Microgels density

The intrinsic viscosity of microgels described in [9] decreased with increasing fractions of the crosslinking monomer to about 8 ml/g which was still above the theoretical value for hard spheres of about 2.36 ml/g according to the Einstein equation and assuming a density of 1.1 g/ml. Obviously, due to the relatively low fraction of the crosslinking monomer, these microgels did not behave like hard spheres and were still swellable to some extent. 

The experimental data obtained with macrogels formed in the presence of solvents, agreed well with Eq. (5) [99,105,108]. In order to check the applicability of this equation to microgels, the experimental data reported by Hoffmann [70] are used. He prepared a series of microgels with different crosslink densities, using toluene as a solvent, at Q°° = 5. Qvwas calculated from the reported data... 

The [r ] of microgels increases slightly with the concentration of an external electrolyte (Fig. 23). Probably a slope of [r ] / Mw > 0 is caused by the presence of the electrolyte which decreases the density of these microgels. 

A possible reason for the inaccessibility of a part of the acid groups could be the crosslink density which depends on the composition of the microgels. However, because the number of titratable acid groups does not depend on the composition and, therefore, on the crosslink density of the microgels, it must be concluded that electrostatic forces prevent ions from entering the microgel particles. 

Fig. 49. A sketch of the segment density profile for a microgel. The various bars indicate the position of the radius of gyration, the expected equivalent sphere radius and the hydrodynamic radius, respectively1881...

Inhomogeneous open networks characterized by spatial fluctuations of the crosslink density (nodular/globular morphologies, microgels, see Chapter 7). 

Fig. 12 Radial density

Such microgel nanoparticles with varying gelatin concentration and crosslinking density have a high potential for use in drug delivery applications. The gelatin nanoparticles can also be used as template particles for the formulation of apatite... 

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