Shanghai, China – While there is growing interest in including polyols from bio-sources in polyurethanes, renewable diisocyanates are a different story. A team in the department of polymeric materials at Tongji University in Shanghai is looking to address this, by using bio-based sources for both. They also aim to improve the PU’s biodegradability by modifying the diols.
They took commercially available bio-based vanillin, and used this to make a vanillin-based diol that contains ester bonds. This was then reacted with L-lysine diisocyanate and trimethylol propane as a crosslinker. The result was a series of bio-based thermoset PUs with a bio-based content above 70%.
They found their new PUs had comparable mechanical properties to commercial thermoset PUs. They also had higher toughness than previous bio-based analogues.
The ester bond in the vanillin-based polyol facilitated the complete degradation of the PU in a 0.1M solution of sodium hydroxide within 3.5 hours. They believe this should enable the monomers to be recovered.
The work has been published in the journal ACS Applied Polymer Materials.
