Eco-friendly cyclam based coatings for biofouling prevention

Inês Maria Maia Nunes

Key information

Authors:

Inês Maria Maia Nunes (Inês Maria Maia Nunes)

Supervisors:

Elisabete Ribeiro Silva Geraldes; Luís Gonçalo Andrade Rodrigues Alves (Luís Gonçalo Andrade Rodrigues Alves)

Published in

01/20/2021

Abstract

Cyclam derivatives were synthesised, characterized, and incorporated into polyurethane-based coating formulations to create an alternative system for water bio-decontamination. The results showed that despite the proved antimicrobial potential of the cyclam-based antimicrobials, and those to be incorporated in silicone-based coatings to originate antimicrobial coatings, their behaviour changed after their incorporation in polyurethane (PU)-based formulations. PU coatings containing cyclam derivatives did not evidence significant antimicrobial effects against Methicillin-resistant Staphylococcus aureus and Escherichia coli. The lack of activity was associated with the high compatibility of the cyclam structural functionality that promoted their strong chemical binding with the polymeric coating matrix. Reactivity studies of the cyclam-derived compounds with 4,4’-methylene diphenyl diisocyanate (MDI), a representative isocyanate-based component of a PU-based formulation, revealed the formation of urethane- and urea-type bonds depending on the functionality of the pending arm present in the cyclam ring. This chemical compatibility of cyclam derivatives with polyurethane matrices also promoted their effective immobilization, avoiding any leaching of cyclam derivatives from submerged coated substrates into waters after a 45 days immersion period.