Static SIMS spectra of polystyrene obtained by ‘living’ radical polymerization. Part II: Molecular weight quantification based on end groups

✍ Scribed by Vanden Eynde, X.; Bertrand, P.

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 377 KB
• Volume: 26
• Category: Article
• ISSN: 0142-2421
• DOI: 10.1002/(sici)1096-9918(199807)26:8<579::aid-sia404>3.0.co;2-z

✦ Synopsis

A series of low-polydispersity polystyrenes with molecular weight ranging from 2000 to 130 000 synthesized by atom transfer radical polymerization were analyzed by time-of-Ñight secondary ion mass spectrometry. The polymer end groups obtained by this polymerization process are hydrogen at one end and bromide at the other end.

The great sensitivity of these end groups towards the ion beam-induced emission yield of secondary ion fragments allows the direct quantiÐcation of the molecular weight of the polystyrene at the surface. However, before applying any quantiÐcation method, several steps have to be performed : the peak assignment of the characteristic end group fragments and the choice of the spectrum normalization method. The inÑuence of two normalization procedures is compared for two quantiÐcation methodsÈthe characteristic peak intensity ratios and a chemometric method (principal component analysis)Èin order to achieve molecular weight determination of the polystyrene at the surface. It is shown that, depending on the normalization procedure used, very di †erent results can be obtained for both quantiÐcation methods. The validity of the procedures is also discussed.