Degradation of nanofiber layers made of biobased polyamide 4

Abstract

Based on renewable raw materials, polyamide 4 has excellent mechanical properties, high hydrophilicity, and cotton-like water sorption. The problem is its low thermal stability near its melting point, which does not allow melt processing. With the development of the technology of electrostatic spinning of polymers from solutions, the attention of researchers has returned to polyamide 4. In this work, nanofiber layers of polyamide 4 with molar masses of 18,000 and 280,000 g/mol and diameters of 350±60 and 270±10 nm, respectively, were prepared by electrostatic spinning from a mixed solution of formic acid and dichloromethane. Subsequently, the layers were subjected to degradation in phosphate buffer at 37 and 60°C. The electrostatic spinning process was shown to result in a decrease in the molar mass of the samples. During degradation in buffer at pH 7.4, the molar mass does not change significantly, but there is a change in the structure of the nanofibrous layers by bonding of the fibers, especially for low molecular weight PA4. In contrast to other studies, polyamide 4 is hydrolytically stable even in the form of nanofiber layers.