Kinetic analysis of polydicyclopentadiene oxidation

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. b s t r a c tThe in situ thermal oxidation of thin unstabilized polydicyclopentadiene was studied by TGA to monitor mass gain, and DSC to characterize hydroperoxides concentration. Results were discussed using kinetic analysis, which allowed the estimation of activation energies for key reactions of the oxidation process. Activation energy for termination was shown to be higher than in hydrocarbon liquids, which was discussed from the theory of diffusion controlled reactions, and a possible link with local motions associated with sub-glassy transition. Activation energy of thermal decomposition of hydroperoxides was found lower than for model hydroperoxides, suggesting an accelerating effect of organometallic catalysts. Despite those two results that indicate a poor thermal stability of thin pDCPD films, measurements of oxygen diffusivity at several temperatures show that oxidation remains confined in a relatively thin surface layer which would allow the pDCPD properties to be preserved.

Air Activated Self‐Decontaminating Polydicyclopentadiene PolyHIPE Foams for Rapid Decontamination of Chemical Warfare Agents

“…Figure b depicts the hydroperoxide concentration (mol kg −1 ) over time; initially, hydroperoxide content increases rapidly in the first week reaching a maximum of 1.73 mol kg −1 at 7 d before slowly decreasing to half of its original level at the last time point collected, day 65. Other studies investigating thin films of polyDCPD exhibit similar trends, a peroxide maximum followed extended period of decrease, if only at shorter time‐scales due to utilization of higher temperatures and/or pure oxygen atmospheres . Temperature and atmospheric composition plays an important role in the kinetics and accumulation of peroxide species in pDCPD networks .…”

“…Over a period of two months thermal analysis and gravimetric measurements of pDCPD 89 foams were performed as the samples aged under ambient conditions. Figure a indicates an average percent mass increase of 38% for pDCPD 89 foams due to the accumulation of oxygen species, with the majority of the increase occurring in the first 10 d. Previous work by Defauchy et al and Richaud et al demonstrated that hydroperoxide content of polymers, including polyDCPD, may be measured using DSC . During heating, the decomposition of hydroperoxide has a characteristic exotherm centered at 140 °C (Figure S5, Supporting Information); the concentration of hydroperoxide in the foam could be ascertained by integrating this exotherm and dividing by the decomposition enthalpy (Δ H OOH = ≈440 kJ mol −1 ) .…”

“…The average mass percent gain of the five independent samples of aged foams was measured using the microbalance of a Discovery TGA thermogravimetric analyzer (TA Instruments). Thermal analysis of hydroperoxide content was performed using a Discovery DSC (TA Instrument) equipped with TRIOS software; hydroperoxide concentration (mol g −1 ) was estimated using a previously reported Δ H OOH = 440 kJ mol −1 . Approximately 2–4 mg disc‐shaped samples (4.5 × 1.5 mm) of unaged or aged polyDCPD foam were sealed in Tzero aluminum pans and heated from 30 to 300 °C at a rate of 10 °C min −1 under a N 2 ‐purged atmosphere.…”

“…Recently, Kovacic et al demonstrated the ring‐opening metathesis polymerization (ROMP) of polyHIPE monoliths composed of dicyclopentadiene and norbornene; the polydicyclopentadiene (polyDCPD) polyHIPEs exhibited impressive mechanical properties and demonstrated utility as porous scaffolds for the in situ synthesis of zinc‐ and copper‐based MOFs . Interestingly, polyDCPD exhibits fast oxidation kinetics that results in the accumulation of stable oxidization species (e.g., hydroperoxide) . In general, polyolefins are susceptible to peroxide formation and oxidized polypropylene has previously demonstrated reactivity toward alkyl sulfides …”

“…[40][41][42][43] Interestingly, polyDCPD exhibits fast oxidation kinetics that results in the accumulation of stable oxidization species (e.g., hydroperoxide). [44,45] In general, polyolefins are susceptible to peroxide formation [46][47][48] and oxidized polypropylene has previously demonstrated reactivity toward alkyl sulfides. [46] Herein, this unique oxidation chemistry of polyDCPD is exploited to react and decontaminate sulfide-containing CWA simulants: Demeton-S and 2-chloroethyl ethyl sulfide (CEES).…”