Mechanical properties and thermal stability of intermolecular-fitted poly(vinyl alcohol)/α-chitin nanofibrous mat

The major disadvantage of electrospun nanofibrous mats is their poor mechanical properties, which result from interfibrillar slips, porous structures, and the isotropic conformation of functional groups in fibers. In this work, we develop a tough electrospun mat without cost of both the stiffness and extensibility by combining two mutually exclusive polymers, i.e., generally "ductile" poly(vinyl alcohol) (PVA) and "stiff" α-chitin. The toughness of PVA/α-chitin is considerably higher (∼20 times) compared to PVA via intermolecular-fitted design and stoichiometric balance between hydrogen bonding donors and acceptors. Moreover, consistently oriented functional groups that are perpendicular to nanofibers improve mechanical properties. As a result, stiffness and extensibility are simultaneously increased by ∼19.3 and ∼3.8 times, respectively compared to PVA. The thermal stability with a 2.80-fold larger melting enthalpy of 823.95 ± 7.05 J g^-1 than PVA. The great thermomechanical performance provides an insight for molecular design in electrospun nanofibers with chitin polymorphs.