Poly(vinyl acetate) was hydrolyzed in acetic acid/water medium with hydrochloric acid as the catalyst to produce random poly(vinyl acetate-co-vinyl alcohol) copolymers. Mole fractions of vinyl alcohol (VA) and vinyl acetate (VAc) at various water/(acetic acid) ratio were determined via titration and NMR, and the equilibrium constant K_eq of the reaction was studied. K_eq was constant, 0.75 (±0.06), when the reaction solvent was dominated by acetic acid, but it showed a deviation when the water mole fraction in the reaction medium was larger than 0.70. We attribute the deviation to the hydrophobic interaction.

Poly(vinyl acetate)를 물과 초산용액에서 염산촉매 하에 가수분해 시켜 random poly(vinyl acetate-co-vinyl alcohol)를 합성하였다. 물과 초산의 비율에 따른 vinyl acetate (VAc)와 vinyl alcohol (VA)의 몰분율을 적정법과 NMR에 의해서 결정하고 25℃에서의 반응평형상수 K_eqeq는 용매중의 물의 비율이 낮을 때는 일정한 값(075±0.06)을 가졌으나, 용매중의 물의 몰분율이 높을 때는 증가하였다. 반응용매에서 차지하는 물의 몰분율이 클 때 hydrophobic interaction에 의하여 반응평형상수가 변화하였다고 사료된다.

Keywords: poly(vinyl acetate-co-vinyl alcohol); hydrolysis of poly(vinyl acetate); equilibrium constant; hydrophobic interaction