The review article presented here comprehensively highlights the various fundamental aspects of polymer blends from molecular level miscibility to the evolution of bi-phasic morphology, under different processing conditions, that are essential for exploring their potential in membrane applications. It also compares and contrasts the existing practices in membrane development such as phase inversion, track etching etc., for alternative and economical strategies to develop novel membranes. The key role of rheology on the evolution of morphology during processing and post-processing operations such as compression molding, annealing etc. has been discussed under the framework of different techniques for the preparation of thin membranes. The different hierarchical porous structures (micro and nano), developed by selectively etching one of the components from binary blends, and their application in separation technology have been highlighted and the results have been compared against the existing solutions. The effect of various processing parameters and ratio of the blend component that decides the final morphology of the membrane has been discussed. The unimpeded permeation of fluids is discussed with respect to the different morphology that is generated during their fabrication and the reasons for their clogging, fouling etc. have been extensively discussed. Further, different strategies like in situ and ex situ strategies modification of the membrane surface have been discussed with respect to antibacterial and antifouling properties. The efficacies of various in situ and ex situ strategies to render the surface antibacterial is elaborated with respect to water purification applications. © 2018 Elsevier B.V.