Influences of co-solvent on hydrogen bond reorganization in ternary poly(vinyl alcohol) solutions

1H NMR, viscometric and refractometric methods were applied in this work in order to study comparisons in thermodynamics between poly(vinyl alcohol)/water/co-solvent ternary solutions with various organic co-solvents. 1H NMR studies revealed that hydrogen bonds between 1,4-butanediol and 2,4-pentanediol (poly(vinyl alcohol) model) molecules are stronger than the hydrogen bonds formed between 2,4-pentanediol and other considered solvents. From rheological and viscometric experiments, it was established that ternary solutions of poly(vinyl alcohol) with 1,4-butanediol as co-solvent show an essential increase in the values of reduced viscosity above 35 °C. The observed critical temperature phenomenon was also confirmed by measurement the refractive index of the appropriate solutions and was further described in terms of ΔHA, ΔGA, and ΔTSA calculated in accordance to the Frenkel–Eyring activation theory. Based on the collected data, the revealed effect was attributed to the H-bonds reorganization that occurs after activation at definite temperature. It was concluded that aqueous solutions of poly(vinyl alcohol) with 10 wt.% of 1,4-butanediol are thermodynamically more favorable compared with binary poly(vinyl alcohol)/water systems.