I use PDMS to build a microfluidic system, but it is not hardening at all, although I use TEOS as a cross-linker and also ATPES in a ratio of 1:10, and it's been 3 days at 80 degrees of 3 ml cast on a glass slide.
Was the temperature consistent through out the period? Consider using higher temperature as it may accelerate the curing process If there is no progress at 80 degrees