Characterization of lipid-templated silica and hybrid thin film mesophases by grazing incidence small-angle X-ray scattering.
The nanostructure of silica and hybrid thin film mesophases templated by phospholipids via an evaporation-induced self-assembly (EISA) process was investigated by grazing-incidence small-angle X-ray scattering (GISAXS). Diacyl phosphatidylcholines with two tails of 6 or 8 carbons were found to template 2D hexagonal mesophases, with the removal of lipid from these lipid/silica films by thermal or UV/O3 processing resulting in a complete collapse of the pore volume. Monoacyl phosphatidylcholines with single tails of 10-14 carbons formed 3D micellular mesophases; the lipid was found to be extractable from these 3D materials, yielding a porous material. In contrast to pure lipid/silica thin film mesophases, films formed from the hybrid bridged silsesquioxane precursor bis(triethoxysilyl)ethane exhibited greater stability toward (both diacyl and monoacyl) lipid removal. Ellipsometric, FTIR, and NMR studies show that the presence of phospholipid suppresses siloxane network formation, while actually promoting condensation reactions in the hybrid material. 1D X-ray scattering and FTIR data were found to be consistent with strong interactions between lipid headgroups and the silica framework.
Dunphy
Darren R
DR
University of New Mexico/NSF Center for Micro-Engineered Materials, Department of Chemical and Nuclear Engineering, Albuquerque, New Mexico 87131, USA.
Alam
Todd M
TM
Tate
Michael P
MP
Hillhouse
Hugh W
HW
Smarsly
Bernd
B
Collord
Andrew D
AD
Carnes
Eric
E
Baca
Helen K
HK
Köhn
Ralf
R
Sprung
Michael
M
Wang
Jin
J
Brinker
C Jeffrey
CJ
D008055:Lipids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry*; D010743:Phospholipids / Q000737:chemistry; D053838:Scattering, Small Angle; D012822:Silicon Dioxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014961:X-Ray Diffraction; D014965:X-Rays
D008055:Lipids; D010743:Phospholipids; D012822:Silicon Dioxide