What if we could print and reuse the
same piece of paper without the recycling process or any ink? This
could be a reality in the near future. Scientists have developed a
process to print words on a "paper" using light. The
surface that they have experimented on is a type of plastic, however,
further work will be done to use the same principles to print on our
traditional paper. The process involves a reaction between dyes that
are added to the paper and UV light.
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| One-use newspaper could be a thing of the past! |
The rewritable plastic film, or
"paper", is made by adding a dye, a catalyst and a
thickening agent. The film is exposed to UV light and words that are
printed on a stencil are transferred onto the film. The main idea
behind this reaction is that electrons are moved around when exposed
to UV light and oxygen. This is an example of a redox, or
oxidation-reduction reaction. The paper is colored by the dye, and
when it is exposed to the UV light the dye gains electrons (this is
the reduction reaction) and the color disappears. When exposed to
oxygen in the air, the dye loses electrons (the oxidation reaction)
and the color reappears. Cellulose is added to the paper to slow the
reaction. Otherwise, the words would fade away much more quickly than
we could read them! So far, the researchers are able to print on the
paper up to 20 times without losing contrast and resolution. The
printing remains on the paper for several days. It is possible to
speed up the "erasure" of the words on the paper by
exposing it to a heat source. This type of printing would be best for
periodicals, such as a newspaper where it is read and then discarded
as the writing is only temporary. The long term goal of the project
is to develop the process on traditional paper that would be able to
rewritten up to 100 times.
See the process here:
Although this technology is not
practical for household use yet, it seems that it could be a viable
option in the future to reduce waste and cost of printing on paper.
According to the EPA, we use
an average of 69 million tons of paper and paperboard in the U.S.
each year and more than 2 billion books, 350 million magazines and 24
billion newspapers are published each year. If we could revolutionize
how we print on paper, some of these numbers would definitely
decline. It also sparks the imagination for fun, but perhaps less
practical uses- spy messages, pirate treasure maps, scavenger
hunts...
What do you think? Comment below!
Read more:
- Science News for Students: "Rewritable paper: Prints with light, not ink"
- Nature Communications: "Photocatalytic colour switching of redox dyes for ink-free light-printable rewritable paper" (Abstract)
- Science Nutshell: "UV Light Used to Create a Rewritable Paper"
Oxidation-Reduction Reaction Activities and Paper Recycling Resources:
- "Kool Colors" A Redox Reaction Activity Using Kool-Aid and Steel wool
- Exploratorium: "Copper Caper"An oxidation reaction experiment with pennies
- Wonder Whiz Kids: Explanations of Redox Reactions
- All About Paper Recycling
- Zoom Kids: Recycled Paper Project
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