The present work provides an ideal model for intra-chain energy transfer study in conjugated polymer through shielding the polymer backbone by using bulky polyhedral oligomeric silsesquioxanes (POSS). POSS provides a circumference shielding of the polymer backbone to prevent closed packing of the polymer chains, allowing the intra-chain energy transfer dominating in large concentration range. Bi-functional POSS (B-POSS) is specially designed to separate donor (fluorene) and acceptor (benzothiadiazole) within the polymer chain. The dynamics of energy transfer in poly(fluorene-POSS-alt-POSS-benzothiodiazole) (PTBtTbOFl(3)) is studied by steady state as well as time resolved fluorescence spectroscopy at different donor/acceptor ratios. Results reveal that POSS can effectively shield inter-chains energy transfer of the polymers, suggesting it is an effective model for energy transfer study with less inter-chains effects. PTBtTbOFl(3) works as a chemosensors is also reported in the detection of explosive derivatives. These results provide insights for optimizing nanostructured materials for use in optoelectronic devices. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1225-1233