Base-assisted elemental sulfur-based multicomponent polymerizations to synthesize asymmetric polythioureas

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Synthesis

Background:

• Polythioureas are versatile polymers with applications in materials recovery, electronics, and adhesives.
• Existing synthetic routes often rely on expensive, toxic monomers and struggle to produce diverse structures like asymmetric aromatic polythioureas.

Purpose of the Study:

• To develop a general, efficient, and versatile synthetic method for producing a wide range of polythioureas.
• To explore the structural diversity, properties, and potential applications of newly synthesized polythioureas.

Main Methods:

• A base-catalyzed multicomponent polymerization (MCP) reaction involving elemental sulfur, diisocyanides, and diamines.
• Synthesis of various aliphatic, aromatic, and semi-aromatic polythioureas, including asymmetric structures.
• Characterization of polymer properties such as molecular weight, thermal stability, and mercury ion absorption.

Main Results:

• The MCP method successfully produced polythioureas with high molecular weights (up to 107,700 g/mol) and yields (up to 99%).
• Aromatic polythioureas with varying aromatic spacers were synthesized, demonstrating structural tunability.
• The synthesized polythioureas showed high thermal stability (Tg 121–169 °C) and efficient Hg²⁺ absorption from polluted water, with aromatic variants performing best.

Conclusions:

• A novel and broadly applicable MCP approach enables the synthesis of diverse polythioureas.
• The dynamic covalent nature of thioureas allows for controllable degradation, enhancing sustainability.
• These polythioureas are promising functional materials for environmental remediation, particularly mercury removal.