Kinetic and Mechanistic Insights into Thermally Initiated Polymerization of Cyanate Esters with Different Bridging Groups

Abstract

This study investigates the kinetics of thermally initiated polymerization of aryl cyanates with different bridging fragments ((CH3)2C, S, and O). To minimize the effect of impurities on the kinetics, the aryl cyanates are synthesized in a highly pure form. The rates of polymerization are measured by differential scanning calorimetry (DSC) and treated by an advanced isoconversional method. The DSC measurements indicate that the ((CH3)2C‐ and S‐bridging monomers have, respectively, the lowest and highest reactivities. The observed variation of the activation energy with conversion and temperature is determined to be in agreement with the two‐step kinetic model by Kamal. Estimating the parameters of the Kamal model has provided mechanistic insights into the polymerization process. The enhanced reactivity of the S‐bridged monomer is found to be associated with acceleration of the first step that demonstrates an increased value of the preexponential factor. The acceleration is linked to higher polarizability of this monomer that can promote stronger intermolecular interaction and preferred orientation of the reacting species.

A Promising Energetic Polymer from Posidonia oceanica Brown Algae: Synthesis, Characterization, and Kinetic Modeling

“…Kinetic parameters (activation energy, pre‐exponential factor, and mathematical reaction mechanism) from non‐isothermal data can be computed by isoconversional and non‐isoconversional procedures . However, it was reported by several authors that utilizing isoconversional methods conducts to more effective kinetic parameters compared to non‐isoconversional approaches as recommended by the international confederation for thermal analysis and calorimetry (ICTAC) …”

“…[43][44][45] However, it was reported by several authors that utilizing isoconversional methods conducts to more effective kinetic parameters compared to non-isoconversional approaches as recommended by the international confederation for thermal analysis and calorimetry (ICTAC). [46,47] To the best of author's knowledge, no work has been carried out to produce cellulose nitrate and MCCN from POBA-C and POBA-MCC, respectively, and their comparison with traditional NC from cotton and MCCN from commercial MCC. Hence, this current study aimed to exploit POBA leaves largely available in Algeria as raw material to isolate cellulose and microcrystalline cellulose and access their suitability as polymer precursor to synthesize NC and MCCN via sulfonitric nitration process.…”

Interpretation and Physical Meaning of Kinetic Parameters Obtained from Isoconversional Kinetic Analysis of Polymers

“…A higher reactivity of a sulfur-bridged monomer compared to its carbon-bridged analog was found. This was explained by the larger value of the pre-exponential factor for the metal-catalyzed step of the reaction, due to a higher polarizability that induces a stronger intermolecular interaction between molecules and promotes preferred orientation of the reacting monomers [ 24 ].…”

Polymerization Kinetics of Cyanate Ester Confined to Hydrophilic Nanopores of Silica Colloidal Crystals with Different Surface-Grafted Groups

“…Ammonium hydroxide solution (25% of NH 3 , TatChemProduct, Kazan, Russia), tetraethylorthosilicate (TEOS, >99.9%, ALDRICH Chemistry, Saint Louis, MI, USA), tetrabutylammonium hydroxide solution (40% in water, Fluka Analytical, Saint Louis, MI, USA), 1,3-propanesultone (98%, ALDRICH Chemistry, Saint Louis, MI, USA), bisphenol E (>98%, TCI, Zwijndrecht, Belgium), phosphorus pentoxide (99%, Vecton, Saint Petersburg, Russia), n -hexane (>98%, EKOS-1, Moscow, Russia), toluene (99.5%, EKOS-1, Moscow, Russia), and tetrahydrofuran (THF, >98%, ChemMed, Kazan, Russia) were purchased and used without additional purification. Bisphenol E cyanate ester of purity 99.5% was synthesized according to the previously described synthetic procedure ( Figure 1 ) [ 32 , 33 ]. The purity of synthesized monomer was no less than 99.5% according to high-performance liquid chromatography (HPLC).…”

“…This model was used because of its ability to imitate the autocatalytic kinetics which appears to be characteristic of the cyanate esters polymerization [ 42 ]. Furthermore, this model is similar to the Kamal reaction model [ 43 ], which has been used successfully to treat the kinetics of cyanate ester polymerization [ 32 , 44 ].…”