JP Journal of Solids and Structures
Volume 2, Issue 2, Pages 151 - 175
(July 2008)
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INCLUSION OF POLYMER SPHERES INTO MESOPOROUS THIN FILMS - FILM STRUCTURE AND MECHANICAL PROPERTY MEASUREMENT
Rory L. Rice (Ireland), Richard A. Farrell (Ireland), Graham L. W. Cross (Ireland), Justin D. Holmes (Ireland) and Michael A. Morris (Ireland)
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Abstract:
Macroporosity is introduced into mesoporous thin films (MTFs) by the inclusion of micron-sized polystyrene spheres into the sol-gel precursor used to generate the mesoporous films. High quality crack-free and well-adhered films can be produced from these materials and calcined films show a combination of macro- and mesoporosity throughout the structure but the mesopores tend to follow the radius of curvature of the macropore spaces and not intersect them. Moreover, we also found that the polymer spheres and the resultant spherical void space formed by calcination (and resultant combustion of the polymer) are strongly deformed by the stresses within the film. The deformation of the spheres and voids are analysed to estimate the internal stresses within the films. The internal stress in calcined surfactant-free films is considerably greater than that of films simply dried and still containing the surfactant phase. The results are compared to nanoindentation measurements and provide a reliable accuracy of the elastic modulus of these materials. The mechanical properties of these systems are discussed. |
| Keywords and phrases: mesoporous thin films, polystyrene microsphere, calcination. |
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