March - Vol 70, No 6 - International Technology and Engineering ...

and engineers for years. “Individual nano-size building
blocks such as nanotubes, nanosheets, and nanorods are
ultrastrong. But larger materials made out of bonded nanosize
building blocks were comparatively weak” (Biomimicry
and Nanotechnology, 2007, p. 1). Kotov explained “When you
tried to build something you can hold in your arms, scientists
had difficulties transferring the strength of individual
nanosheets or nanotubes to the entire material. We’ve
demonstrated that one can achieve almost ideal transfer of
stress between nanosheets and a polymer matrix” (p. 1).
The process of making such a plastic is possible due to the
creation of a special machine that is able to build material
one nanoscale layer after another. In much the same way,
Mother of Pearl, the silver lining of mussel and oyster
shells, is also built layer by layer. It is described as one of
the toughest natural mineral-based materials. Imitating this
same process, the machine uses a robotic arm to take a small
piece of glass, about the size of a stick of gum, and dip it
into a vial containing a glue-like polymer solution and then
into a second vial holding liquid consisting of a dispersion of
clay nanosheets. Once those layers have dried, the process
is repeated. It required 300 layers to create a piece of
material as thick as a sheet of plastic wrap (Biomimicry and
Nanotechnology, 2007).
Kotov (2007) explains that the success of the project is due
to what he refers to as a “Velcro Effect,” which is created
when the two chemicals are merged on the piece of glass.
The glue-like polymer is actually polyvinyl alcohol. This
substance, combined with the clay nanosheets, allows the
mixture to form cooperative hydrogen bonds. If these bonds
are broken, they are able to reform another bond in a new
place. This is one reason why the material is so strong. A
second reason for its unique strength is in the placement of
the bonds. They are layered in much the same way as bricks
would be stacked, in an alternating layer (Biomimicry and
Nanotechnology, 2007).
Using much the same technology, National Polymer
Laboratories in Chagrin Falls, OH, are working to create
polymeric materials that are used to enhance the capabilities
of adhesives, coatings, and nanocomposites. Their materials
can be used to “improve adhesion and bonding properties,
barrier properties, fire retarding properties, chemical
resistance, dimensional stability, impact resistance,
conductivity, electrostatic discharge, and EMI shielding”
(National Polymer Laboratories, nd, para. 3).
Risks of Nanotechnology
While the future of nanotechnology is very promising
and lucrative, it is still a relatively new form of science/
engineering. Consequently, risks are inherent and
unpredictable. Nanotechnology is multiplying its
applicability exponentially. Unfortunately, those who are
researching the social and ethical consequences of the
applications of these studies have been unable to keep up.
Therefore, for many nanotechnology developments, those
risks are still undefined.
In regard to the process created by the researchers at
Stanford University for water purification, there lie
questions about unanticipated health effects. Although
initial studies did not reveal a release of mass material from
the coated cotton fabric, it does not mean that over time
there will not be at least trace amounts of carbon nanotubes
(CNTs) and silver nanowires (AgNWs) present. At that
point, it is necessary to know what effect that will have,
particularly on individuals’ health (Schoen et al., 2010).
Questions concerning the use of nanotechnology in
medicine are also of significance. To employ microscopic
robotic “bugs” to infiltrate the blood stream and annihilate
foreign intruders in a human may cause many potential
patients to wonder about their safety and predictability.
Questions such as: “Can these ‘bugs’ be absorbed by the
brain?” “What are the required exposure rates to such
medical robotic bugs?” and “What will be the level of
damage done?” exist in the minds of medical doctors and
patients alike.
Science Daily (2008) published work accomplished by
Massachusetts Institute of Technology (MIT) and the
Woods Hole Oceanographic Institution (WHO) describing
a study they have conducted on the effect of the process
of making nanotubes on the environment. The benefits
of carbon nanotubes are exciting. They are 10,000 times
thinner than a human hair, stronger than steel, more
durable than a diamond, and they conduct heat and
electricity with efficiency that competes with copper wires
and silicon chips. However, the cost to the environment of
creating such technology has not been studied sufficiently.
Massachusetts Institute of Technology and the Woods
Hole Oceanographic Institution researchers analyzed ten
commercially made carbon nanotubes. Where toxicity
studies done before had assumed that all nanotubes were
the same, this study revealed that the ten nanotubes were
made of different compositions. The significance of this
study predicts it will now be more difficult to trace the
effects of the carbon nanotubes on the environment. In
studies conducted in the past, these colleagues found that
the process of manufacturing nanotubes resulted in at least
15 aromatic hydrocarbons, including four different types
of polycyclic aromatic hydrocarbons similar to those found
15 • Technology and Engineering Teacher • March 2011