Smita Mankar’s thesis contributes with important knowledge on biobased polyesters

Smita Mankar defended her thesis in February 2023 within STEPS work package two: biobased polymers. It was entitled: Toward Biomass-Derived Recyclable Polyesters. Photo: Kennet Ruona.

Smita Mankar’s thesis focused on producing biobased building blocks that can enhance the thermal, mechanical and barrier properties of bio-based polyesters. She has also studied new recycling strategies for biobased plastics by using chemicals or enzymes. These strategies may shed some light on the design of recyclable biobased plastics.

In her research, she is motivated by knowing that she can contribute to the sustainability of the future of plastics. Another important thing is that she gets to test her own ideas to figure out if they will work.

She defended her thesis in February 2023 within STEPS work package two: biobased polymers. She was based at the Centre for Analysis and Synthesis.

What was your RESEARCH about?

Plastics are widely used every day, in our clothes, lunch boxes, mobile phones and in many other things. But their large production from non-renewable fossil resources, and limited recycling methods is an issue.

In my thesis, I have made very interesting biobased building blocks and used them to make biobased plastics. I have also studied new recycling strategies for biobased plastics by using chemicals or enzymes. These strategies may shed some light on the design of recyclable biobased plastics.

What are the main findings?

My findings include the following:

• Newly synthesised biobased building blocks can enhance the thermal, mechanical and barrier properties of biobased polyesters.

• The use of vanillin and other biobased building blocks can effectively reduce greenhouse gas emissions.

• Recycling loops can be improved by designing monomers with cleavable structures.

• Polyesters with vanillin-based structures can be enzymatically degraded.

• Aliphatic polyesters with rigid units can combine excellent thermal properties and biodegradability.

Did anything surprise you during your work?

The chemical structures of building blocks are very important. If we are introducing new structures, they should impart some amazing properties to the plastic. In my work, I also studied chemical recycling of plastics. Interestingly, I found that the recycling loop can be made shorter by breaking only a few bonds in the plastic during recycling. We can use these recycled products for making the same polymers with a less energy consuming process.

How does your work relate to other research on plastics?

Currently biobased monomers are being researched very intensively. But we should not aim to only make new monomers and new plastics. Recycling, biodegradability and greenhouse gas emissions should be included from the start when you develop new polymers in the laboratory. This is what I have done in my research.

How can your research be used by stakeholders?

I made different types of building blocks for polyesters. Some polyesters have properties that make them suitable to make them into chemically recyclable fibres for clothing.

Some polyesters are good to use for packaging purposes, as they have good barrier performance, transparency and heat resistance up to 105 degree (glass transition temperature, which is the temperature at which 30–50 carbon chains start to move) which is currently what everyone is looking for in plastics.

What are your views on the plastic system?

Currently, we are still using plastics (99 percent) that are made from fossil resources. This is definitely not sustainable.

To make plastics more sustainable, various strategies have been implemented /policies have been made. In my point of view, we should follow the three R:s; Reduce, Reuse and Recycle. Use less plastics, use recyclable plastics, and use biomass resources for making transitions toward sustainable plastics.

In packaging, sometimes various layers are used for improving barrier for moisture, oxygen, etc. However, recycling of such types can sometimes be difficult. I wonder if we can we make plastics for packaging which will not need many layers and will be easily recyclable.

What drives you as a researcher?

Knowing that I can contribute to the sustainability of the future of plastics makes me very happy. Another important thing is that I get to collaborate with researchers in different areas. I also get to work on my ideas/strategies and if it doesn’t work out, I get to know why it didn’t work out by doing experiments on my own.

Download Smita Mankars thesis at lub.lu.se: Toward Biomass-Derived Recyclable Polyesters

Read about STEPS Work Package Two: Biobased Polymers and Upscaling