Spontaneous adsorption on a hydrophobic surface governed by hydrogen bonding.
Spontaneous adsorption from solution onto solid surface is a common phenomenon in nature, but the force that governs adsorption is still a matter of considerable debate. (1, 2) We found that surfactants and cellulose adsorb from solution onto a poly(methyl methacrylate) (PMMA) surface in an ordered and cooperative way governed by hydrogen bonding. The glucose rings of n-dodecyl-beta-D-maltoside (DDM) and hydroxyethylcellulose (HEC) stand perpendicular to the surface, H-bond to the surface COOMe groups with their C=O and Me-O bonds parallel to the surface, and form a tight monolayer. The non-H-bonded COOMe groups orient their C=O bonds perpendicular to the surface. In contrast, the glucose rings of hydrophobically modified hydroxyethylcellulose (HMHEC) lie flat with the side chains perpendicular to the surface and H-bond to the perpendicular-oriented C=O groups. The non-H-bonded COOMe groups orient their C=O bonds parallel but Me-O bonds near-perpendicular to the surface for stabilizing HMHEC. The current work provides a detailed picture of how surface-active molecules interact with a solid surface and self-assemble into greatly different architectures.
Dang
Fuquan
F
Health Technology Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho 2217-14, Takamatsu 761-0395, Japan. fuquan-dang@aist.go.jp
Hasegawa
Takeshi
T
Biju
Vasudevanpillai
V
Ishikawa
Mitsuru
M
Kaji
Noritada
N
Yasui
Takao
T
Baba
Yoshinobu
Y
D000327:Adsorption; D002240:Carbohydrate Sequence; D002482:Cellulose / Q000031:analogs & derivatives / Q000737:chemistry*; D005960:Glucosides / Q000737:chemistry; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D018625:Microscopy, Atomic Force; D008969:Molecular Sequence Data; D015394:Molecular Structure; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
D005960:Glucosides; D013501:Surface-Active Agents; C040358:dodecyl maltoside; D002482:Cellulose; C002283:hydroxyethylcellulose; D019904:Polymethyl Methacrylate