Counterion effect in acid synthesis of mesoporous silica materials

Hong Ping Lin, Chia Pei Kao, Chung Yuan Mou, Shang Bin Liu

Research output: Contribution to journalArticle

102 Citations (Scopus)

Abstract

Mesoporous silica materials with well-ordered hexagonal structure were synthesized under acidic conditions by using various acid sources HX. The induction time for the formation of mesostructural precipitation increases in the lyotropic series HNO3 < HBr < HC1 < H2SO4 under the same acid concentration. The induction rates are analyzed with a micelle-catalyzed reaction scheme. The order in induction time reflects the strength in counterion binding of X". Nitric acid with the highest binding strength of counterion tends to form very long micelles. We have determined the counterion association constants and found the degree of counterion dissociation under synthetic conditions in solution. The association is only partial during the early morphologysetting stage. HNO3 is a suitable acid source for preparing silica ropes of hierarchical order, consisting of silica fibers formed from parallel nanosized channels. The elongation of the surfactant micelles and shearing flow are the controlling factors in the morphology. Temperature, acid concentration, surfactant chain length, and the addition of polar solvent also have strong influence on the morphology and nanostructure of the mesoporous materials under acidic conditions.

Original languageEnglish
Pages (from-to)7885-7894
Number of pages10
JournalJournal of Physical Chemistry B
Volume104
Issue number33
Publication statusPublished - 2000 Aug 24

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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