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71.
72.
An efficient and eco-friendly procedure for one-pot synthesis of β-amino carbonyl compounds by three-component reaction of aromatic aldehydes, acetophenone, and aromatic amines via a Mannich type reaction using a stable tightly bound complex, titanium tetrachloride incorporated crosslinked polystyrene copolymer (PS/TiCl4), as a water tolerant, recoverable, and reusable polymeric Lewis acid catalyst in ethanol at room temperature is reported. The complex of the polystyrene and TiCl4 provides a shelf-stable acidic, water tolerant material, and it is not easily hydrolyzed by water. Our findings thus show a novel and improved modification of the Mannich type reaction in terms of mild reaction conditions, clean reaction profiles, applicability to various substrates using a simple workup procedure which makes this reaction an interesting alternative to previously applied procedures. The recyclability of the catalyst makes this protocol environmentally benign. 相似文献
73.
Soy protein concentrate, a biodegradable renewable resource agricultural biopolymer, has been cross-linked with formaldehyde for better processing material. Thermogravimetric analysis of the biopolymer has been followed using a computer analysis method, Lotus package, developed by us for assigning the degradation mechanism. A number of equations have been used to evaluate the kinetic parameters. The mechanism of degradation of the biopolymer is explained on the basis of the kinetic parameters. 相似文献
74.
R.J.P. Corriu D. Leclercq P.H. Mutin A. Vioux 《Journal of Sol-Gel Science and Technology》1997,8(1-3):327-330
Silicon oxycarbide phases with different O/Si ratios were prepared by pyrolysis of highly cross-linked polysiloxane precursors. Their structure was investigated using quantitative 29 Si solid-state NMR and X-ray photoelectron spectroscopy (XPS). The prominent part played by the redistribution reactions on the ceramic yield, the composition of the oxycarbide phases and their structure was illustrated. In a large range of compositions the oxycarbide phases formed by pyrolysis at moderate temperature (<1000°C) may be described as a purely random arrangement of CSi4 tetrahedra and Si–O–Si bridges. 相似文献
75.
76.
Xiaohong Wang Guohua Jiang Yin Wang Rijing Wang Xinke Sun Ruanbing Hu 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(6):644-652
Biomimetic core cross-linked nanocarriers (CCL-NCs) with zwitterionic shell was constructed from an amphiphilic block copolymer poly(2-(dimethylamino) ethyl methacrylate-co-carboxybetaine)-b-polystyrene ((PDMAEMA-co-PCB)-b-PS) via mini-emulsion RAFT polymerization. CCL-NCs present in this report possess properties of redox-sensitivity, limited unspecific protein adsorptions and low cytotoxicity, which highly enhance their potential application in drug delivery. Morphology of CCL-NCs was characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. The control release process has also been investigated under three different conditions with or without dithiothreitol (DTT) at pH 5.4, 6.5 and 7.4. 相似文献
77.
Ivan Hudec Eugen Špirk Jáan Grom Anna Grusková Jozef Sláma 《Journal of Macromolecular Science: Physics》2013,52(2):171-180
The mechanical and Theological properties of blends based on commercial types of thermoplastic elastomers (TPEs) Finaprene with polystyrene and ethylene-vinylacetate copolymer, used as suitable materials to produce highly filled composites with magnetically hard fillers, have been investigated. The influence of a 90% to 93% filler content and the morphology of the fillers on mechanical, Theological, and magnetic properties of composites is discussed. The influence of changes of other technological parameters, such as type of treatment of the fillers and type of mixer, on properties of composites has been studied. 相似文献
78.
A sensitive method for the separation/analysis of Co(II) was described. The β-cyclodextrin cross-linked polymer (β-CDCP) was synthesized and used as solid phase extraction material (SPE) to separate/pre-concentrate trace cobalt coupled with inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of Co(II). The method was based on α-pyridylazo-β-naphthol (PAN) as the complexing agent for Co(II)-PAN at neutral condition and the adsorption behavior of Co(II)-PAN on β-CDCP was studied. Further, p-octylpolyethylene-glycolphenyl ether (Triton X-100) as environment-friendly eluant was used. The linear range, detection limit (DL) and the relative standard deviation (R.S.D.) was 5.0-160.0 ng/mL, 5.84 ng/L and 2.27% (n = 3, c = 30.0 ng/mL) respectively. The enhancement factor was 10. Moreover, the β-CDCP could be used repeatedly and offered better recovery and estimation of standard samples. 相似文献
79.
交联三嗪类聚合物的制备及其成炭性研究 总被引:1,自引:1,他引:0
通过异氰尿酸三缩水甘油酯与三聚氰胺的本体熔融聚合反应,合成了一种交联结构的三嗪类聚合物成炭剂,它显示出良好的热稳定性和耐水性,其制备过程不需溶剂,简单易行,且无有害物质排放.这种新型交联聚合物与聚磷酸铵复配(质量比1:5)而组成的膨胀型阻燃剂,应用于聚丙烯阻燃.当膨胀阻燃剂用量为阻燃聚丙烯的32%时,燃烧测试分析表明,所获得的炭层展现出致密连续的结构,其阻燃氧指数达到32,垂直燃烧FV-0,热释放速率峰值为486kJ/m2,比纯PP降低了47.5%,而有焰燃烧时间为714s,比纯聚丙烯增加54.9%. 相似文献
80.
E. M. Belavtseva E. F. Titova V. I. Lozinsky E. S. Vainerman S. V. Rogozhin 《Colloid and polymer science》1984,262(10):769-774
The influence of freezing on the properties of forming cross-linked polyacrylamide gels as examplified by the system: water — acylamide — N,N-methylene-bis-acrylamide — (ammonium persulfate + N,N,N,N'-tetramethylethylenediamine) was investigated. In cryostructurization, the freezing out of the solvent is shown to lead to a decrease in the critical concentration of gelation due to the concentrating effects of the reacting substances. A comparative analysis of the osmotic characteristics of gels prepared in liquid or crystallized solvent media is presented. 相似文献