Extremely crosslinked silicones  were prepared by the hydrosilylation reaction of two cyclic monomers, 1,3,5,7-tetramethylcyclotetrasiloxane (D4H) and 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasilxane (D4V), in the presence of ppm Kastedt's catalyst. The D4H/D4V network is UV/Vis transparent and thermally stable up to 500 �C. Compared to traditional silicone elastomers, these exhibit a high Young's modulus (1.29�0.04 GPa) and high hardness (0.337�0.02 GPa) according to nanoindentation results. Multiple additional mechanical tests also demonstrate the elasticity of this material. Atomic force microscopy reveals that the free surfaces of D4H/D4V silicone are �molecularly smooth� showing root mean square (RMS) roughness values of ~0.1 nm. This material is still as hydrophobic as silicone elastomers with water contact angles of TA /TR = 109�/92�.  The combination of low surface energy, transparency, hardness, elasticity and thermal stability make this an unusual and interesting material.

Rediscovering silicones, part 1, extremely crosslinked PDMS: A low surface energy, unfilled, UV/vis-transparent, thermally stable, molecularly smooth, hard, and elastic material

241st National Meeting (2011)

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