TY - JOUR
T1 - Poly(N-isopropylacrylamide) grafting on aluminium to actively switch its surface drag in water
AU - Hyakutake, Tsuyoshi
AU - Navrotskiy, Alexander V.
AU - Morita, Katsuaki
AU - Kato, Junji
AU - Sakaue, Hirotaka
AU - Novakov, Ivan A.
AU - Nishide, Hiroyuki
PY - 2010/10
Y1 - 2010/10
N2 - Active control of flow over object surfaces achieved by means of mechanical and/or electrical methods has recently been studied. However, there has been no report on actively switching the surface drag of an object by chemical modification of the object's surface. Poly(N-isopropylacrylamide) (PNIPA) was grafted onto the surface of an aluminium (Al) substrate via (A) surface-initiated atom transfer radical polymerization and (B) radical polymerization with an azo-group surface initiator. The grafting density was 0.19 and 0.15 chains nm-2, respectively. The water contact angle of the PNIPA-grafted Al surface reversibly changed between 55° and 82° for (A) and between 42° and 65° for (B) at temperatures of 25 and 40 °C, which was ascribed to the temperature-responsive, hydrophilic-hydrophobic switching of the grafted PNIPA surface. The PNIPA grafting was applied on the surface of an ogive-shaped Al model. The normalized dropping speed of the model in water increased 1.1 times at 42 °C in comparison to that at 22 °C. Switching of the surface drag of PNIPA-grafted Al in water was demonstrated on the basis of the hydrophilicity and hydrophobicity of the grafted Al surface, the switching occurring with a change in temperature.
AB - Active control of flow over object surfaces achieved by means of mechanical and/or electrical methods has recently been studied. However, there has been no report on actively switching the surface drag of an object by chemical modification of the object's surface. Poly(N-isopropylacrylamide) (PNIPA) was grafted onto the surface of an aluminium (Al) substrate via (A) surface-initiated atom transfer radical polymerization and (B) radical polymerization with an azo-group surface initiator. The grafting density was 0.19 and 0.15 chains nm-2, respectively. The water contact angle of the PNIPA-grafted Al surface reversibly changed between 55° and 82° for (A) and between 42° and 65° for (B) at temperatures of 25 and 40 °C, which was ascribed to the temperature-responsive, hydrophilic-hydrophobic switching of the grafted PNIPA surface. The PNIPA grafting was applied on the surface of an ogive-shaped Al model. The normalized dropping speed of the model in water increased 1.1 times at 42 °C in comparison to that at 22 °C. Switching of the surface drag of PNIPA-grafted Al in water was demonstrated on the basis of the hydrophilicity and hydrophobicity of the grafted Al surface, the switching occurring with a change in temperature.
KW - Graft polymerization
KW - Poly(N-isopropylacrylamide)
KW - Surface modification
KW - Temperature sensitive
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U2 - 10.1002/pi.2887
DO - 10.1002/pi.2887
M3 - Article
AN - SCOPUS:78649472333
SN - 0959-8103
VL - 59
SP - 1436
EP - 1440
JO - British Polymer Journal
JF - British Polymer Journal
IS - 10
ER -