Organically Functionalized Mesoporous Silica by Co‐structure‐Directing Route

Abstract

This article provides a brief overview of functional mesoporous silica materials synthesized by the co‐structure‐directing route, which is distinct from conventional synthesis strategies. In these systems, organosilane serves as the co‐structure‐directing agent (CSDA), which provides critical interactions between the template and organic part of the organosilane to form mesostructures, thus retaining the organic groups on the pore surface after removal of the template by extraction. i) The formation of anionic‐surfactant‐templated mesoporous silicas (AMSs) has been achieved by the co‐structure‐directing route, which leads to a variety of mesostructures, porous properties and morphologies. ii) Other co‐structure‐directing systems for synthesizing mesoporous silicas have also been achieved, including systems using cationic surfactants and non‐surfactants, and systems using DNA for constructing nanofibers and DNA–silica liquid crystalline complexes. iii) Evidence for the regular arrangement of functional groups on the pore surface resulted from the co‐structure‐directing effect has been discussed. Also included is a brief description of the application, future requirements, and trends in the development of mesoporous materials by the co‐structure‐directing route.

Carboxylic acid-functionalized porous silica particles by a co-condensation approach

“…From this, it can be concluded that only with a defined amount of sodium hydroxide, a well-pronounced pore system can be obtained and that therefore the amount of sodium hydroxide in the sol must be well adjusted. This strong dependence of the pore structure on the amount of sodium hydroxide or the alkalinity of the system has already been reported by Che et al [25]. The authors addressed the problem that under strong alkaline conditions CES is highly hydrated and therefore exhibit only weak interactions with the cationic headgroup of the surfactant.…”

“…Due to the negative charged carboxylate group of 5-(triethoxysilyl)-pentanoic acid, the organosilane serves as a co-structure-directing agent (CSDA), providing strong electrostatic interactions with the cationic headgroups of the CTAB micelles. This bridging effect of the CSDA between the organic and the inorganic species favors their self-organization and the formation of a periodically arranged pore systems [25,37].…”

“…Reasons for this are that pore blocking, which is an inherent problem in subsequent modification reactions can be avoided and that the number of processing steps can be reduced to a minimum. However, only few papers are known in which carboxylic acid-derivatized silica materials are prepared via cocondensation of tetraalkoxysilanes with carboxylic acidfunctionalized silanes [23][24][25]. This can be explained by the fact that only a few carboxylic acid-functionalized silanes are available [26,27].…”

Silica‐based Ceramics: Mesoporous Silica

“…It has been widely reported that the particle sizes can be tuned by controlling synthetic parameters, such as pH, reaction time and temperature [147][148][149][150][151][152][153][154][155][156][157][158][159], and by adding certain compounds such as organics and organosilanes [160][161][162]. These parameters are greatly associated with the hydrolysis and condensation of the silica sources (e.g., TEOS).…”

Twisted and tubular silica structures by anionic surfactant fibers encapsulation

“…Their large surface area and pore volume have found numerous applications in separation and adsorption techniques, they can play a role as a support for catalysis, costly biomolecules and drug delivery systems, moreover they found application in sensor industry, optoelectronics and recently in metamaterials study and fabrications [1][2][3][4][5][6][7][8][9][10][11][12]. Particularly silica as an inert and cost-effective material was in the focus of interest.…”