Modulation of swelling of PVA hydrogel by polymer and crosslinking agent concentration

PVA chemical hydrogel can absorb a large amount of water to produce swelling, and the degree of swelling impact on its physical properties and applications significantly. Polymer and crosslinking agent concentration in the gelation stage can modulate degree of swelling and the structure of the hydrogel network. In order to further understand the modulation mechanism, it is necessary to develop method to establish model of hydrogel network and use it to calculate the degree of swelling. In this paper, a method for simulating PVA chemical hydrogel cross-linking reaction process and constructing a hydrogel network structure based on stochastic process is proposed. Using this method, the influences of amount of PVA and the amount of crosslinking agent on the network structure are obtained. The free energy and swelling degree of the hydrogel are calculated using the constructed hydrogel network. The quantitative relationship between the amount of PVA, crosslinking agent and the actual swelling degree of the hydrogel is obtained. The calculation results show that the increase of the PVA concentration and the decrease of the amount of the cross-linking agent can promote the swelling of the hydrogel. The calculated results of swelling degree are in good agreement with the experimental results. The method proposed in this paper can be used as an effective tool to study the network structure and mechanical properties of hydrogels.