Jowan Rostami1,Korneliya Gordeyeva1,Tobias Benselfelt1,2,Ekeram Lahchaichi1,Stephen Hall3,Anastasia Riazanova1,Per Larsson1,Goksu Cinar Ciftci1,Lars Wagberg1
KTH Royal Institute of Technology1,Nanyang Technological University2,Lund University3
Jowan Rostami1,Korneliya Gordeyeva1,Tobias Benselfelt1,2,Ekeram Lahchaichi1,Stephen Hall3,Anastasia Riazanova1,Per Larsson1,Goksu Cinar Ciftci1,Lars Wagberg1
KTH Royal Institute of Technology1,Nanyang Technological University2,Lund University3
Highly anisotropic cellulose nanofibrils (CNFs) have gained much attention in recent years due to many desirable properties, such as biocompatibility, high surface area, high Young’s modulus, and versatile surface chemistries. These biodegradable nanorods are a great substitute for petroleum-derived polymers in the development of more sustainable and renewable 3D lightweight materials. Owing to their high aspect ratios, CNFs can create gel networks at very low solid contents, making the fabrication of low-density materials, e.g. aerogels, possible. In the present contribution, a green and facile process is developed to obtain air-dried and wet-stable aerogels, with a biofunctionality created by the incorporation of protein containing metal-organic frameworks (MOFs). Via the combination of anionic CNFs with calcium carbonate particles (CaCO<sub>3</sub>) and alginate, an interpenetrated and homogenous gel network is obtained. By then freezing the hydrogels, the components can be compressed to create pore walls and a highly porous structure, that later can be subjected to acid containing acetone. During this solvent exchange procedure, two steps occur simultaneously: the exchange of water to acetone as well as the acid dissolution of the CaCO<sub>3</sub> particles. The dissolution of the particles results in the release of CO<sub>2</sub> gas and calcium ions that crosslink the network. The acetone soaked meso- and microporous aerogels are then air-dried, creating an aerogel with wet-stability and shape-recovery properties, in combination with a high compressive modulus and a favorable surface area. To showcase the potential of these material properties in more advanced applications, the aerogels are further functionalized with protein saturated MOFs in aqueous media. The application of these hybrid aerogels are then demonstrated in a controlled release study, where the disassembly of the protein saturated MOFs is made possible through pH stimuli, releasing the active proteins.