Atomic force microscopy, supramolecular structures

In the author s opinion, the better approach to experimentally study the morphology of the silica surface is with the help of physical adsorption (see Chapter 6). Then, with the obtained, adsorption data, some well-defined parameters can be calculated, such as surface area, pore volume, and pore size distribution. This line of attack (see Chapter 4) should be complemented with a study of the morphology of these materials by scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning probe microscopy (SPM), or atomic force microscopy (AFM), and the characterization of their molecular and supramolecular structure by Fourier transform infrared (FTIR) spectrometry, nuclear magnetic resonance (NMR) spectrometry, thermal methods, and possibly with other methodologies. 

Li, T., Morris, K.R. Park, K. (2000) Influence of solvent and crystalline supramolecular structure on the formation of etching patterns on acetaminophen single crystals a study with atomic force microscopy and computer simulation, J. Phys. Chertu B, 104, 2019-2032. 

In conclusion, it should be pointed out that none of the physicochemical techniques discussed above permits the direct measurement of the elements of the polymeric materials porous structure we measure the properties of the systems where the polymers interact with certain test substances (nitrogen, mercury, water, polystyrene standards, ions, etc.), and not the dimensions of the pores or other supramolecular elements of the material. Therefore, the evaluation of the surface area and diameters of pores available to the molecules of these substances must be considered as indirect methods of examining the porous structure. Because of this, all calculations are based on assuming certain models of the structure of the material and accepting certain assumptions as to the mechanism of interaction between the material and test molecules. Only transmittance, scanning, and, in particular, atomic force microscopy can be considered as direct methods of measuring dimensions and distances. However, up to now the last technique has not been appHed to microporous hypercrosslinked polymers. 

Micic, M., Radotic, K., Jeremic, M., Djikanovic, D., and Kammer, S. B. 2004. Study of the lignin model compound supramolecular structure by combination of near-held scanning optical microscopy and atomic force microscopy. Colloids SurfB Biointerfaces 34, 33-40. 

Atomic Force Microscopy (AFM) has been used to characterize the differing supramolecular structures of A -alkyl-D-gluconamide adsorbates and N- n-alkyl)-A -D-maltosylsemicarbazone adsorbates (on silica, graphite). An analysis of a P-CD fibre-optic chemical sensor (pyrene binding) has been discussed. ... 

Direct Observation of Supramolecular Structures of Biorelated Materials by Atomic Force Microscopy... 

FIGURE 7.12 Images of cast films prepared from solution of 18 and 19 obtained by scanning electron microscopy (a) and atomic force microscopy (b). (c) Plausible supramolecular polymeric structures. 

---