BY MARIA BURKE
Plastic made from hemp – a non-psychoactive type of cannabis – could be a renewable replacement for plastics derived from fossil fuels, such as polyethylene terephthalate (PET). Unlike most plant-based plastics, US researchers have found their hemp version could be melted and stretched into different shapes but could also cope with hot water.
Most plant-based polymers lack PET’s stretchability and high glass transition temperature and are more expensive to produce. In addition, the catalysts used to produce them often require high temperatures and are challenging to remove, making them impractical for large-scale production.
Gregory Sotzing of the University of Connecticut and colleagues from Purdue University have developed polycannabidiol carbonate (pCBDC), a 92% bio-based thermoplastic; CBD is the main compound in hemp flowers. They report that pCBDC is strong with both a high glass transition temperature (95°C) and hydrophobicity, meaning it could withstand hot water. It also demonstrated excellent stretch processability; it could extend up to 1,600% of its size. (HD Davis et al, Chem Circularity, 2026, 1, 100018).
‘Very few, if any, plastics made from natural resources have this [high glass transition temperature],’ Sotzing says. ‘This polycarbonate also has – as a smooth film – a very high contact angle with water [making it hydrophobic]. We were not expecting our polyCBD-carbonate to have a higher contact angle than most polyolefins.’ Materials with this property can be used as nanoparticles for drug delivery and for catheter coatings.
‘Current day polycarbonate is made from bisphenol-A, a known endocrine disruptor,’ he adds. ‘The hope is that CBD can replace bisphenol-A found in today’s processed plastics.’ However, the team notes that the commercial relevance of pCBDC will rely on CBD feedstock costs continuing to decline. CBD remains considerably more expensive than PET feedstocks, but initial pCBDC production could focus on higher-value applications.
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