Interaction of Poly(N-isopropylacrylamide) with Sodium Dodecyl Sulfate below the Critical Aggregation Concentration

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• 作者：Nobuo Uehara ; Minami Ogawa
• 刊名：Langmuir
• 出版年：2014
• 出版时间：June 10, 2014
• 年：2014
• 卷：30
• 期：22
• 页码：6367-6372
• 全文大小：349K
• 年卷期：v.30,no.22(June 10, 2014)
• ISSN：1520-5827

文摘

Interaction between the thermoresponsive polymer poly(N-isopropylacrylamide) (P-NIP) and sodium dodecyl sulfate (SDS) both above and below its phase transition temperature was examined under dilute conditions. Above the lower critical solution temperature (LCST) of P-NIP (32 掳C), 0.01 wt % P-NIP specifically interacted with 1.0 脳 10^鈥? mol/L SDS to form a precipitate. However, when SDS was added at concentrations above or below 1.0 脳 10^鈥? mol/L, the P-NIP solution remained clear above the LCST. A fluorometric probe, N-phenyl-naphthalene, indicated that the hydrophobicity of the aggregates composed of P-NIP and SDS changed at an SDS concentration of 1.0 脳 10^鈥? mol/L. Although the hydrophobicity of the precipitate was similar to that of P-NIP alone at less than 1.0 脳 10^鈥? mol/L, it approached that of SDS homomicelles as the SDS concentration increased above 1.0 脳 10^鈥? mol/L. Dynamic light scattering and turbidimetry studies showed no P-NIP phase transition above an SDS concentration of 1.0 脳 10^鈥? mol/L, which is much lower than the reported critical association concentration (CAC) of SDS with P-NIP. This indicates that P-NIP interacted with SDS above the LSCT at much lower SDS concentration than the reported CAC.