Oxidation of poly(1,3‐cyclohexadiene): Influence of the polymer chain structure

Abstract

The influence of the microstructure on the oxidation of poly(1,3‐cyclohexadiene) (PCHD) homopolymer, obtained by anionic polymerization with alkyllithium/amine systems, was investigated for the first time. PCHD has a structure consisting of a main chain formed by 1,2‐addition (the 1,2‐CHD unit) and 1,4‐addition (the 1,4‐CHD unit). The molar ratio of 1,2‐CHD/1,4‐CHD units in the polymer chain strongly influenced the extent of oxidation of PCHD. A polymer chain with a high content of 1,4‐CHD units was easily oxidized by air and 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ). In contrast, the progress of oxidation was prevented in the case of PCHD containing 52% of 1,2‐CHD units. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 837–845, 2006

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

“…In previous papers, [31,33,34] we revealed that the dehydrogenation of PCHD was strongly affected by the molar ratios of 1,2-CHD/1,4-CHD units. In addition, it was discovered that the degree of dehydrogenation could be controlled by the reaction conditions.…”

“…As described in previous papers, [31,33,34] this dehydrogenation reaction is an aromatization; therefore, the extent of dehydrogenation for PCHD (conversion from 1,2-CHD and/or 1,4-CHD units to 1,2-phenylene (1,2-Ph) and/or 1,4-phenylene (1,4-Ph) units) can be estimated by a decrease in olefinic signals (Ho at ca. 5.7 ppm, 2H per CHD unit) and an increase in aromatic signals for the Ph units (Hp at ca.…”

“…[31,33] b) Estimated from 1 H NMR spectra of pre-polymers. [31,32] Thermal Degradation of Poly(1,3-cyclohexadiene) and its Dehydrogenated Derivatives:. .…”

“…the conversion from 1,3-CHD to PCHD) for each sample was almost the quantitative yield (>99 wt.-%). The 1,2-CHD/ 1,4-CHD units molar ratios were estimated by 1 H NMR, [31,32] and the results are summarized in Table 1. Subsequently, in order to determine the thermal degradation of PCHD, thermogravimetric (TG) analysis was conducted for each polymer under a nitrogen atmosphere.…”

“…[12,19,29 -34] Recently, we investigated the influence of the molar ratio of 1,2-CHD/1,4-CHD units on the dehydrogenation of PCHD. [31,33,34] As a result, the synthesis and properties of completely dehydrogenated PCHD as a soluble polyphenylene (PPH) homopolymer were reported for the first time (Scheme 1). [33] Frey et al reported the thermal degradation of dehydrogenated PCHD, and the formation of weight residue (i.e.…”