On the salt‐linkage formations of porous and nonporous silica particles with trimethylammonium glycol chitosan iodide

Abstract

The stoichiometry of the salt-linkage formations of nonporous and porous silica particles with trimethylammonium glycol chitosan iodide (TGCI) was investigated by comparing the results of colloid titration and adsorption experiments with those of potentiometric titrations.The surface charge (Q) of colloidal silica as function of pH was evaluated by means of the colloid titration with TGCI. On the other hand, the density (0) of = SiOo groups of silica gel at different pH was also evaluated by the adsorption experiment of TGCI. These results obtained were compared with the Q vs. pH and D vs. pH curves which were obtained by the potentiometric titrations at various ionic strengths for colloidal silica and silica gel, respectively. It was concluded that the -SiO@ groups on the surface of nonporous colloid silica form the salt-linkages stoichiometrically with @N(CH3)3-groups in TGCI, whereas the salt-linkage formation between @N(CH3)3-groups in TGCI and =SiOo groups of silica gel does not follow the stoichiometric relationship, since the salt-linkages of the = S O o groups in the pores of the silica gel could be affected by the steric hindrance of the TGCI chain.

Adsorption of poly(diallyldimethylammonium chloride) on colloid silica from water and salt solution

“…To further investigate the stoichiometry of salt-linkage formation, the pH dependence of Ap was compared with that of D. The result for PDDA is shown in Figure 2, together with that for TGCI, already reported. 15 It is found that at pH > 6 a fair correlation between Ap and D is Figure 3. Adsorption isotherm of PDDA(nf) on colloid silica from 0.2 N NaCl solution.…”

“…The curve of Ap vs. pH (O) for PDDA(nf) was obtained from the adsorption experiments in the absence of salt under the conditions of Ca = 2 g/L and C{ -1 X 10"4-1 X 10~3 mol/L, while that (•) for TGCI was cited from ref 15. The D vs. pH curve (full line) was determined by the potentiometric titration with NaOH for colloid silica suspended into 1 N NaCl solution (see ref15).…”

Complexation of Proteins with a Strong Polyanion in an Aqueous Salt-free System

“…Even if the formal charges of a protein in a salt solution can be determined using appropriate approaches such as potentiometric titration and electrophoresis, ,,− , the data obtained may not be identical with the number of protein charges responsible for the formation of an intrapolymer PPC. The reason is that PPC formation promotes the dissociation of counterions and/or protons; for example, and/or In fact, it has been demonstrated that the dissociation of counterions and/or protons occurs not only in the formation of PPCs 3,5,11,18 but also in the formation of salt linkages between oppositely charged polyions and colloid particles. − Therefore, the present study focused on finding a key to understanding the detailed mechanism of PPC formation using a salt-free system.…”

Conductometric and Light Scattering Studies on the Complexation between Cationic Polyelectrolyte Nanogel and Anionic Polyion

“…Many studies have employed the conductometric method for examining the stoichiometry of PEC formation; for example, see refs and as reviews and refs − as original papers in which the stoichiometry was studied at a certain ratio of [∼A − X + ] to [∼C + Y − ] or vice versa − such as the end point of colloid titration, and over a wide range of [∼A − X + ]/[∼C + Y − ] or vice versa. − However, we should note that (i) the PEC obtained from a polyanion−polycation mixture with a ratio of [∼A − X + ]/[∼C + Y − ] = 1 is a 1:1 stoichiometric complex when [∼A − X + ] = [X + ] and [∼C + Y − ] = [Y − ] can be observed, but (ii) at the ratios of [∼A − X + ]/[∼C + Y − ] ≠ 1 it is not clear whether the PEC formed is stoichiometric or nonstoichiometric even though [∼A − X + ] = [X + ] at [∼A − X + ] < [∼C + Y − ] or [∼C + Y − ] = [Y − ] at [∼A − X + ] > [∼C + Y − ]. This is because there are two different models in PEC formation: , random model (RM) in which the added polyions “uniformly” bind to all of the oppositely charged polyions in the system, and all-or-none model (AONM) in which a part of the polyions in the system “preferably” bind to the added polyions of opposite charge to “entirely” neutralize their electric charges, so that the other part of the polyions in the system remains uncomplexed with the added polyion.…”