杏吧原创

PULSATING liquid crystal molecules dangling from the molecular backbone of a
rubbery polymer could be used to make a nano-pump, say scientists in
Germany.

Liquid crystals are used in displays because their molecules can twist in an
electric field to block light. But getting liquid crystals to do useful
mechanical work is difficult, because the molecules float free. 鈥淚f you push on
them, they鈥檒l just flow away,鈥� says Walter Lehmann of the University of
Leipzig.

Not any more. Lehmann鈥檚 team has linked liquid crystal molecules to chains of
rubbery polymers called polysiloxanes. 鈥淵ou can think of them as hanging down
like the teeth of a comb,鈥� says Lehmann. Attaching bridging molecules to
parallel polysiloxane chains gives the material strength.

Lehmann made a thin film of the material. As it solidified, it formed a stack
of molecular layers, each with vertically aligned liquid crystal molecules. When
he applied an electric field to the film, the molecules started to rotate,
pulling the layers closer together. 鈥淭his makes the film get thinner,鈥� says
Lehmann. 鈥淵ou could make waves on the surface if you want, or roll them up to
make a tube for a pump.鈥� Experts say the material would be more useful if it
could be made in blocks rather than films. Ian Sample