Ots Preparation - Ossila FACT1 User Manual

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Appendix IV - OTS Preparation
Getting a good OTS preparation on a substrate surface can increase mobilities by orders of
magnitude, however getting a good monolayer can be hard to achieve.
In general OTS will polymerise over time when exposed to ambient conditions resulting and "stringy"
white aggregates in the bottle. As such, we generally store OTS under inert atmosphere (N2
glovebox).
However, in order to get a good coating on a substrate, a small amount of water is beneficial for the
cross-linking process. For this reason (and also the amount of solvents used) we generally prepare
OTS substrates under ambient conditions. The choice of solvent is also critical and we have found
cyclohexane to work well using the following procedure.
OTS preparation procedure:

OTS stored under inert atmosphere (N2 glovebox).

Small amount of OTS mixed 1:9 with anhydrous cyclohexane in inert conditions (glovebox).

Clean substrates placed in a beaker with lid and immersed in HPLC grade cyclohexane under
ambient conditions.

OTS:cyclohexane mixture removed from glovebox and small amount added to beaker to
produce overall concentration of 1 mMol.

Left under ambient conditions for 20 mins.

2x dump rinses in cyclohexane

Baked on hotplate under ambient conditions at 150 C
The above recipe should result in a water contact angle of around 110 °C or greater.
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