We have demonstrated here the dissociation behavior of carboxylic groups at the open end of Single\|Walled Carbon Nanotubes(SWNTs) by tip chemistry. SWNTs were cut into short pipes by acid oxidation and thus carboxyli...We have demonstrated here the dissociation behavior of carboxylic groups at the open end of Single\|Walled Carbon Nanotubes(SWNTs) by tip chemistry. SWNTs were cut into short pipes by acid oxidation and thus carboxylic groups were produced at the end of the tubes. The SWNTs can be immobilized onto AFM tips by surface condensation between amino\|terminated self\|assembled monolayers(SAMs) on AFM tips and carboxylic groups at the end of SWNTs. The p\%K\%\-\{1/2\} value of the SWNTs was then obtained from the force titration measurements of the SWNTs tips \%vs\%. hydroxyl\|terminated SAMs. The results showed a different force titration behaviour and variable p\%K\%\-\{1/2\} values among different SWNTs tips, indicating the variations in the chemistry from tube to tube.展开更多
The associations of triblock copolymer made of acrylic acid, methyl acrylic acid and butyl acrylate in aqueous solution as well as in NaCl and CaCl 2 solutions were studied by using fluorescence. The micelle like clus...The associations of triblock copolymer made of acrylic acid, methyl acrylic acid and butyl acrylate in aqueous solution as well as in NaCl and CaCl 2 solutions were studied by using fluorescence. The micelle like clusters(MLCs) of copolymer formed is able to solubilize non polar material. A little electrolytes added in the copolymer solution can increase the value of critical aggregation concentration( ρ ac ) and micropolarity. But with the increase of the concentration of electrolytes, the value of ρ ac and micropolarity will decrease. When there is NaCl with fixed concentration in the systems, the process of the MLCs loosening is relaxed because of the charge screening. In the systems with fixed CaCl 2 concentration, Ca 2+ induced the cross link of -COO - groups, so the interface between the MLCs and the water is not obvious and the big MLCs is formed between the clusters.展开更多
文摘We have demonstrated here the dissociation behavior of carboxylic groups at the open end of Single\|Walled Carbon Nanotubes(SWNTs) by tip chemistry. SWNTs were cut into short pipes by acid oxidation and thus carboxylic groups were produced at the end of the tubes. The SWNTs can be immobilized onto AFM tips by surface condensation between amino\|terminated self\|assembled monolayers(SAMs) on AFM tips and carboxylic groups at the end of SWNTs. The p\%K\%\-\{1/2\} value of the SWNTs was then obtained from the force titration measurements of the SWNTs tips \%vs\%. hydroxyl\|terminated SAMs. The results showed a different force titration behaviour and variable p\%K\%\-\{1/2\} values among different SWNTs tips, indicating the variations in the chemistry from tube to tube.
文摘The associations of triblock copolymer made of acrylic acid, methyl acrylic acid and butyl acrylate in aqueous solution as well as in NaCl and CaCl 2 solutions were studied by using fluorescence. The micelle like clusters(MLCs) of copolymer formed is able to solubilize non polar material. A little electrolytes added in the copolymer solution can increase the value of critical aggregation concentration( ρ ac ) and micropolarity. But with the increase of the concentration of electrolytes, the value of ρ ac and micropolarity will decrease. When there is NaCl with fixed concentration in the systems, the process of the MLCs loosening is relaxed because of the charge screening. In the systems with fixed CaCl 2 concentration, Ca 2+ induced the cross link of -COO - groups, so the interface between the MLCs and the water is not obvious and the big MLCs is formed between the clusters.
基金supported by the National Natural Science Foundation of China(20873033,20973043)National Key Basic Research Program of China(973)(2007CB936800,2006CB932100)~~
