| Abstract Scope |
Soft materials are used in high-volume applications such as tires as well as in emergingbiomedical devices. However, they break easily. The waste tires and their debris pollute theenvironment, and the low fracture resistance of soft materials makes their use in biomedicalapplications impractical. In this talk, I will discuss how the topology of polymer networks affectsfracture properties such as toughness and fatigue resistance. We have shown thatentanglements stiffen the polymer network but do not embrittle it. Consequently, a polymernetwork in which entanglements outnumber crosslinks achieves both high modulus andtoughness, overcoming long-standing modulus-toughness conflict. This principle is based on thenetwork structure, not chemistry, so it can be applied to various material systems andfabrication processes.] Also, we have shown that the fatigue threshold of rubbers can begreatly improved by deconcentrating the stress at the crack tip by designing the molecularstructure of filled rubbers. |