(605e) Synthesis and Characterization of Organic-Functionalized Pure-Silica-Zeolite

As the feature size of next-generation microprocessors
decreases, the need for low-dielectric constant (low-k) materials with high
mechanical strength is an increasing concern.  Many potential porous materials
take advantage of the low k value of air, which is about 1, but they are often
amorphous in nature and thus lack mechanical strength.  Porous zeolites,
however, are highly crystalline and have a high elastic modulus while retaining
the low k values of amorphous porous silica materials.[1] 
Since water has a high k value, moisture adsorption is a serious concern for
all porous low-k materials.  Consequently, along with low k and high elastic
modulus values, hydrophobicity is becoming an increasingly important parameter.[2]^,[3] 
To combat this problem, post-spin-on silylation treatments with
chlorotrimethylsilane and hexamethyldisilazane have been performed, and
pure-silica zeolite (PSZ) MFI has been functionalized with
methyltrimethoxysilane.[4] 
Here, we report an organic functionalized pure-silica zeolite with an MFI-type
structure prepared through a direct-synthesis method by adding a fluorinated
silane to the synthesis solution, and the added fluorine functionality
increased the hydrophobicity of the zeolite.  The zeolite was characterized by x-ray
diffraction, ²⁹Si solid-state nuclear magnetic resonance spectroscopy,
nitrogen adsorption, FT infrared spectroscopy, and thermogravimetric analysis. 
Spin-on films from the nanoparticle suspension exhibited higher water contact
angles than pure-silica zeolite MFI films, and the zeolite powders had low
water content.