Distribution of molecularly imprinted polymer layers on macroporous silica gel particles by STEM and EDX

Using transmission electron microscopy (TEM) in parallel and scanning mode (STEM) combined with energy dispersive X-ray spectroscopy (EDX) the distribution of molecularly imprinted polymer layers covalently grafted on the inner and outer surface of macroporous silica gel particles was observed. The grafting was achieved using a special initiator system (iniferter) and applied on a well known model system producing molecularly imprinted layers with l-phenyl alanine analide (l-PA) as template. By staining the sample with RuO4 before its embedment in epoxy resin and cutting ultra thin slices it was possible to identify the stained grafted polymer on the silica matrix by EDX. Based on this, complete particle slices could be investigated by visual means according to the presence or absence of grafted polymer and its layer homogeneity.