Speaker
Description
Hydrogels are highly versatile and environmentally responsive materials, designed through specific chemical composition and synthesis methods. The solvent absorption capability in hydrogels can be either enhanced or inhibited by various environmental stimuli, such as temperature, pH, light, or specific ions and molecules. This responsiveness makes hydrogels ideal materials for developing smart devices capable of adapting to changing conditions.
In our previous work, we explored the relationship between processing and properties by predicting the swelling behavior of temperature-responsive hydrogels based on their synthesis procedures. In the current study, we focus on investigating the relationship of structural parameters of hydrogels with their swelling behavior, as conceptualized based on the Flory-Rehner theory. These conceptualized parameters are challenging to determine experimentally but are highly valuable for explaining the swelling behavior of hydrogels with different compositions and synthesis procedures. This approach aims to unravel the relationship between inner structure and properties.
Building on Flory-Rehner theory, the basic understanding of swelling behavior, including volume phase transition, etc., are discussed from the viewpoints of structure, dynamics, kinetics and equilibrium thermodynamics. The structural parameters to describe the polymer structures involve the degree of polymerization between crosslinks, number of ionic groups on the chain between crosslinks, and polymer volume fraction in the reference state. Regarding the aspect of thermodynamics, the Flory-Huggins interaction parameter quantifies the energy of interdispersed polymer and solvent molecules. In temperature-sensitive hydrogels, the interaction parameter varies with temperature.
Based on the models of experimentally observed phenomena, various mathematical expressions of the interaction parameter as the function of temperature are provided in the literature. Inserting the mathematical expression of the interaction parameter into Flory-Rehner theory, we are able to model the swelling behavior of temperature-responsive hydrogels. Inversely, we can investigate the structural parameters of hydrogels based on the swelling behavior data collected from experiments utilizing a data-driven approach. Specially, through Bayesian Optimization, we optimize the structural parameters of the model built on Flory-Rehner theory by training it with the experimental swelling behavior data. This makes the present research a crucial step toward establishing the complete PSPP (Processing-Structure-Property-Performance) linkage for hydrogels.
