Physical properties and ion permeability of crosslinking hydrogel membrane based on poly(vinyl alcohol) for soilless cultivation

Abstract Crosslinking hydrogel membranes were prepared by esterification reaction with different ratios of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). The purpose of the study was to research the effect of the crosslinking agent PAA on the hydrogel properties of the membranes used for soilless cultivation. Increasing of PAA ratio resulted in a significant increase in the crosslinking density ( ρ x ) and a decrease in the average molecular weight of the polymer chain between the crosslinks () and the mesh size (ξ) of the hydrogel membranes. In addition, the ion permeability coefficient decreased when the PAA ratio increased. Increasing the PAA ratio significantly affected water uptake value, tensile strength, and elongation of the hydrogel membranes. A PVA:PAA ratio of 9:1 was suitable for plant cultivation. The cultivated plants germinated well and generated many small fine roots on the upper surface of the hydrogel membrane. These small fine roots adhered well to the hydrogel membrane to absorb the water and feed nutrient ions. This finding showed that the hydrogel membranes have the potential of being used for soilless cultivation in controlled experimental conditions.