Quantification of polystyrene blend surfaces based on end group ToF-SIMS analysis

Abstract

In this work, two sets of low molecular weight polystyrene blends were studied. The first one is composed of two polystyrenes with, at one end, tertiary or secondary butyl end group ( sec- and tert-) and hydrogen end group (–H) at the other end. ToF-SIMS spectra show a linear dependency with bulk concentration. Due to the slight difference of molecular structures between sec- and tert-butyl end group, no difference of surface free energy and surface state is expected. Then, the observed linear dependency implies that the matrix effect is insignificant. The second set of polymer blends are composed of polystyrenes with, at one end, tertiary or secondary butyl end group ( sec- or tert-) and at the other end, hydrogen (–H) or trimethyl silyl (–Si(CH 3) 3, TMS) end group, respectively. With the results from the first set of blends, we were able to quantify the sec-PS–Si concentration at the surface as compared to the bulk, using univariate and multivariate techniques. The different methods establish that all these polystyrene blends present a bulk-like surface. The principal component analysis (PCA) seems to be interesting for the study of ternary polymer blends.