Bio-inspired functional materials

The thesis shows strategies how to learn from Mother Nature to make functional materials. Firstly, inspired by lotus leaf and water strider, superhydrophobic and superoleophobic surfaces are prepared from nanofibrillated cellulose aerogels. Furthermore, we explore potential applications of the superhydrophobic and superoleophobic materials for carrying cargo on liquid surfaces and continuous propulsion. Interestingly, the self-propelled locomotion has constant velocity and can last for prolonged time. This allows transduction of chemical energy into motility and could open doors for new generation of autonomous miniaturized soft devices. Subsequently, superhydrophobic and superoleophobic surfaces are made from silica aerogel, and the emphasis is on the damage resistance of superhydrophobicity and superoleophobicity. After mechanical abrasion with sandpaper, the superhydrophobicity and superoleophobicity retain. More interestingly, the contact angle hysteresis for water and oil decreases after abrasion with sandpaper. The last part of the thesis is about bio-inspired tough materials from nanofibrillated cellulose and nanoclay. By a simple method of centrifugation, bulk nanocomposites are achieved that have a high work to fracture of 23.1 MJ/m3 with high strain to failure of 36% under compression. Considering the simple preparation methods and bio-based origins of nanocellulose and clay, the tough material shows potential in applications for sustainable and environmentally friendly materials in construction and transportation