聚丙烯酸與四聚乙二醇單辛醚系統之熱力學性質探討

高分子/界面活性劑系統已被廣泛應用於商用產品上，因此，高分子/界面活性劑系統間彼此作用力，受到許多研究與探討。在此研究中，我們利用恆溫滴定熱卡計 (ITC)、表面張力儀與 pH 計，以量測聚電解質 Poly(acrylic acid) (PAA) 與界面活性劑 n-octyltetraoxyethylene (C8E4) 間的交互作用力，藉以判別此系統的各項熱力學性質。當我們逐次將 C8E4 加入 PAA 溶液後，加入的 C8E4 達一定量時，會開始吸附在 PAA 分子鏈上，我們定義開始吸附到 PAA 上的濃度為臨界聚集濃度 (critical aggregation concentration , CA) 。接著，持續加入 C8E4 於系統中，直到 C8E4 在 PAA 高分子鏈上吸附達飽和，定義此濃度為飽和濃度 (saturation concentration, Cs)。當達飽和濃度後，繼續滴入 C8E4 達某一特定濃度時，C8E4 可在 PAA 溶液中，形成 C8E4 自身的微胞，此濃度定義為第二次臨界微胞濃度 (second critical micelle concentration, Cm)。本研究藉由恆溫滴定熱卡計、表面張力儀與 pH 計所測得之數據，以判別 PAA / C8E4 系統中各特徵濃度(CA、Cs 與 Cm)，並仔細探討三種方法間，是否符合熱力學一致性。

關鍵字

聚電解質；界面活性劑；吸附；表面張力；吸放熱

並列摘要

Polymer–surfactant mixtures have been used in a wide range of commercial applications. Therefore, their behavior is of great interest. In this study, isothermal titration calorimeter (ITC), surface tension and pH meter are applied to investigate the interaction between the surfactant n-octyltetraoxyethylene (C8E4) and the weakly dissociated polyelectrolyte, poly(acrylic acid) (PAA). When the surfactant C8E4 is added into the PAA solution, the critical aggregation concentration (CA) is defined as the onset concentration of binding surfactant onto polymer. While surfactant is further added into the system until polymer is saturated with bound surfactant. That defines the saturation concentration (Cs). The second critical micelle concentration (Cm) is then defined as the concentration where the surfactant starts to form free micelles beyond the saturation concentration. In this study: ITC, surface tension and pH data are applied to extract the information of CA, Cs and Cm. The consistency between these three methods is carefully examined and discussed.

並列關鍵字

surfactant ； polyelectrolyte ； adsorption ； surface tension ； enthalpy

參考文獻

陳柏嘉 (2008), 碩士學位論文, 聚丙烯酸與離子型界面活性劑作用之熱力學性質探討, 國立台灣大學化學工程研究所.

王楷翔 (2009), 碩士學位論文, 聚電解質與離子型界面活性劑作用之熱力學性質探討, 國立台灣大學化學工程研究所.

Anghel, D. F., Saito, S., Baran, A. and Iovescu, A. (1998). “Interaction between Poly(acrylic acid) and Nonionic Surfactants with the Same Poly(ethylene oxide) but Different Hydrophobic Moieties” Langmuir 14: 5342-5346

Anghel, D. F., Saito S., Iovescu A., Baran, A. (1994). “Some critical points in the interaction between homogeneous non-ionic surfactants and poly(acrylic acid)” Colloids and Surfaces 90: 89-94

Bell, C. G., Breward, C. J. W., Howell, P. D., Penfold, J., Thomas, R. K. (2010). “A theoretical analysis of the surface tension profiles of strongly interacting polymer–surfactant systems” Journal of Colloid and Interface Science 350: 486–493

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聚丙烯酸與四聚乙二醇單辛醚系統之熱力學性質探討

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