Janus film based on konjac glucomannan with excellent flame retardancy enhanced by hollow glass microspheres

developing green packaging materials that combine degradability and flame retardancy has become an urgent need for industry development. In this work, a novel asymmetric superhydrophobic/hydrophilic Janus flame retardant film (CA-KGM-HGM) was developed by introducing hollow glass microspheres (HGM) into a mixed system of chitosan (CA) and konjac glucomannan (KGM) through physical blending. The experimental results showed that HGM forms a dense physical barrier in the konjac glucomannan matrix to enhance the flame retardancy of the film. The peak heat release rates of CA-KGM film and CA-KGM-HGM film were 127.28 W/g and 60.24 W/g, respectively. In addition, the prepared flame retardant packaging film not only has excellent flexibility, no cracks after folding, and can restore its original state, but also exhibits special properties of hydrophobicity on the upper surface and hydrophilicity on the lower surface. Furthermore, the CA-KGM-HGM film exhibits excellent biodegradability and can be completely degraded in natural soil within 15 days. CA-KGM-HGM film solves the flammability and poor biodegradability problem of traditional packaging film materials and has potential applications in the fields of food and electronic packaging.