由凝膠滲透層析量測之柱狀寡聚物及高分子的分子量校正參數

Fragment Parameters for the Calibration of Molecular Weights of Rod-Like Oligomers/Polymers by Gel Permeation Chromatography

陳致君(Chih-Chun Chen)

指導教授 ： 陸天堯

國立臺灣大學/理學院/化學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.02520

摘要

凝膠滲透層析法對於寡聚物與高分子的數目平均分子量(Mn)、重量平均分子量(Mw)與分子量分布指數(PDI)提供了非常好的量測，而聚苯乙烯是最常被拿來使用的標準品。然而，凝膠滲透層析法實際上測量的是與聚合物樣品本身分子形狀有關的水合體積，所以每當樣品的分子形狀或是水合體積跟聚苯乙烯不同時，常會出現分子量量測值(Mn)與實際值(Mr)的誤差。這個現象在黏度較高的聚噻吩等柱狀高分子中更常被發現。
我們研究了許多使用凝膠滲透層析法量測含有噻吩、噻吩并噻吩、苯環、雙鍵與三鍵分子的柱狀寡聚物/高分子的分子量，進而建立了一系列校正參數。藉由這些參數，我們可以得到較為準確的已校正分子量(Mc)。參數的範圍由0.16到1.18，這些參數的數值是從調整測量分子量(Mn)與實際分子量(Mr)的斜率而來，如果已校正分子量(Mc)與實際分子量(Mr)相當，則斜率則為1。已校正的分子量(Mc)是由式子Mc = [ciFi]Mn 所得。Fi 是該分子組成分量，ci 則是校正參數。總共有超過84% 的校正分子量(Mc)含有12% 以內對於實際分子量(Mr)的誤差。

關鍵字

凝膠滲透層析法 ； 分子量校正

並列摘要

Gel permeation chromatography (GPC) offers a powerful tool to determine number average molecular weight (Mn) and weight average molecular weight (Mw), of a polymer, from which polydispersity (PDI) of the polymer is obtained. Polystyrenes are commonly used as the reference in GPC analyses. What GPC measures is the hydrodynamic volume of a polymeric sample which is closely related to the shape of the polymeric molecules. Thus, when the molecular shape or hydrodynamic radius of a polymer is different from that of polystyrene references, the deviation of molecular weights of polymers from the exact values is frequently observed. This is particularly true for rod-like polymers such as oligo/polythiophenes that exhibit larger intrinsic viscosity than that for highly folded polymers.
A set of new empirical parameters ci of commonly used fragments including a range of different substituted thiophenes, benzenes, pyridines, ethylenes, ethynylenes as well as butadienes for the calibration of the inflated Mn data obtained by GPC measurements for rod-like oligomers/polymers has been established. The parameters, ci, are ranging from 0.16 to 1.18, and they are obtained by adjusting the slopes of the plots of Mn versus the real molecular weights, Mr, for a series of oligomers and polymers to approximately 1. The calibrated molecular weights, Mc, are calculated based on equation, Mc = [ciFi]Mn, where Fi indicates the fragment fraction for the corresponding fragment ci in an oligomer/polymers, and match nicely with Mr of oligomers/polymers. More than 84% of calculated Mc values are within 12% deviating from the real molecular weights, Mr.

並列關鍵字

GPC ； molecular weight calibration

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