Nascent 'disentangled' block copolymers of Ultra-high Molecular Weight Polyethylene (UHMWPE) with a reduced number of entanglements were synthesized having protonated (hPE) and deuterated (dPE) PE blocks. Due to different melting temperatures of the block materials in our copolymers we expect to be able to separately change the entanglement density and crystallisation state (nascent or melt-crystallised) of each block. Both of these characteristics provide distinct scattering shapes allowing us to follow these changes, so that we will be able to see how the dPE and hPE blocks mix and entangle with each other as well as within their own regions. This gives new insight related to the question of how well long chains of deuterated and protonated polyolefins mix and, crucially, how this mixing is influenced by the density of entanglements and original crystalline structure of the polymer.