帶相反電性之聚電解質/界面活性劑系統添加鹽類的效應其熱力學性質探討與雙成分共聚物高分子形成水凝膠之動態效應

A Study on Thermodynamic Properties of Oppositely Charged Polyelectrolyte/Surfactant system in the Presence of Salts and Dynamic Effect of Hydrogel Formation for Binary Copolymer System

廖芝婷(Zhi-Ting Liao)

指導教授 ： 陳立仁

國立臺灣大學/工學院/化學工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202100091

摘要

本研究主要分成兩部分，第一部分探討聚電解質/界面活性劑系統中的交互作用情形，第二部分探討界面活性劑Pluronics由溫度改變所引起水凝膠的生成行為。
在第一部份中，透過恆溫滴定熱卡計、表面張力儀以及電導度計研究聚電解質聚丙烯酸於半稀釋纏繞區間濃度下與陽離子型界面活性劑溴化十六烷基三甲銨 (C16TAB)添加鹽類後之間的交互作用，並改變系統溫度 (25 oC及35 oC)、鹽類濃度 (0.001 m及0.005 m)以及鹽類種類 (氯化鈉及溴化鈉)觀察其變化。我們發現當鹽類存在於聚電解質/界面活性劑 (PES)系統時，各特徵濃度會隨鹽類濃度上升而下降，但臨界聚集濃度 (CAC)則相反，另一方面，添加NaBr相對於NaCl對系統的影響較為劇烈，使單體分子排列更緊密，進而促使界面活性劑形成微胞。
第二部分中使用普朗尼克 (Pluronic)三段式共聚合物，因為其雙親性及生物可分解的特質，應用十分廣泛。本實驗研究高濃度共聚物溶液隨溫度升高疏水作用上升，促使微胞堆疊成水凝膠，我們使用Pluronic F108、F108+P103 (2:1)、F108+P103 (1:2)和P103皆在30 wt%濃度下研究由溫度改變所引起的水凝膠生成行為，有趣的是，30 wt% P103系統在不同溫度區間會出現兩個凝膠態，其獨特的相行為變化值得我們持續深入研究。除了巨觀的相行為變化外，同時也探討巨觀行為背後水凝膠晶相微觀結構的轉變，當升溫速度上升，系統凝膠化的範圍會縮小。另一方面，根據小角X光散射實驗 (SAXS)，不同升溫速度會影響水凝膠在不同溫度下的晶相結構變化，但晶體結構的整體轉變最終會趨於平衡態的結果。

關鍵字

聚電解質 ； 界面活性劑 ； 混合微胞 ； 恆溫滴定熱卡計 ； 水凝膠 ； 動態效應

並列摘要

This study is divided into two parts. The first part discusses the interaction between the polyelectrolyte/surfactant system, and the second part discusses the hydrogel formation behavior of the Pluronic induced by temperature changes.
The first part of this work, we explore the effect of adding salt on the interaction between cationic surfactant and anionic polyelectrolyte in the semi-dilute unentangled regime through different techniques such as isothermal titration calorimetry, surface tensiometer and conductometry. We established three different perspectives to observe: system temperature (25 oC and 35 oC), salt concentration (0.001 m and 0.005 m) and the type of salt (NaCl and NaBr). It is found that the values of characteristic concentration decrease as the salts concentration increase except the critical aggregation concentration in the polyelectrolyte/surfactant system. On the other hand, the addition of NaBr effects the system more dramatically than NaCl, which makes the unimer molecules close packing and promote surfactant form into micelles.
In the second part of this work, we use Pluronic, a series of amphiphilic and biodegradable tri-block copolymer, has been widely used. First, we study hydrogel formed by the packing of micelles in concentrated solution, raising temperature of the system induces the hydrophobic effect and promotes packing of micelles into hard gel. We focused on the temperature induced changes of gel formation using Pluronic F108, F108+P103 (2:1), F108+P103 (1:2) and P103 in the concentration of 30 wt%. Interestingly, 30 wt% P103 system shows apparent two gel states in different temperature region and its unique phase behavior changes are worthy of further study. In addition to the changes of macroscopic phase behavior, the transformation of the hydrogel crystal phase microstructure behind the macroscopic behavior is also discussed. As heating rate increases, gelation window becomes smaller. On the other hand, according to the small-angle X-ray scattering experiment (SAXS), different heating rates lead to microstructural changes of crystalline structure at different temperatures, but all the structural evolutions are the continuous process toward equilibration for hydrogel.

並列關鍵字

Polyelectrolyte ； Surfactant ； Mixed micelles ； Isothermal titration calorimetry ； Pluronic ； Gel ； Kinetic effect

參考文獻

1.Myers, D. Surfaces, interfaces, and colloids: principles and applications. Second edition, vol. 4, John Wiley Sons, Inc., (1999).

2.Li, Y., Chen, X., Zhang, M., Luo, W., Yang, J. Zhu, F. Macromolecular aggregation of aqueous polyacrylic acid in the presence of surfactants revealed by resonance rayleigh scattering. Macromolecules 41, 4873–4880 (2008).

3.Wang, X., Li, Y., Li, J,. Wang, J., Wang, Y., Guo, Z. Yan, H. Salt effect on the complex formation between polyelectrolyte and oppositely charged surfactant in aqueous solution. J. Phys. Chem. B 109, 10807–10812 (2005).

4.Nagarajan, R. Amphiphilic surfactants and amphiphilic polymers: Principles of molecular assembly. ACS Symp. Ser. 1070, 1–22 (2011).

5.Alexandridis, P. Alan Hatton, T. Poly(ethylene oxide)poly(propylene oxide)poly(ethylene oxide) block copolymer surfactants in aqueous solutions and at interfaces: thermodynamics, structure, dynamics, and modeling. Colloids Surfaces A Physicochem. Eng. Asp. 96, 1–46 (1995).