Polybutadiene modified by epoxidation. 1. Effect of polybutadiene microstructure on the reactivity of double bonds

Designed Monomers and Polymers

Hajifatheali

2011

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.

Section: H-nmr Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Designed Monomers and Polymers

Hajifatheali

2011

“…According to our obtained results from spectra, the findings are similar to previously reported data by elsewhere [28] . In addition, the assignment of cis, trans and vinyl epoxy groups in the epoxidized products were based on the data reported by Gemmer and Golub [29] and Zuchowska [30] . A comparison of epoxidized and unepoxidized HTPB in the 1 HNMR spectra showed that signals at 5.3 ppm, 5.4 ppm, 4.9 and 5.6 were pertained to cis, trans, and vinyl double bonds, respectively.…”

Section: Characterization Of the Epoxidized Polymersmentioning

confidence: 99%

Cloisite 15Aº nanoclay as an effective PTC for the epoxidation of hydroxyl terminated polybutadiene (HTPB)

Nataj

2014

Polímeros

A simple method is reported for the epoxidation of hydroxyl-terminated polybutadiene (HTPB) by using in-situ generated dimethyl dioxirane (DMD) as an oxidant and Cloisite 15Aº nanoclay as a phase-transfer catalyst (PTC). In order to find the optimum reaction conditions, real time analyses of the products as well as epoxidation progress, followed by 1HNMR and FTIR techniques at various reaction times and different PTC concentrations, were done. Obtained data revealed the selectivity of DMD/ Cloisite 15Aº in predominant cis double bonds epoxidation in comparison with trans and pendant vinyl functional groups.

“…The assigning of cis, trans and vinyl epoxy groups was based on data reported by Akcelrud et al [5], Zuchowska [9] and Gemmer and Golub [23]. By the comparison of the peak areas for epoxy protons at 2.7 and 3.0 ppm with the unreacted one, it was found that the absorption at 2.7 ppm was related to the trans, whereas the one at 3.0 ppm was related to the cis epoxy protons, respectively (Fig.…”

Section: Characterization Of the Epoxidized Htpbmentioning

confidence: 99%

“…Modification of the HTPB moiety in HTPB-based polyurethane membranes has been reported by using in situ-generated peracid and products spectra analysis indicated the formation of undesired side-products [7,8]. Other organic peracids and peroxy acids often show significant side-reactions and gelation at high epoxidation levels, due to presence of unreacted acids that cause ringopening of epoxy groups [9]. To overcome these problems, attempts have been made to epoxidation of double bonds with in situ-generated DMD [10 -13].…”

Section: Introductionmentioning

confidence: 99%

Chemoselective epoxidation of hydroxyl-terminated polybutadiene (HTPB) using in-situ generated dimethyl dioxirane (DMD)

Designed Monomers and Polymers

Mozaffari

2007

Abstract-In this report hydroxyl-terminated polybutadiene (HTPB) was functionalized to epoxidized HTPBs containing various epoxide group moieties by using in situ-generated dimethyl dioxirane (DMD) as oxidant and tetra-n-butyl ammonium bromide as a phase-transfer catalyst (PTC) in convenient, simple and mild conditions. The system shows to be sensetive to electronic, steric and chain microstructure factors and reveals the high reactivity of cis in comparison with trans and vinyl double bonds. 1 H-NMR, 13 C-NMR and FT-IR spectra analysis of the products reveal that no significant side reactions take place in this system even at high epoxidation levels. Influences of various factors, i.e., reaction time and the PTC concentration were investigated in detail. Also, it was found that double bonds oxidized chemoselectively in comparision with terminal hydroxyl groups.