Porous Hydrogels: Present Challenges and Future Opportunities

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Hydrogels are widely used materials, but understanding porous hydrogels requires distinct modeling.
• Dense hydrogels have well-established theories for swelling, diffusion, and mechanical properties.
• Porous hydrogels, with physical pores beyond polymer network spaces, present unique challenges.

Purpose of the Study:

• To critically review the physical properties of porous hydrogels.
• To explore and categorize methods for producing porous hydrogels.
• To propose future research directions for modeling porous hydrogel physical properties.

Main Methods:

• Review of existing theories on swelling kinetics, equilibrium swelling, structure-stiffness, and solute diffusion in dense hydrogels.
• Categorization of porous hydrogel fabrication methods into kinetic and templating approaches.
• Discussion of specific techniques within each category: bubble generation (reactions, gas injection, phase separation, electrospinning, freeze-drying) and templating (solid-phase, self-assembled amphiphiles, emulsion, foam).

Main Results:

• Identified limitations in current models for dense hydrogels when applied to porous structures.
• Detailed review of various pore formation strategies, highlighting their potentials and challenges.
• Established a framework for understanding and designing porous hydrogels based on their physical properties.

Conclusions:

• Porous hydrogels offer unique advantages over dense counterparts due to their physical pore structures.
• Further development of theoretical models is crucial for predicting and controlling porous hydrogel behavior.
• Advancements in fabrication techniques will enable tailored design of porous hydrogels for specific applications.