Greener Organic-Phase Selection for Interfacial Nylon 6,6 Synthesis under Controlled Fiber-Withdrawal Conditions

Abstract

Interfacial polymerization is a widely used technique in making nylon 6,6 by reacting aqueous 1,6-hexanediamine with adipoyl chloride in n-hexane solution that yields continuous polyamide film at the interface of these two immiscible solvents. N-Hexane, however, poses serious health and environmental threats, requiring less harmful substitutes. In this study, the ability of three alternative solvents, ethyl acetate, 2-methyltetrahydrofuran, and cyclopentyl methyl ether to replace n-hexane without considerable decrease in the efficiency of polymer formation or quality of fibers will be examined. The process will be carried out under controlled monomer concentrations, temperatures, volumes of phases and controlled motor withdrawal rate. The polymers obtained will be characterized based on dry yield, rate of fiber formation, linear density, tensile strength, elongation, and strand homogeneity. Polyamide formation will be confirmed through Fourier-transform infrared spectroscopy and its melting behavior and relative crystallinity will be assessed using differential scanning calorimetry. Moreover, each solvent will be evaluated for waste production, ability to be recovered, hazards, and other parameters characteristic for green chemistry. It will help understand how such characteristics of the solvent as polarity, water solubility, density and ability to dissolve monomers affect interfacial nylon formation. This study may help identify a less hazardous organic phase for the synthesis of nylon 6,6 while providing an alternative to the classic nylon rope experiment.