Fabrication of hybrid inorganic-organic foams by atomic layer deposition and sequential infiltration synthesis*

Open-cell polymer foams are widely used in various applications, such as supporting material, heat insulator, chemical or oil absorbent, acoustic or energy damper etc. However, the mechanical strength, abrasion resistance, prone to flaming and degradation remain a challenge in these foams due to the softness associated with the polymers. Herein, we modify the conventional polymeric foams to hybrid polymer-ceramic foams using atomic layer deposition (ALD) and sequential infiltration synthesis (SIS) for metal oxide growth (e.g., ZnO, Al₂O₃ and TiO₂) onto and within the polymer strands of the foam, respectively. ALD offers sub-nm precision in coating thickness while SIS offers unique process for growth of nanoclusters within the polymer. This highly versatile system enables application-based design of nano- to macro-scale structures and hybrid composition in foams. Detailed analysis of ceramic growth on and within the foams and correlation between the physical, chemical, mechanical and flame-retardance properties varied by structural and composition parameters enables the optimization of the hybrid composite, achieving the desired performance.