Styrene-based imaging systems

As mentioned above, the spm is mostly limited to sampling the near-sinface region of a polymer system. A new technique based on tmafm has been developed to enable volume imaging with the spm. This study tracked a series of height and phase images of a styrene-butadiene-styrene (SBS) triblock polymer microdomain as the surface was being removed 7.5 nm at a time with a plasma etcher. These data are illustrated in Figure 10 (65). 

As described below, the HAS-derived nitroxides in heterophasic polymer systems perform a triple role. First, they provide the contrast needed in the imaging experiments. Second, they enable the visualization of polymer morphology, based on the detection of two dynamically different components detected in the ESR spectra of the nitroxides in ABS, for example, the two sites, fast (F) and slow (S), have been assigned to location of nitroxides in butadiene-rich and styrene-acrylonitrile (SAN)-rich domains, respectively. Third, the spatial variation of the ESR spectra of nitroxides (in terms of intensity and line shapes) with treatment time, t, provides detailed information on the extent of degradation in the different miCTodomains. These experiments made possible the determination of the concentration profiles of the nitroxides from ID ESRl, and also of the spectral profiles from 2D spectral-spatial ESRI, both in a nondestructive way. In these studies the nitroxides, which are the contrast agents, are part of the systan therefore these studies represent the evolution of ESRl techniques beyond phantoms. 

The system based on acetal-protected poly(vinylphenols) has the advantages that most chemically amplified photoresists have demonstrated, such as high sensitivity as the result of catalytic nature of deprotection reaction. However, the novel design of the system based on poly[4-(l-phenoi ethoi )styrene] shows several other advantages also. The imaging chemistry of fiiis system is illustrated in Scheme 2. 

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