Arrangements of cationic starch of varying hydrophobicity on hydrophilic and hydrophobic surfaces.
Arrangements of cationic starches hydrophobized by acetylation (CS-acet) deposited from aqueous electrolyte solutions onto hydrophilized and hydrophobized silica surfaces were investigated by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. The influence of electrolyte composition, acetylation degree of cationic starch (DS(ACET)), and deposition method was examined. On a hydrophobic substrate, CS-acet formed an open film with structure strongly dependent on DS(ACET) and electrolyte composition of the solution. On a hydrophilic substrate, acetylation increased the hydrophobicity of the film when the starch was deposited by adsorbing. When deposition was made by spin coating, i.e., the CS-acet was forced onto the substrate, the hydrophobic tuning by acetylation was lost. The films deposited by spin coating were thicker and considerably rougher than those deposited by adsorbing.
Kontturi
Katri S
KS
Laboratory of Forest Products Chemistry, Helsinki University of Technology, P.O. Box 6300, FIN-02015 TKK, Finland. katri.kontturi@tkk.fi
Holappa
Susanna
S
Kontturi
Eero
E
Johansson
Leena-Sisko
LS
Hyvärinen
Sari
S
Peltonen
Soili
S
Laine
Janne
J
D000107:Acetylation; D002412:Cations / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D018625:Microscopy, Atomic Force; D012822:Silicon Dioxide / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013213:Starch / Q000737:chemistry*; D013499:Surface Properties
D002412:Cations; D004573:Electrolytes; D012822:Silicon Dioxide; D013213:Starch