Synthesis and characterization of hydrophobic and mesoporous silicate–silsesquioxane hybrid copolymers

• Mesoporous and hydrophobic silicate–silsesquioxane hybrid copolymers were synthesized.
• The hydrophobicity of the polymers depended on the degree of polymer branching.
• The indented structure of polymer separate the silanol groups in the polymer.
• This separation causes the polymer to exhibit relatively hydrophobic characteristics.

Mesoporous and hydrophobic silicate–silsesquioxane hybrid copolymers were synthesized from tetraethoxysilane and methyltrimethoxysilane by hydrolysis and condensation polymerization using a basic catalyst. The porosity and hydrophobicity of the calcined copolymers were studied by measuring the adsorption isotherms of water and using several other techniques, such as solution and solid-state 29Si-NMR spectroscopy, small-angle X-ray scattering (SAXS), and 1H-MAS NMR spectroscopy. The porous structure of the calcined polymers was influenced by the branched polymer structure and the high condensation ratio of the rigid polymer framework. The hydrophobicity of the polymers depended on the number of residual silanol groups and the degree of polymer branching. The highly branched polymer had an indented surface that caused the polymer to exhibit relatively hydrophobic characteristics owing to segregation of the silanol groups.

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