Equilibrium swelling of thermo-responsive copolymer microgels

Area of Science:

• Polymer Science
• Materials Science
• Biomedical Engineering

Background:

• Thermo-responsive (TR) hydrogels exhibit a volume phase transition temperature (Tc) crucial for biomedical applications.
• Tuning Tc is essential but requires precise knowledge of comonomer concentrations, which is often unknown for macroscopic and microgels.
• Existing methods for modulating Tc involve copolymerization with hydrophilic or hydrophobic comonomers.

Purpose of the Study:

• To develop a simple model for predicting the equilibrium swelling of TR copolymer gels.
• To determine the molar fractions of comonomers needed for fine-tuning the critical temperature (Tc) of TR hydrogels.
• To provide an explicit expression for Tc as a function of comonomer molar fraction.

Main Methods:

• Developed a simple model for equilibrium swelling of TR copolymer gels.
• Fitted model parameters using swelling diagrams of macro- and microgels with N-isopropylacrylamide.
• Performed numerical analysis to compare with experimental swelling curves.

Main Results:

• Achieved good agreement between experimental swelling curves and the model's numerical analysis.
• Derived an explicit expression relating the volume phase transition temperature (Tc) to comonomer molar fraction.
• Validated the model's predictive capability for Tc by comparing with experimental observations.

Conclusions:

• The developed model accurately predicts the swelling behavior of TR copolymer gels.
• The derived expression enables precise prediction and tuning of the critical temperature (Tc) for TR hydrogels.
• This work provides a valuable tool for designing TR hydrogels with specific properties for biomedical applications.