Polymers polymer bridging

Fig. 4. (a) Polymer bridging between particles and (b), particle stabilization by adsorbed polymer (32). 

FIG. 10 SEM micrographs of (a) sUica nanoparticle/polymer [Si02/PDADMAC)3]-coated PS lat-ices and (b) hollow silica capsules. The hollow sUica capsules were obtained by calcining coated particles as shown in (a). The calcination process removes the PS core and the polymer bridging the silica nanoparticles, while at the same time fusing the silica nanoparticles together. Some of the silica capsules were deliberately broken to demonstrate that they were hollow (b). (From Ref. 106.)... 

The polymerization applied produces spherical polymer particles (1-10 pm diameter) connected by polymer bridges [3]. Thus, a one-piece polymer phase is obtained. The interstices between the particles have a characteristic length of a few micrometers. Overall, the polymer structure can be ascribed as lose. 

Zinc halide complexes with acetophenone have been structurally characterized and form monomeric or polymeric structural motifs.346 The bromide and iodide derivatives are monomeric and the chloride derivative is a coordination polymer with bridging chlorides. 

Adsorption on Kaolinite. As for polyacrylamides, adsorption of XCPS on kaolinite is conducted as a function of S/L and the results extrapolated to S/L=0. However, the S/L dependence of XCPS adsorption on kaolinite is considerably less than that for HPAM. This is due to the flat conformation of the adsorbed molecules of semirigid xanthan (25) compared to the more extended conformation of flexible HPAM (27). The absence of loops and tails in the adsorbed XCPS layer thus diminishes the probability of flocculation of particles by polymer bridging. The slight dependence in adsorption on S/L may therefore be attributed to coagulation of particles induced by Ca. ... 

Fig. 1 Schematic representation of a bundle and a bundle aggregate in a polymer chain. Bridges, loops, and crystallized stems are evidenced...

The problems associated with the application of this (or any other) model have been discussed. Because of the form of the typical isotherm, which exhibits a broad plateau region, fitting of experimental results to the model requires that data be obtained over a very broad range of concentrations. This is often very difficult to accomplish in practice, especially when difference methods are used to determine the amount of polymer adsorbed. Evaluation of adsorption in real systems is further complicated by a lack of knowledge of the available solid surface area. The latter may be affected by particle size, shape and surface topography and by polymer bridging between particles. 

The increase in the rheological parameters, ri0> G0 and 1(5 with reduction in surface coverage points towards an increase in particle interaction. This could be the result of either flocculation by polymer "bridging" (which is favourable at coverages <0.5) or as a result of coagulation due to the van der Waals attraction between the "bare" patches on the particles. In the absence of any quantitative relationship between interaction forces and rheology, it is clearly difficult... 

B. Jiang, S.-W. Yang, R. Niver, and W.E. Jones, Jr., Metalloporphyrin polymers bridged with conjugated cyano-substituted stilbene units, Synth. Met., 94 205-210, 1998. 

U. Scherf and K. Mullen, Polyarylenes and poly(arylene vinylenes), 7. A soluble ladder polymer via bridging of functionalized poly(p-phenylene)-precursors, Makromol. Chem., Rapid Commun., 12 489-497, 1991. 

This type of mechanism is likely to be partly operative in systems containing inorganic electrolytes as, for example, in the case of aluminium species. Some polyelectrolytes may also induce flocculation by charge neutralisation but the adsorbed polymer may also be able to bridge from one particle surface to another ( polymer bridging ). 

Figure 7.7 Diagramatic representation of flocculation by polymer bridging.

The parallel with two radicals on neighbouring polymer strands bridging together to form a crosslink is apparent. 

L. Cohen-Tannoudji, E. Bertrand, L. Bressy, C. Goubault, J. Baudry, J. Klein, J.-E. Joanny, and J. Bibette Polymer Bridging Probed by Magnetic Colloids. Phys. Rev. Lett. 94, 038301 (2005). 

C. Goubault, E. Leal-Calderon, J.-L. Viovy, and J. Bibette Self-Assembled Magnetic Nanowires Made Irreversible by Polymer Bridging. Langmuir 21, 3725 (2005). 

Ligand terdentate. Tetragonal polymer with bridging O atoms qq... 

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