Harnessing nanoconfinement-enhanced hydrogen bonding and multi-scale structures for high-performance sustainable foam materials

Developing sustainable, high-performance materials is crucial to meet the growing demand for eco-friendly, multifunctional solutions across industries. Traditional plastic-based foams can take centuries to degrade, contributing significantly to environmental pollution. This study introduces an innovative organic-inorganic composite ink suitable for direct ink writing to fabricate high-strength, sustainable foam materials. The ink formulation is composed of gelatin, hydroxypropyl methylcellulose, and Co 3 O 4 -loaded silica nanofibers (named as CSNFs). The foam prepared from this ink is named as GC, where GC-10 represents GC containing 10 wt% CSNFs. The nanoscale dimensions and high surface area of CSNFs facilitate physical entanglement within the foam matrix. Additionally, H-bond nanoconfinement, combined with the organic-inorganic multi-scale network, significantly enhances the structural stability of GC foams. The formulated ink demonstrates excellent printability, forming a porous structure after freeze-drying. GC-10 exhibits enhanced thermal insulation (0.048 W/m•K), high mechanical performance (compression modulus of 3111.1 ± 300 kPa), and reduced smoke toxicity, with a peak CO release 72.4 % lower than GC. Notably, GC foams can be recycled without any loss in performance. Additionally, CSNFs are recoverable through centrifugation, minimizing environmental impact. This closed-loop recycling strategy, incorporating water solvent recovery, addresses a critical need in sustainable materials engineering. It emphasizes the potential of organic-inorganic integration in developing high-performance, multifunctional materials.