Formation of a Polyelectrolyte Complex from Carboxymethyl Cellulose and Poly(ethylenimine)

Abstract

Formation of a polyelectrolyte complex was investigated as a function of pH by using carboxymethyl cellulose and poly(ethylenimine) as polyanion and polycation components, respectively. Experimental data on turbidity and conductometric and potentiometric titrations led to the conclusion that the formation of the polyelectrolyte complex did not obey stoichiometry. Such a result may be attributed to the less flexible nature of the polyanion molecular chains and to the distribution of ionizable groups on the chains of both components.KEY WORDS Polyelectrolyte Complex I Stoichiometry 1 Carboxymethyl Cellulose I Poly(ethylenimine) 1 Turbidity 1 When a polyelectrolyte reacts with an oppositely charged polyelectrolyte in an aqueous solution, a polyelectrolyte complex is formed. The complex formation with polyelectrolytes may differ from salt formation with microelectrolytes from the viewpoint of molecular conformations, i.e., the formation of a polyelectrolyte complex may not necessarily always be stoichiometric, if, for example, the chain are rigid. The reaction to form a polyelectrolyte complex is influenced by the degree of polymerization, the ionic strength of the medium, the reaction temperature, etc., and depends on pH if at least either the polyanion or the polycation is a weak polyelectrolyte. The polyelectrolyte complex is obtained in the state of a precipitate, a gel or a sol, depending on conditions. In a previous paper/ we have reported a thermodynamic investigation on the complex coacervation phenomena, a phase separation in which polyelectrolytes participate, by using a polycation and a polyanion, both prepared from poly(vinyl alcohol).Backbone chains of vinyl polymers, for example, are regarded to be flexible, while chains of polysaccharides and of polypeptides under some particular conditions are considered to be rigid. The chain flexibility of component polymers should affect the formation and the structure of the complex.In most papers reported to data, complex formations performed under a stoichiometric relation have been investigated. The colloid titration 2 ' 3 is performed under such a conditions. Michaels 4 has pointed out that the reaction of two strong polyelectrolytes with opposite charges, sodium poly(styrene sulfonate) and poly(vinylbenzyl trimethyl ammonium chloride), was stoichiometric. Hosono 5 examined the complex formation from partially sulfated poly(vinyl alcohol) and poly(vinyl alcohol) partially acetallyzed with diethoxy ethyl trimethyl ammonium salt, both of which are strong polyelectrolyte, and has pointed out that the reaction was stoichiometric and did not depend on the pH of the medium.With respect to complexes made by reaction of a strong polyelectrolyte with a weak polyelectrolyte, Fuoss, et al.,6 showed that poly(4-vinyl-n-N-butyl pyridonium bromide) (strong polybase) reacted with sodium polyacrylate (weak polyacid) in nearly stoichiometrical equivalence, and Hosono, et al.,7 have pointed out that partially sulfated poly(vinyl alcohol) reacted with partially aminoa...

Structural Determinants of the Stability of Enzyme‐Responsive Polyion Complex Nanoparticles Targeting Pseudomonas aeruginosa’s Elastase

“…Interestingly, P2 SH showed the smallest range of formulation that yielded colloidally stable particles (Figure ), suggesting again that this peptide may adopt a different conformation in solution. The deviation from the theoretical neutral point at N : COOH=1 : 1 towards B‐PEI‐rich mixtures had been previously described for other B‐PEI‐containing PIC nanoparticles, and it is likely a result of the incomplete protonation of all amines in B‐PEI due to Coulombic interactions between neighboring ammonium groups . Similarly, since peptides with higher multivalencies should have stronger affinities for B‐PEI, the exchange of the peptides with higher multivalency (i. e. P3 SH and P4 SH ) between PIC nanoparticles and the solution should be slower than for the smaller peptides, thus trapping colloidally stable intermediates even at N : COOH ratios that should favor the formation of neutral PIC nanoparticles.…”

Mesophase separation and probe dynamics in protein–polyelectrolyte coacervates

“…Non-stoichiometric PDADMAC-BSA coacervates are formed in 50 mM NaCl. 31 Non-stoichiometric coacervation was also found by Sato and Nakajima 32 in salt-free mixtures of a weak rigid polyanion, carboxymethyl cellulose, with a flexible weak polycation, polyethylenimine. Non-stoichiometry, i.e.…”

Colloidal polyion complexation from sodium poly(acrylate) and poly(vinyl ammonium) chloride in aqueous solution

“…Fuoss and Sadek 2 reported stoichiometric complexation between sodium poly(acrylate) (NaPA) or sodium poly(styrene sulfonate) and poly(4-vinyl-N-butylpyridinium) chloride, and other researchers [3][4][5] later reported stoichiometric complexation for different polyelectrolyte pairs (Table 1). On the other hand, Tsuchida et al 6 and Nakajima and his group [7][8][9] observed non-stoichiometric complexation of the polyion pairs listed in Table 1. The latter findings indicate that not only the electrostatic attraction but also the hydrophobic interaction among polyion chains has important roles in polyion complexation in aqueous solution.…”