Nanoclay-Mediated Epoxidation of HTPB Using In-Situ-Generated Dimethyl Dioxirane

Abstract

This paper reports on the epoxidation of hydroxyl-terminated polybutadiene (HTPB) using in-situ-generated dimethyl dioxirane (DMD) as an oxidant and nanoclay as a phase-transfer catalyst (PTC) at 25 • C. The aim was to consider in detail the functionality of isomeric C=C bonds under different reaction circumstances combining reaction time and different percentages of PTC/oxone (w/w). The data revealed the selectivity in the oxidation of cis double bonds in comparison with trans and vinyl ones. The products were characterized using 1 H-NMR, 13 C-NMR and FT-IR; no side-reactions were observed. In addition, it was found that the hydroxyl group of the polymer chain remained unaffected in the epoxidation reaction although no conditional controls were implemented. It was proven that this method is easy and convenient and that the reaction conditions are straightforward.

Chain Extension, Phase Interface Reparation and Mechanical Property of Recycled Acrylonitrile‐Butadiene‐Styrene by Epoxidized Styrene‐Butadiene‐Styrene

“…The peaks at 2.95 and 2.92 ppm are related to the cis ‐epoxy hydrogen atoms. The peaks at 2.72 and 2.69 ppm are related to the trans ‐epoxy hydrogen atoms, [ 50,52 ] while the peak of hydrogen atom for the by‐product methyl ester in ESBS is at 2.21 ppm. The reaction mechanism diagram is shown in Figure 2.…”

“…The mechanism of SBS epoxidation is shown in Figure 2a. [52,53] The ester group and hydroxyl group were produced from the side reaction between epoxy group and formic acid. The strong peak at 1236 cm −1 is due to the vibration absorption of the ether bond.…”

Catalytic performances of copper and lead (2-guanidino-benzimidazoliume) complexes in polybutadiene (PB) and hydroxyl-terminated PB epoxidation

“…Utilizing catalysts in the epoxidation of olefins, mainly metal catalysts such as metal salts, and complexes have become a significant research area in organic synthesis over the last decade. We have previously epoxidized PB and HTPB using in situ-generated DMD with different catalysts: tetra-n-butyl ammonium bromide as a phase-transfer catalyst (PTC), 14,15 molybdenum trioxide, 16 transition metal salts, 17 Cloisite 30B as a PTC, 18,19 nano titanium dioxide, 20 and copper (Cu/2,2 0 -diamino-4,4 0 -bithiazole complex. 21 For the current study, we determined to epoxidize PB and HTPB using Cu/2guanidinobenzimidazoliume (GBH) and lead (Pb)/GBH complex as catalyst.…”