Colloidal systems probe microscopy

Alternatively, one may employ colloidal probe atomic force microscopy (AFM) to measure force distance curves such as the ones plotted in Fig. 5.1 [162]. The important difference between SFA and colloidal probe AFM experiments is that in the latter the entire force distance curve is accessible rather than only that portion satisfying Eq. (5.66) [163, 164]. In Ref. 164 a comparison is presented between theoretical and experimental data for confined poly-electrolyt.e systems. 

In a recent study Raj et al. presented the first direct study of adhesion forces, by colloidal force microscopy, between smooth PLA films representing the polymer matrix, and a microbead of cellulose that mimics the cellulose material in flax fibers [65]. Normalized adhesion force measurements demonstrated the importance of capillary forces when experiments were carried out under ambient conditions. Experiments, conducted under dry air allowed for the deduction of the contribution of pure van der Waals forces, and the results, through the calculation of the Hamaker constant, show that these forces, for the PLA/cellulose/air system, were lower than those obtained for the cellulose/cellulose/air system and hence underlined the importance of optimizing the interface among these materials. The study demonstrated the capacity of AFM to probe direct interactions in complex systems by adjusting the nature of the surface and... 

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