Effect of alkanol surface grafting on the hydrophobicity of starch-based films.

The surface hydrophobicity of starch-based films could be regulated using a two-step surface modification method. Such modification was realized by grafting with alkanols of different chain lengths (hexanol, dodecanol and octadecanol) on the surface of starch-based films. The grafting of alkanol increased the mobility of glycerol as the plasticizer within the film surface. Also, this grafting increased the mass ratio of carbon to oxygen on the film surface but reduced the mass ratio of carbon to nitrogen. Under the same reaction conditions, there were fewer dodecyl chains grafted onto the film surface than hexyl or octadecyl chains. Furthermore, the results revealed that the surface hydrophobicity of starch-based films could be enhanced by simply increasing the alkyl chain length. Also, fewer alkyl chains tended to reduce the surface hydrophobicity of the films. These results are valuable for the rational design of starch-based materials with demanded hydrophobic properties.