Additive-Free Method for Enhancing the Volume Phase Transition Rate in Light-Responsive Hydrogels: A Study of...

Area of Science:

• Materials Science
• Polymer Chemistry
• Soft Matter Physics

Background:

• Light-responsive hydrogels offer potential in shutters, valves, and drug delivery.
• Current limitations include slow volume phase transition kinetics.
• Accelerating response times is crucial for practical applications.

Purpose of the Study:

• To investigate micro-nano bubble water as a solvent to enhance hydrogel response rates.
• To study the effect of bubble water preparation on poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM-co-AAc) hydrogel kinetics.
• To establish a simple, additive-free method for tuning hydrogel response.

Main Methods:

• Preparation of PNIPAM-co-AAc hydrogels using micro-nano bubble water.
• Characterization using dynamic light scattering (DLS), dissolved oxygen (DO) measurements, Young's modulus, scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy.
• Analysis of light-induced volume transition kinetics.

Main Results:

• Hydrogels prepared with bubble water exhibited over two orders of magnitude faster volume transition rates.
• Response rate was modulated by adjusting the standing time of the bubble water.
• Cooperative diffusion coefficients correlated linearly with Young's modulus and swelling ratio.

Conclusions:

• Micro-nano bubble water significantly accelerates hydrogel volume phase transition kinetics.
• Bubbles act as efficient water channels, modulating the hydrogel response rate.
• This method provides a simple, additive-free approach to tune hydrogel responsiveness for diverse applications.