In situ FTIR spectroscopy study on the rapid dissolution process of modified poly(vinyl alcohol)

Abstract

In this article, modified poly(vinyl alcohol) (m-PVA) has been synthesized via copolymerization of vinyl acetate in methanol by adding comonomers acrylic acid and butyl acrylate followed by saponification. This modified poly(vinyl alcohol) can be completely dissolved into water before 60 °C without agitation. The rapid dissolution process of m-PVA was investigated by temperature-dependent Fourier transform infrared (FTIR) spectroscopy from 20 °C to 85 °C. The results showed that the wavenumber ranges of m-PVA in the O-H stretching and bending bands beyond the measuring range of the spectrometer were much larger than those of common PVA. This demonstrated that m-PVA chains could interact with water molecules more strongly and form hydrogen bonds with the hydroxyl groups of water more easily. The introduction of carboxyl groups destroyed the chemical regularity of polymer chains, which led to the decreasing crystallinity degree and imperfect crystal structures. Both the lower crystallinity degree and imperfect crystal structures were crucial factors to the rapid dissolution of m-PVA. Moreover, traditional Fourier transform infrared (FTIR) spectra, ¹H nuclear magnetic resonance (¹H NMR), and differential scanning calorimetry (DSC) were also applied to study the m-PVA in this paper.

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