Dual Responsive Block Copolymer Micelles Functionalized by NIPAM and Azobenzene

Area of Science:

• Polymer Chemistry
• Materials Science
• Nanotechnology

Background:

• Amphiphilic diblock copolymers are crucial for self-assembly into nanostructures like micelles.
• Stimuli-responsive polymers offer controlled release capabilities for various applications.
• Azobenzene and N-isopropylacrylamide are known for their photo- and thermo-responsive properties, respectively.

Purpose of the Study:

• To synthesize a novel amphiphilic diblock copolymer with dual responsiveness to heat and light.
• To investigate the self-assembly behavior and micelle formation of the synthesized copolymer.
• To evaluate the stimuli-responsive release of encapsulated substances from the polymer micelles.

Main Methods:

• Synthesis of the diblock copolymer using Atom Transfer Radical Polymerization (ATRP).
• Characterization of the copolymer's structure and properties.
• Formation and characterization of polymer micelles.
• Investigation of temperature-dependent size changes and release profiles.
• Assessment of light-induced changes in micellar core hydrophobicity and stability.

Main Results:

• A novel amphiphilic diblock copolymer containing poly(ethylene oxide), azobenzene methacrylate, and N-isopropylacrylamide was successfully synthesized.
• The copolymer self-assembled into micelles exhibiting dual responsiveness to temperature and light.
• Micelle size was temperature-dependent, leading to reversible release of encapsulated substances during heating and cooling.
• Light exposure induced reversible changes in micellar core hydrophobicity via azobenzene H-aggregation without micelle disruption or substance leakage.

Conclusions:

• The synthesized copolymer forms stable, dual-responsive micelles suitable for controlled substance release.
• The light-induced reversible hydrophobicity change offers a non-disruptive method for modulating micelle properties.
• This material holds promise for applications in smart drug delivery and nanotechnology.