Microgel preparation

The first report on the preparation of microgel-stabilized metal nanoclusters was published in 1997 by Antonietti et al. [11a], who utilized polystyrene-based microgels prepared... 

PVCL microgels prepared via covalent binding of PEO exhibit different temperature dependence (Fig. 19). In this case, a considerable increase in the diffusion coefficient takes place above the LCST of PVCL. The sudden increase may be attributed to the shrinking of the particle, which leads to an increase in the rate of its translational diffusion and, consequently, also in the rate of diffusion of the grafts bound to the particle surface. The values of the diffusion coefficients above the LCST should be taken as apparent ones, as the measurements were complicated by the heterogeneity of the collapsed samples. 

Because the composition of microgels prepared by micro-ECP of EUP and styrene with AIBN as initiator remains constant and irrespective of the reaction... 

Microgels prepared in that way are hydrophilic, stable and do not tend to agglomerate. By oxidation of the diol group with sodium periodate a free aide-... 

Compared with rigid microgels, the intrinsic viscosity of microgels prepared from the comonomer mixture mentioned before is higher, but the slope of the curve in Fig. 56 is still low because the composition of these microgels was close to the limit of stability. 

Fig. 57. Diameters of microgels prepared with different emulsifier concentrations (SDS). Composition (mol %) NjN -tetramethylenebismethacrylamide (10%),N-n-hexylmethacrylamide, propenic acid amide-N-(4-methyl-2-butyl-l,3 dioxolane (50%)...

Pelton and coworkers showed that the size of PNIPAAm microgels decreases by a factor of 10 if sodium dodecyl sulfate (SDS) is used in the polymerization procedure [61]. Lyon s group used SDS for stabilization of PNIPAAm microgels prepared with PEG diacrylates of different PEG chain length [62], To investigate the influence of polymerization conditions on internal structure of PNIPAAm microgels, SDS was used in batch and semibatch polymerization processes [63],... 

Figure 14a shows the Rh (at 20°C) for microgels prepared at different NP concentrations. The increase of the NP concentration in the reaction mixture reduces the size of the microgel considerably (from 220 to 80 nm). However, as indicated in... 

In the following section, the chemistries used for crosslinking are presented in more detail. Microgels prepared from biopolymers and synthetic prepolymers will subsequently be addressed in Sects. 3 and 4, respectively. 

Disulfides form spontaneously by autoxidation of thiols upon exposure to air. This process is, however, relatively slow and not useful for most microgel preparation techniques. Thus, oxidizing catalysts such as diamide [21], peroxides [22], and sodium tetrathionate [23], or a catalyst based on Fenton chemistry [24], are often applied in order to shorten the oxidation time. 

An excellent review by Funke et al., Microgels — Intramolecularly CrossHnked Macromolecules with a Globular Structure [229], analyzed the synthesis conditions and properties of various microgels prepared according to the above-mentioned three approaches. 

Goh, E. C., Stover, H. D. (2002). Cross-linked poly (methacrylic acid-co-poly(ethylene oxide) methyl ether methacrylate) microspheres and microgels prepared by precipitation polymerization A morphology study, 35, 9983-9989. 

---