Temperature-Responsive Analysis and HPLC Separation of Vinyl Acetate-Vinyl Alcohol Copolymer

Vinyl acetate-vinyl alcohol copolymer (VAc-VOH) exhibits amphiphilicity, leading to phase transitions and unique solubility based on the solvent mixture ratio. In this report, we examined the effects of solvent composition and temperature on the micellar and aggregate states of the copolymer in solution using reversed-phase chromatography with the non-porous ODS Presto FF-C18 column and NMR.

The results showed that, despite having almost the same average monomer composition, the copolymer with blocky VOH groups exhibited a phenomenon where some parts eluted without retention. This is likely due to the formation of hydrophilic micelles with VOH groups facing outward, preventing hydrophobic interactions with the ODS stationary phase.

Fractionation of the elution peaks followed by NMR and other experiments suggested that the retained components had a higher VAc composition, while the non-retained components had a higher VOH composition, indicating micelle formation by the VAc-VOH copolymer.

The Presto FF-C18 column with non-porous packing material has the characteristic of recognizing the hydrophobicity of the polymer's outer surface at the particle surface, which serves as the separation field. Thus, even with similar degrees of polymerization, significant differences in retention can be observed due to micellar structures, as seen in this study.

The non-porous ODS Presto FF-C18 column is actively used in polymer analysis research.

• 22nd Polymer Analysis Conference Poster
  

  (Provided by Dr. Koichi Migite and Dr. Shuhei Ogawa, Faculty of Science and Engineering)