Chewing gum, the most popular snack in America, can be traced back to ancient Greece. Over the past two centuries, gum manufacturers have embraced materials science to produce a product that has a wide variety of benefits, from cavity protection to enhanced mental concentration. However, this treat is also polluting streets, sidewalks, and buildings around the world. In an effort to solve this problem, engineers have employed amphiphilic polymers to develop a "low-adhesion" chewing gum that can be easily removed from surfaces, offering a more environmentally-friendly product. This innovative technology can help save millions of dollars in clean-up costs and be applied to other markets, including personal care products, paints, and coatings.
A relaxing stroll in the park can instantly turn into an unpleasant experience when you step on that sticky, saliva-soaked piece of gunk on the pavement. No matter how much you curse, scrape, and peel, it seems to be stuck on the sole of your shoe forever. Why is this piece of gum so difficult to remove? For years, engineers wondered the same thing.
Equipped with a new understanding of materials science, the study and application of properties of matter, researchers at the University of Bristol in England have developed a solution to the messy problem of gum pollution. Their invention of "Clean Gum" signifies a major leap in an industry that stretches across the globe.
A Brief History of Chewing Gum
Chewing gum was named the number one snack choice by Americans in 2005 (American Dietetic Association). It was first used in ancient Greece as an edible treat made from mastiche, a chewy tree sap, and has since evolved into an indigestible confection that people grind their teeth on to freshen their breath after meals, focus during an exam, or even curb their appetite at work. Over the years, gum makers replaced spruce-sap gum bases with petroleum-derived paraffin wax. Despite the increased flavor and sweetness of paraffin gums, they lacked the soft texture or "chewiness" of sap-based gums (Burks 1).
In the 1870s, American inventor Thomas Adams began experimenting with chicle, a sticky substance found in the sapodilla tree. He tried using the rubbery sap to make rain boots, toys, and masks before he realized that the adhesive properties of chicle made it a poor substitute for rubber. Frustrated with his failed attempts, he popped a piece of chicle in his mouth and began chewing on a new idea. With the help of his sons, Adams heated the chicle with sugar and decided to turn their creation into a new product. In the following months, he founded Adams Sons & Co. and the first chewing gum factory in the world and began producing flavored gum made from sapodilla tree sap ("Chewing Gum").
After World War II, engineers developed gum bases that used synthetic polymers instead of the naturally occurring bonds in tree sap. These man-made rubbers have the same elastic characteristics of chicle, but are less expensive to manufacture and do not require the widespread tapping of trees (Revolymer). The use of synthetic polymers in chewing gum signified a major breakthrough in materials science and chemical engineering.
Today, the average American chews 300 sticks or 1.5 pounds of gum per year (Burks). Spurred on by popular demand, gum makers are constantly improving their products by optimizing "chewiness," retaining flavor, and enhancing texture. They have developed practical gums that help reduce nicotine cravings, protect teeth, and even deliver caffeine, vitamins or therapeutic drugs.
