Today's society could not exist without plastic, from cheap mass-produced products to specialized high-tech materials. However, the use of plastics also has disadvantages. These include the consumption of fossil fuels and increasing amounts of waste. Making high-quality plastics from biomass that can be broken down into reusable components could be a new strategy to reduce these disadvantages. The “destruction mechanism” would be sent with light of a certain wavelength, as demonstrated by researchers on the subject.
Biomass is a sustainable, often dirt-cheap raw material that is gaining popularity in making high-quality plastics. However, biobased plastics have the same problem of insufficient recycling. Plastics must be consistently stable during use, without the possibility of premature degradation. Recycling should ideally be upcycling rather than downcycling. The building blocks created must be convertible to another high-quality material. These should ideally be monomers that can be repolymerized to make similar high-performance polymers.
To tackle this challenge, an interdisciplinary team of researchers from the United States – Jayaraman Sivaguru of the Center for Photochemical Sciences, Bowling Green State University in Bowling Green, Ohio, and Mukund P Sibi and Dean C Webster of North Dakota State University in Fargo – have opted for biobased plastics whose degradation can be triggered by irradiation with light. They were able to develop cross-linked polymers that contain vanillin-based building blocks in their backbone. Vanillin can be produced from materials such as lignin, a byproduct of cellulose production.
The vanillin derivative developed by the team absorbs light at 300 nm and enters an excited state. This leads to a chemical reaction that initiates the breakdown of the polymer. Because this wavelength is not included in the spectrum of sunlight that reaches Earth, unplanned degradation is avoided. The researchers managed to recover 60 percent of the monomers, which could be polymerized again without loss of quality.
Photodegradable, recyclable and renewable cross-linked polymers made from biomass sources are a promising approach to producing more sustainable plastics. Light-induced degradation is environmentally friendly and offers the advantage of spatial and temporal control.
The research was funded by the National Science Foundation.
Source: Bioenergy news
