C. Guermeur et al., Hybrid polydimethylsiloxane-zirconium oxo nanocomposites. Part 1 Characterization of the matrix and the siloxane-zirconium oxo interface, J MAT CHEM, 9(3), 1999, pp. 769-778
Hybrid materials made from polydimethylsiloxane and zirconium oxo species h
ave been synthesized. They exhibit a high degree of homogeneity and dispers
ion for Zr/Si molar ratios ranging between 0.2 and 0.9. These hybrid materi
als show good mechanical integrity and transparency. They have been charact
erized by Si-29, O-17 and C-13 MAS-NMR as well as FTIR, SAXS and dynamic me
chanical analysis (DMA). These polydimethylsiloxane/zirconium oxopolymers a
re hybrids which consist of amorphous zirconium oxo domains of about one to
two nanometers in diameter. The mean correlation distance between the zirc
onium-oxo domains decreases from about 6 to 2 nm when the Zr/Si ratio incre
ases. The siloxane species (chains and loops) have an average chain length
that decreases from approximatively 15-20 silicon atoms to 3 silicon atoms
with increasing zirconium content. The interface between siloxane and zirco
nium oxo domains is composed primarily of Zr-O-Si(CH3)(2) bonds and hydroge
n bonds, their relative proportion being a function of the zirconium conten
t. The curing of these hybrid materials at 140 degrees C completes consolid
ation of the hybrid network, without affecting the overall characteristics
of the organic-inorganic interface. Curing at 200 degrees C induces the los
s of small silicic species and the increase of cross-linking points in the
siloxane regions. For samples with a high zirconium content (Zr/Si = 0.9) c
uring at 200 degrees C also induces an increase in the number of the Zr-O-S
i interface bonds.