Colloid Composition

The all-important problem of stability was receiving further attention in the United States of America during this pre-World War I period. J. B. Bronstein took out a number of U. S. patents covering the stabilization of starch nitrate with borates, soda ash, lime, and the like. His contributions to the U. S. patent literature, for the purpose of improved stabilization treatments and for the increased efficiency of explosive compositions of starch nitrate, extended from 1907-26 and J. B. Bronstein, Jr., was granted a patent in 1939 for improving colloidal compositions of starch nitrate. 

Cluster small or colloid compositions of transition metal oxides or metal hydroxides. 

Colloidal composite microparticles have been prepared by polymerizing A-methyl pyrrole on structured poly(iV-isopropylacrylamide) (PNIPAAm) microgel particles. The maximum amount of CP that can maintain colloidal status of the formed composite was 4.5 vol% relative to the microgel volume, and the conductivity of the composite was on the order of S cm [133]. Similar coUoidal dispersions of CP composites have... 

Shim, G.H., Han, M.G., Sharp-Norton, J.C., Creager, S.E., Foulger, S.H., 2008. Inkjet-printed electrochromic devices utilizing polyaniline-silica and poly(3,4-ethylenedioxythiophene)-silica colloidal composite particles. J. Mater. Chem. 18,594-601. 

The colloidal system was separated by means of precipitation using acetic acid ethyl ester according to Neumann [4-10] in colloids (precipitate) and dispersion medium. The portion of the precipitate soluble in n-pentane is defined as petroleum resins, the portion soluble in benzene as asphaltenes. The colloidal composition of the samples is given in Table 4-10. 

Table 4-28 Correlation of thermoanalytical index numbers with the colloidal composition (Experiments in argon)...

The colloidal composition of each sample was analysed using the colloid precipitation according to Neumann [4-10] (Table 4-48) ... 

The atomic ratio H C demonstrates relatively weak aromacity for bitumens, dispersion medium and petroleum resins, whereas the asphaltenes possess a considerably higher aromacity. Despite differences in the colloid composition, differences of the H C ratios of the individual bitumens are very small, as shown by the small coefficients of variation V in Table 4-53 ... 

The colloid composition of the blown bitumens shows higher asphaltene content and lower dispersion medium content than that of the distillation bitumens. 

A fairly close correlation of the consistency data with the colloid composition or the particle mass, is only possible for bitumens from the same refinery and from crude oils of nearly the same origin. 

These results had not been expected, considering the different origins of the samples, their different colloid compositions, and their different average molecular weights. Element analysis proved that the H/C ratios of the distillation bitumens, and of the blown bitumens and their colloid components, show very small variations (Tables 4-53 and 4-54). 

The activation energy of the pyrolysis reaction shows a linear relationship with analytical data such as the nitrogen and sulfur contents, whereas no correlation could be found with the average molecular weight, the colloid composition, or the H/C ratio (Table 4-141). 

The behavior of a vacuum residue from a Venezuelan crude was simulated by a distillation bitumen B80 (according to DIN 1995). Further, a vacuum residue of a Middle East crude (VR Kuwait) and its colloid components, i.e. dispersion medium, petroleum resins, and asphaltenes were investigated. Those substances were characterized by element analysis and average relative particle weight (molecular weight) (Table 4-200) and by analysis of their colloid composition according to Neumann [4-10] (Table 4-201). 

It is more easy to survey the various points when we set aside for the moment the simultaneously varying water content and thus restrict ourselves to the colloid compositions of the total mixture, the coacervates and the equilibrium liquids. ... 

G) and gum arabic contents (% A) of coacervate and equilibrium liquid. In the two last columns of the table one now finds the colloid compositions of the coacervate and the equilibrium liquid calculated from the above, both expressed in % A (= 100A/A + G). 

In Fig. 22 the colloid compositions of coacervate (column 6) and equilibrium liquid (column 7) are plotted as a function of the mixing proportion of the two sols (column 1). Two separate curves result, C for the coacervate, E for the equilibrium liquid. These curves intersect at the equivalent mixing proportion. Here or at any rate nearly here lies the electrophoretic reversal of charge point of the coacervate. 

The second auxiliary line ( Equiv. ), drawn horizontally through the equivalence point, reproduces the colloid composition of the equivalent coacervate. 

Since the mixtures were prepared by mixing two equally concentrated sols, the colloid compositions of the total mixtures lie on the third added auxiliary line ( M ) which goes through the origin at an angle of 45°. 

Since at the equivalent mixing proportion the colloid composition of the coacervate is the same as that of the equilibrium liquid, it is thus also equal to that of the total mixture. The third auxiliary line drawn at an angle of 45° thus also goes through the intersection of the curves C and E. 

Fig. 22. Changes in the colloid composition of complex coacervate and equil- ibrium liquid in an isohydric (pH 3.5) series of mixtures of equally concentrated (2%) sols of gelatin (G) and gum arabic (A).

Curves C and E give the colloid compositions of the coacervates and equilibrium liquids. 

At the equivalent mixing proportion the curves C and E intersect, the colloid composition of both is necessarily equal to that in the total mixture. 

At other mixing proportions of the sols the colloid compositions of coacervate, equilibrium liquid and total mixture are no longer equal. 

Fig. 24. Changes in the colloid composition of complex coacervate and equilibrium liquid on varying the pH while the mixing proportion (1 1) of the 2% gelatin and gum arabic sols remains constant.

Ordinates as in Fig. 22 (see p. 361). The colloid compositions of the total mixtures lie on the horizontal dotted line, those of the coacervates on curve C, those of the equilibrium liquids on curve E. 

At other pH values these three colloid compositions are no longer equal. 

The dotted curve rising obliquely to the left gives the colloid compositions of the equivalent coacervates (and equilibrium liquids) corresponding to the various pH values. 

These colloid compositions (columns 6 and 7) are reproduced as functions of the pH by the curves C and E. The colloid proportions of the total mixtures lie on a horisiontal line M (dotted) because they only refer to the same mixing proportion (50% A). 

In the figure is also drawn a curve ( Equiv. ) on which the colloid compositions of the equivalent coacervates, corresponding to various pH s, lie. (column 8). Since here or very near by lies the reversal of charge, that curve divides the plane of the figure into a positive (left) and a negative half (right). 

At constant mixing proportion this tendency can only be satisfied at one pH value. At the remaining pH values this is not the case but this tendency is manifested by the fact, that from a given total mixture (for example or m ) a coacervate (ci or C5) is formed which lies considerably closer in colloid composition to the equivalent coacervate corresponding to that pH than the total mixture and an equilibrium liquid (ci or t ) which lies appreciably further away from it. 

Properly spoken these line arc projections of tie lines occurring in the tetrahedral isotherm Water G+4 iV. The fourth component, water, has however been left out of consideration in the triangles of figs. 32 and 33, which represent only the colloid compositions of the mixtures. 2 e.g. shape of the viscosity-pH curve. See p. 208, Fig. 20,... 

From an investigation into the course of the tie lines in the ellipse (the region in which two coexisting coacervates are produced) it has now appeared that this dotted line is itself a tie line so that with the choice of the total mixture a the colloid compositions of these coacervates are given by the intersections 1 (the G - - A -I- n coacervate) and 2 (the G - - N + a coacervate) of the dotted line with the ellipse. 

The typical morphological pictures of composite coacervate drops discussed up to now are encountered in total mixtures within the ellipse which lie on or near the reversal of charge line (for example a in Fig. 8). The contrast in colloid composition of the coexisting coacervates is the greatest here. 

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