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  • 1 Department of Chemistry, Lehman College, City University of New York, Davis Hall, 250 Bedford Park Boulevard West, Bronx, NY, USA, 10468
  • 2 Department of Materials Science and Engineering, Rutgers University, 607 Taylor Road, Piscataway, NJ, 08854, USA
  • 3 Department of Chemistry, Rutgers University, Camden, NJ, 08102, USA
  • 4 Department of Chemistry, Temple University, Philadelphia, PA, 19122, USA
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Abstract

Hybrid melting gels were prepared by a sol–gel process, starting with a mono-substituted siloxane and a di-substituted siloxane, methyltrimethoxysilane (MTES) together with dimethyldimethoxysilane (DMDES). Five gel compositions were prepared with concentrations between 50% MTES–50% DMDES and 75% MTES–25% DMDES (in mol.%). The consolidation temperature, the treatment temperature after which the melting gel no longer softens, increased from 135 to 160 °C with a decrease in the amount of the mono-substituted siloxane. The glass transition temperature, recorded with differential scanning calorimetry, decreased from −0.3 to −56.7 °C with a decrease in the amount of the mono-substituted siloxane. When a sample was heat treated isothermally for 2 h at the consolidation temperature, the glass transition temperature increased by about 15°, indicating further crosslinking of the siloxane network.

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