能量消散型石英晶體微天平於pH敏感型聚電解質膨潤行為之研究

Swelling Behavior of pH-Responsive Polyelectrolytes Revealed by Quartz Crystal Microbalance with Dissipation (QCM-D)

黃薈芸(Hui-Yun Huang)

指導教授 ： 薛景中

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202004032

摘要

近年來，pH敏感型材料的發展逐漸開始受到關注並廣泛應用於各個層面。舉例來說，在藥物標靶方面，該材料具特定反應條件的性質能夠用來控制分子投放的時機與位置。而聚電解質帶有可解離之基團，配合電荷密度的變化，pH值便可作為調控其膨潤行為的條件之一。當環境pH值偏離等電位點 (IEP) 時，分子鏈因帶電而互相排斥，導致結構膨潤並舒展開來，原先包覆在內的物質便有機會釋放而出.。此次使用的pH敏感型聚電解質係以分別帶有酸、鹼性基團的甲基丙烯酸 (MAA) 和N-(3-二甲氨基丙基)甲基丙烯醯胺 (DMAPMA) 作為單體所合成，其展現的表面電位及等電位點則根據兩種官能基的混合比例而有所不同。
本研究將在貼近生物體內滲透壓的環境下，透過能量消散型石英晶體微天平 (QCM-D) 對該合成聚電解質於不同pH值下的膨潤行為進行觀察，並以所得數據探討其相應機制與內部結構變化。從結果可以發現，隨著環境pH值越加偏離等電位點，聚電解質的膨潤效應也逐漸增強，引入的水分造成質量上升，故共振頻率降低。另一方面，水分含量的增加也會導致高分子鍵結原有的彈性式微，整體表現更貼近黏性性質，進而反映在升高的能量消散值上。

關鍵字

pH敏感型高分子 ； 電荷調控 ； 能量消散型石英晶體微天平 ； 膨潤行為

並列摘要

Over the past few years, pH-responsive materials have drawn attention due to their diverse applications. For example, for targeted drug delivery, these materials provide means to accomplish controlled release of molecules. With dissociable functional groups, the swelling behavior of polyelectrolytes can be adjusted by pH through the changes in charge density. When the environmental pH deviates from the IEP, charged chains will repel with each other and form a swollen structure. The embedded cargos therefore have a chance to be released. In this work, methacrylic acid (MAA) and N-[3-(dimethylamino)propyl] methacrylamide (DMAPMA) were co-polymerized to provide acidic and basic functional groups, respectively. In addition, the surface potential and isoelectric point (IEP) were tailored by the ratio of these functional groups.
The synthesized polyelectrolytes were characterized by quartz crystal microbalance with dissipation (QCM-D) under physiological ionic strength of different pHs, and the swelling kinetics and conformation changes inside the structure were evaluated from the data obtained. It was found that when the polyelectrolytes were exposed to pHs further away from their IEPs, the decreasing resonant frequency (Δf) indicated more water was incorporated into the film as the polymers swelled more significantly. On the other hand, the increase in water uptake also enhanced the viscosity comparing with the intrinsic elasticity of polymer chains, which was reflected on the increase of energy dissipation (ΔD).

並列關鍵字

pH-responsive polymers ； charge-tunable ； QCM-D ； swelling behavior

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