Emerging research trends in the field of polyurethane and its nanocomposites: Chemistry, Synthesis, Characterization, Application in coatings and Future perspectives

Abstract

Polyurethane (PU) coatings are widely used in various industries due to their excellent mechanical strength, along with abrasion, chemical and weather resistance. Recently, use of dynamic bonds to increase the recyclability and self-healing properties of PU is being extensively explored. Incorporation of nanofillers into the PU matrix can further enhance their performance as a coating matrix for application demanding thermal stability, mechanical strength, abrasion resistance, corrosion resistance, foul resistance, smudge resistance and UV resistance. It has been reported that inclusion of nanofillers, like nano-silica, graphene, organoclay, zinc oxide and titanium dioxide can provide enhanced functionalities to the PU matrix owing to their small size and high surface area-to-volume ratio to design tailor made PU coatings with desired properties. This review highlights the classification of PUs based on different dynamic chemistry for imparting self-healing and recyclability properties to the polymer matrix. Further, it will also provide a detailed insight regarding various polyol sources used for the synthesis of PUs, technologies adopted to incorporate nanofillers into the PU matrix for developing PU nanocomposite for coating applications and properties associated with these coatings. A brief conclusion highlighting the present challenges and future prospects of the PU nanocomposite coatings is also presented. Graphical abstract: [Figure not available: see fulltext.].