Modelling the kinetics and structural property evolution of a versatile reaction: aqueous HCN polymerization

Area of Science:

• Polymer Chemistry
• Materials Science
• Prebiotic Chemistry

Background:

• Hydrogen cyanide (HCN) polymers have potential applications in high-performance coatings and adhesives with biomedical uses.
• The synthesis of HCN polymers in aqueous media at high temperatures is relevant to both origin-of-life studies and materials science.
• Previous research indicated the potential of HCN polymers, necessitating kinetic analysis for development.

Purpose of the Study:

• To analyze the kinetics of HCN polymerization in an aqueous medium at high temperatures.
• To identify a suitable kinetic model for the formation of insoluble HCN polymers.
• To determine kinetic parameters and understand the reaction mechanism for potential industrial scale-up.

Main Methods:

• Gravimetric measurements were used to study the precipitation polymerization of HCN in water under isothermal conditions (75-90 °C).
• The Kamal-Sourour autocatalytic kinetic model was applied to describe the polymerization process.
• Isoconversion methods were employed to analyze activation energy variations, complemented by elemental analysis, FTIR, and SEM characterization.

Main Results:

• The Kamal-Sourour model effectively described the overall formation of the insoluble HCN polymer.
• Key kinetic parameters, including reaction orders, kinetic constants, and activation energy, were determined.
• A significant autocatalysis effect was observed, indicating a robust and straightforward polymerization process.

Conclusions:

• The aqueous HCN polymerization is autocatalytic, robust, and heterogeneous, making it suitable for materials science applications.
• This study provides the first systematic kinetic analysis of HCN polymerization, deepening the understanding of this complex reaction.
• The findings bridge interests in prebiotic chemistry and the development of novel materials for coatings and adhesives.