Development of an NMR-based quantification method for the main components in VAE-type adhesives/emulsions

Area of Science:

• Polymer Chemistry
• Analytical Chemistry

Background:

• Accurate quantification of main components in Vinyl Acetate Ethylene (VAE)-type adhesives and emulsions is essential for quality control.
• Existing methods may lack precision or efficiency for analyzing VAE's core constituents: oxyacetyl, vinyl, and vinyl alcohol groups.

Purpose of the Study:

• To establish a reliable and efficient method for quantifying the primary components of VAE-type adhesives/emulsions.
• To compare the efficacy of 1H NMR normalization-based and internal standard-based quantification methods.

Main Methods:

• Investigated solubility of dried VAE samples, identifying Dimethyl sulfoxide (DMSO) as an optimal solvent.
• Assigned proton chemical shifts in 1H NMR spectra for oxyacetyl, vinyl, and vinyl alcohol groups.
• Developed and validated a 1H NMR internal standard-based quantification method using benzyl benzoate.

Main Results:

• The 1H NMR internal standard method demonstrated high accuracy, closely matching classical methods for oxyacetyl group quantification.
• The established method exhibited excellent repeatability (RSD < 5%) and reproducibility (RSD < 5% for vinyl and oxyacetyl, < 11.24% for vinyl alcohol).
• 13C NMR internal standard method was found unsuitable due to high concentration and time requirements.

Conclusions:

• A 1H NMR internal standard-based quantification method is established as a suitable technique for determining the main components in VAE-type adhesives/emulsions.
• This method provides accurate, repeatable, and reproducible results, enhancing VAE analysis.
• The study highlights the advantages of 1H NMR internal standardization over normalization and 13C NMR for VAE component analysis.