Oxidation and epoxidation of poly(1,3‐cyclohexadiene)

Abstract

Poly(1,3-cyclohexadiene) (PCHD) derivatives were synthesized via facile chemical modification reactions of the residual double bond in the repeat unit. The oxidation and degradation of PCHD was investigated to enable subsequent controlled epoxidation reactions. PCHD exhibited a 15% weight loss at 110°C in the presence of oxygen. The oxidative degradation, demonstrated by gel permeation chromatography (GPC) and 1 H NMR spectroscopy, was attributed to main-chain scission. Aldehyde and ether functional groups were introduced into the polymer during the oxidation process. PCHD was quantitatively epoxidized in the absence of deleterious oxidation with meta-chloroperoxybenzoic acid. 1 H and 13 C NMR spectroscopy confirmed that polymers with controlled degrees of epoxidation were reproducibly obtained. Epoxidized PCHD exhibited a glass-transition temperature at 154°C, which was slightly higher than that of a PCHD precursor of a nearly equivalent molecular weight. Moreover, GPC indicated the absence of undesirable crosslinking or degradation, and the molecular weight distributions remained narrow. The thermooxidative stability of the fully epoxidized polymer was compared to that of the PCHD precursor, and the epoxidized PCHD exhibited an initial weight loss at 250°C in oxygen, which was 140°C higher than the temperature for PCHD.

Thermal Degradation of Poly(1,3‐cyclohexadiene) and its Dehydrogenated Derivatives: Influence of a Controlled Microstructure

“…[35] For PPH-1, a gradual thermal degradation process was observed, and the weight residue for PPH-1 was approximately 55 wt.-% at 800 8C. On the other hand, a two-stage thermal degradation process was observed for PPH-3, with approximately 10% weight loss in the first stage.…”

“…[35] The second stage degradation occurred in the region between 310 and 370 8C and the third stage degradation between 370 and 600 8C. The remaining PCHD was completely decomposed and consumed at 600 8C.…”

“…[2] However, the dehydrogenated polymer was obtained by chlorination and pyrolysis procedures, and it was insoluble in all solvents due to an uncontrolled polymer chain. Long et al reported the mechanism of thermal degradations of PCHD [35] and dehydrogenated PCHD-polystyrene (PSt) copolymer. [36] However, to date, there has been no report for the thermal degradation of a soluble dehydrogenated PCHD homopolymer.…”

Hydrocarbon-based fuel cell membranes: Sulfonated crosslinked poly(1,3-cyclohexadiene) membranes for high temperature polymer electrolyte fuel cells

“…Assignment of thermal mass loss events based on related reported work [16,31] is as follows: For all samples, except unsulfonated XPCHD, there is mass loss of~5e20% at about 95 C. This initial loss is believed to be due to polymer chain depolymerization, which proceeds until more thermally stable units on the polymer backbone are reached [16]. The remaining backbone remains thermally stable until 200 C, after which more depolymerization takes place.…”

Spontaneous Generation of Giant Liposomes from an Oil/Water Interface

“…In addition, we revealed that the n ‐BuLi/TMEDA and s ‐BuLi/DABCO systems produced a high content of 1,2‐CHD units and 1,4‐CHD units in the polymer chain, respectively. After our discovery of those initiator systems, many researchers have studied these initiator systems in an attempt to further improve them 24–32. Until now, the n ‐BuLi/TMEDA and s ‐BuLi/DABCO systems are still the most effective initiator systems for the anionic polymerization of 1,3‐CHD.…”