A versatile, additive-free post-polymerisation functionalisation method for acyclic diene metathesis (ADMET) derived polymers, utilising 1,2,4-triazoline-3,5-dione (TAD) chemistry, is reported. Several diene monomers have been synthesised starting from 10-undecenoic acid derivatives and subsequently polymerised via ADMET polymerisation reaction. Post-polymerisation functionalisation of the poly-unsaturated macromolecules with several substituted TAD compounds was shown to achieve full conversions within 6 hours. Also, the functionalised polymers could be chemically crosslinked with a bivalent triazolinedione crosslinker. The glass transition temperature of the resulting materials could be tuned by varying the degree of functionalisation, the polymer backbone, the TAD substituent and the crosslinking density.