Spreading of diblock copolymer droplets: A probe of polymer micro-rheology |
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Authors: | A B Croll and K Dalnoki-Veress |
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Institution: | (1) Department of Physics & Astronomy and the Brockhouse Institute for Materials Research, McMaster University, Hamilton, ON, Canada |
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Abstract: | We present an experimental study of the spreading dynamics of symmetric diblock copolymer droplets above and below the order-disorder
transition. Disordered diblock droplets are found to spread as a homopolymer and follow Tanner’s law (the radius grows as
R ∼ t
m , where t is time and m = 1/10 . However, droplets that are in the ordered phase are found to be frustrated by the imposed lamellar microstructure.
This frustration is likely at the root of the observed deviation from Tanner’s law: droplet spreading has a much slower power
law ( m ∼ 0.05±0.01 . We show that the different spreading dynamics can be reconciled with conventional theory if a strain-rate-dependent
viscosity is taken into account. |
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Keywords: | PACS" target="_blank">PACS 83 80 Uv Block copolymers 68 08 Bc Wetting 82 35 Gh Polymers on surfaces adhesion 47 55 D- Drops and bubbles |
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