Tough macroporous phenolic resin/bacterial cellulose composite with double-network structure fabricated by ambient pressure drying

In this work, a large size of macroporous phenolic resin (PR)/bacterial cellulose (BC) composite with double-network structure was fabricated simply by soaking, heating, solvent exchange, and ambient pressure drying. The mechanism and influence factors for the fabrication of this macroporous composite were systematically elaborated. One network of macroporous composite was composed of PR beads, and the other derived from original BC nanofibers. They supported and reinforced each other, avoiding the collapse of interconnected porous structure and achieving low density (0.29 g/cm³), high porosity (77.7%), low thermal conductivity (0.10 W/m K), and excellent compressive strength (7.97 ± 2.24 MPa). Through further carbonization, carbon counterpart that maintained fine structure and good performance can also be obtained. The surface of macroporous composite was extremely hydrophilic. On the contrary, its carbon counterpart possessed a highly hydrophobic surface (contact angle = 118.2°). These properties suggest that the macroporous composite and carbon counterpart may have potential applications for filtration, separation, and thermal insulation materials. Moreover, this work will provide a novel perspective for the fabrication of porous composites with BC as the template and 3D nanofiber reinforcement simultaneously.