Castor oil-based omniphobic polyurethane coatings

A recently conducted study reportstransparent polyurethane coatings with high hardness, anti-smudge and anti-corrosive properties.

A bottle of castor oil.
The worldwide energy demand and the oil price have motivated the use of bio-based Image source: Alexander Ruiz - (symbol image).

Polymeric coating technology provides a cost-effective and convenient solution for the surface pollution and corrosion issues on various substrates. Now, a series of transparent and omniphobic bio-based polyurethane (PU) coatings with high hardness, excellent anti-smudge and anti-corrosion properties were prepared by using castor oil as bio-polyol, hexamethylene diisocyanate trimer (HDIT) as a cross-linking agent, and a small amount of monocarbinol terminated polydimethylsiloxane (PDMS-OH) as an eco-friendly anti-fouling agent. Effects of the R-value (mole ratio of isocyanate groups to hydroxyl groups) and dosage of PDMS-OH (wt%) on the PU-PDMS coating’s hardness, surface wettability, anti-smudge and anti-corrosion performance have been thoroughly investigated. It was found that the higher R-value led to increased coating hardness.

Anti-smudge properties

Various simulated water-based contaminants could quickly slide off from the coating surface without leaving any traces. Writing traces of oil-based marker could be shrunk immediately after writing and wiped clean from coating surface completely. Such anti-smudge properties could be maintained even after 1000 cycles of polishing. Moreover, the anti-corrosion performance of these PU-PDMS coatings has been investigated through electrochemical tests. The obtained coatings could offer better corrosion protection for tinplate than the regular PU coatings.

The study has been published in Progress in Organic Coatings, Volume 172, November 2022.

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