The Surface Analysis Laboratory
A Study of the Interfacial Interaction between
Methylene Diphenyl Diisocyanate (MDI) and
Metals by XPS
Sabrina Tardio
Department of Mechanical Engineering Sciences
The Surface Analysis Laboratory
2 July 2014
Project Aim
The Surface Analysis Laboratory
Interface interaction
MDI
In order to understand the
adhesion of PU on metal
substrates.
• Stainless steel
(316L)
• Iron
• Molybdenum
• Nickel
• Chromium
Isocyanate Reactivity
The Surface Analysis Laboratory
• 𝐑 − 𝐍𝐂𝐎 + 𝐇𝟐 𝐎 → 𝐑 − 𝐍𝐇 − 𝐂𝐎𝐎𝐇 → 𝐑 − 𝐍𝐇𝟐 + 𝐂𝐎𝟐
• 𝐑 − 𝐍𝐂𝐎 + 𝐑 − 𝐍𝐇𝟐 → 𝐑 − 𝐍𝐇 − 𝐂𝐎 − 𝐍𝐇 − 𝐑
• 𝐑 − 𝐍𝐂𝐎 + 𝐑𝐈 − 𝐎𝐇 → 𝐑 − 𝐍𝐇𝐂𝐎𝐎𝐑𝐈
Stainless steel surface is made of metal oxide, metal
hydroxide and adsorbed water.
𝐑 − 𝐍𝐂𝐎 + 𝐌 − 𝐎𝐇 → 𝐑 − 𝐍𝐇𝐂𝐎𝐎𝐌
This is our research imperative!
C1s High Resolution Spectra
The Surface Analysis Laboratory
Pure MDI
1
1
Steel (with carbon
contam.)
1
2
4
3
1
1
New peak indicate the
formation of a M-C bond:
Organometallic complex??
Interface:
3 nm of MDI on
stainless steel
C1s N=C=O Region
Pure MDI
Pure MDI
The Surface Analysis Laboratory
Interface
Steel (with carbon contam.)
MDI/Pure Fe: C1s
The Surface Analysis Laboratory
Interface
MDI/Fe: «carbidic» peak
MDI/Mo and MDI/Ni : no «carbidic» peak but
interaction between with nitrogen!!!
Conclusions
The Surface Analysis Laboratory
MDI/Steel and MDI/Fe interfaces:
• M-C interaction
Peak at 283.6 eV
• Formation of
Peak at 289.2 eV
MDI/Mo and MDI/Ni interfaces
• M-N interaction
New doublets in the metal peaks
(see poster!)