The client requested hydrophobic pipette tips to ensure complete release of each liquid sample. They requested an additive to make the tips more hydrophobic. As such tips are typically made of polypropylene (PP), which is already hydrophobic, the options are limited. Also, their test liquid was a protein solution and it was vital to make sure it did not become contaminated via migration of the additive.
The usual low molecular weight, wax type products, would dissolve in the water and contaminate the sample. Furthermore, they are not very hydrophobic. Having worked extensively in this area, I was aware of one additive that would give a lower surface energy and zero contamination. I obtained a sample through contacts and had it sent overnight to their production facility in Asia.
The results were very encouraging with a clear improvement in performance and a side benefit of the additive was good mold release of the parts. Finally, a way to make hydrophobic pipette tips without expensive coatings.
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