Rational Design of Macrocellular TiO
2
and V
2
O
5
Monoliths Obtained Through Soft
Chemistry and Air-liquid Foams
F. Carn
1
, N. Steunou
2
, A. Colin
3
, J. Livage
2
, C. Sanchez
2
and R. Backov
1,*
1 Centre de Recherche Paul Pascal CNRS UPR 8641, 115 Ave Albert Schweitzer, 33600 Pessac,
France, 2 LCMC Laboratoire de Chimie de la Matière Condensée, UMR-7574 CNRS, 4 Place
Jussieu, Université Pierre et Marie Curie, Paris CEDEX 05, 3 Laboratoire du Futur, UMR CNRS-
Rhodia FRE2771, IECB, 2 rue Robert Escarpit, 33607 Pessac, France.
backov@crpp-bordeaux.cnrs.fr
ABSTRACT
Chemistry of shapes appears as a strong interdisciplinary field of research that
encompasses both the area of soft matter, physical-chemistry and soft chemistry. In this general
context, hierarchical inorganic macrocellular monoliths have been obtained using air-liquid
foams as a macroscopic pattern while lyotropic mesophases are employed to create porosity at
the mesoscale. At the macroscopic length scale, both cell sizes and shapes as well as the Plateau
borders thickness and topologies can be designed with a strong degree of control. Some examples
with different inorganic network as TiO
2
and V
2
O
5
are depicted with specific characterizations.
INTRODUCTION
One interesting strategy to obtain hierarchically organized structures is to maintain
micellar organization on the mesoscale while promoting mineralization at the macroscopic
interfaces induced from metastable thermodynamic systems as air-liquid [1] or biliquid foams[2].
Other strategies for obtaining complex textures are based on the use of either preformed
nanopatterns [3] or micro-organism [4], enhancing the impact of the growing field of chemistry
of “shapes” [5]. In the specific context where metastable thermodynamic systems are used as
macroscopic patterns, disorganized macroporous inorganic materials have been generated using
either effervescence [6] or strong stirring [7]. More recently our group has developed a new
process to obtain macrocellular silica monoliths with a high degree of control over both cell sizes
and morphologies [1]. This strategy makes the use of a sol-gel foaming process where the foam’s
water volumic fraction is controlled when performing the sol-gel chemistry. In the present study,
we address the possibility of extending this non-static patterning method toward others inorganic
precursors: titanium isopropoxide [8] or metavanadate [9].
EXPERIMENTAL DETAILS
Titanium dioxide foams syntheses. Solutions were prepared by mixing a cationic
(tetradecyltrimethylamonium bromide, TTAB) or an anionic surfactant (sodiumdodecylsulfate,
SDS), water, titanium isopropoxide and HCl. Typically, titanium isopropoxide is added to an
aqueous solution of TTAB (35wt%) or SDS (15wt%) in order to reach a proportion of 10wt%.
The pH solution is then fixed to pH=1 by adding HCl (37%). The previous mixture is submitted
to a strong stirring during 30 min to homogenize the solution and evaporate ethanol produced by
the hydrolysis of the titanium alkoxide. A particulate sol can be obtained by aging after 20h.
Foam is obtained by bubbling perfluorohexane saturated nitrogen into the plexiglas column
containing the foaming solution (2,5cm x 2,5cm x 60cm high) with nitrogen through a porous
EE9.5.1 Mater. Res. Soc. Symp. Proc. Vol. 847 © 2005 Materials Research Society