A Review on Auxetic Polymeric Materials: Synthetic Methodology, Characterization and their Applications

Over the last three decades, there has been considerable interest in the captivating mechanical properties displayed by auxetic materials, highlighting the advantages stemming from their distinct negative Poisson's ratio. The negative Poisson's ratio observed in auxetic polymeric materials is a result of the distinctive geometries of their unit cells. These unit cells, encompassing structures such as chiral, re-entrant, and rotating rigid configurations, are carefully engineered to collectively generate the desired auxetic behaviour. This comprehensive review article explores the field of auxetic polymeric materials, offering a detailed exploration of their geometries, fabrication methods, mechanical properties, and characterisation. The diverse applications of these materials in impact/ballistic, acoustic, automotive, biomedical, sports, shape memory, strain sensors, electromagnetic shielding, smart filters, and rehabilitation fields are thoroughly examined. Furthermore, the article emphasises the significance of auxetic behaviour in enhancing mechanical performance while shedding light on the challenges and limitations associated with large-scale fabrication of auxetic materials.