I think there should be a comma before "and vice versa".
While a person with more subject area knowledge might have taken your intended meaning, I read it as "In an oil-water system, if the particle contact angle is larger than 90°, showing greater affinity for the oil phase, then the system is likely to be a W/O emulsion, and if the system is a W/O emulsion, then it is likely that the particle contact angle is larger than 90°". The term "vice versa' generally refers to reversing between the terms, not reversing within the terms. So I think it's not so much that "vice versa" in general is inappropriate in academic writing as that you are not using the term correctly.
A correct formulation would be "An oil-water system with a particle contact angle larger than 90°, and one with angle less than 90°, are, respectively, likely to be a W/O emulsion, and an O/W emulsion". Or "In an oil-water system, larger contact angles show greater affinity for the oil phase, and crossing from less than 90° to greater than marks a transition from O/W emulsion being more likely to W/O being so."