Effect of Stereoregularity and Molecular Weight on the Mechanical Properties of Poly(vinyl alcohol) Hydrogel

The effect of the stereoregularity and molecular weight of poly(vinyl alcohol) (PVA) on the mechanical properties of hydrogel was investigated. Compressive strength, creep behavior, and dynamic viscoelasticity were measured on hydrogels of syndiotacticity-rich PVA derived from poly(vinyl pivalate) (D-p = 1690 diad-syndiotacticity = 61%, D-p = 8020 diad-syndiotacticity 62%) and atactic PVA (D-p = 1750 diad-syndiotacticity 54%, D-p = 7780 diad-syndiotacticity = 54%). Increasing the molecular weight of molecular chains constituting the gel improved the compressive strength of atactic PVA hydrogel. The stereoregularity of PVA had a greater effect than molecular weight on the strength of the hydrogel. Gel prepared from 8.8 g/dL syndiotacticity-rich PVA had a high compressive modulus of 10 kPa, and the compressive modulus of the gel prepared from 3.3 g/dL was comparable with that of atactic PVA hydrogel prepared with more than 6 g/dL. The dynamic storage modulus of the gel derived from syndiotacticity-rich PVA was remarkably higher than that of the atactic PVA gel and remained constant up to 60 degrees C. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 573-578, 2011