Decamethylcyclopentasiloxane (D5)

D5 has a lower vapor pressure (~28 Pa at 25°C) than D4 (~133 Pa), giving a slower, more controlled evaporation rate. In dry-film release coatings and slip additives, D5 acts as a volatile carrier that deposits a thin silicone layer on the substrate surface as it evaporates, without leaving sticky residue. D4 evaporates too quickly for some applications, leaving insufficient time for surface orientation. D5 is also preferred as an intermediate for high-MW silicone resins via cationic ROP because its larger ring size gives lower ring strain, producing narrower PDI distributions under mild conditions.