We are spraying PCL using chloroform, and then dry in various conditions (vacuum or N2, 30°C to 50°C). At different time points, we measure the residual chloroform via headspace GC (150°C). When we dry at 30°C, we get a decreasing curve nicely ending up at a residual 500ppm after 24 hours of drying. But when we dry at 50°C, the residual chloroform is non detectable after as early as 5 hours, and stays at zero for ever. It is as if the chloroform was totally trapped in the PCL layer. The fact that it happens at a certain temperature makes me think of a chemical reaction between PCL and CHCl3: is anyone aware of such a reaction?
Dear Christophe Bureau,
I can imagine that your problem is a migration problem. Like all physical-chemical processes, migrations are temperature-dependent. The speed of migration is certainly much higher at 50° C than at 30° C. In addition, surface phenomena such as increased pore formation can also occur. My experience with migration problems is based on problems of analyte migration in PTFE coated septa in headspace gas chromatography. Especially halogenated organic solvents migrate into the PTFE coating.
I hope my ideas will bring you on the right way.
With kind regards and stay healthy
Joachim Horst
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