In the present work, new thermally stable polymers containing 1,3,4-oxadiazole units have been synthesized through Huisgen reaction of the aromatic bis-tetrazole compounds with the aromatic/aliphatic bis-acid chloride...In the present work, new thermally stable polymers containing 1,3,4-oxadiazole units have been synthesized through Huisgen reaction of the aromatic bis-tetrazole compounds with the aromatic/aliphatic bis-acid chlorides in pyridine as solvent. The obtained polymers are insoluble or slightly soluble in polar aprotic solvents such as DMSO and DMF. Thermal analyses of the polymers using DSC and TGA techniques showed that the polymers had improved thermal stabilities. The model reaction was also investigated and the resulting bis-1,3,4-oxadiazole compounds were characterized by conventional spectroscopic methods.展开更多
An account of the experiments on preparing polystyrene （PS） nanocomposites through grafting the polymer onto organophilic montmorillonite is reported. Cloisite 20A was reacted with vinyltrichlorosilane to replace th...An account of the experiments on preparing polystyrene （PS） nanocomposites through grafting the polymer onto organophilic montmorillonite is reported. Cloisite 20A was reacted with vinyltrichlorosilane to replace the edge hydroxyl groups of the clay with a vinyl moiety. Because the reaction may liberate HC1, it was performed in the presence of sodium hydrogencarbonate to prevent the exchange of quaternary alkylammonium cations withH＋ ions. Only the silanol groups on the edge of the clay react with vinyltrichlorosilane. The radical polymerization of the product with styrene as a vinyl monomer leads to chemical grafting of PS onto the montmorillonite surface. The homopolymer formed during polymerization was separated from the grafted organoclay by Soxhlet extraction. Chemical grafting of the polymer onto Cloisite 20A was confirmed by infrared spectroscopy. The prepared nanocomposite materials and the grafted nano-particles were studied by XRD. Exfoliated nanocomposites may be obtained for 0.5 wt%-1wt% clay content. The nanocomposites were studied by thermogravimertic analysis （TGA） dynamic thermal analysis （DTA） and dynamic mechanical analysis （DMTA）.展开更多
A novel aromatic diamine,2-（5-（3,5-diaminophenyl）-l,3,4-oxadiazole-2-yl）pyridine（POBD）,containing a pyridine ring and a 1,3,4-oxadiazole moiety,was synthesized.It was used in a polycondensation with various arom...A novel aromatic diamine,2-（5-（3,5-diaminophenyl）-l,3,4-oxadiazole-2-yl）pyridine（POBD）,containing a pyridine ring and a 1,3,4-oxadiazole moiety,was synthesized.It was used in a polycondensation with various aromatic and aliphatic diacid chlorides to generate a series of new aromatic polyamides with pendant 1,3,4-oxadiazole groups.The prepared polyamides were characterized by IR,elemental analysis and through the synthesis of model compounds.Thermophysical properties of the synthesized polyamides have been studied by DSC,TGA and inherent viscosity measurements. Relatively high inherent viscosity values（0.76-1.62 dL/g,in 0.125%H_2SO_4 at 25℃） were observed for these compounds. Number average molecular weight（M_n） of the polymers was measured by vapor phase osmometry（VPO）.The introduction of bulky side chains in the structure of aromatic polyamides led to increased solubility of these polymers in common polar and aprotic solvents,such as DMF,DMSO,NMP and DMAc,which allowed thin films to be cast from polymer solutions. The highest molecular weight（M_n = 51190） was observed for polymer（DC）,which was prepared from pyridine-2,6-dichlorocarbonyl.展开更多
基金supported by the Graduate Council of University of Mohaghegh Ardabili(Iran)
文摘In the present work, new thermally stable polymers containing 1,3,4-oxadiazole units have been synthesized through Huisgen reaction of the aromatic bis-tetrazole compounds with the aromatic/aliphatic bis-acid chlorides in pyridine as solvent. The obtained polymers are insoluble or slightly soluble in polar aprotic solvents such as DMSO and DMF. Thermal analyses of the polymers using DSC and TGA techniques showed that the polymers had improved thermal stabilities. The model reaction was also investigated and the resulting bis-1,3,4-oxadiazole compounds were characterized by conventional spectroscopic methods.
基金supported by the Research Council of the University of Mohaghegh Ardabili(Iran)
文摘An account of the experiments on preparing polystyrene （PS） nanocomposites through grafting the polymer onto organophilic montmorillonite is reported. Cloisite 20A was reacted with vinyltrichlorosilane to replace the edge hydroxyl groups of the clay with a vinyl moiety. Because the reaction may liberate HC1, it was performed in the presence of sodium hydrogencarbonate to prevent the exchange of quaternary alkylammonium cations withH＋ ions. Only the silanol groups on the edge of the clay react with vinyltrichlorosilane. The radical polymerization of the product with styrene as a vinyl monomer leads to chemical grafting of PS onto the montmorillonite surface. The homopolymer formed during polymerization was separated from the grafted organoclay by Soxhlet extraction. Chemical grafting of the polymer onto Cloisite 20A was confirmed by infrared spectroscopy. The prepared nanocomposite materials and the grafted nano-particles were studied by XRD. Exfoliated nanocomposites may be obtained for 0.5 wt%-1wt% clay content. The nanocomposites were studied by thermogravimertic analysis （TGA） dynamic thermal analysis （DTA） and dynamic mechanical analysis （DMTA）.
基金financially supported by the Graduate Council of the University of Mohaghegh Ardabili(Iran)
文摘A novel aromatic diamine,2-（5-（3,5-diaminophenyl）-l,3,4-oxadiazole-2-yl）pyridine（POBD）,containing a pyridine ring and a 1,3,4-oxadiazole moiety,was synthesized.It was used in a polycondensation with various aromatic and aliphatic diacid chlorides to generate a series of new aromatic polyamides with pendant 1,3,4-oxadiazole groups.The prepared polyamides were characterized by IR,elemental analysis and through the synthesis of model compounds.Thermophysical properties of the synthesized polyamides have been studied by DSC,TGA and inherent viscosity measurements. Relatively high inherent viscosity values（0.76-1.62 dL/g,in 0.125%H_2SO_4 at 25℃） were observed for these compounds. Number average molecular weight（M_n） of the polymers was measured by vapor phase osmometry（VPO）.The introduction of bulky side chains in the structure of aromatic polyamides led to increased solubility of these polymers in common polar and aprotic solvents,such as DMF,DMSO,NMP and DMAc,which allowed thin films to be cast from polymer solutions. The highest molecular weight（M_n = 51190） was observed for polymer（DC）,which was prepared from pyridine-2,6-dichlorocarbonyl.
