Compact formation bulk density

Compaction, that is, redaction of voids and increase in bulk density and bond formation... 

In the case of a loosely structured, highly solvated train-loop-tail-like conformation of the adsorbed layer, as is the case with flexible polymers, the density of the adsorbed layer approaches that of the bulk solution and, hence, the contribution from dispersion (London-van der Waals) interactions may be negligibly small. However, for the formation of a compact adsorbed protein layer, dispersion interactions have to be taken into account. 

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