ORIGINAL PAPER Chemical and structural characterisation of DGEBA-based epoxies by time of flight secondary ion mass spectrometry (ToF-SIMS) as a preliminary to polymer interphase characterisation Sven Passlack & Alexander Brodyanski & Wolfgang Bock & Michael Kopnarski & Melanie Presser & Paul Ludwig Geiß & Gunnar Possart & Paul Steinmann Received: 10 October 2008 / Revised: 15 January 2009 / Accepted: 21 January 2009 / Published online: 12 February 2009 # Springer-Verlag 2009 Abstract Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has become a powerful tool in the field of surface analysis since it provides information about the top few monolayers of a sample, i.e. on the chemical composition of the sample surface. Thus, the general question arises whether a surface-sensitive technique like ToF-SIMS would be appropri- ate to detect systematic chemical and/or structural changes in organic bulk polymers caused by varying a chemical content of the initial components or by tracking, e.g. curing processes in such materials. It is shown that careful sample preparation and the use of multivariate methods permit the quantitative acquisition of chemical and structural information about bulk polymers from the secondary ion signals. The hardener concentration and a cross-linking coefficient in diglycidyl ether of bisphenol A based epoxies were determined by ToF-SIMS measurements on samples with different resin to hardener ratio and varying curing time. In future work, we will use the developed method to investigate the local composition of adhesively bonded joints. In particular, the mapping of the chemical and structural properties in the so-called interphase will then be of interest. Keywords Surface analysis . Mass spectrometry . SIMS . Polymer . Interphase Introduction The mechanical and structural properties of polymers in adhesively bonded joints have been shown to undergo significant changes in the vicinity of the substrate compared to the bulk material. Such altered polymer regions (so-called interphases) have often a thickness of about 100 μm or even more. Explanations for the changes of the polymer network formation in the interphase could be steric hindrances, orientation effects, selective adsorption, local segregation or curing shrinkage caused by the presence of the substrate surface. Nonetheless, a quantitative characterisation of this micro-region in adhesively bonded joints is still a major challenge. In recent years, some progress is achieved in the field of the mechanical properties of interphases (see, e.g. [1–4] as well as [5, 6]). In this paper, we present our first efforts to gain chemical and structural information on the interphase by applying time-of-flight secondary ion mass spectrometry (ToF-SIMS) with the help of multivariate data analysis. Static secondary ion mass spectrometry (SIMS) is a successful method for chemical analysis that has been applied to polymer surface characterisation from the beginning of the Anal Bioanal Chem (2009) 393:1879–1888 DOI 10.1007/s00216-009-2639-6 S. Passlack : A. Brodyanski (*) : W. Bock : M. Kopnarski Institute for Surface and Thin Film Analysis (IFOS) and research center OPTIMAS, Trippstadter Straße 120, 67663 Kaiserslautern, Germany e-mail: brodyanski@ifos.uni-kl.de M. Presser : P. L. Geiß Workgroup for Materials and Surface Technologies, University of Kaiserslautern, Building 44, 67663 Kaiserslautern, Germany G. Possart : P. Steinmann Chair of Applied Mechanics, University of Erlangen-Nuremberg, Egerlandstraße 5, 91058 Erlangen, Germany