From Nanotech to Nanoscience

Chi Chan

The term nanotechnology gained popularity in the 1970s and 1980s, but technologies that use tiny or “nanosized” objects have been around for centuries. Hundreds of years before this modern term was coined, scientists were using the properties it describes to manufacture cutting edge goods and to explore the world around them. Nanosized particles have recently been discovered in artifacts dating back to the 16th and 17th centuries, and Enlightenment-era nanoscience has influenced today’s advanced, high-tech research.

Medieval artisans discovered through alchemical experimentation that adding gold chloride to molten glass resulted in a red tint, and adding silver nitrate turned the glass yellow. The technique reached its height during the 16th through 18th century and resulted in some of the world’s most spectacular stained glass windows. Recently scientists analyzed stained glass from this era and discovered that the technique, possibly dating back to the 10th century, worked because of nanotechnology; analysis of the stained glass revealed that gold and silver nanoparticles, acting as quantum dots, reflected red and yellow light, respectively.

From the 12th to 18th century, Middle Eastern metalsmiths also practiced a form of nanotechnology. Using steel ingots imported from India, Damascene metalsmiths forged blades sharper and more durable than western blades, especially those of the Crusaders. The exact process for producing these highly prized blades remained a closely guarded trade secret, handed down only from teacher to apprentice. Scientists and historians have postulated that as Indian steel mines were depleted mining shifted elsewhere, and eventually the ingots no longer had the specific composition required to produce Damascus steel. Since the method no longer worked, it was lost through the ages. In 2006 materials scientists, using high-resolution transmission electron microscopy, found traces of carbon nanotubes and nanowires present in Damascus steel blades. They theorized that these nanowires, encapsulated by the carbon nanotubes, were responsible for Damascus steel’s legendary sharpness and durability.

In the late 19th and early 20th centuries, industrialists used carbon black, which has since been discovered to be a nanomaterial. At the turn of the century, scientists found that carbon black could reinforce rubber and thus improve its strength, tensile properties, and tear and abrasion resistance. Carbon black also increased the hardness of vulcanized natural rubber. Manufacturers soon applied this discovery commercially. In 1910 BFGoodrich began adding carbon black filler to extend the life span of its tires, and today virtually all automotive tires are reinforced with carbon black. Recently scientists have discovered that carbon black’s reinforcement properties can be attributed to the interaction between the rubber and the nanosized carbon particles’ grain.

In all of these cases manufacturers were unaware that they were using what we now call nanotechnology, and the scientific principles behind these technologies were not fully understood until much later. Nonetheless, if one looks closely at history there are cases in which the scientific theory was understood before the application was developed—a model that current nano--technologists and materials scientists emulate.

In 1773 Benjamin Franklin wrote a letter to the English physician and chemist William Brownrigg that detailed his observations on the effects of oil on water. In his letter Franklin describes a voyage at sea on which he observed that greasy water dumped by the ship’s cooks had a calming effect on the ship’s wake. Franklin learned that the calming effect of oil on water was common seafarers’ knowledge, but no one really understood how it worked. After arriving on shore in London, the intrigued Franklin conducted an experiment on a windy day in a pond at Clapham Common. He deposited a teaspoon of oil at the edge of the pond where waves were forming and moving out toward the middle. The waves and wind spread the oil across the pond, and more than a square acre of turbulent water was quickly calmed. Even large leaves and twigs on the surface of the pond were pushed aside by the thin film of oil.

While similar observations were made as far back as Pliny the Elder, Franklin was the first to theorize this phenomenon using scientific principles. In his letter to Brownrigg, Franklin proposed that a mutual repulsion existed between water and oil particles. The repulsion’s force was so strong that it caused the oil to push itself away from the water and produce a widespread, nearly invisible film on top of the water.