The beginning of the (chlorofluorocarbons) era started in 1928, when ' were invented by a Du Pont chemist. ' were best known as "freons" and became famous as a safe, nonflammable refrigerant. It's invention became a great triumph when Freon took the place of sulfur dioxide or ammonia which was used as the working liquid in refrigerators. It eventually became widely used in automobile air conditioners and nontoxic propellants in aerosol cans. It's insulating properties also was used for blowing agents for plastics and foam cups. Thus s became u ....