Silica
aerogels, which are constructed with silica nanoparticles
and numerous nanoscale pores, have many outstanding attributes, but
they are usually brittle and hydrophilic. For the construction of
a robust aerogel, the novel polyhedral oligomeric silsesquioxane (POSS)
was introduced to prepare a series of aerogels possessing particles
covered with elastic cushion to improve the mechanical property. The
multialkoxy POSS, which possessed stiff Si–O–Si nanocages
and flexible alkyl chains, was synthesized via thiol–ene click
chemistry. After a facile and efficient approach, a partially ordered
structure of SiO2 nanoparticles and organic elastic cushion
would form spontaneously within the aerogels. With the POSS as the
only precursor, several outstanding attributes were achieved in a
single aerogel such as high specific surface area (SSA), high compression
strength, high compression modulus, and noticeable compression flexibility.
Meanwhile, the aerogel was superhydrophobic of which the contact angle
(CA) was higher than 153°. Moreover, the potential application
of oil–water separation is also presented.
Octa(dimethylethoxysiloxy) POSS (ODES) was synthesized successfully and used as the novel curing agent to prepare RTV silicone rubber (SROD) with outstanding mechanical properties and thermal stability. Compared with the silicone rubber cross-linked by tetraethoxysilane (SRTE), the novel RTV silicone rubber using octa(dimethylethoxysiloxy) POSS as a cross-linker had better mechanical, thermal, and optical properties. The highest tensile strength of SROD reached 1.26 MPa, which is three times that of SRTE. Besides, the decomposition temperature of 10% weight loss reached 507.7°C, exceeding that of SRTE by nearly 150°C. In addition, it was remarkable that due to the good compatibility of ODES with the silicone rubber matrix, the series of SROD showed good transmittance, greater than 87%. The thermal decomposition process of SROD was investigated by TGA coupled with real-time FTIR, and the results revealed the rigid structure and large steric hindrance of ODES that efficiently blocked the “backbiting” of the polysiloxy chains and delayed the end-induced ring decomposition, and consequently, improved the thermal stability of SROD significantly.
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