Double-stimuli-responsive spherical polymer brushes with a poly(ionic liquid) core and a thermoresponsive shell

Area of Science:

• Polymer Chemistry
• Materials Science
• Nanotechnology

Background:

• Poly(ionic liquid) (PIL) nanoparticles offer unique properties for various applications.
• Grafting stimuli-responsive polymer shells onto nanoparticles can enhance their functionality.
• Poly(N-isopropyl acrylamide) (PNIPAM) is a well-known thermoresponsive polymer.

Purpose of the Study:

• To synthesize and characterize poly(ionic liquid) nanoparticles grafted with PNIPAM brushes.
• To investigate the stimuli-responsive behavior of these hybrid nanoparticles in aqueous solutions.
• To evaluate the impact of PNIPAM grafting on the colloidal stability of PIL nanoparticles.

Main Methods:

• Aqueous dispersion polymerization of vinyl imidazolium-based ionic liquid monomers.
• Grafting of PNIPAM brushes from nanoparticle surfaces via atom transfer radical polymerization (ATRP).
• Characterization of nanoparticle size, stability, and stimuli-responsiveness (temperature, ionic strength).

Main Results:

• PIL nanoparticles with tunable sizes (25-120 nm) were successfully synthesized.
• PNIPAM brushes were effectively grafted onto the PIL nanoparticle surfaces.
• The resulting NP-g-PNIPAM particles showed enhanced colloidal stability at high ionic strength.
• A decrease in hydrodynamic radius was observed above the LCST of PNIPAM due to brush collapse.

Conclusions:

• The synthesis of stimuli-responsive NP-g-PNIPAM hybrid nanoparticles is feasible.
• These hybrid nanoparticles exhibit tunable size and improved colloidal stability.
• The grafted PNIPAM brushes provide controlled responsiveness to temperature and ionic strength, leading to potential applications in drug delivery and sensing.