Supramolecular route to well-ordered metal nanofoams.

Metal nanofoams with a porosity above 50% v/v have recently attracted great interest in materials science due to their interesting properties. We demonstrate a new straightforward route to prepare such nanofoams using diblock copolymer-based PS-block-P4VP(PDP) supramolecules that self-assemble into a bicontinuous gyroid morphology, consisting of PS network channels in a P4VP(PDP) matrix. After dissolving the PDP, the P4VP collapses onto the PS struts and a free-standing bicontinuous gyroid template of 50-100 µm thickness and interconnected, uniformly sized pores is formed. The hydrophilic P4VP corona facilitates the penetration of water-based plating reagents into the porous template and enables a successful metal deposition. After plating, the polymer is simply degraded by heating, resulting in a well-ordered inverse gyroid nickel foam. Essential to this approach is the removal of only one part of the matrix (i.e., PDP). Therefore, the template accounts for 50% v/v or more. The porosity characteristics (amount, size of pores) can be tuned by selecting the appropriate copolymer and by adjusting the amount of PDP.