Microwave-promoted continuous flow synthesis of thermoplastic polyurethane-silver nanocomposites and their antimicrobial performance

Abstract

Thermoplastic polyurethane-silver nanocomposites (PU-Ag NCs) have considerable potential in many medical applications due to their superior mechanical and antimicrobial properties. Herein, a microwave-promoted flow system is successfully employed for continuous in situ manufacturing of PU NCs having spherical silver nanoparticles (AgNPs) without any reducing agent at similar to 40 degrees C in approximately 4 minutes. The main experimental parameters, including microwave power, metal salt concentration, polymer concentration, and flow rate, are optimised for the reproducible synthesis of AgNPs (similar to 5 nm) in the PU matrix, characterised by HRTEM-EDS and DLS analysis. XRD patterns indicate an increase in PU crystallinity with decreased particle size. Conventional heating flow synthesis at similar to 50 degrees C or microwave-batch synthesis (MWB) at similar to 44 and similar to 50 degrees C is ineffective in preparing AgNPs, and only large AgNPs (>100 nm) are synthesised at 70 degrees C in the MWB reactor. PU-Ag NC films bearing small AgNPs (similar to 5 nm) exhibit superior antibacterial activity (>97%) against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus compared to large NPs (similar to 218 nm). The proposed method may manufacture other metal-polymer matrix composites.