Synthesis of PMOs with Surfactants

Another approach for the functionalization of mesoporous material is the PMO. It is a special type of mesoporous organosilica with integrating organic groups (R) such as (R 0)3-Si-R-Si-(0R)j (R = methane, ethane, ethylene, acetylene, tris[3-(trimethoxysilyljpropyljisocyanurate, porphyrin, and so on) inside the siliceous walls. 

In case of ionic surfactants, MCM-41 type of PMOs containing traws-l,2-bis(4-pyridyl)ethylene incorporated in the silica walls synthesized by TEOS and trans-l,2-bis[N-(trimethoxysilylpropyl)pyridiumyl]ethylene (t-BES) as silicon sources and CTABr surfactant are worth mentioning [64]. PMOs with a carbapalladacycle complex, TEOS, and CTAB have been also prepared by Corma et al. [65]. 

Ozin and coworkers [30] reported PMOs with l,2-(bistriethoxysilyl) ethene under basic conditions using CTAB as the surfactant, which are called ethane-hridged PMOs. Recently, the new surfactant template alkylated imidazolium, belonging to a class of interesting organic salts, has been used as head group of such ILs ]66]. 

At nearly the same time as the report of PMO synthesized by CTAB, PMOs with large pores of 6.0-7.4 nm in diameter were synthesized using a triblock copolymer as template. Caber and coworkers [67] reported a PMO that was synthesized by the acid-catalyzed hydrolysis and condensation of bis-(triethoxysilyl)ethane (BTSE) using the triblock copolymer Pluronic P123 as the SDA. Another report deals with 

Till now, the PMO was usually prepared under strongly acidic or basic conditions. Most PMOs usually need strong interaction between the surfactant micelles and hydrolyzed organosilicas for the formation of the mesoporous stracture. So, finding mild conditions for the synthesis of PMOs still remain significant challenges. Mild conditions, such as weak acidic or basic, could seriously decrease the interactions between surfactant micelles and hydrolyzed organosilicas which form the ordered mesoporous structure. Recently, li [69] reported the mild pH conditions for the synthesis of PMOs. 

---