Functionalization of terminal carbon atoms of hydroxyl terminated polybutadiene by polyazido nitrogen rich molecules

Abstract

We report a novel synthetic approach for the attachment of the polyazido nitrogen rich molecule on to the hydroxyl terminated polybutadiene (HTPB) backbone. The terminal carbon atoms of the HTPB are functionalized by attaching cyanuric chloride (CYC) covalently on the HTPB backbone. Further reaction of this modified HTPB with sodium azide yields polyazido nitrogen rich HTPB. The unique physico-chemical properties and the microstructure of the HTPB do not get affected upon modification. IR, gel permeable chromatography (GPC) and absorption spectroscopy studies prove that the polyazido nitrogen rich molecules are covalently attached at the terminal carbon atoms of the HTPB. The π electron delocalization owing to long butadiene chain, strong electron withdrawing effect of the triazine molecules are the major driving forces for the covalent attachment of the triazine at the terminal carbon atoms of the HTPB. The disruption of the intermolecular hydrogen bonding between the terminal hydroxyl groups of the HTPB chains and the presence of hydrogen bonding between the N atoms of the triazine ring with OH group of the HTPB are observed. Theoretical study also reveals the existence of the hydrogen bonding between the OH and N. Theoretical calculation shows that the detonation performance of the polyazido nitrogen rich HTPB are very promising.

Triazine functionalized hydroxyl terminated polybutadiene polyurethane: Influence of triazine structure

“…Synthetic procedure used in this work for the modification of HTPB to produce HTPB-CYC, HTPB-CBDT and HTPB-DT are similar to our previous report [44,45]. The characterization of these samples were carried out using spectroscopic technique and found to be matching well with our earlier results.…”

“…sodium azide and dimethyl formamide to synthesize HTPB-DT and HTPB-CBDT, respectively as per our previously reported procedures [44,45]. Scheme 1 shows the chemical structures of HTPB and all three modified HTPBs.…”

“…7). All the pre-polymers have two bands one is at 280 nm corresponding to p / p * transition of trans microstructure of parent HTPB backbone other one is at 230e240 nm which is from combination of microstructure of parent HTPB backbone and triazine moiety [44,45]. It is clear that all these absorption peaks are shifted towards higher wavelengths in PUs.…”

“…CBDT is an important biologically active molecule and fluorescence active. CDT is a promising energetic molecule having density equal to TNT (1.64 g/cc), and higher detonation pressure (21.75 GPa) and velocity of detonations (7.21 km/s) [44]. We have prepared PUs from these three modified HTPB based diols with various diisocyanates and studied their mechanical properties.…”

Self Assembly in Functionalized Butadiene Based Polyurethanes

“…For this, we have selected dinitrochlorobenzene (DNCB), cyanuric chloride (CYC), 2‐chloro‐4, 6‐bis (dimethylamino)‐1, 3, 5‐triazine (CBDT), 1‐chloro3, 5‐diazido‐2, 4, 6‐ triazine (CDT) to modify the HTPB backbone by attaching these functionalities on the terminal carbons of HTPB to obtain terminal functionalization. These four terminally functionalized HTPB molecules contain aromatic and heterocyclic aromatic rings having different substituents with varying nature . Polyurethanes were synthesized utilizing these four terminally functionalized HTPB diols with various diisocyanates.…”