Tapping mode AFM evidence for an amorphous reticular phase in a condensation-cured hybrid elastomer: alpha,omega-dihydroxypoly(dimethylsiloxane)/poly(diethoxysiloxane)/fumed silica nanoparticles

J Am Chem Soc. 2004 Oct 6;126(39):12284-5. doi: 10.1021/ja0474345.

Abstract

A new surface phenomenon is reported for hybrid nanocomposites comprising (1) a low Tg poly(dimethylsiloxane) (PDMS) phase cross-linked by (2) a siliceous phase (SP) generated by in situ hydrolysis/condensation of poly(diethoxysiloxane) (PDES), and (3) fumed silica nanoparticles (FSN). After ambient temperature cure, tapping mode atomic force microscopy (TM-AFM) easily reveals near-surface FSN. For nanocomposites with higher PDES content, FSN surprisingly "disappear" after a further cure at 100 degrees C. The observation is explained by further condensation of extant siliceous fragments creating an amorphous reticular phase, which acts as a mechanical barrier between the FSN and the AFM tip.

Publication types

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

MeSH terms

  • Biocompatible Materials / chemistry
  • Dimethylpolysiloxanes / chemistry*
  • Microscopy, Atomic Force / methods
  • Nanotechnology / methods
  • Particle Size
  • Silicon Dioxide / chemistry*
  • Silicone Elastomers / chemistry*
  • Siloxanes / chemistry

Substances

  • Biocompatible Materials
  • Dimethylpolysiloxanes
  • Silicone Elastomers
  • Siloxanes
  • Silicon Dioxide