Thiourea-Based Polymers as Functional Materials: Synthetic Challenges, Supramolecular Design, and Emerging...

Thiourea-based polymers are an emerging class of functional materials characterized by strong directional hydrogen bonding, tunable polarity, and versatile supramolecular interactions. These features enable materials with adaptive mechanical behavior, molecular recognition capability, and environmental responsiveness. Despite their promise, the development of thiourea-functionalized polymers remains limited by persistent synthetic challenges, including poor solubility, competing side reactions, restricted architectural control, and difficulties in scalable processing. In addition, existing literature has largely focused on small-molecule thiourea systems, leaving polymer-level structure-property relationships insufficiently explored. This review critically examines recent advances in the design, synthesis, and functional applications of thiourea-based polymers, emphasizing structure-defining synthetic constraints, supramolecular organization, and materials performance. Strategies for incorporating thiourea motifs into polymer backbones, side chains, and cross-linked networks are discussed in relation to their influence on hydrogen-bonding networks, mechanical integrity, and environmental stability. Emerging applications in optoelectronic, separation, self-healing, and biomedical materials are highlighted, and key challenges and opportunities for sustainable design and scalable fabrication are identified.