9/14/2010
7,794,834
Nematic elastomer fiber with mechanical properties of a muscle
Nacri et al of the US Navy have developed  a fiber having a polymeric backbone with a liquid crystalline side group and a crosslinking side group, both bonded to the backbone. Uniaxial contraction of the material can be achieved in the fiber through the nematic to isotropic phase transition.  The backbone of the copolymer may be, but is not limited to, polyacrylic, polysiloxane, or polynorbornene.  When the fiber is made, the liquid crystalline side groups may have orientational order. When a stimulus such as thermal, electrical, or photo is applied to the fiber, these side groups can become substantially reoriented or disordered. This can have the effect of changing the dimensions of the fiber, such as shortening the length of the fiber.  The nematic elastomers can be drawn into well-oriented fibers that can show muscle-like physical properties with an elongation Up to 35% and blocked stress of 450 kPa very similar to that of skeletal muscles.  (RDC 11/19/2010)