Recently, researchers at the University of California, Berkeley invented a new chemical process that can recycle waste plastic bags (mainly polyethylene PE) and convert them into more valuable adhesives, realizing the upgrade of polyethylene Recycling.
According to reports, UC Berkeley professor of organic chemistry and research team leader John Hartwig and his colleagues used a catalyst based on ruthenium (gold spheres in the middle) to add specific to the polyethylene polymer chain.
The chemical group (OH (red) in this case), which forms an oxidized polyethylene.
It can be firmly attached to metal and retains the unique plastic characteristics of polyethylene.
Researcher Katerina Malollari has made 11 attempts and it is difficult to separate the water-based latex paint from Ox-LDPE, which was basically difficult to adhere to ordinary plastics before.
"Polyethylene chains usually have 2,000 to 10,000 carbon atoms, and each carbon atom has two hydrogen atoms-in fact, it is a sea of CH2 groups called methylene groups.
We consulted the literature.
, Looking for active catalysts that we can find for functionalization of methylene positions.
" Professor Hartwig said.
Considering that solid recycled plastics need to be melted, this requires that the catalyst used for polyethylene recycling and modification can work in high temperature and non-polar solvents in order to be mixed with non-polar polyethylene.
Hartwig and postdoctoral assistant Liye Chen studied a ruthenium-based catalyst (polyfluororuthenium porphyrin) that can meet these requirements and can add OH groups to the polymer chain without polymerizing the highly reactive hydroxyl groups.
Material chain breaks.
The researchers found that catalysis chemically changes less than 10% of the polymer, but it greatly enhances its ability to adhere to other surfaces.
The improvement of polyethylene’s adhesiveness has potential for application.
For example, artificial hip and knee implants usually combine polyethylene with metal parts.
The improvement of polyethylene’s adhesiveness can make it better.
Ground adheres to the metal.
Functionalized polyethylene can be used for wire coating, to provide glue that holds other polymers together (such as milk cartons), or to make more durable plastic and metal composites, such as toys.
Professor Hartwig said that the current process is not economical enough in industry, but it can be improved.
This research and development also means that other catalysts can work with other types of plastics (such as polypropylene in recycled plastic bottles) to produce economically attractive, high-value products.