Gold nanoparticles (GNs) are prepared through in situ reduction using NaBH4 in the presence of homopolymer PDMAEMA. The sizes of the GNs can be adjusted by alternating the molar ratio of gold to DMAEMA. Pure PDMAEMA a...Gold nanoparticles (GNs) are prepared through in situ reduction using NaBH4 in the presence of homopolymer PDMAEMA. The sizes of the GNs can be adjusted by alternating the molar ratio of gold to DMAEMA. Pure PDMAEMA aqueous solution shows a phase-transition at 50°C at pH 10 and 25°C at pH 14, while PDMAEMA-supported GNs aqueous solution shows a phase-transition at 47°C at pH 10 because of the increasing hydrophobic property resulting from GNs. Due to the pH and temperature-responsible characteristics of PDMAEMA, the resulting PDMAEMA-supported GNs exhibit pH adjustable temperature-responsive characteristics in optic and catalytic aspects. Under an acidic condition (pH 2), the GNs show unchanged surface Plasmon absorbance with a peak of 518 nm in a temperature range from 20 to 65°C. Under a basic condition (pH 10), the GNs first show the same absorbance with a peak at 518 nm in a temperature range from 20 to 40°C, and then the absorbance red shifts from 518 to 545 nm as temperature increases from 40 to 65°C. When the GNs are used as catalysts to catalyze the reduction of p-nitrophenol, the catalytic activity can be adjusted by changing the permeation of reactants in the PDMAEMA layer at low and high temperatures, respectively.展开更多
Aggregation of 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin (TPPS) was investigated in complex micelles composed of poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP) and poly(2-(dimethylamino)ethyl m...Aggregation of 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin (TPPS) was investigated in complex micelles composed of poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP) and poly(2-(dimethylamino)ethyl methylacrylate)-b-poly(Nisopropylacrylamide) (PDMAEMA-b-PNIPAM) in aqueous solutions.The resultant complex micelles had a complex P4VP/ PDMAEMA/TPPS core and a mixed PEG/PNIPAM shell.Different noncovalent interaction modes between the porphyrin and each copolymer accomplished a co-effect on the aggregation of TPPS.The formation of aggregates was pH-dependent.At pH 3.2–6.5,TPPS existed as a mixture of H-aggregates and monomers because of the aromatic-aromatic interaction with P4VP and electrostatic interaction with PDMAEMA.The monomers translated into J-aggregates,stabilized by electrostatic interaction with the both polyelectrolyte blocks,upon decreasing the pH to 1.6.The free-base monomer was the one and only form for the dye at pH 11.0 due to aromatic stacking with the pyridyl rings.展开更多
The spatiotemporal dynamics of the hydrogen peroxide-thiosulfate-sulfite-perchlorate acid system was in-vestigated in reaction-diffusion medium. In the Petri dish, pulse waves were discovered, which had the maximum li...The spatiotemporal dynamics of the hydrogen peroxide-thiosulfate-sulfite-perchlorate acid system was in-vestigated in reaction-diffusion medium. In the Petri dish, pulse waves were discovered, which had the maximum life-time and the maximum traveling distance when the initial concentration of thiosulfate was increased. In addition, pulse waves contracted back before disappearing, and the pulse waves with red spot were observed when the initial concen- tration of hydrogen peroxide was higher. The experimental results were analyzed and explained according to the reac- tion mechanism of positive and negative feedback in this system.展开更多
基金Supported by the National Natural Science Foundation of China (Grant No. 20774051)Program for New Century Excellent Talents in Universitiesthe Outstanding Youth Fund (Grant No. 50625310)
文摘Gold nanoparticles (GNs) are prepared through in situ reduction using NaBH4 in the presence of homopolymer PDMAEMA. The sizes of the GNs can be adjusted by alternating the molar ratio of gold to DMAEMA. Pure PDMAEMA aqueous solution shows a phase-transition at 50°C at pH 10 and 25°C at pH 14, while PDMAEMA-supported GNs aqueous solution shows a phase-transition at 47°C at pH 10 because of the increasing hydrophobic property resulting from GNs. Due to the pH and temperature-responsible characteristics of PDMAEMA, the resulting PDMAEMA-supported GNs exhibit pH adjustable temperature-responsive characteristics in optic and catalytic aspects. Under an acidic condition (pH 2), the GNs show unchanged surface Plasmon absorbance with a peak of 518 nm in a temperature range from 20 to 65°C. Under a basic condition (pH 10), the GNs first show the same absorbance with a peak at 518 nm in a temperature range from 20 to 40°C, and then the absorbance red shifts from 518 to 545 nm as temperature increases from 40 to 65°C. When the GNs are used as catalysts to catalyze the reduction of p-nitrophenol, the catalytic activity can be adjusted by changing the permeation of reactants in the PDMAEMA layer at low and high temperatures, respectively.
基金supported by the National Natural Science Foundation of China (50830103 & 20904025)National Basic Research Program of China (973 Program,2011CB932500)the Open Research Fund Program of ChangChun Institute of Applied Chemistry Chinese Academy of Sciences
文摘Aggregation of 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin (TPPS) was investigated in complex micelles composed of poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP) and poly(2-(dimethylamino)ethyl methylacrylate)-b-poly(Nisopropylacrylamide) (PDMAEMA-b-PNIPAM) in aqueous solutions.The resultant complex micelles had a complex P4VP/ PDMAEMA/TPPS core and a mixed PEG/PNIPAM shell.Different noncovalent interaction modes between the porphyrin and each copolymer accomplished a co-effect on the aggregation of TPPS.The formation of aggregates was pH-dependent.At pH 3.2–6.5,TPPS existed as a mixture of H-aggregates and monomers because of the aromatic-aromatic interaction with P4VP and electrostatic interaction with PDMAEMA.The monomers translated into J-aggregates,stabilized by electrostatic interaction with the both polyelectrolyte blocks,upon decreasing the pH to 1.6.The free-base monomer was the one and only form for the dye at pH 11.0 due to aromatic stacking with the pyridyl rings.
基金This work was supported by the National Natural Science Foundation of China(Grant No.20103010)the Excellent Young Teachers Program of MOE,China.
文摘The spatiotemporal dynamics of the hydrogen peroxide-thiosulfate-sulfite-perchlorate acid system was in-vestigated in reaction-diffusion medium. In the Petri dish, pulse waves were discovered, which had the maximum life-time and the maximum traveling distance when the initial concentration of thiosulfate was increased. In addition, pulse waves contracted back before disappearing, and the pulse waves with red spot were observed when the initial concen- tration of hydrogen peroxide was higher. The experimental results were analyzed and explained according to the reac- tion mechanism of positive and negative feedback in this system.
