Aggregation of fluorophore-containing molecules results in an increase of the local concentration of fluorophore and a suitable geometric relation between fluorophores, which leads to the formation of excimer or excip...Aggregation of fluorophore-containing molecules results in an increase of the local concentration of fluorophore and a suitable geometric relation between fluorophores, which leads to the formation of excimer or exciplex. It proved to be of great importance in the investigation of molecular aggregation in solution. Wu et al. have reported the observa-展开更多
Temperature dependent phase behavior of Pseudo-ternary Thiourea X-100 + 1-hexanol (1:5 molar ratios)/oil/water systems is reported. The influence of nature of hydrocarbon oil and type of electrolytes (weak as well as ...Temperature dependent phase behavior of Pseudo-ternary Thiourea X-100 + 1-hexanol (1:5 molar ratios)/oil/water systems is reported. The influence of nature of hydrocarbon oil and type of electrolytes (weak as well as strong) has been investigated on the temperature induced phase behavior of the ternary system. At surfactant concentration, Φs = 40%, a “nose shaped” microemulsion region is observed. Below one-phase microemulsion region, Lα phase appears. The presence of NaCl decreases the domain size of 1Φ micellar region whereas oxalic acid first decreases the domain below Φw 18 in the lower boundry of the phase diagram. The critical weight fraction of water, Φwcri decreases in presence of both electrolytes. However, Φwmax increases in presence of oxalic acid and remains constant in presence of NaCl as compared to salt free system. Furthermore, when cyclohexane was replaced by a longer straight chain hydrocarbon, dodecane, the domain of the one-phase microemulsion region is tremendously increased.展开更多
The aqueous solutions of poly(e-caprolactone-co-lactide)-poly(ethylene glycol)poly(e-caprolactone-co-lactide) undergoing sol-gel transition as the temperature increases from 20 to 50℃were successfully prepared. The t...The aqueous solutions of poly(e-caprolactone-co-lactide)-poly(ethylene glycol)poly(e-caprolactone-co-lactide) undergoing sol-gel transition as the temperature increases from 20 to 50℃were successfully prepared. The thermogelling triblock copolymers were synthesized by subtle tuning of the chemical composition and the hydrophilicity/hydrophobicity balance. The sol-gel transition was studied focusing on structure-property relationship. The amphiphilic copolymer formed micelles in aqueous solutions. It is believed to have potential applications in drug delivery and tissue engineering.展开更多
Abstract We report on the rheological behavior of wormlike micelles constructed by ionic liquid surfactant [Csmim]Br （1-octyl-3-methylimidazolium bromide） and anionic surfactant sodium oleate （NaOA） in aqueous sol...Abstract We report on the rheological behavior of wormlike micelles constructed by ionic liquid surfactant [Csmim]Br （1-octyl-3-methylimidazolium bromide） and anionic surfactant sodium oleate （NaOA） in aqueous solution. The effects of surfactant composition, total surfactant concentration, added salts, and temperature were investigated. The prevailing surfactant effect at lower concentration and the leading cosolvent effect at higher concentration of [Csmim]Br may be the main reasons for appearance of well-established maximum in key rheologi- cal parameters with variation of surfactant composition and total surfactant concentration. The Cole-Cole plots demon- strate that the systems （total surfactant concentration falls within 0.17-0.35 mol. L- 1 and molar ratio 0.33≤R ≤ 0.50） fit the Maxwell＇s mechanical model as linear viscoelastic fluid. The addition of NaBr or sodium salicylate decreases significantly the viscosity and the relaxation time of the wormlike micelle solution but cannot change the value of plateau modulus Go. The present system has low rheological tolerance to temperature. The increase of temperature decreases the average contour length and viscosity of wormlike micelles and thus strengthens the relaxation progress of diffusion and weakens the relaxation progress of reptation. Increasing the temperature also decreases the value of plateau modulus G0 and shifts the minimum value of the loss modulus G″min to higher frequencies.展开更多
文摘Aggregation of fluorophore-containing molecules results in an increase of the local concentration of fluorophore and a suitable geometric relation between fluorophores, which leads to the formation of excimer or exciplex. It proved to be of great importance in the investigation of molecular aggregation in solution. Wu et al. have reported the observa-
文摘Temperature dependent phase behavior of Pseudo-ternary Thiourea X-100 + 1-hexanol (1:5 molar ratios)/oil/water systems is reported. The influence of nature of hydrocarbon oil and type of electrolytes (weak as well as strong) has been investigated on the temperature induced phase behavior of the ternary system. At surfactant concentration, Φs = 40%, a “nose shaped” microemulsion region is observed. Below one-phase microemulsion region, Lα phase appears. The presence of NaCl decreases the domain size of 1Φ micellar region whereas oxalic acid first decreases the domain below Φw 18 in the lower boundry of the phase diagram. The critical weight fraction of water, Φwcri decreases in presence of both electrolytes. However, Φwmax increases in presence of oxalic acid and remains constant in presence of NaCl as compared to salt free system. Furthermore, when cyclohexane was replaced by a longer straight chain hydrocarbon, dodecane, the domain of the one-phase microemulsion region is tremendously increased.
文摘The aqueous solutions of poly(e-caprolactone-co-lactide)-poly(ethylene glycol)poly(e-caprolactone-co-lactide) undergoing sol-gel transition as the temperature increases from 20 to 50℃were successfully prepared. The thermogelling triblock copolymers were synthesized by subtle tuning of the chemical composition and the hydrophilicity/hydrophobicity balance. The sol-gel transition was studied focusing on structure-property relationship. The amphiphilic copolymer formed micelles in aqueous solutions. It is believed to have potential applications in drug delivery and tissue engineering.
基金This work is supported by the National Natural Science Foundation of China （Grant Nos. 21173079, 91334203 and 21476072）, the 111 Project （No. B08021） and the Fundamental Research Funds for the central universities of China.
文摘Abstract We report on the rheological behavior of wormlike micelles constructed by ionic liquid surfactant [Csmim]Br （1-octyl-3-methylimidazolium bromide） and anionic surfactant sodium oleate （NaOA） in aqueous solution. The effects of surfactant composition, total surfactant concentration, added salts, and temperature were investigated. The prevailing surfactant effect at lower concentration and the leading cosolvent effect at higher concentration of [Csmim]Br may be the main reasons for appearance of well-established maximum in key rheologi- cal parameters with variation of surfactant composition and total surfactant concentration. The Cole-Cole plots demon- strate that the systems （total surfactant concentration falls within 0.17-0.35 mol. L- 1 and molar ratio 0.33≤R ≤ 0.50） fit the Maxwell＇s mechanical model as linear viscoelastic fluid. The addition of NaBr or sodium salicylate decreases significantly the viscosity and the relaxation time of the wormlike micelle solution but cannot change the value of plateau modulus Go. The present system has low rheological tolerance to temperature. The increase of temperature decreases the average contour length and viscosity of wormlike micelles and thus strengthens the relaxation progress of diffusion and weakens the relaxation progress of reptation. Increasing the temperature also decreases the value of plateau modulus G0 and shifts the minimum value of the loss modulus G″min to higher frequencies.
