In Situ Attenuated Total Reflection (ATR/FT-IR) Tribometry: A Powerful Tool for Investigating Tribochemistry at the Lubricant–Substrate Interface

Mangolini, Filippo; Rossi, Antonella; Spencer, Nicholas D.

doi:10.1007/s11249-011-9868-5

Cited by 24 publications

(27 citation statements)

References 54 publications

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“…The TriboChemist (see also Fig. 1) is a novel in situ technique that provides information on the dynamics of adsorbed layers during friction (33). The TriboChemist is comprised of an ATR-FTIR spectrometer (Cary 600 Series FTIR spectrometer; Agilent Technologies, Santa Clara, USA) and a tribometer (sliding wear tester TR-17; Ducom Instruments Pvt.…”

Section: Methodsmentioning

confidence: 99%

Extracellular Polymeric Matrix Production and Relaxation under Fluid Shear and Mechanical Pressure in Staphylococcus aureus Biofilms

Hou

Veeregowda

Belt-Gritter

et al. 2018

Appl Environ Microbiol

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The viscoelasticity of a biofilm's EPS (extracellular-polymeric-substance) matrix conveys protection against mechanical challenges, but adaptive responses of biofilm inhabitants to produce EPS are not well known. Here, we compare the response of a biofilm of an EPS producing (ATCC 12600) and non-EPS producing (5298) strain to fluid shear and mechanical challenge. Confocal-Laser-Scanning-Microscopy confirmed absence of calcofluorwhite-stainable EPS in biofilms of 5298. ATR-FTIR spectroscopy combined with tribometry indicated that the polysaccharide production per bacterium in the initial adhering layer was higher during growth at high shear than at low shear and this increased EPS production extended to entire biofilms, as indicated by tribometrically measured coefficients of friction (CoF). CoFs of biofilms grown under high fluid shear were higher than when grown under low shear, likely due to wash-off of polysaccharides. Measurement of a biofilm's CoF implies application of mechanical pressure that yielded an immediate increase in polysaccharide band area of ATCC 12600 biofilms due to their compression that decreased after relieving pressure to the level observed prior to mechanical pressure. For biofilms grown under high shear, this coincided with a higher %whiteness in Optical-Coherence-Tomography-images indicative of water outflow, returning back into the biofilm during stress relaxation. Biofilms grown under low shear however, were stimulated during tribometry to produce EPS, also after stress relieve. Knowledge of factors that govern EPS production and water flow in biofilms will allow better control of biofilms under mechanical challenge and understanding of the barrier properties of biofilms toward antimicrobial penetration. Adaptive responses of biofilm inhabitants in nature to environmental challenges such as fluid shear and mechanical pressure, often involve EPS production with the aim of protecting biofilm inhabitants. EPS can assist biofilm bacteria to remain attached or impede antimicrobial penetration. The tribochemist is a recently introduced instrument, allowing to study initially adhering bacteria to a Germanium crystal using ATR-FTIR spectroscopy, while simultaneously allowing measurement of the coefficient of friction of a biofilm, serving as an indicator of the EPS content of a biofilm. EPS production can be stimulated by both fluid shear during growth and mechanical pressure, while increased EPS production can continue after pressure relaxation of the biofilm. Since EPS is pivotal in the protection of biofilm inhabitants against mechanical and chemical challenges, knowledge the factors that make biofilm inhabitants decide to produce EPS as provided in this study, are important for the development of biofilm control measures.

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Section: Methodsmentioning

confidence: 99%

Extracellular Polymeric Matrix Production and Relaxation under Fluid Shear and Mechanical Pressure in Staphylococcus aureus Biofilms

Hou

Veeregowda

Belt-Gritter

et al. 2018

Appl Environ Microbiol

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“…The band at approximately 600 cm -1 is assigned to the C-S bond that could belong to organic sulfide compounds [35,37], whereas the band at approximately 550 cm -1 could belong to the Zn-O bond [38][39][40]. The bands at 2,967, 2,923, and 2,848 cm -1 were assigned to the asymmetric stretching vibrations of CH 3 and CH 2 , and the symmetric stretching vibration of the CH 3 bonds, respectively [35,41,42]. The two peaks at 1,458 and 1,378 cm -1 correspond to the deformation vibrations of CH 3 /CH 2 , and the symmetric deformation of the CH 3 bond, respectively [35,[41][42][43].…”

Section: Atr-ftirmentioning

confidence: 99%

Differences in nano-topography and tribochemistry of ZDDP tribofilms from variations in contact configuration with steel and DLC surfaces

et al. 2021

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In this work, we evaluated the effect of the counter-body material (the same or dissimilar) and contact configuration (moving or stationary body), at similar contact tribological conditions, on the tribochemical and nanotopography characteristics of adsorbed surface films. Zinc dialkyldithiophosphate (ZDDP), the best performing anti-wear additive, was used in self-mated steel/steel and DLC/DLC contacts, which were compared with mixed steel/DLC and DLC/steel contacts in 1-h and 6-h sliding tests. The macroscale (tribometer) and nanoscale (atomic force microscopy) friction, thickness, topography, and chemical (attenuated total reflection-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy) properties of the tribofilms were studied. The results revealed unexpectedly large differences in all the studied tribofilm parameters; this is because all the tribofilms are completely different; this includes the chemical composition, which is known to have a crucial effect on the nano- and macro-scale tribological properties. These results clearly demonstrate that the surface material, additives, and common contact operating parameters, that is, pressure, velocity, and temperature, crucially affect the ZDDP tribofilm as well as the position of the moving or stationary surface within the contact, and the material of the moving/stationary bodies.

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“…The Tribochemist is a novel in situ technique that provides information on the dynamics of adsorbed layers during friction [14]. The Tribochemist is an integrated device consisting of an ATR-FTIR spectrometer (Cary 600 series FTIR Spectrometer; Agilent Technologies, Santa Clara, CA, USA) and a tribometer (sliding wear tester TR-17; Ducom Instruments Pvt.…”

Section: Tribochemistry Of Water Moleculesmentioning

confidence: 99%

“…The instrument is based on a standard pin-on-plate tribometer [13], in which the plate has been replaced by an attenuated total reflection (ATR) crystal made of either Ge (germanium) or Si (silicon). This set-up enables real-time and in situ ATR-FTIR spectra and friction data to be obtained simultaneously in order to monitor changes in the structure and composition of lubricating films under tribological conditions [14,15].…”

Section: Introductionmentioning

confidence: 99%

Structured free-water clusters near lubricating surfaces are essential in water-based lubrication

Hou

Veeregowda

Vries

et al. 2016

J. R. Soc. Interface.

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Water-based lubrication provides cheap and environmentally friendly lubrication and, although hydrophilic surfaces are preferred in water-based lubrication, often lubricating surfaces do not retain water molecules during shear. We show here that hydrophilic (428 water contact angle) quartz surfaces facilitate water-based lubrication to the same extent as more hydrophobic Si crystal surfaces (618), while lubrication by hydrophilic Ge crystal surfaces (448) is best. Thus surface hydrophilicity is not sufficient for water-based lubrication. Surface-thermodynamic analyses demonstrated that all surfaces, regardless of their water-based lubrication, were predominantly electron donating, implying water binding with their hydrogen groups. X-ray photoelectron spectroscopy showed that Ge crystal surfaces providing optimal lubrication consisted of a mixture of -O and ¼O functionalities, while Si crystal and quartz surfaces solely possessed -O functionalities. Comparison of infrared absorption bands of the crystals in water indicated fewer bound-water layers on hydrophilic Ge than on hydrophobic Si crystal surfaces, while absorption bands for free water on the Ge crystal surface indicated a much more pronounced presence of structured, free-water clusters near the Ge crystal than near Si crystal surfaces. Accordingly, we conclude that the presence of structured, free-water clusters is essential for water-based lubrication. The prevalence of structured water clusters can be regulated by adjusting the ratio between surface electron-donating and electron-accepting groups and between -O and ¼O functionalities.

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In Situ Attenuated Total Reflection (ATR/FT-IR) Tribometry: A Powerful Tool for Investigating Tribochemistry at the Lubricant–Substrate Interface

Cited by 24 publications

References 54 publications

Extracellular Polymeric Matrix Production and Relaxation under Fluid Shear and Mechanical Pressure in Staphylococcus aureus Biofilms

Extracellular Polymeric Matrix Production and Relaxation under Fluid Shear and Mechanical Pressure in Staphylococcus aureus Biofilms

Differences in nano-topography and tribochemistry of ZDDP tribofilms from variations in contact configuration with steel and DLC surfaces

Structured free-water clusters near lubricating surfaces are essential in water-based lubrication

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