Improvement of reversible compressibility of ultralight carbon nanotube/carboxymethyl cellulose materials through hydrophobic surface treatment

The mechanical properties of ultralight materials are influenced by their constituent materials, internal porous structures, and surface states. The surface chemical state is particularly crucial for materials composed of hydrophilic polymers such as cellulose, where interactions with ambient water are significant. In this study, we report that the reversible compressibility of ultralight carbon nanotube (CNT)/carboxymethyl cellulose (CMC) materials can be enhanced by hydrophobic surface treatment with silane coupling agents. We examined the treatment conditions for hydrophobization and investigated their impact on the microstructure and surface chemical properties of the ultralight material. The hydrophobized ultralight CNT/CMC materials with a bulk density of 1.6 mg/cm³ demonstrated superior reversible compressibility, with a 65% recovery rate even under high humidity conditions (80% RH).