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Science Technology

Plastic That Changes Shape In Light 123

JLavezzo writes "Picture a flower that opens when facing the sunlight. In work that mimics that sensitivity to light, MIT Engineer Robert Langer and his German colleagues have created the first plastics that can be deformed and temporarily fixed into shape by light. This material could one day lead to medical devices that build themselves inside a patient's body, or door latches that can be opened with a flashlight. Additional commentary available at The Science Blog"
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Plastic That Changes Shape In Light

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  • by Greg Wright ( 104533 ) * on Friday April 15, 2005 @06:48PM (#12250472) Journal
    They, the scientists, have been able to do this for some time with
    heat. The link below is to an article that shows a 30 gram weight
    being lifted and lowered by a type of polymer know as nematic
    elastomers. 55 D-FA8F-1C5F-B882809EC588ED9F

    they also say in the above article(link) that, "..light can also induce
    shape changes anywhere from 10 to 400 percent [in the polymer]."
    However, it takes a hours for it to return to the original shape.

    One of the best applications,in my opinion, for any fast-acting shape
    changing polymer would be as artificial muscles. Not sure how
    practical or easy that might be. You would have to get the temperature
    range, where the shape changing takes place, down pretty low and find
    a way to control it outside of the body's heat influence. I am sure
    there are other problems as well.

  • clarfication (Score:5, Informative)

    by morcheeba ( 260908 ) on Friday April 15, 2005 @06:54PM (#12250543) Journal
    Just to clarify... this plastic changes shape in response to various wavelengths of light... not the quantity, as has been previously done []. (Note - the older technology has been adapted for cell phones, too [])
  • by mesach ( 191869 ) on Friday April 15, 2005 @07:00PM (#12250610)
    One of the first widespread uses maybe but not first purpose. It was used in medical means over 20 years after its invention.

    Pasted from the straight dope []

    "Super glue, Krazy glue, Eastman 910 and similar glues are all a special type of glue called cyanoacrylates. Cyanoacrylates were invented in 1942 by Dr. Harry Coover of Kodak Laboratories during experiments to make a special extra-clear plastic suitable for gun sights. He found they weren't suitable for that purpose, so he set the formula aside. Six years later he pulled it out of the drawer thinking it might be useful as a new plastic for airplane canopies. Wrong again--but he did find that cyanoacrylates would glue together many materials with incredible strength and quick action, including two very expensive prisms when he tried to test the ocular qualities of the substance. Seeing possibilities for a new adhesive, Kodak developed "Eastman #910" (later "Eastman 910") a few years later as the first true "super glue." In a now-famous demonstration conducted in 1959, Dr. Coover displayed the strength of this new product on the early television show "I've Got a Secret," where he used a single drop placed between two steel cylinders to lift the host of the show, Garry Moore, completely off of the ground.

    The use of cyanoacrylate glues in medicine was considered fairly early on. Eastman Kodak and Ethicon began studying whether the glues could be used to hold human tissue together for surgery. In 1964 Eastman submitted an application to use cyanoacrylate glues to seal wounds to the United States Food and Drug Administration (FDA). Soon afterward Dr. Coover's glue did find use in Vietnam--reportedly in 1966 cyanoacrylates were tested on-site by a specially trained surgical team, with impressive results."
  • Other related work (Score:5, Informative)

    by karvind ( 833059 ) <karvind&gmail,com> on Friday April 15, 2005 @07:36PM (#12250915) Journal
    Another field where MIT work can be useful is space antennae. Here an optical signal would initiate a sequence of changes in the shape, causing the antenna to refocus on a different point in space.

    OSU had developed light-tunable plastic magnets []. Here the plastic material becomes 1.5 times more magnetic when blue light shines on it. Green light partially reverses that effect.

    Another interesting work is from PSU on PLZT [], this new material shows a large piezoelectric effect in response to near-ultraviolet light. Piezoelectric materials convert electricity into mechanical energy -- movement. When an electric current is run through piezoelectric ceramic, the ceramic changes size -- it shrinks or expands. Certain ferroelectric materials exhibit stronger photovoltaic (light into electricity) effects. Combining these ferroelectrics with piezoelectrics (electricity into motion), researchers created a single material that would convert light directly into motion.

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