Journal article

Atomic Force Microscopy and Angular-Dependent X-ray Photoelectron Spectroscopy Studies of Anchored Quaternary Ammonium Salt Biocides on Quartz Surfaces

Rachel T Mathew, Ralph P Cooney, Jenny Malmstrom, Cohn S Doyle



A siloxane surface-anchored quaternary ammonium salt (AQAS: BIOSAFE HM4100 in this study) has been chemisorbed onto a quartz substrate. The aim of this study is to elucidate, using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), the structure of the chemisorbed AQAS layers. The AQAS biocide includes a C18 alkyl chain previously invoked in lysis potency. The AQAS coverage appears in zones on the surface, which include a first layer (2.6 ± 0.1 nm) and multilayering that were explored using AFM. The XPS data exhibited two N 1s signals at about 402 and 399 eV, with only the former exhibiting angular dependence. This signal at 402 eV was assigned to the first anchored la..

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University of Melbourne Researchers


Awarded by New Zealand Ministry of Business, Innovation and Employment (MBIE)

Funding Acknowledgements

The authors are grateful to the New Zealand Ministry of Business, Innovation and Employment (MBIE) for funding for the multiyear programme "The Biocide Toolbox" (contract UOA1410). R.T.M. is grateful to The Biocide Toolbox for a PhD scholarship to undertake this and related research. The authors acknowledge the valuable scientific support and advice received from Professor Michael Higgins (University of Wollongong, Australia), Professor Bryony James (Faculty of Engineering, University of Auckland, NZ), Dr Sudip Ray (MBIE, The Biocide Toolbox, University of Auckland), Jacqui Ross (BIRU, University of Auckland, NZ), Associate Professor Simon Swift (Medical Microbiology, University of Auckland, NZ), and to other members of the Biocide Toolbox Team.