Aluminum oxide substrates, spectra

The first example of a high resolution solid-state 2D N PISEMA NMR spectrum has been reported for a transmembrane peptide aligned using hydrated cylindrical lipid bilayers formed inside nanoporous anodic aluminum oxide substrates. Using N and P NMR spectra, both the phospholipids and the protein transmembrane domain were shown to be uniformly aligned in the nanopores. 

Dehydration of gibbsite under pressure in moist air produces boehmite (aluminum oxide mono-hydrate). An infrared spectrum of boehmite (Kaiser substrate grade alumina) is shown in Figure 3c. 

The concept that by carrying out a surface analysis on a model specimen one can obtain direct access to the interphase chemistry is a potentially very exciting and rewarding idea. The interaction of PMMA with various metals (as exemplified hyO Fig. 10.14 above) has been studied in some detail using high resolution XPS (Leadley and Watts 1997). In this work the manner in which PMMA formed specific interactions with oxidized metal surfaces was studied by the nature of the fine structure in the XPS spectrum. In this manner, it was possible to show that the polymer formed hydrogen bonds with oxidised silicon (an acidic substrate), a bidentate structure with oxidised aluminum (an amphoteric substrate) and would undergo acyl nucleophilic attack with oxidised nickel (a basic substrate). 

In the case of the GPS organosilane adhesion promoter applied to aluminum (and used as a substrate in the data of Fig. 10.13), ToF-SIMS has established the formation of a covalent bond between the GPS molecule and the oxidized aluminum substrate (Abel et al. 2000). The chemistry leading to the formation of the diagnostic fragment (Al-O-Si at m/z = 70.9534 u) and the high resolution spectrum at a nominal mass of 71 u is shown in Fig. 10.15. The formation of the specific bond is associated with good durability of the resultant bond, and examination of the fracture surfaces of failed joints shows that the presence of the ion in the ToF-SIMS spectrum correlates well with good durability. 

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