Dual-responsive capsules with tunable low critical solution temperatures and their loading and release behavior

Area of Science:

• Polymer Chemistry
• Materials Science
• Nanotechnology

Background:

• Stimuli-responsive materials are crucial for advanced applications like drug delivery.
• Developing capsules with tunable properties based on environmental factors is an active research area.
• Polydopamine coatings offer versatile platforms for surface-initiated polymerization.

Purpose of the Study:

• To synthesize dual-responsive polymer capsules sensitive to both pH and temperature.
• To investigate the influence of pH and temperature on the encapsulation and release of dyes.
• To explore the potential of these capsules for controlled release applications.

Main Methods:

• Surface-initiated atom-transfer radical polymerization (SI-ATRP) was used to graft copolymer brushes.
• Polydopamine (Pdop)-coated SiO2 nanoparticles served as a template for capsule formation.
• The SiO2 core was subsequently removed to yield hollow capsules.
• Uptake and release studies were conducted using cationic (rhodamine 6G) and anionic (methyl orange) dyes.

Main Results:

• Successfully prepared dual-responsive capsules from poly[2-(2-methoxyethoxy)ethyl methacrylate] and poly[oligo(ethylene glycol) methacrylate].
• Capsule permeability and dye interaction were significantly influenced by solution pH and temperature relative to the Lower Critical Solution Temperature (LCST).
• Selective uptake and release of rhodamine 6G and methyl orange were observed, demonstrating pH and temperature-dependent behavior.

Conclusions:

• The synthesized capsules exhibit dual responsiveness to pH and temperature, enabling controlled dye encapsulation and release.
• These findings highlight the potential of these smart capsules for applications in sensing and targeted delivery systems.
• The methodology provides a versatile route for creating functional nanocarriers with tunable environmental sensitivity.