Effect of ionic strength of the solution of some hydrogen - bonded interpolymer complexes on the stability and thermodynamic parameters

Abstract

Effect of ionic strength of the solution of some hydrogen-bonded interpolymer complexes on the stability and thermodynamic parameters Summary-The effect of ionic strength of the solution on the complex formation of poly(acrylic acid) (PAA) with poly(vinyl pyrrolidone) (PVP) has been studied in aqueous solutions containing various inorganic salts (NaCl, KCl, NH 4 Cl). Stability constant (K s), degree of linkage (θ) and related thermodynamic parameters (∆G 0 , ∆H 0 and ∆S 0) have been compared for different complexation systems. The comparative study indicated considerable difference in the values of these parameters, which has been explained on the basis of relative strength of H-bond present in different systems.

Atrazine immobilization on sludge derived biochar and the interactive influence of coexisting Pb(II) or Cr(VI) ions

“…The net effect of inorganic salts on atrazine sorption is determined by two opposite factors. On the one hand, an increase in the solution ionic strength can partially dissociate hydroxyl groups on SDBCs, disfavoring the H-bond with atrazine (Vasheghani et al, 2009). However, on the other hand, the addition of inorganic salts reduces the double layer thickness and strengthens the hydrophobic interactions that facilitate atrazine sorption (Ureña-Amate et al, 2005).…”

Effect of various types of interaction on the stability of some ternary interpolymer complexes involving poly(ethylene imine), poly(acrylic acid) and poly(ethylene glycol)

“…The thermodynamic parameters Δ H 0 and Δ S 0 can be calculated from the temperature dependence of K for the complexes using the following relationships:1, 2, 23, 14 where Δ G 0 is the change in standard free energy and R is the molar gas constant.…”

“…The different trends observed for Δ H 0 and Δ S 0 are obviously related to differences in the nature of the interactions involved for a particular pair of reacting units for each system. The net enthalpy change (Δ H 0 ) and overall change in entropy (Δ S 0 ) during interpolymer complex formation consist of three basic steps: (1) desolvation, in which the absolute value is related to the strength of interaction between solvent and each polymer component (Δ H 1 ), (2) complex formation by electrostatic and hydrogen‐bonding interactions (Δ H 2 ) and (3) conformational change involving complex formation (Δ H 3 ) 1, 2, 14…”

“…The net enthalpy change ( H 0 ) and overall change in entropy ( S 0 ) during interpolymer complex formation consist of three basic steps: (1) desolvation, in which the absolute value is related to the strength of interaction between solvent and each polymer component ( H 1 ), (2) complex formation by electrostatic and hydrogen-bonding interactions ( H 2 ) and (3) conformational change involving complex formation ( H 3 ). 1,2,14 Therefore, the overall change in H 0 and S 0 is the sum of these contributions. Since the contribution to each system will be different for various systems, different values for H 0 and S 0 are understandable.…”

“…Temperature dependence of standard enthalpy change H 0 for complexation systems I (A), II (B), III (C) and IV (D).the following relationships:1,2,23,14 …”