Hydrocarbon permselective membranes comprising of Poly (dimethylsiloxane) (PDMS) with Zeolitic Imidazole Framework (ZIF)-8 nanocrystals have been explored. ZIF-8dPDMS membranes of different ZIF-8 loadings were prepared in different solvents. The polymer chain conformations were observed by Ornstein-Zernike model fit to their small-angle neutron scattering profiles. The chain conformations were found to be varied for the membranes with different ZIF-8 loadings. The Debye-Anderson-Brumberger model showed larger scattering domains for the ZIF-8dPDMS membranes prepared in toluene than the membranes prepared in n-heptane. The membrane (toluene) of optimal ZIF-8 loading exhibited ~60% increment of hydrocarbon permeability but ~2% increment of N₂ permeability as against ~300% increment of hydrocarbon permeability and >30% of N₂ permeability for the membrane (nheptane) of the similar ZIF-8 loading. This different phenomenon of hydrocarbon permeability enhancement for the membranes with the ZIF-8 loading can be attributed to their different membrane nanostructures.