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A group of researchers has used molecular-scale imaging to identify structural defects in plastic materials commonly used in electronics, revealing limitations that could affect the performance of flexible, low-cost devices.
The findings, published in Nature Communications, point to flaws that emerge during a popular method of synthesising conductive plastics called aldol condensation. While the technique is often preferred for being scalable and metal-free, researchers say it can introduce defects that restrict conductivity and reduce the efficiency of next-generation electronics.
Zooming In On Defects
Conductive plastics known as conjugated polymers are used in a range of emerging technologies, from biosensors to thermoelectric generators. Their appeal stems from their ability to be printed on thin, flexible substrates and operate without the need for rare metals.
The research team, led by Professor Giovanni Costantini from the University of Birmingham, examined four polymers produced via aldol condensation. Using scanning tunnelling microscopy (STM) and electrospray deposition (ESD), they were able to observe the structure of each polymer chain at the molecular level.
“The aldol condensation process can create defects in the polymer sequences, like missteps in a molecular dance, which can disrupt the flow of electrons through the material,” said Costantini. “Our findings could have wide-reaching implications for the development of high-performance, flexible, low-cost electronics and help reduce reliance on rare or toxic metals in manufacturing.”
Two Types Of Polymer Defects
The study identified two main categories of structural flaws:
- Coupling Defects: These occur when monomers attach in the wrong orientation or at incorrect sites, creating kinks or distortions in the polymer chain.
- Sequence Defects: These appear when the regular pattern of monomers is broken, for instance when identical units align back-to-back instead of alternating.
Such defects are difficult to detect using traditional techniques, which the researchers say may explain why their effects have been largely overlooked until now.
Engineering A Cleaner Synthesis
The team found that chemical design tweaks and purification of the polymer building blocks before synthesis could significantly reduce defects. In one approach, researchers created small molecules using aldol condensation and then linked them together using a separate coupling technique. This produced polymer chains with fewer errors in structure.
“This is a major step forward in understanding how to make better-performing, more sustainable materials for electronics,” said Costantini. “It shows that even green chemistry needs careful control to deliver the best results.”
International Collaboration
The research involved contributors from multiple global institutions, including the University of Birmingham, University of Oxford, University of Warwick, Université de Lorraine, Stanford University, MIT, Princeton University, Peking University and Anhui University.
Last Updated on August 2, 2025 by Nick Ross
