'Satisfactory work' is fine. That's because 'satisfactory' is an adjective premodifying the noun 'work'.
'Work satisfactory' isn't really acceptable. It depends on whether 'work' is a noun or a verb.
Example: 'The manager thought the account clerk's work satisfactory.' In this case work is a noun so satisfactory is post modifying it.
But:
'He completes his work satisfactory' is not grammatically acceptable since here 'work' is a verb and verbs are modified by adverbs not adjectives so you should use 'satisfactorily'.