Mesoglobules

Keywords Colloidal stability Globule Mesoglobule Thermoresponsive polymers Abbreviations... 

Fig. 16 The thermal response of different polymeric structures based on PVCL and the amphiphilic macromonomer MAC11EO42. Left Shrinking of the grafted PVCL microgel. Right Heat-induced aggregation of the graft copolymer and formation of a mesoglobule [181]...

Fig. 27 Apparent hydrodynamic radius (Rh) of the mesoglobules formed by quickly heated aqueous solutions of the homopolymer PVCL or the graft copolymers with varying concentrations. (Reprinted with permission from Ref. [180] copyright 2005 Elsevier)...

Fig. 33 Scaling of the molar mass of PNIPAM mesoglobules (M 8) vs. their radius of gyration (i g) with fractal dimensionality 2.7 (filled symbols) and the shape factor J g/J h (open symbols). The conditions at which mesoglobules were formed correspond to those in Table 2 Mw = 27300gmol 1, non-equilibrium heated (circles) Mw = 160000gmol 1, nonequilibrium heated (triangles) Mw = 160000gmoL1, equilibrium heated (squares). (Reprinted with permission from Ref. [ 147] copyright 2005 Elsevier)...

Factors affecting the size of the mesoglobules include polymer concentration, i.e. the size increases with solution concentration and, more importantly, heating rate (Fig. 34). Thus, a fast increase in temperature (nonequilibrium heating) leads to mesoglobules of smaller size than those formed upon slow heating through the sample LCST [ 141 -145,147]. The chemical composition of... 

Fig. 34 The effects of the heating rate and dilution with hot water of mesoglobules of PNIPAM 160000gmoL1 on and Kc/Ig=w°-. equilibrium heated ( ), nonequilibrium heated (A), dilution of 0.12 gL-1 solution (A), and dilution of 0.08 gL-1 solution (o). All the solutions are at 50 °C. dn/dc = 0.20 cm3 g 1. (Reprinted with permission from Ref. [147] copyright 2005 Elsevier)...

What could be the reason for this remarkable slowing down of aggregate association Why are mesoglobules not as sticky as anticipated, given the thermodynamically poor conditions to which they are subjected ... 

Can vitrification of PVCL, PNIPAM, and PNIPMA also take place within mesoglobules generated upon heating aqueous solutions of the respective polymers above their LCST A mesoglobule formed by a large number of short chains is expected to have a lower Tg than a single chain of the same size, since as a rule the Tg of a polymer increases with molar mass [334]. The physical state of... 

We examine next how the viscoelastic effect, recently discussed in the literature [190,267-270], may also account for the resistance of globules and mesoglobules against precipitation. 

Both experimental evidence and theoretical models are needed to delineate the parameters controlling the properties of stable globules and mesoglobules in thermodynamically poor conditions. They may lead to the rational design of families of particles that may find important practical applications in various fields. 

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