Even though it dates back already to 2002, this article still represents an excellent account both in tracing the evolution of the intra-European S&T co-operation and relating it to EU integration and EU external relations. Science diplomacy was not yet a prominent concept then (the term occurs only once in the article), but it maps all the important dimensions and ramifications of what we might refer to today as ‘EU science diplomacy’ with detailed knowledge.
Stein, J.A. (2002). Science, Technology and European Foreign Policy: European Integration, Global Interaction. Science and Public Policy, 29(6), pp. 463–477.