Terminal functionalized hydroxyl-terminated polybutadiene: An energetic binder for propellant

Abstract

We report the functionalization of hydroxyl terminated polybutadiene (HTPB) backbone by covalently attaching 1-chloro-2, 4-dinitrobenzene (DNCB) at the terminal carbon atoms of the HTPB. The modification of the HTPB by the DNCB does not alter the unique physico - chemical properties and the microstructure of the parent HTPB. IR, 1H-NMR, 13C-NMR, size exclusion chromatogra-phy (SEC) and absorption spectroscopy studies prove that the DNCB molecules are covalently attached to the terminal carbon atoms of the HTPB. The p electron delocalization owing to long polymer chain, strong electron withdrawing effect of the DNCB molecule are the major driving forces for the covalent attachment of the DNCB at the terminal carbon atom of the HTPB. We are the first to observe the existence of intermolecular hydrogen bonding between the terminal hydroxyl groups of the HTPB. IR study shows that the attached DNCB molecules at the terminal carbon atoms of the HTPB breaks the intermolecular hydrogen bonding between the HTPB chains and forms a hydrogen bonding between the NO2groups of the DNCB and the OH groups of the HTPB. Absorption spectral study of the modified HTPB indicates the better delocalization of p electron of butadiene due to the strong electron withdrawing effect of the DNCB molecules. Theoretical calculation also supports the existence of hydrogen bonding between the OH and NO2groups. Theoretical calculation shows that the detonation performance of both the DNCB and the HTPB-DNCB are promising. HTPB-DNCB is the new generation energetic binder which has potential to replace the use of HTPB as binder for propellant. © 2009 Wiley Periodicals, Inc.