Abstract
Average molecular weights and molecular distributions of polyethylene glycol (PEG) as a byproduct in ethylene oxide adduct nonionic surfactants (EO-SAA) were studied by gel permeation chromatography (GPC).
Every PEG were perfectly separated from various EO-SAA through the reversed-phase column chromatography.
Standard PEG (n=5, 6, 7, 8, 9, and 10) were isolated from the commercial PEG 300 by recycle GPC and the purities of them were identified by GC. Average molecular weights per 1 Å of them were found to be calculated as 24 by making that of polystylene as 41.
By using this value, the chromatograms of each PEG, the calibration curve of standard polystylene and a curve-reader CPU system, the average molecular weights of PEG in EO-SAA could be easily determined.
The average molecular weights of isolated PEG in EO-SAA of ether type were shown to be almost constant values, while those in ester type were dependent on the EO molecular numbers of the original EO-SAA. The values of those in Tween type EO-SAA coincided with those of the average 20 molecular numbers of EO-SAA of ester type.
Further, the molecular distributions of various commercial PEG were also presented in this paper.
