Time‐of‐flight secondary ion mass spectrometric analysis of polymer surfaces and additives

Abstract

This paper presents the application of static time-of-flight secondary ion mass spectrometry (ToF-SIMS) to the analysis of polymeric materials, including chemically modified polymers and polymer additives. Through the detection of intact functionalized oligomers, analysis of poly(styrene) functionalized with perfluoroalkyl chlorosilane provides confirmation of a successful endgroup termination for a living polymerization. The calculated molecular weight distribution also is in good agreement with chromatographic results. High mass resolution studies allow monitoring of the hydrogenation of a poly(butadiene) polymer through increases in oligomer mass due to proton addition. The quantitative ToF-SIMS results for the extent of hydrogenation for a specific oligomer are lower than the values averaged over all oligomers as determined by magnetic resonance. The usefulness of ToF-SIMS for determination of trace-level polymer additives is demonstrated for linear low-density poly(ethy1ene) (LLDPE). Application of a 150 nm thick evaporated Ag pattern enables in situ detection of the five trace additives present in the LLDPE matrix, and also provides information on additive surface migration and surface oxidation. A study of the silver cationization process for the silver-patterned LLDPE surface suggests differences in diffusion and/or ionization processes for two additives. This is confirmed with mass-resolved ion imaging to show the lateral distribution of the silvercationized signals for various polymer additive molecular ions. Finally, poly(styrene) (M,, = 1300) coated with a continuous silver overlayer is investigated. The ToF-SIMSdetermined molecular weight distribution shifts to lower masses, suggesting the greater diffusion of shorter polymer chains through the silver overlayer.

Cluster secondary ion mass spectrometry of polymers and related materials

“…In metal-assisted SIMS, the sample is coated with a thin layer of a metal, such as Au or Ag, which can result in significant enhancements in signal (by a factor of 10 or more) and the formation of additional adduct ions (Grade & Cooks, 1978;Linton et al, 1993). In matrix-enhanced SIMS, the sample is placed in a signal enhancing matrix (such as sinapic acid) and analyzed in a similar manner as Matrix-Assisted Laser Desorption Ionization (MALDI) (Wu & Odom, 1996;Wittmaack et al, 2000).…”

Surface Passivation of (100)-Oriented GaAs with Ultrathin Fluoropolymer Films Deposited by Radio Frequency Magnetron Sputtering of Poly(tetrafluoroethylene)

“…21,22 Figure 2 shows the positive ion ToF-SIMS spectra of the s-PTFE on the GaAs͑100͒ surface. The assignments of the positive ion fragments associated with the CF 2 repeat units are given in Table I.…”

Surface Analysis of Organic Materials with Polyatomic Primary Ion Sources

“…In metal-assisted SIMS experiments or "MetA-SIMS," 119 -125 the sample is coated with a thin layer of a metal, such as Au or Ag in a controlled manner, such that significant enhancements in molecular signal are observed, along with the formation of additional adduct ions (e.g., M + Ag + ). 116,119 This enhances the sensitivity of the method, in particular for the higher mass region of the mass spectrum. The first observation of MetA-SIMS enhancement was shown by Bletsos and coworkers, who deposited a Ni grid onto poly(dimethyl siloxane) (PDMS) and PTFE samples in order to alleviate charging effects.…”