Adjustable water contact angle by nano composite structure with different thermal expansion

The fabricated AAO has hexagonally arranged nanosize holes under specific conditions. Paraffin was filled in the holes of AAO. While the AAO is hydrophilic, paraffin is hydrophobic. In addition, the coefficients of thermal expansion (CTE) of AAO and paraffin are quite different. Thus, the composite surface becomes able to have different roughness at different temperature. The range of the CA on the composite surface was 63 to 113*. The CA increased as the temperature varied from 1 to 40°C. In the range of temperature, 1 to 40°C the result from the experiment shows very similar trend to the calculated result. The CA difference between measurements and calculations is very small and this is because the real AAO has a little roughness and theoretical roughness is totally flat.