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Self‐assembled monolayers of octadecylphosphonic acid and polymer films: Surface chemistry and chemical structures studied by time‐of‐flight secondary ion mass spectrometry
Author(s) -
Nie HengYong
Publication year - 2017
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.6296
Subject(s) - monolayer , secondary ion mass spectrometry , chemistry , polymer , static secondary ion mass spectrometry , analytical chemistry (journal) , polystyrene , mass spectrometry , contact angle , chemical engineering , ion , nanotechnology , materials science , organic chemistry , chromatography , engineering
With the ever‐decreasing thickness of functional organic thin films, surface sensitive analytical techniques are required to probe surface/interface chemistry and structural changes of ultra‐thin organic films such as self‐assembled monolayers (SAMs) of amphiphilic molecules and polymeric coatings. Time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) fits this requirement because it is extremely surface sensitive and provides rich chemical information. In this article prepared for celebrating the 35th anniversary of our lab as a surface analysis service provider and a surface science research center, we highlight our TOF‐SIMS studies on exploring the surface chemistry of SAMs of octadecylphosphonic acid. Due to our contribution to developing the fast growth method of delivering octadecylphosphonic acid SAMs via the use of solvents having a dielectric constant of 3 to 5, we will review the formation mechanisms of SAMs. We will also review our recent results that demonstrated the feasibility of using the ion intensity ratio between C 6 H − and C 4 H − to differentiate the chemical structures of several polymers and depth profiling the cross‐linking degree of a polymer. In this article, we show results from principal component analysis on numerous C n H − intensity data from multiple spectra obtained from polyethylene, polypropylene, polyisoprene, and polystyrene. This multivariate analysis method allowed us to better understand the relationships between the polymers and between C n H − , as well as verify the rationale for the selection of C 4 H − as the reference ion for normalization. We demonstrate that together with principal component analysis, TOF‐SIMS is unique in differentiating chemical structures of polymers. Copyright © 2017 John Wiley & Sons, Ltd.