Synthesis of Hybrimers

Siloxane-based hybrid materials (hybrimers) prepared by sol-gel process present many advantages for the design of materials [60-62, 66, 67, 71] . Firstly, many precursors are commercially available or can be modified or synthesized; secondly, the control of precursor reactivity can be achieved by controlling the catalysts; thirdly, transparent films or monoliths having good robustness can be easily processed; and finally, the resulting materials are not toxic. Figure 13.1 shows a schematic diagram of the synthesis of the hybrimers. Typical precursors of the hybrimers are organically modified silicone alkoxides (organo-alkoxysilanes) of general formula R'.Si(OR)4-n where R' can be any organo-functional group and R is an alkyl group. The formation of siloxane Si-O-Si network follows the classical sol-gel route which is as follows.

Hydrolysis:

Polycondensation:

R' is non-reactable

R'nSi(OR)4-n Organoalkoxysilane

R' is non-reactable

R'nSi(OR)4-n Organoalkoxysilane

hydrolysis

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