Influence of solvent on thermodynamic parameters and stability of some multicomponent polymer complexes involving an acrylic polymer, poly (ethylene imine) and poly (vinyl pyrrolidone)

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

“…The complex formation in such systems is controlled by several critical factors such as minimal molecular weight, critical pH of complexation, minimal amount of active group sequence, solvent nature, temperature etc. [17,32,34]. Given all this, to study the effect of ionic strength on stability constant K s and related thermodynamic parameters of PAA/PVP complexes in aqueous solutions, several two-component interpolymer complexes were prepared by mixing of PAA with stoichiometric quantities of PVP (1:1 molar ratio) in pure aqueous medium and in the mediums containing inorganic salts such as NaCl, KCl or NH 4 Cl (systems I-IV, see Table 1).…”

“…The procedure chosen for calculations of the stability constant K s and degree of linkage θ of interpolymer complexes was the same as in earlier communications [17,32,[34][35][36]. The degree of linkage θ is defined as the ratio of the binding groups to the total number of potentially interacting groups [equation 1] and it is related to the stability constant K s of the interpolymer complex by the equation 2 The stability of these complexes in different media at higher temperature is likely to be influenced by the relative strength of H-bonds present in them.…”

“…However, hydrogen bonds -which are mainly formed at a relatively low temperature -weaken with temperature increase. Hence the stability of IPC greatly depends on a delicate balance between the contributions of hydrogen bonding and hydrophobic interactions [10,[15][16][17]. Hydrophobic interactions can also be affected by different substances added to the aqueous solutions.…”

Thermodynamic parameters of poly(ethylene glycol) from dielectric relaxation studies

“…Microwave dielectric relaxations studies in general and specifically on polymers have gained importance in recent times, in view of the insight it can give in understanding molecular dynamics,1–6 which may influence the applications in different fields like Pharmaceutical excipients, cosmetic preparations, Industrial and biological solvents, Chemical intermediates, etc. The electric field vector component of the microwave influences the dipole moment of the individual unit of the polymer molecule and tends to orient them in the direction of the electric field vector 4–9. If appropriate frequency of the microwave is under use, then microwave frequencies are capable of influencing the orientation polarization of the polar polymer materials 10–14.…”

“…The orientation polarization being temperature dependent2, 15–20 helps to obtain meaningful information, like shape, size, and the rotating molecular entities. The molecular dynamics is characterized by the observed values of relaxation times4–9 in microwave frequency region. The dielectric relaxation measurements have been shown to be reliable for investigating the rotational motion of a dipolar unit of a polar polymer in a dilute solution prepared with nonpolar solvent.…”