Separation of complex branched polymers by size-exclusion chromatography probed with multiple detection

Area of Science:

• Polymer Chemistry
• Analytical Chemistry

Background:

• Size-exclusion chromatography (SEC) is a key technique for polymer characterization.
• Universal calibration relates polymer elution to hydrodynamic volume, enabling molecular weight determination via viscometry and light scattering.

Purpose of the Study:

• To investigate the validity and limitations of universal calibration for branched polyacrylates using tetrahydrofuran as eluent.
• To analyze the impact of branching on molecular weight separation and local polydispersity in SEC.

Main Methods:

• Size-exclusion chromatography (SEC) with tetrahydrofuran eluent.
• Viscometry and light scattering for molecular weight determination.
• Analysis of local polydispersity within elution slices.

Main Results:

• Universal calibration is applicable to branched polyacrylates in THF.
• SEC provides incomplete molecular weight separation, characterized by local polydispersity.
• Increased branching per chain leads to a decrease in local polydispersity.

Conclusions:

• While universal calibration is valid, SEC resolution is limited for branched polymers.
• Highly branched polyacrylates exhibit improved molecular weight separation due to reduced local polydispersity.