Thermoresponsive poly(N-isopropylacrylamide) nanogels/poly(acrylamide) nanostructured hydrogels

Here we report the preparation and characterization of nanostructured thermo-responsive poly(acrylamide) (PAM)-based hydrogels. The addition of slightly crosslinked poly(N-isopropylacrylamide) (PNIPA) nanogels to AM reactive aqueous solution produces nanostructured hydrogels that exhibit a volume phase transition temperature (T_VPT). Their swelling kinetics, T_VPT's and mechanical properties at the equilibrium-swollen state (H_eq) are investigated as a function of the concentration of PNIPA nanogels in the nanostructured hydrogels. Nanostructured hydrogels with PNIPA nanogels/AM mass ratios of 20/80 and above exhibit higher H_eq and longer time to reach the equilibrium swelling than those of the conventional PAM hydrogels. However, the PNIPA nanogels possess thermo-responsive character missing in conventional PAM hydrogels. The T_VPT of nanostructured hydrogels depends on PNIPA nanogel content but their elastic and Young moduli are larger than those of conventional hydrogels at similar swelling ratios. Swelling kinetics, T_VPT, and mechanical properties are explained in terms of the controlled in-homogeneities introduced by the PNIPA nanogels during the polymerization.     

Vibrational Spectroscopic Study of （E）-3-（4-fluorophenyl）-N-[4-（phenylamino） quinazoline-7-yl] Acrylamide

Geometry optimization and subsequent harmonic vibration calculations of prior synthesized (E)-3-(4-fluorophenyl)-N-[4-(phenyl-amino) quinazoline-7-yl] acrylamide were carried out by DFT/B3LYP method with both 6-31G and 6-311G basis sets.The Infrared (IR) spectrum of the title compound was recorded in the field of 400-4000 cm 1 and then assigned.The correlation analyses between the scaled theoretical vibration frequencies and the experimental ones indicate that there exist good linearity relationships since the correlation coefficients R 2 are larger than 0.999.The intramolecular interactions existed in the title molecule were confirmed by the Atoms in molecules (AIM) method,and their influences on the absorption frequency were also investigated.     

Polymer complexes. LV. Spectroscopic,thermal studies,and coordination of metal ions N-[3-(5-amino-1,2,4-triazolo)] acrylamide polymer complexes

Novel polymeric complexes with a potentially bidentate ligand formed by amidation of 3,5-diamino-1,2,4-triazole with acryloyl chloride were synthesized and characterized on the basis of elemental analyses, IR, ¹H-NMR, UV-Vis, magnetic susceptibility measurements, molar conductance, and thermal analyses. The molar conductance data reveal that all the polymer complexes are non-electrolytes. Spectral studies reveal that the free ligand coordinates bidentate to the metal ion through the oxygen of the carbonyl and azomethine of the heterocyclic ring. Elemental analyses of the polychelates indicate the metal to ligand ratio of 1?:?1/1?:?2. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry has been proposed for each polymeric complex. The electron spin resonance spectral data of the Cu(II) complex showed that the metal–ligand bonds have considerable covalent character. The thermal behavior of these chelates shows that the polymer complexes lose coordinated water in the first step immediately followed by decomposition of the anions and ligand molecules in a subsequent step.     

Pd@GO/Fe3O4/PAA/DCA: a novel magnetic heterogeneous catalyst for promoting the Sonogashira cross-coupling reaction

Abstract

A hybrid system involving graphene oxide (GO), magnetic oxide (Fe₃O₄), acrylamide and dicyandiamide was prepared via amine functionalization of GO/Fe₃O₄ by means of covalent bonding with acrylamide and subsequent reaction with dicyandiamide to provide a multinitrogen containing polymer on the surface of GO. This hybrid system was utilized as a heterogeneous catalyst support for immobilizing Pd nanoparticles to provide the hybrid, Pd@GO/Fe₃O₄/PAA/DCA. This nano-Pd composite was characterized using Fourier transform infrared, transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometer, thermogravimetric analysis, X-ray diffraction, and ICP techniques and used for promoting Sonogashira cross-coupling under mild reaction conditions. This heterogeneous and magnetic catalyst was easily separated by external magnet and was reused in a model reaction, efficiently up to six times with slight loss of catalytic activity and Pd leaching, showing the suitability of GO/Fe₃O₄/PAA/DCA for embedding Pd nanoparticles. To check the effect of the number of surface nitrogens of the polymeric chain on the catalytic performance, the activity of the catalyst was compared with Pd@GO/Fe₃O₄/PAA; increased number of the surface nitrogens on the chain polymer leads to higher loading of Pd and lower the Pd leaching.     

Review of recent advances in the preparation of organic polymer monoliths for liquid chromatography of large molecules

In recent years the use of monolithic polymers in separation science has greatly increased due to the advantages these materials present over particle-based stationary phases, such as their relative ease of preparation and good permeability. For these reasons, these materials present high potential as stationary phases for the separation and purification of large molecules such as proteins, peptides, nucleic acids and cells. An example of this is the wide range of commercial available polymer-based monolithic columns now present in the market.     

N-取代丙烯酰胺的等离子体引发聚合及聚合物性能研究

温敏树脂;N取代丙烯酰胺的等离子体引发聚合及聚合物性能研究     

聚(丙烯酰胺-丙烯酸十八酯)的合成及其增稠性能

共聚合;聚(丙烯酰胺-丙烯酸十八酯)的合成及其增稠性能     

The preparation and reactivity of metal-containing monomers. 54. Thermolysis of the acrylamide monomer [Co(CH2=CHCONH2)4(H2O)2](NO3)2

The kinetics and pathways of thermolysis of the Co(II) complex with acrylamide, [Co(CH₂=CHCONH₂)₄(H₂O)₂](NO₃)₂ (1) were studied. The rate of gas evolution is satisfactorily approximated by a first-order equation of autocatalysis. The composition of gaseous and solid products of thermolysis of 1 was studied by IR spectroscopy, mass spectrometry, and electronic microscopy. Thermal transformations of acrylamide complex 1 include three macro stages: dehydration, polymerization of the dehydrated monomer, and thermooxidative destruction of the resulting polymer.     

Cobalt activation of Bacillus BR449 thermostable nitrile hydratase expressed in Escherichia coli

Expression of nitrile hydratase enzymes utilized in a new “green” process for acrylamide production has proven difficult in Escherichia coli owing to lack of a cobalt transport system to introduce the required cobaltion into this host. We describe the expression of a thermostable nitrile hydratase from a moderatethermophile Bacillus sp. BR449 in E. coli in which the cobaltrequired for enzyme activation is introduced by incubation, of the apoenzyme in the presence of Co⁺⁺ ion at 50°C, yielding active and thermostable, enzyme.     

丙烯酰胺共聚合及产物分散性的研究

采用水溶性引发体系研究了丙烯酰胺的均聚以及与几种乙烯基单体的共聚反应。探讨了引发剂、温度、单体浓度及加热时间对所得聚合物相对分子质量及其分散性能的影响。对产物的结构特性和相对分子质量分布进行了表征,并考察了共聚物的分散性能。丙烯酰胺共聚物同均聚物相比,分散性能有明显的改善。