Micellization and Gelation of Mixed Copolymers P123 and F127 in Aqueous Solution

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• 作者：Chiraphon Chaibundit ; Ná ; gila M. P. S. Ricardo ; Flá ; via de M. L. L. Costa ; Stephen G. Yeates ; Colin Booth
• 刊名：Langmuir
• 出版年：2007
• 出版时间：August 28, 2007
• 年：2007
• 卷：23
• 期：18
• 页码：9229 - 9236
• 全文大小：147K
• 年卷期：v.23,no.18(August 28, 2007)
• ISSN：1520-5827

文摘

The micellization in dilute aqueous solution of Pluronic copolymers P123 (E₂₁P₆₇E₂₁) and F127 (E₉₈P₆₇E₉₈) andmixtures of the two was investigated using static and dynamic light scattering. Gelation of concentrated solutions ofthe two copolymers and their mixtures was studied using tube inversion and oscillatory rheometry. The two copolymerscomicellized to give micelles with narrow size distributions. Clouding temperatures and critical micelle temperaturesdecreased as the proportion of P123 in the mixture was increased. Micelle association numbers of the mixed micelleslay between the values found for micelles of P123 and F127 alone, whereas micelle radii passed through maximumvalues in the range 0-50 wt % P123. As judged by the ratio of the thermodynamic to the hydrodynamic radius, themicelle interaction potential changes gradually from soft to hard as the proportion of P123 in the mixture is increased.Regions of cubic and hexagonal (birefringent) gel were defined for concentrated solutions. The high-temperatureboundary of the 30 wt % cubic gel decreased monotonically from 90 to 43 ges/entities/deg.gif">C as the proportion of P123 in the mixturewas increased from 0 to 100 wt %, whereas the low-temperature boundary was essentially constant at 15 ± 3 ges/entities/deg.gif">C.Increasing the proportion of P123 in the mixture at 25 ges/entities/deg.gif">C increased the concentration at which the cubic gel was firstformed and decreased the concentration at which the hexagonal gel was first formed.