Poly(hexamethylene biguanide) hydrochloride (PHMB)-based materials: synthesis, modification, properties, determination, and application

As one of the major derivatives of biguanides, poly(hexamethylene biguanide) hydrochloride (PHMB) is a well-known commercially available polycationic antiseptic and disinfectant. PHMB is the hydrochloride salt of an amino polymer composed of an average of 12-16 biguanide groups separated by hydrophobic hexamethylene segments in the main chain. As a result, PHMB combines the advantageous characteristics of the biguanide group and polymeric polyelectrolyte. Currently, PHMB is regarded as a versatile biguanide-containing cationic polyelectrolyte, thus having a wide range of application prospects such as photoelectrical devices, gene delivery, clean coloration, CO₂ capture, and uranium recovery, as well as the well-accepted antimicrobial behavior. More interestingly, PHMB exhibits a remarkable ability to overcome charge screening limitations caused by inorganic salts when used for flocculating wastewater. Even though PHMB has been extensively reviewed in terms of its antimicrobial/antiviral activity and clinical applications over the past few decades, a comprehensive review on the synthesis, modification strategies, quantitative determination, and applications of PHMB in recent years is still lacking. Herein, we for the first time present a timely review to give a panoramic view of PHMB covering these aspects. The review article presented here may shed light on a more rational exploration of PHMB-based materials for various applications.