I would like share few suggestions regarding this problem
1. PLGA is one kind of organic polymer and this type of material has less contrast in side the TEM chamber due to their
poor conductivity for this need to use Lacey carbon TEM grid in order to enhance the better contrast.
2. If you want to take better image - Need use 200 kv field emission gun TEM at low resolution.
Hopefully this will work for all kinds of polymeric materials
With regards
Poliraju.K