Nafion/醇/水溶液之光散射與黏彈性研究

李淑珍

指導教授 ： 余子隆 ； 林秀麗

元智大學/工程學院/化學工程與材料科學學系/碩士(2002年)

摘要

本實驗是以動態光散射及動態流變儀研究Nafion聚合物溶液的分子鏈運動行為，並以薄膜滲透壓儀量測聚合物分子聚集情形。動態光散射是偵測分子團聚集情形的良好工具，從動態光散射的數據得知，Nafion在CH3OH/H2O(重量比4:1)混合溶劑中，濃度在1 mg/ml時，有一relaxation mode，但在濃度超過3 mg/ml，此鬆弛模式有向長鬆弛時間位移的趨勢，顯示高濃度情況下，有高分子聚集的現象發生，Nafion分子出現兩種聚集行為：(1)經由主鏈產生的一次聚集(primary cluster)，(2)一次聚集後，再經由外圍帶電荷的離子官能基相互銜接形成的離子二次聚集(ionic secondary cluster)。在薄膜滲透壓方面，由數據推測，Nafion濃度高於0.8~1 mg/ml時，可能Nafion分子產生聚集行為，使得溶質粒子數減少。由動態黏彈性量測得的數據顯示，logG’數值呈三段變化，隨頻率由低頻區逐漸往上增加，而logG”數值則隨頻率先上升而後下降，而有一極大值出現。在低頻時， 與一般flexible polymer溶液的數據相似，但在 rad/sec則有 的數據出現，此為一般polymer溶液所沒有的現象，推測可能為分子團聚集現象所造成。由動態光散射數據顯示，添加NaCl可以抑制Nafion在甲醇水溶液中的分子聚集行為。數據也顯示出Nafion在不同醇類溶劑中出現不同的運動行為，增加醇類的碳原子數，可以提高溶劑對Nafion的溶解能力。

關鍵字

動態光散射 ； 全氟磺酸離子交換樹酯 ； 疏水性聚集 ； 離子性聚集

並列摘要

In this research work, Physical properties of Nafion solution were studied. Dynamic light scattering (DLS), membrane osmometer, and rheometer were used to study the solution properties of Nafion in mixtures of alcohols/water solvents. Dynamic light scattering data of Nafion/methanol/water solution revealed that, at a concentration below 3 mg/ml, it has one relaxation mode, but at concentrations above 5 mg/ml, two relaxation modes were observed with slow mode shifted to longer time relaxation while Nafion concentration was increased, Membrane osmometer data showed that π/C decreased with increasing Nafion concentration, while Nafion concentration was between 0.8 mg/ml and 1 mg/ml, indicating the aggregation of Nafion molecules. The rheometic experiment also showed the aggregation behavior in Nafion solution.The aggregation behavior of Nafion/alcohols/water solution is attributed two types of clusters: one is primary hydrophobic cluster, the other is ionic secondary cluster.

並列關鍵字

HASH(0xaa95ea8)

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