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

Official URL: https://dx.doi.org/10.1039/d2re00049k

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 ∼40 °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 (∼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 ∼50 °C or microwave-batch synthesis (MWB) at ∼44 and ∼50 °C is ineffective in preparing AgNPs, and only large AgNPs (>100 nm) are synthesised at 70 °C in the MWB reactor. PU-Ag NC films bearing small AgNPs (∼5 nm) exhibit superior antibacterial activity (>97%) against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus compared to large NPs (∼218 nm). The proposed method may manufacture other metal-polymer matrix composites.