1st, put ur flask(open system) in liquid nitrogen bath for 10 mins. Never close ur flask when freezing, since liquid oxygen may explode!
2nd, attach the flask to lyophilizer overnight.
[ Last edited by aircraftvip on 2012-5-23 at 00:12 ]
you can try CLSM
In my opinion, SEM observation after freeze-drying of the gel is worthless. Nonporous hydrogels will also show porous structure after freeze-drying.
PS: If you want to see the structure of IPN, I don't think any microscopy can be used to observe this matter.