Mode of action
The sol-gel polymerization of Si Ti Zr sols is interesting due to the possibility of controlling several properties such as the refractive index, the thermal expansion coefficient, and the resistance against alkaline corrosion attack in the final products (i.e., optical devices, photonics, sensors, and catalysts). The polymerization route can be directed toward the formation of a hybrid organic-inorganic system using a modifying agent such as 2-(methacryloyloxy) ethyl acetoacetate (MEEAH), that can act as a bidentate (bridging or chelating) agent and offers the possibility of being organically polymerizable due to the presence of unsaturated C C bonds in the molecule. The presence of C-C bonds in MEEAH allowed to perform simultaneously the organic and inorganic polymerization while maintaining the homogeneity of the sols and gels. Regarding the partial charge values, in all cases, δ(MEEA?) are negative, indicating that it can easily bond Ti and Zr. On the other hand, δ(OPrn) and δ(OPri ) values are positive in all the molecules where MEEA? is also present, and therefore those species (OPrn and OPri ) are labile[1].
References
[1] J. Méndez-Vivar. “The Role of 2-(Methacryloyloxy) Ethyl Acetoacetate in the Polymerization of Hybrid Multicomponent (Si, Ti, Zr) Sols.” Journal of Sol-Gel Science and Technology 25 3 (2002): 249–254.
