The Young's modulus decreases for both systems with increasing porosity (i.e. decreasing density) as expected. In the case of MSSQ-SiO2, the Young’s modulus decay can be fit with a power law, as suggested from previous studies and accepted models for silicates. Surprisingly, however, the ethylene bridged oxycarbosilane (Et-OCS) produced by hydrolysis of BTESE behaves differently as evidenced by the linear decay of the Young’s modulus as a function of density. Other bridged OCS materials, e.g. that prepared from BTESM with non-ionic surfactants including amphiphilic block copolymers also show linear modulus vs density relationship.

References:
G. Dubois et al., US 7,229,943 (2007)
Dubois et al., Adv. Mat. 2007, 19, 3989-3994.