Investigating the Formation of Polymer-Nanoparticle Complex Coacervate Hydrogels Using Polymerization-Induced...

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Anionic nanogels synthesized via polymerization-induced self-assembly (PISA) form hydrogels at pH ≥ 7.5.
• These hydrogels exhibit limited properties without additional components.

Purpose of the Study:

• To develop enhanced hydrogel properties using polymer-nanoparticle-based complex coacervates (PNCCs).
• To investigate the formation mechanism and properties of PNCC hydrogels formed by anionic nanogels and cationic branched poly(ethylenimine) (bPEI).

Main Methods:

• Synthesis of poly(3-sulfopropyl methacrylate)-block-poly(2-(methacryloyloxy)ethyl succinate) (PKSPMA-PMES) nanogels using RAFT-mediated PISA.
• Characterization of PNCC hydrogel formation using dynamic light scattering (DLS) and aqueous electrophoresis.
• Optimization of PNCC hydrogel properties by varying pH and bPEI-to-nanogel mass ratio (MR).

Main Results:

• The addition of bPEI to PKSPMA-PMES nanogels formed PNCC hydrogels with significantly improved properties.
• Maximum gel strength of 1300 Pa achieved at 20% w/w bPEI/nanogel concentration, pH 9, and MR of 0.1.
• All PNCC hydrogels exhibited shear-thinning behavior and rapid recovery after shear removal, with pH-dependent efficiency.

Conclusions:

• PNCC hydrogels offer a promising route to advanced hydrogel materials with tunable mechanical properties.
• The pH and bPEI concentration are critical factors in controlling PNCC hydrogel formation and performance.
• These PNCC hydrogels demonstrate potential for applications requiring robust, self-healing, and shear-responsive materials.