Transition from transparent aerogels to hierarchically porous monoliths in polymethylsilsesquioxane sol-gel system

Kazuyoshi Kanamori, Yasunori Kodera, Gen Hayase, Kazuki Nakanishi, Teiichi Hanada

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

A transition from hierarchical pore structures (macro- and meso-pores) to uniform mesopores in monolithic polymethylsilsesquioxane (PMSQ, CH3SiO1.5) gels has been investigated using a sol-gel system containing surfactant Pluronic F127. The precursor methyltrimethoxysilane (MTMS) undergoes an acid/base two-step reaction, in which hydrolysis and polycondensation proceed in acidic and basic aqueous media, respectively, as a one-pot reaction. Porous morphology is controlled by changing the concentration of F127. Sufficient concentrations of F127 inhibit the occurrence of micrometer-scale phase separation (spinodal decomposition) of hydrophobic PMSQ condensates and lead to well-defined mesoporous transparent aerogels with high specific pore volume as a result of the colloidal network formation in a large amount of solvent. Phase separation regulates well-defined macropores in the micrometer range on decreasing concentrations of F127. In the PMSQ-rich gelling domain formed by phase separation, the PMSQ colloidal network formation forms mesopores, leading to monolithic PMSQ gels with hierarchical macro- and meso-pore structures. Mesopores in these gels do not collapse on evaporative drying owing to the flexible networks and repulsive interactions of methyl groups in PMSQ.

Original languageEnglish
Pages (from-to)336-344
Number of pages9
JournalJournal of Colloid And Interface Science
Volume357
Issue number2
DOIs
Publication statusPublished - 2011 May 15
Externally publishedYes

Keywords

  • Aerogels
  • Hierarchically porous gels
  • Macroporous
  • Mesoporous
  • Polymethylsilsesquioxane
  • Sol-gel

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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