Contact Angle Results on Polycaprolactone (PCL) Fiber and Film

<strong>Contact</strong> <strong>Angle</strong> <strong>Results</strong> on Polycaprolactone (PCL) Fiber and Film
PCL Fiber – CONTROL
82 0
PCL Fiber
High water contact angle means the material is Hydrophobic and thus exhibits poor cell‐material
interactions.
PCL Fiber – NaOH treated
42 0
After treating the PCL fiber with 1M NaOH for 3 hours at room temperature, the water contact angle
decreases meaning the NaoH hydrolyzed the ester bonds of PCL resulting in carboxyl functional groups
on the PCL surface. These functional groups contribute to the lower water contact angle, thus making
the fiber surface less hydrophobic. This can be seen by the lower angle observed above compared to the
control.
The above pictures were taken by a Nikon camera and the experiment was done manually
instead of using a goniometer. The goniometer setup used to take contact angle pictures of PCL films
below was not able to do same for fibers due to its limitations.

PCL films were cast in a standard 6‐well culture plate, thus overcoming the size limitations of
goniometer. Each film had a diameter of 35 mm and were dried before performing the test.
PCL Films – Control
73 0 64 0
A high water contact angle can be seen here just as the Fiber.
PCL Film – Plasma treated
Plasma treatment decreases the angle a little but not significantly. It is important to note that the
contact angle analysis was done after 4 days of plasma treatment.

PCL Film – Plasma + NaOH treatment
NaOH treatment following plasma treatment showed result similar to the Fiber.
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Conclusion:
NaOH treatment is an aqueous based treatment. By principle, aqueous treatments should not work on
any hydrophobic surface e.g. polycaprolactone (PCL). Thus a pretreatment of PCL with plasma was
essential. Plasma increases the surface energy of a surface, thus making it less hydrophobic, which is
essential for an aqueous based (NaOH) treatment.
<strong>Contact</strong> angle pictures of PCL fiber treated with NaOH were taken October 2012 before we
decided to do plasma pretreatment. Since then, we performed the contact angle test on plasma treated
fiber and plasma + NaOH treated fiber. The test showed complete wettability meaning a water contact
angle of 0 0 . Further tests are needed to be conducted on the fiber using goniometer setup.