Step-growth acyclic diene metathesis (ADMET) polymerization chemistry followed by exhaustive hydrogenation offers a new alternative in modeling ethylene/1-hexene (EH) copolymers. In contrast to chain-growth chemistry, this new approach produces well-defined, defect-free primary structures. This report describes the synthesis, characterization, and thermal behavior of ADMET-produced polyethylene materials containing either precisely or irregularly spaced butyl branches, the latter to serve as models for ethylene/1-hexene copolymers made via chain-growth chemistry. The thermal behavior of the new materials was studied using differential scanning calorimetry, and detailed NMR and IR analyses permitted the characterization of the primary structures. Properties of the here presented ethylene/1-hexene copolymers models can be varied from semicrystalline to fully amorphous by precise control of comonomer content and spacing.