A family of precision ethylene/vinyl chloride polymers synthesized via acyclic diene metathesis (ADMET) followed by exhaustive hydrogenation is described in which chlorine atoms are present on each and every ninth, 15th, and 21st carbons, respectively, in the series. Detailed H-1 NMR and C-13 NMR experiments are used to establish the precise nature of the polymers and assign absolutely the observed NMR signals to the corresponding atoms in the precise repeat unit. Thermal analysis via TGA and DSC is also presented. Decomposition behavior measured by TGA indicates a distinct mechanism for decomposition for these precise polymers relative to PVC and random EVC polymers, highlighted by an enhanced stability to thermal HCl loss induced by inhibition of the cooperative zipper mechanism for HCl found in PVC. A homopolymer-like crystallization and melting behavior is inferred from sharp DSC peaks, indicative of a precise polymer structure in which long chain segments, incorporating the halogens, build the core crystal, as opposed to the sequence selection mechanism that operates in random EVC polymers.