A Robust Cross-Linking Strategy for Block Copolymer Worms Prepared via Polymerization-Induced Self-Assembly

Area of Science:

• Polymer Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Polymerization-induced self-assembly (PISA) is a powerful technique for creating complex polymer architectures.
• Thermoresponsive hydrogels are of interest for various applications but often lack stability.

Purpose of the Study:

• To synthesize and characterize novel worm gels with tunable properties using PISA.
• To investigate the effect of glycidyl methacrylate (GlyMA) content on worm gel thermoresponsiveness and stability.
• To explore the potential for post-polymerization modification and cross-linking of the worm gels.

Main Methods:

• Reversible addition-fragmentation chain transfer (RAFT) polymerization of 2-hydroxypropyl methacrylate (HPMA) and GlyMA.
• Polymerization-induced self-assembly (PISA) in concentrated aqueous solution.
• ¹H NMR kinetics, temperature-dependent oscillatory rheology, dynamic light scattering, and transmission electron microscopy (TEM).
• Post-polymerization cross-linking using 3-aminopropyltriethoxysilane (APTES).

Main Results:

• A series of free-standing worm gels were prepared with varying GlyMA content (0-20 mol %).
• Higher GlyMA content reduced thermoresponsiveness, with no degelation observed at 20 mol % GlyMA.
• Cross-linking via epoxy-amine reaction with APTES created stiffer worm gels that remained stable upon cooling.
• Cross-linked worms with ≥10 mol % GlyMA resisted dissociation in methanol or anionic surfactant, unlike linear worms.

Conclusions:

• GlyMA incorporation in HPMA-GlyMA copolymers effectively tunes the thermoresponsive behavior and stability of PISA-derived worm gels.
• Post-polymerization cross-linking offers a route to robust, non-degelating worm gels with enhanced structural integrity.
• The developed worm gels demonstrate potential for applications requiring stable hydrogel structures.