Dichloromethane expands the material

1. Dichloromethane expands the material Polyurethane waste is piling up in landfills, but scientists have a possible solution: they have developed a method to make polyurethane degradable. Once the service life of the original product ends, this polymer can be easily dissolved in raw materials to make new products such as super glue. These polyurethanes can also be used in micro capsules, which can be opened to release biological fungicides and other items. The researchers will present their results today at the American Chemical Society Fall 2019 National Conference and Exposition. "Millions of tons of polyurethane are produced every day, and they are widely used in foam, plastics, sports shoes, insulation materials and other products," said Ephraim Morado, a doctoral student who introduced the research at the conference. "But when people use up, these materials are usually discarded." He pointed out that waste polyurethane was either landfilled or burned, which required a lot of energy and produced toxic by-products. He said: "As an alternative, we hope to develop the next generation of polyurethane, which is easy to degrade and can be reprocessed into a new material, which can then be commercialized, such as adhesives or coatings." Of course, Morado is not the only one looking for ways to reuse polymers. "Many people interested in recycling are trying to make a polymer that can be decomposed into their original starting materials and then re manufactured into the same polymer," said Dr. Steven Zimmerman, the lead researcher of the project. Zimmerman, whose laboratory is located at the University of Illinois at Urbana Champaign, added: "We are taking a very different intermediate approach, which may be more interesting in the short term because it is easier and cheaper." "We are trying to break down our polymers into some other starting materials familiar to the industry." The key difference between the standard polyurethane and the Morador version is that hydroxyacetal is added as one of the monomers, together with the traditional monomers. Zimmerman's team used a special iodine acetal for the first time to produce biodegradable polymers and polyacrylamide gel. In earlier studies, polymers were soluble in slightly acidic water. Morado invented a new type of acetal, which was added to his unconventional polyurethane, so that he could dissolve the polymer without water. After several months of research, he found that the solution of trichloroacetic acid and dichloromethane (an organic solvent) can dissolve polyurethane in 3 hours at room temperature. This is in sharp contrast to the harsh conditions of

2. typical incineration methods, which require more than 1400 degrees Fahrenheit (about 1450 degrees Celsius) to avoid the formation of toxic gases. Unlike water, dichloromethane expands the material. This expansion enables the acid to reach the main chain of the polyurethane molecular chain, which can be broken at the position of the acetal group. Alcohol monomers will be released during degradation, and these monomers can be used to manufacture new products such as adhesives with performance comparable to super glue. Morado also created other polyurethane containing acetaldehyde, which can trigger degradation when exposed to light. He used these materials to make microcapsules containing herbicides and even fungicides to kill barnacles and other creatures attached to the ship's hull. He and Zimmerman are also developing an adhesive that dissolves when a few drops of acid are added to the dichloromethane solvent. One potential application is on the circuit board. If the original chip fails, the chip safely stuck on the circuit board can be replaced. In addition, the team is studying polyurethanes that can also be degraded under more mild conditions, such as exposure to vinegar. This is particularly useful for home applications such as degradable sutures or removable easels.