界面活性劑微胞化過程之機制與熱力學性質探討

A Study on the Mechanisms and Thermodynamic Properties of Micellization of Surfactants

曾學文(Hsueh-Wen Tseng)

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(2013年)

https://doi.org/10.6342/NTU.2013.10020

摘要

本研究主要分成兩部分，第一部分探討界面活性劑Pluronics形成混合微胞的機制與熱力學性質，第二部分探討聚電解質/界面活性劑系統中的交互作用情形。
在第一部分中，藉由高感度微分掃描式熱卡計和粒徑分析儀觀察不同Pluronics系統形成混合微胞的過程機制。Pluronics是一系列結構為聚氧乙烯-聚氧丙烯-聚氧乙烯的界面活性劑。實驗探討的混合系統包含Pluronic L92 + F68 / F88 / F98 / F108和Pluronic L92 + P84 / F87 / F88；其中，L92 單成份系統在溫度高於臨界微胞溫度(critical micelle temperature, CMT)之後形成層板狀的聚集，其他的Pluronics皆是形成球形的微胞。Pluronic F68、F88、F98和F108這四種Pluronics分子具有相同的親水/疏水片段比例，但分子鏈長不同，實驗結果發現雙成份系統中F108、F98的疏水片段較L92疏水片段長或相同，可以主導形成混合微胞的過程，將L92包覆在內形成球形的混合微胞。L92 + F88系統受L92濃度影響會有不同的混合微胞形成機制；L92 + F68系統因兩成份鏈長以及CMT相差較大，會在系統中分別形成各自的微胞。
P84、F87和F88則是分子中具有相同分子量的疏水片段，但有不同的親水片段鏈長，此系列探討不同比例的親疏水片段對系統的影響，實驗結果發現親疏水片段比例對於系統形成混合微胞的影響沒有明顯的趨勢，但三系統所形成的混合微胞皆受L92的主導，不夠穩定，可能不足以當作藥物釋放的載體。
第二部分中，利用核磁共振儀、恆溫滴定熱卡計和表面張力儀觀察聚電解質Poly acrylic acid (PAA)與非離子型界面活性劑Tetraethylene glycol monooctyl ether (C8E4)、Pentaethylene glycol monooctyl ether (C8E5)之間的交互作用情形，以了解微胞形成的機制與熱力學性質分析。實驗結果發現，將界面活性劑C8E4或C8E5加入PAA溶液後，當濃度超過臨界聚集濃度 (critical aggregation concentration, CA)後，C8E4 (C8E5)會開始附著到PAA分子鏈上，同時也會開始形成自由微胞，此與一般認為界面活性劑會先被吸附至PAA長碳鏈上，直到PAA長碳鏈達到飽和後界面活性劑才會開始形成自由微胞的現象不同，因為C8E4和C8E5屬於非離子型的界面活性劑，和陰離子型的聚電解質PAA之間沒有強烈的靜電吸引力，而是藉由疏水作用力而產生較弱的交互作用。

關鍵字

界面活性劑 ； 聚電解質 ； 微胞 ； 混合微胞 ； 混微胞複合物 ； 微分掃描式熱卡計 ； 恆溫滴定熱卡計

並列摘要

The first part of this work, we study mixed-micelle formed mechanism and thermodynamic properties of the binary Pluronics system by differential scanning calorimeter (DSC) and Particle Size Analyzer. Pluronics are copolymers which have poly (ethylene oxide) – poly (propylene oxide) – poly (ethylene oxide) (PEO-PPO-PPO) structure. We investigate several mixed-systems including Pluronic L92 + F68 / F88 / F98 / F108 and Pluronic L92 + P84 / F87 / F88. In individual system, L92 forms lamellar aggregation when temperature is higher than its critical micelle temperature (CMT), and other Pluronics form spherical micelles.
F68, F88, F98 and F108 have the same ratio of hydrophilic segments to hydrophobic segments, but different chain lengths. Then we can identify the influence of molecule chain length on mixed-micellization. F108 has larger hydrophobic segment than L92. The L92 + F108 system is dominated by F108 to form spherical mixed – micelles, as well as the L92 + F98 system. The mechanism of L92 + F88 system is affected by L92 concentration. In L92 + F68 system, they form individual micelles.
P84, F87 and F88 have same chain length of hydrophobic segments, but different chain lengths of hydrophilic segments. Compare the three different systems (L92 + P84 / F87 / F88), we can analyze the effect of different ratios of hydrophilic segments to hydrophobic segments on the micelle formation mechanism. However there is no significant trend according to these three different ratios. In these three systems, the micelle formation mechanism is still dominated by L92. The mix-micelles are too unstable to be applied as drug release carriers.
In the second part of this work, we use nuclear magnetic resonance (NMR), isothermal titration calorimeter (ITC) and tensiometer to explore the interaction between nonionic surfactant and anionic polyelectrolyte. Two systems tetraethylene glycol monooctyl ether (C8E4) + poly acrylic acid (PAA) and Pentaethylene glycol monooctyl ether (C8E5) + poly acrylic acid (PAA) are examined. It is found the interaction mechanism of these two systems is different from that of cationic surfactant + anionic polyelectrolyte system. There is no strong electrostatic attraction between C8Ej and PAA. When the surfactant C8Ej starts to bind to PAA chain, C8E4 molecules also simultaneously form free micelles.

並列關鍵字

surfactant ； pluronic ； C8E4 ； C8E5 ； polyelectrolyte ； poly(acrylic acid) ； PAA ； mixed micelle ； polyelectrolyte-surfactant complexes ； differential scanning calorimeter ； DSC ； isothermal titration calorimetry ； ITC

參考文獻

Alakhov, V.; Klinski, E.; Li, S. M.; Pietrzynski, G.; Venne, A.; Batrakova, E.; Bronitch, T.; Kabanov, A., “Block Copolymer-Based Formulation of Doxorubicin. From Cell Screen to Clinical Trials.” Colloids and Surfaces B-Biointerfaces 1999, 16(1-4), 113-134.

Alexandridis, P.; Hatton, T. A., “Poly (Ethylene Oxide) - Poly (Propylene Oxide) - Poly (Ethylene Oxide) Block-Copolymer Surfactants in Aqueous-Solutions and at Interfaces - Thermodynamics, Structure, Dynamics, and Modeling.” Colloids and Surfaces A-Physicochemical and Engineering Aspects 1995, 96(1-2), 1-46.

Anghel, D. F.; Saito, S.; Baran, A.; Iovescu, A., “Interaction between Poly (Acrylic Acid) and Nonionic Surfactants with the Same Poly (Ethylene Oxide) but Different Hydrophobic Moieties.” Langmuir 1998, 14(19), 5342-5346.

Anghel, D. F.; Saito, S.; Iovescu, A.; Baran, A., “Some Critical Points in the Interaction between Homogeneous Non-Ionic Surfactants and Poly (Acrylic Acid).” Colloids and Surfaces A: Physicochemical and Engineering Aspects 1994, 90(1), 89-94.

Attwood, D.; Florence, A. T., “Surfactant Systems : Their Chemistry, Pharmacy, and Biology.” Chapman and Hall, New York, 1983.