Plastic
- a brilliant material!
For more than hundred years, we have known that metals
conduct current and that plastics are good insulators,
but almost 25 years ago it was descovered, more or less
by accident, that even plastics can, under certain circumstances,
conduct current. That was a discovery that led to the
Nobel Prize in chemistry year 2000, and that opened our
eyes for tis new and exciting scientific field in the
borderland between chemistry and physics. It gave us
inspiration to carry trough a project in this field that
le tus combine theoretic knowledge with experimental
research.
In our school laboratory we have synthesised an elecrically
conductive plastic, polypyrrol by polymerisation of pyrrol
on a film of P-4-VP-Cu2+-complex. We measured the conductivity
of different samples to a value between 300 and 3000
Siemens/metres. This is about one hundred thousand times
less then copper but comparable to doped silicon, as
used in microelectronic devices.
Measurements at different voltages in the range 0-30
V indicate that the current is always proportional to
the voltage as expected for ohmic behaviour.
Conductive plastic will most likely replace metals in
several business areas, because of the lower material
costs and weight, better processability and flexibility.
Scientsts have already found several applications, for
example in digital electronics and nicrosurgery. But
using electroluminicent polymers, which emit light in
response to an applied voltage, it is possible to produce
light emitting diodes and screens of plastics.
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