Fragment Parameters for the Calibration of Molecular Weights of Rodlike Oligomers/Polymers by Gel Permeation Chromatography
journal contributionposted on 24.11.2015, 00:00 by Chih-Chun Chen, Chih-Wei Chen, Kamani Satyanarayana, Tien-Yau Luh
Molecular weights for rodlike polymers determined by the gel permeation chromatography (GPC) method are in general inflated when polystyrene references are used. In this paper, we have established a set of new empirical parameters, χi, 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 rodlike oligomers/polymers. The χi parameters are accessed by adjusting the slopes of the plots of Mn relative to the real molecular weights, Mr, for a series of oligomers/polymers of different structural varieties to approximately 1. The calibrated molecular weights, Mc, are calculated based on the equation, Mc = [Σ χiFi]Mn, where Fi stands for the percent of the total number of fragment Φi in an oligomer/polymer, which matches nicely with the Mr of oligomers/polymers. More than 84% of the calibrated Mc values are within 12% deviation from the real molecular weights Mr.