Does the Varying Reactivity in the Transient Polymer Network through Dynamic Exchange Regulate the Closed-Loop...

Area of Science:

• Polymer Chemistry
• Materials Science
• Sustainable Engineering

Background:

• Global plastic waste poses significant environmental challenges, contributing substantially to carbon emissions.
• Current recycling methods for postconsumer recycled plastics often lead to property degradation, hindering circular economy goals.
• Achieving net-zero carbon emissions necessitates innovative strategies for plastic waste management and recycling.

Purpose of the Study:

• To develop a novel biobased molecule for enhancing the properties and recyclability of postconsumer recycled polypropylene (PCR-PP).
• To investigate the formation and properties of covalent adaptable networks (CANs) in modified PCR-PP.
• To establish structure-property correlations and understand the role of varying reactivity in polymer network topology for closed-loop circularity.

Main Methods:

• Synthesis of a designer biobased molecule, maleated castor oil (mCO), for grafting onto PCR-PP.
• Creation of single and dual covalent adaptable networks (CANs) using the modified PCR-PP.
• Evaluation of the mechanical properties, reprocessability, and recycling efficiency of the resulting PCR-PP Vitrimers.

Main Results:

• The synthesized mCO effectively grafted onto PCR-PP, forming a transient network and preventing chain scission.
• The resulting PCR-PP Vitrimers exhibited excellent reprocessability with over 90% property recovery after five recycling cycles.
• Varying reactivity in the transient polymer network was shown to influence stress relaxation, flow activation energy, and crystalline morphology.

Conclusions:

• A novel biobased approach enables the creation of high-performance, recyclable polypropylene vitrimers from postconsumer waste.
• The study highlights the critical role of transient network design and varying reactivity in achieving closed-loop circularity for plastics.
• This research offers a promising pathway for sustainable plastic recycling, contributing to carbon emission reduction goals.