Describes the Agilent PLgel MIXED-D and GPC/SEC application for measuring styrene/isoprene block copolymers.
The document explains how Gel Permeation Chromatography (GPC) can be used to estimate the relative proportion of components in a blend of Styrene-Isoprene (SI) diblock and SIS triblock copolymers. Unlike random copolymers, block copolymers contain isolated blocks of homopolymers linked at terminal positions, producing materials with novel properties such as surfactant characteristics.
The note details a specific analysis example where high-efficiency Agilent PLgel MIXED-D columns resolve the SI and SIS components based on their size difference in solution. The chromatogram allows for quantification, showing that an increase in diblock proportion reduces the viscosity and modulus of the product, which is useful for applications like pressure-sensitive labels.
These columns resolve the SI and SIS components of a blended product based on their size difference in solution, which allows for quantification of the relative proportion of the two components.
The analysis used columns that are 300 x 7.5 mm with a particle size of 5 µm.
The SI content in the described commercial blend is approximately 42%.