphase-separation morphology at the nanometer level owing to the chemical linkage between both segments. On the other hand, the polymer hybrids linking PHEMA segment (PP-PHEMA hybrids) were also obtained by the radical polymerization of HEMA with PP-Br in o-xylene slurry at 25 °C. TEM observation suggested that the polymerization mainly initiated on the surface of the PP-Br powder, led to the peculiar core-shell-like morphology. These PP-PHEMA hybrid powders showed a good affinity with water due to the hydrophilicity of the PHEMA segments.     

Segmented polymer networks based on poly(N-isopropyl acrylamide) and poly(tetrahydrofuran) as polymer membranes with thermo-responsive permeability

Segmented polymer networks (SPNs) containing a polymer with a lower critical solution temperature were prepared by free radical copolymerization of poly(tetrahydrofuran) (PTHF) bis-macromonomers with N-isopropyl acrylamide (NIPAA). The PTHF bis-macromonomers, which were prepared by living cationic polymerization of tetrahydrofuran, were provided with acrylate or acrylamide end-groups by end-capping the living polymer chains with acrylic acid and 3-acrylaminopropanoic acid, respectively. Differential Scanning Calorimetry (DSC) experiments showed clearly that, for the same fractions of both network components, the phase morphology of the SPNs was highly influenced and adjustable by the nature of the end-groups of the bis-macromonomer as a result of their copolymerization behavior with NIPAA. For the same type of multi-component networks, the morphology changed from a heterogeneous up to a rather homogeneous nature by application of bis-macromonomers with, respectively, acrylate or acrylamide end-groups during their preparation. Swelling and DSC experiments on the swollen SPNs revealed, respectively, that the swelling properties and the cloud point temperature (T_cp) could be controlled by the network composition. The thermo-responsive water permeability and the possible application of the SPNs as pervaporation membranes for the separation of a water/isopropanol mixture were investigated as a function of temperature and network composition. The permeability and selectivity of the membranes decrease when the T_cp is reached. The permeability increases while the selectivity decreases with decreasing crosslink density or higher overall hydrophilicity of the SPNs.     

Synthesis and characterization of sulfonated poly(phenylene oxides) as membranes for polymer electrolyte membrane fuel cells

The synthesis of a thermally stable proton conducting polymer based on poly(phenylene oxide) (PPO) was carried out using 2,6‐dimethylphenol (DMP) and 2‐allylphenol (AP) as monomers. The copolymers using the two monomers were prepared with DMP to AP molar ratios of 20:80, 40:60, 60:40, and 80:20. The polymers and the copolymers were blended with poly(vinylidene fluoride) and cast as membranes. All the membranes were sulfonated and characterized for their suitability as a polymer electrolyte membrane. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1792–1798, 2002     

Synthesis and characterization of poly(o-ethoxyaniline): A processable conducting polymer

The synergic effect of the substituentlike ethoxy group on the electronic properties of conducting polyaniline was investigated. The presence of substituents affects not only the electrochemical polymerization window but also brings about changes in optical and electronic properties of the parent polymer polyaniline. The study indicates that electrochemical polymerization of (o-ethoxyaniline) yields a conducting polymer that shows a multiple color transition (yellow → green) on switching the potential between the reduced and oxidized states with an electrochromic response time of 40 ms in addition to its solubility in dimethyl sulfoxide, N-methyl pyrrolidinone, etc. However, the chemical polymerization of the monomer yields a crimson red polymer that is less conducting but has solubility in ethanol/methanol. Evaluation of this alcohol soluble polymer as a corrosion inhibitor for iron in acidic medium shows that it offers corrosion inhibition efficiency of 90%. © 1995 John Wiley & Sons, Inc.     

Synthesis and properties of polymer brush consisting of poly(phenylacetylene) main chain and poly(dimethylsiloxane) side chains

A novel polymer brush consisting of poly(phenylacetylene) (PPA) main chain and poly(dimethylsiloxane) (PDMS) side chains was synthesized by the polymerization of phenylacetylene-terminated PDMS macromonomer (M-PDMS). The macromonomer was prepared by the esterfication of monohydroxy-ended PDMS (PDMS-OH, degree of polymerization (DP) = 42) with p-ethynylbenzoic acid. The polymerization of M-PDMS using [(nbd)RhCl]₂/Et₃N catalyst led to polymer brush, poly(M-PDMS), with M_n up to 349?000 (DP of main chain 104). Poly(M-PDMS) with narrow molecular weight distribution (M_n = 39?900, M_w/M_n = 1.11) was obtained with a vinyl-Rh catalyst, [Rh{C(Ph)CPh₂}(nbd){P(4-FC₆H₄)₃}]/(4-FC₆H₄)₃P. Poly(M-PDMS)s were brown to orange viscous liquids and soluble in organic solvents such as toluene and CHCl₃. The UV-vis absorptions of poly(M-PDMS) were observed in the range of 350-525 nm, which are attributable to the PPA main chain.     

Synthesis and characterization of an interpenetrating polymer network composed of poly(methacrylic acid) and poly(vinyl alcohol)

Temperature and pH‐responsive interpenetrating polymer network (IPN) hydrogels, constructed with poly(methacrylic acid) (PMAA) and poly(vinyl alcohol) (PVA), by a sequential IPN method, were studied. The characterization of IPN hydrogels was investigated by Fourier‐transform infrared spectroscopy, differential scanning calorimetry (DSC) and swelling under various conditions. The IPN hydrogels exhibited relatively high swelling ratios, in the range 230–380 %, at 25 °C. The swelling ratios of the PMAA/PVA IPN hydrogels were pH and temperature dependent. DSC was used for the quantitative determination of the amounts of freezing and non‐freezing water. The amount of free water increased with increasing PMAA content in the IPN hydrogels. Copyright © 2004 Society of Chemical Industry     

Synthesis of poly(N,N-dimethylaminopropylacryl amide-g-acrylic acid) and crosslinking of its trunk sequence

Summary The graft copolymers composed of weak base and weak acid sequences, i.e., poly(N,N-dimethylaminopropylacryl amide-g-acrylic acid) (poly(DAPA-AA)) including 51–87 mol% of acrylic acid (AA) were prepared by redox system using cerium(IV) ammonium sulfate as initiator. Microphase separation of two sequences was observed in basic casting solvent. The crosslinking of DAPA sequence, which had shown spheric morphology, was carried out by mean of gas-solid phase quaternization reaction with 1,4-dibromobutane. The reaction product was soluble in NaOH aq. or HCl aq. until 4.3% quaternization of DAPA unit without remarkable increase of intrinsic viscosity. And they were found to be very different in solubility from the raw graft copolymer.     

Electropolymerized poly(2-vinylpyridine) coatings as ion-exchange polymer modified electrodes

The effects of pH and of the nature and concentration of the electrolyte on the electrochemical behaviour of the Fe(CN)^3–/4– ₆ charge-transfer reaction at a poly(2-vinylpyridine)-coated electrode formed by electropolymerization have been studied. Cyclic voltammetry during the Fe(CN)^3– ₆ incorporation process was combined with measurement of the saturated concentration of the Fe(CN)^3– ₆ confined in the films to investigate the electrochemical behaviour and the fundamental nature of the ion-exchange polymers. The poly(2-vinylpyridine) films formed by electropolymerization were found to have better properties (i.e., larger amount of Fe(CN)^3– ₆ can be incorporated at various pH values and films are more chemically stable under acidic conditions) as polymer-modified electrodes than those formed by solvent evaporation. Of the various anions studied, ClO^– ₄ was found to be distinct from the others (Cl^–, NO^– ₃, Br^– and SO^2– ₄). On the one hand, the polymer films exposed to ClO^– ₄ are more dense and rigid than those exposed to other anions and show relatively little electroactivity. On the other hand, when the films are exposed to increasing concentrations of Cl^–, the films become more swollen, thereby reducing the resistance within the film and enhancing the rate of charge-transfer from the outer film surface to the electrode surface.