Early Formation Pathways of Surfactant Micelle Directed Ultrasmall Silica Ring and Cage Structures

J Am Chem Soc. 2018 Dec 19;140(50):17343-17348. doi: 10.1021/jacs.8b08802. Epub 2018 Nov 26.

Abstract

By combining a surfactant, an organic pore expander, a silane, and poly(ethylene glycol) (PEG), we have observed the formation of a previously unknown set of ultrasmall silica structures in aqueous solutions. At appropriate concentrations of reagents, ∼2 nm primary silica clusters arrange around surfactant micelles to form ultrasmall silica rings, which can further evolve into cage-like structures. With increasing concentration, these rings line up into segmented worm-like one-dimensional (1D) structures, an effect that can be dramatically enhanced by PEG addition. PEG adsorbed 1D striped cylinders further arrange into higher order assemblies in the form of two-dimensional (2D) sheets or three-dimensional (3D) helical structures. Results provide insights into synergies between deformable noncovalent organic molecule assemblies and covalent inorganic network formation as well as early transformation pathways from spherical soft materials into 1D, 2D, and 3D silica solution structures, hallmarks of mesoporous silica materials formation. The ultrasmall silica ring and cage structures may prove useful in nanomedicine and other nanotechnology based applications.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Benzene Derivatives / chemistry
  • Cetrimonium / chemistry
  • Cryoelectron Microscopy
  • Micelles*
  • Microscopy, Electron, Transmission
  • Models, Chemical
  • Nanostructures / chemistry*
  • Organosilicon Compounds / chemistry
  • Particle Size
  • Polyethylene Glycols / chemistry
  • Silanes / chemistry
  • Silicon Dioxide / chemistry*
  • Surface-Active Agents / chemistry
  • Water / chemistry

Substances

  • Benzene Derivatives
  • Micelles
  • Organosilicon Compounds
  • Silanes
  • Surface-Active Agents
  • tetramethyl orthosilicate
  • Water
  • Polyethylene Glycols
  • tetraethoxysilane
  • Silicon Dioxide
  • mesitylene
  • Cetrimonium