Oil and water.
The reluctance of
these two liquids
to mix together and stay that
way is so well known they
have become cliche
for any two things
that do not go together well.
Currently, there are
ways to mix the two,
but ultimately, they
will separate again.
So what if there was a way to
not only mix oil and water,
but to have the
mixture remain stable
for long periods of time,
perhaps indefinitely?
Well, a team of
researchers at MIT
may have found a
way to do just that.
Here we have oil and
water represented
by the colors red and blue.
Alone, these two liquids
will not mix together.
But add in a
soap-like substance,
called a surfactant, then mix,
and suddenly, the two liquids
will blend.
This type of mixture
of two or more liquids
that are normally immiscible
is called an emulsion.
Now, creating emulsions
is not a new process.
Think of the mixture of oil
and vinegar in salad dressings,
for example.
But the challenge is
to get the emulsions
to remain stable for
longer than a few minutes.
The key to overcoming
ultimate separation
is to have really small,
nano-sized droplets.
When the drops are that small,
gravity cannot overcome them,
and they can remain
suspended indefinitely.
There are ways to do this.
However, the current
industrial processes
are extremely energy
intensive and expensive.
The new process
used in the MIT lab
requires very little energy,
in fact, no mixing at all,
and can remain
stable for months.
This new process takes
a bottom-up approach
by using condensation
to create the droplets.
First, they take a reservoir of
oil with an added surfactant,
place it inside a chamber
with very humid air,
and cool the oil.
As it cools, the
condensing water
forms droplets at
the surface that
spread through the
oil-surfactant mixture,
forming uniform,
nanoscale droplets.
These droplets are so tiny
and uniformed that they
are hard to even see
under a microscope.
The team believes
the approach should
work with a variety of
oils and surfactants.
This new process could provide
design guidelines for use
in particular
applications that have
expiration dates, like
drug delivery, cosmetics,
and processed foods.
