Developments in the field of membrane science and specialty applications have given rise to track-etched membranes with nanochannels having broad ranges of functionality and versatile opportunities. This review is a compilation of the recent progress in methods and applications of grafting inside confined spaces in nanoscale. The emphasis has been made on functionalization of nanochannels of track-etched membranes. Selected current literature on track-etched membranes having nanochannels grafted with various polymers has been reviewed in terms of potential applications of the resulting membrane in the fields of biotechnology, energy and environment. (C) 2014 Elsevier Ltd. All rights reserved.