Quantitative rationalization of the unexpectedly moderate water wettability of poly(vinyl alcohol) surfaces: thermodynamic evaluation and prediction of surface hydrogen bonding.

Guo, Zhuohuan; Ma, Zhuoyuan; Wang, Dayang · Soft Matter · 2025

basic_science · Level V

Where this comes from

Abstract

In this work, a series of poly(vinyl alcohol) (PVA) films with defined but varied water wettability was prepared by curing as-prepared PVA films at systematically adjusted temperatures. The polar components of surface energy (<i>γ</i><sup>s,p</sup>) of the resulting PVA films were calculated and correlated with the molecular configurations of their surface OH groups-free OH (OH<sub>f</sub>), <i>trans</i>-hydrogen bonded OH (OH<sub><i>t</i></sub>), and <i>gauche</i>-hydrogen bonded OH groups (OH<sub><i>g</i></sub>)-with the aid of attenuated total reflectance Fourier transform infrared spectroscopy. By decomposing the <i>γ</i><sup>s,p</sup> values of the PVA films as a sum of the contributions from OH<sub>f</sub>, OH<sub><i>t</i></sub>, and OH<sub><i>g</i></sub> groups, the intrinsic <i>γ</i><sup>s,p</sup> components of and were calculated to be 8.0 mN m<sup>-1</sup> and 9.8 mN m<sup>-1</sup>, respectively, which were substantially smaller than that of . This provided a thermodynamic foundation not only to rationalize the unexpectedly moderated surface hydrophilicity of PVA films but also to quantitatively predict the <i>f</i><sub>HB</sub> component of hydrogen-bonded OH groups on their surfaces according to their water wettability.