A team of researchers at ETH Zurich has developed a one-step chemical process that transforms common plastic waste, including polyethylene (PE) and polypropylene (PP), into high-performance adhesives, offering a potential alternative to conventional recycling methods that degrade plastic quality.<\/p>\n
\u200bThe technique allows scientists to \u201cupcycle\u201d polyolefins, the world\u2019s most widely used plastics, by attaching new polymer chains with tailored chemical functions instead of breaking the materials down into lower-value products.<\/p>\n
\u200bThe breakthrough could help address one of the biggest challenges in plastics recycling. Around 450 million metric tons of plastic are produced globally every year, with polyolefins accounting for roughly half of all plastic consumption. Most are used only once before ending up in landfills or incinerators, while mechanically recycled plastics typically suffer significant quality losses.<\/p>\n
\u200bUnlike conventional recycling, which melts plastics and often produces darker, weaker materials suitable only for products such as paving slabs or plant pots, the new approach retains the polymer backbone while it adds entirely new properties.<\/p>\n
\u201cOur adhesive is a first-generation product,\u201d said Tae-Lim Choi, professor of polymer chemistry at ETH Zurich. \u201cIn the future, plastics with entirely new properties will be possible.\u201d<\/p>\n
The research team, led by Choi, demonstrated the technology by converting discarded plastic bags and bottles into industrial-grade adhesives.<\/p>\n
According to the researchers, the resulting material can bond metals, glass, and wood with sufficient strength for load-bearing and heavy-duty applications used in vehicle and equipment manufacturing.<\/p>\n
\u200bThe process also opens the door to a much broader range of products. By grafting different polymer chains<\/a> onto polyolefins, scientists can introduce chemical functionalities that are missing in conventional plastics, including water-attracting groups, acids, bases, or highly specific reactive chemical groups.<\/p>\n \u200bThis versatility could enable applications reaching far beyond adhesives, researchers said.<\/p>\n Light-triggered chemistry replaces energy-intensive recycling<\/p>\n \u200bOne of the biggest hurdles in recycling polyolefins, which include polyethylene and polypropylene, is their chemical simplicity. Because they consist almost entirely of carbon and hydrogen atoms, they lack the reactive sites needed for selective chemical recycling into their original monomers.<\/p>\n \u200bAs a result, today\u2019s chemical recycling largely relies on pyrolysis, an energy-intensive process that randomly breaks plastics<\/a> apart at high temperatures to produce petroleum-like feedstocks. These feedstocks must then undergo additional processing before they can be turned back into new plastics.<\/p>\n \u200bThe ETH Zurich process takes a different approach.<\/p>\n \u200bInstead of breaking the polymer apart, the researchers dissolve plastic waste in a chlorinated solvent and expose the solution to short-wavelength light. The light generates highly reactive chlorine radicals that activate carbon atoms along the polymer chains without destroying them.<\/p>\n These activated sites then serve as anchors where new polymer chains can grow, letting researchers customize the material\u2019s properties in a single reaction.<\/p>\n The method requires neither expensive catalysts nor high processing temperatures, making it considerably simpler than many advanced plastic recycling technologies currently under development.<\/p>\n \u200bResearchers also say the reaction can be finely controlled by adjusting both the degree of chlorination in the solvent and the wavelength of the light, granting precise control over how many grafting sites form on the plastic.<\/p>\n \u200bPotential uses go beyond adhesives<\/p>\n ETH Zurich has patented the technology and nominated it for the university\u2019s Spark Award, which recognizes its most promising patent applications.<\/p>\n \u200bSince the patent was published six months ago, the researchers said they have already begun working with industry partners.<\/p>\n \u200bOne collaboration is exploring food packaging made from modified polyolefins that not only remain waterproof but also provide improved oxygen barriers, helping reduce oxidation and freezer burn compared with conventional polyethylene and polypropylene<\/a> packaging.<\/p>\n