Prediction and Measurement of the Interparticle Depletion Interaction Next to a Flat Wall

AFM colloidal forces measured between microscopic probes and flat substrates in nanoparticle suspensions

“…Experimental measurements of depletion force performed by Piech et al [29] support this estimation. Using the hydrodynamic force balance apparatus, Piech et al measured the depletion force to be −0.04 mN/m between 10 µm particles in suspensions of nanoparticles having a diameter of 20 to 40 nm.…”

“…The attractive depletion force arises whenever the concentration of polymers, micelles or nanoparticles in a thin liquid film is reduced to that in the bulk. This entropic attraction is caused by imbalance of the osmotic pressure of the polymers, micelles or nanoparticles acting on the larger particle (colloidal probe in the case of our system) and has been the topic of numerous studies [22,[27][28][29][30][31][32][33]. Because a small attractive interaction between the glass probe and silicon wafer was also observed in the experiments with deionized water, the depletion effects are most likely not responsible for the step at ∼5 nm.…”

Dynamic and Static Interactions between Bitumen Droplets in Water

“…The other effect is the premature separation of the doublet caused by the random force that happens to be in the same direction as the hydrodynamic force and thus results in a separation prior to the establishment of the force balance between the hydrodynamic and the colloidal forces. This stochastic nature of doublet breakup has been discussed in detail elsewhere (20). It has been found that the resulting error is significant only if the energy minimum is shallower than 2 kT.…”

“…This corresponds to a determined F coll /a value of 0.1-0.2 µN/m in the data presented in this paper. The actual values of F coll /a could be 50% larger than the determined ones (20). As the determined F coll /a value becomes larger than 0.2 µN/m, the random force effect diminishes and is neglected in this work.…”

In Situ synthesis of poly(styrene-butylacrylate-acrylic acid) latex/barium sulfate nanocomposite and evaluation of their film properties

“…Accordingly, more force is required to break this physical network as the nanopigment level increases. The multifunctionality (carboxyl, ester, and vinyl groups) of PSBA molecules may act as bridges between the latex matrix and BaSO 4 nanoparticles, avoiding the depletion force-induced phase separation [26] during in situ polymerization. Above critical loading of nanopigments, creation of regions of heterogeneity due to the formation of agglomerates of nanoBaSO 4 in matrix is responsible for the reduction in tensile strength.…”