The properties of aqueous two-phase system (ATPS) of mixed solution containing gemini cationic surfactant trimethylene-1,3-bis(dodecyldimethyl ammonium) bromide (12-3-12, 2Br-) and traditional anionic surfactant sodiu...The properties of aqueous two-phase system (ATPS) of mixed solution containing gemini cationic surfactant trimethylene-1,3-bis(dodecyldimethyl ammonium) bromide (12-3-12, 2Br-) and traditional anionic surfactant sodium dodecyl sulfate (SDS) with or without added salt have been studied. An ATPS is formed in a narrow region of the ternary phase diagram different from that of traditional aqueous cationic-anionic surfactant systems. In ATPS region, the lowest total concentration of surfactants varies with the mixing ratio of geminis to SDS. Photographs obtained from freeze-etching, negative-staining and transmission electron microscopy show that the microstructures of two phases are different from each other. Micelles and vesicles can coexist in a single phase. The addition of salts can change the phase diagram of ATPS. Furthermore, the added salts promote the aggregation of rod-like micelles to form coarse network structure that increase the viscosity of solutions. The negative ions of the added salts are the determining factor.展开更多
本文主要研究了阳离子gemini型表面活性剂C12CsC12Br2 (s = 2、6和10)在稀溶液状态下对α-糜蛋白酶活性的影响。在稀溶液体系中我们选择了几种具有典型间隔链长度的gemini表面活性剂12-s-12 (s = 2、6和10)探究不同头基距离的表面活性...本文主要研究了阳离子gemini型表面活性剂C12CsC12Br2 (s = 2、6和10)在稀溶液状态下对α-糜蛋白酶活性的影响。在稀溶液体系中我们选择了几种具有典型间隔链长度的gemini表面活性剂12-s-12 (s = 2、6和10)探究不同头基距离的表面活性剂与α-CT之间不同程度的相互作用,同时将传统单链阳离子表面活性剂DTAB作为对比研究。结果表明,12-s-12/α-CT体系在所研究的浓度范围内均出现“钟形”的超活性区域,催化效果比DTAB/α-CT要好。α-CT相对活性的大小与gemini型表面活性剂的间隔链长度也有关系,即spacer越长,头基的电荷密度相对越小,超活性出现的越早而且最大相对活性值也越高。In this work we studied the catalytic activity of α-chymotrypsin (α-CT) in gemini surfactants C12CsC12Br2 (s = 2, 6, 10) solution. We selected several cationic gemini surfactants (12-s-12, s = 2, 6, 10) to investigate the effects of different spacer lengths on the activity of α-chymotrypsin, meanwhile the conventional single-chain cationic surfactant DTAB was also used as a comparative study. In all cases, the superactivity of 12-s-12/α-CT system appears in a bell-shape in a concentration region below their respective critical micelle concentration and, the catalytic effect is better than that of DTAB/α-CT system. The relative activity of α-CT was related to the spacer chain length of the gemini surfactant, that is, the gemini surfactant with longer spacer might have a much stronger influence on the enzyme activity due to larger size and its stronger hydrophobicity of its head group.展开更多
Rosin,a renewable and abundant resource,has been extensively processed and chemically modified to endow it with special properties,especially in the surfactant industry.In this study,four rosin-based quaternary ammoni...Rosin,a renewable and abundant resource,has been extensively processed and chemically modified to endow it with special properties,especially in the surfactant industry.In this study,four rosin-based quaternary ammonium asymmetric gemini surfactants(RGS-2-n)with different alkyl chain lengths(n=12,14,16,18)were synthesized using a simple two-step method based on dehydroabietylamine as the raw material.The feasibility of these surfactants for cleaning purposes was comprehensively evaluated,suggesting that the surfactants own high surface activity and good cleaning performance.Furthermore,by successfully introducing the amine group of dehydroabietylamine into the hydrophilic group of the surfactants,we avoided its potential harm to the environment and water pollution.Density functional theory proves rosin-based gemini surfactants with asymmetric structure can further improve cleaning efficiency.Overall,our findings suggests that RGS-2-n surfactants are promising and sustainable candidates for cleaning electric plates,and provide new opportunities for rosin application in the electric industry.展开更多
Cationic Gemini surfactants, alkanediyl-α ,ω- bis(dimethyl dodecylammonium bromide) have been synthesized by the following method: firstly dodecyl bromide was prepared by the reaction of dodecanol with bromic acid i...Cationic Gemini surfactants, alkanediyl-α ,ω- bis(dimethyl dodecylammonium bromide) have been synthesized by the following method: firstly dodecyl bromide was prepared by the reaction of dodecanol with bromic acid in the presence of strong sulfuric acid. Dodecylbromide was then reacted with N,N- tetramethyl ethane diamine(or N,N- tetramethyl hexana diamine) to prepare the title- compounds. Micellization of these Gemini surfactants was investigated using conductivity measurement. The results showed that the critical micelle concentration(cmc) of the Gemini surfactants has a much lower value compared with that of the corresponding " monomer" . For a series of the Geminis with the same length(s) in the spacer chain, the cmc decreased with increasing the carbon number (m) in the alkyl chain. The aggregation number(N) of the micelle also drastically decreased with m. For the same value of m, the cmc varied slightly with s, which indicated that the electrostatic interaction between the ionic- groups of the " monomer" has been naturally changed duo to a link between the two ionic- groups of the " monomer" through a spacer. However, N was strongly decreased with s,which may be a reason of steric inhibition coming from the ionic- groups due to a link of spacer. With increasing temperature, micellization of the Gemini surfactants was slightly enhanced.展开更多
基金the National Natural Science Foundation of China (No. 20025618, No. 20236010) Shanghai Municipal Education Commission of China.
文摘The properties of aqueous two-phase system (ATPS) of mixed solution containing gemini cationic surfactant trimethylene-1,3-bis(dodecyldimethyl ammonium) bromide (12-3-12, 2Br-) and traditional anionic surfactant sodium dodecyl sulfate (SDS) with or without added salt have been studied. An ATPS is formed in a narrow region of the ternary phase diagram different from that of traditional aqueous cationic-anionic surfactant systems. In ATPS region, the lowest total concentration of surfactants varies with the mixing ratio of geminis to SDS. Photographs obtained from freeze-etching, negative-staining and transmission electron microscopy show that the microstructures of two phases are different from each other. Micelles and vesicles can coexist in a single phase. The addition of salts can change the phase diagram of ATPS. Furthermore, the added salts promote the aggregation of rod-like micelles to form coarse network structure that increase the viscosity of solutions. The negative ions of the added salts are the determining factor.
文摘本文主要研究了阳离子gemini型表面活性剂C12CsC12Br2 (s = 2、6和10)在稀溶液状态下对α-糜蛋白酶活性的影响。在稀溶液体系中我们选择了几种具有典型间隔链长度的gemini表面活性剂12-s-12 (s = 2、6和10)探究不同头基距离的表面活性剂与α-CT之间不同程度的相互作用,同时将传统单链阳离子表面活性剂DTAB作为对比研究。结果表明,12-s-12/α-CT体系在所研究的浓度范围内均出现“钟形”的超活性区域,催化效果比DTAB/α-CT要好。α-CT相对活性的大小与gemini型表面活性剂的间隔链长度也有关系,即spacer越长,头基的电荷密度相对越小,超活性出现的越早而且最大相对活性值也越高。In this work we studied the catalytic activity of α-chymotrypsin (α-CT) in gemini surfactants C12CsC12Br2 (s = 2, 6, 10) solution. We selected several cationic gemini surfactants (12-s-12, s = 2, 6, 10) to investigate the effects of different spacer lengths on the activity of α-chymotrypsin, meanwhile the conventional single-chain cationic surfactant DTAB was also used as a comparative study. In all cases, the superactivity of 12-s-12/α-CT system appears in a bell-shape in a concentration region below their respective critical micelle concentration and, the catalytic effect is better than that of DTAB/α-CT system. The relative activity of α-CT was related to the spacer chain length of the gemini surfactant, that is, the gemini surfactant with longer spacer might have a much stronger influence on the enzyme activity due to larger size and its stronger hydrophobicity of its head group.
基金supported by National Natural Science Foundation of China(U21A200313)Key Program of Qingyuan Innovation Laboratory(00221003)‘111’program of Fuzhou University.
文摘Rosin,a renewable and abundant resource,has been extensively processed and chemically modified to endow it with special properties,especially in the surfactant industry.In this study,four rosin-based quaternary ammonium asymmetric gemini surfactants(RGS-2-n)with different alkyl chain lengths(n=12,14,16,18)were synthesized using a simple two-step method based on dehydroabietylamine as the raw material.The feasibility of these surfactants for cleaning purposes was comprehensively evaluated,suggesting that the surfactants own high surface activity and good cleaning performance.Furthermore,by successfully introducing the amine group of dehydroabietylamine into the hydrophilic group of the surfactants,we avoided its potential harm to the environment and water pollution.Density functional theory proves rosin-based gemini surfactants with asymmetric structure can further improve cleaning efficiency.Overall,our findings suggests that RGS-2-n surfactants are promising and sustainable candidates for cleaning electric plates,and provide new opportunities for rosin application in the electric industry.
文摘Sora的火爆带动生成式AI主题热度接近2023年下半年来的高点,甚至可以说是该主题的又一个“ChatGPT时刻”。跨入龙年,AI进化的步伐也是龙腾虎跃,AI的巨头之争正在推动产业升级全面提速。除了Sora外,谷歌则在Gemini 1.0基础上推出了升级版Gemini 1.5,各项性能进一步提升;英伟达推出本地AI聊天机器人Chat With RTX;苹果则被传接近完成一款可与微软GITHUBCOPILOT直接竞争的人工智能工具。
文摘Cationic Gemini surfactants, alkanediyl-α ,ω- bis(dimethyl dodecylammonium bromide) have been synthesized by the following method: firstly dodecyl bromide was prepared by the reaction of dodecanol with bromic acid in the presence of strong sulfuric acid. Dodecylbromide was then reacted with N,N- tetramethyl ethane diamine(or N,N- tetramethyl hexana diamine) to prepare the title- compounds. Micellization of these Gemini surfactants was investigated using conductivity measurement. The results showed that the critical micelle concentration(cmc) of the Gemini surfactants has a much lower value compared with that of the corresponding " monomer" . For a series of the Geminis with the same length(s) in the spacer chain, the cmc decreased with increasing the carbon number (m) in the alkyl chain. The aggregation number(N) of the micelle also drastically decreased with m. For the same value of m, the cmc varied slightly with s, which indicated that the electrostatic interaction between the ionic- groups of the " monomer" has been naturally changed duo to a link between the two ionic- groups of the " monomer" through a spacer. However, N was strongly decreased with s,which may be a reason of steric inhibition coming from the ionic- groups due to a link of spacer. With increasing temperature, micellization of the Gemini surfactants was slightly enhanced.
