What Kind of Image is Drawn by a MALDI-Experiment of Grafted Nanoparticles? - How to Distinguish between Chemically and Physically Adsorbed Parts

摘要

The modern MALDI-TOF mass spectrometry is a powerful technique for the fast and accurate determination of a number of polymer characteristics like end group analysis. It can also be used to analyze the grafted shell around silane modified nanoparticles. This shell contains physically and chemically adsorbed parts. It is a question of great interest what kind of adsorbent can be visualized by using MALDI-TOF mass spectrometry, while it is not possible to ionize the whole AEROSIL? particle. Therefore we chose the system MPTMS/AEROSIL?200 to address this issue. We grafted AEROSIL?200 with methacryloxy(propyl)-trimethoxysilane (MPTMS) under acid conditions. The grafted nanoparticles were treated via Soxhlet extraction. The resulting fractions (the washed nanoparticles and the Soxhlet extract) were systematically analyzed by using MALDI-TOF MS as well as the grafted nanoparticles themselves. As a crosscheck MPTMS was homopolymerized and analyzed. Our results show that for the system under investigation there is strong evidence that only the physically adsorbed part can be analyzed via MALDI-TOF MS.