Polycomplexes stability

Since the above discussed mechanisms of interpolymer substitution reactions rest on the most general peculiarities of the structure and properties of the polycomplexes, they must be common for reactions with participation of polycomplexes stabilized by interactions of any nature such as hydrogen bonds, electrostatic, etc. This is confirmed by numerous studies the results of which have been published in recent years. 

Analogous changes are observed for IR-spectra of [TMVEPVP]/[LPAA] complexes. The shifting of the characteristic band of C=0 groups of N-vinylpyrrolidone from v=1672 cm to v=1640 cm and C=0 groups of LPAA from v=1710 cm to v=1730 cm testifies the formation of polycomplexes stabilized by H-bonds. 

Experimental dependencies of the stability of polycomplexes on the length of macromolecules and temperature are, in general, satisfactorily described by Eqs. (7) and (8a) 28,32). However, there are a whole number of objective reasons owing to which these equations may be used for quantitative calculation of the thermodynamic... 

Under matrix polycondensation considerable influence exerted by the stability of the polycomplex of matrix and growing chains also is possible if the direction (mechanism) of the elementary step of the polycondensation depends on where this step takes place — in solution or at the matrix (i.e., with participation of polymer, oligomer and even monomer molecules adsorbed on the matrix). Scheme 14 shows cases corresponding to strong 14a and weak 14b binding of growing chains in a polycomplex ... 

Since the polycomplex is a product of matrix polymerization or polycondensation, each macromolecule of the matrix works as a matrix only once. All attempts to create systems with the workable zip-up mechanism of polymerization of monomer molecules, preliminarily bound with the matrix, with automatic liberation of the formed daughter chain from the matrix, have ended in failure (this was assumed to be possible, when, for instance, stabilization of the monomer-matrix complex takes place due to the presence of the double bond in the monomer 94 95>. 

The stability of complexes formed in non-aqueous media against the destructive action of organic solvents has been studied (DMSO). The PAA-PVP polycomplex retains its compact structure up to 40 vol-% content of DMSO in the mixture with methanol (Fig. 16, curve 2) this follows from the low values of the intrinsic viscosity. A further increase of the DMSO content results in a sharp rise of the viscosity i.e. the complex dissociates. That the complex breaks down in pure DMSO is confirmed by the following facts the intrinsic viscosity of the PAA-PVP system is an additive function of the viscosity of individual polymers in this solvent while in methanol [ 7] of the PAA-PVP system is close to the viscosity of globular proteins. It is of interest that... 

Interactions between chemically and structurally complementary macromolecules have usually a cooperative character. Probably, the formation of cooperative systems involving two (or more) types of bonds at the same time (e.g. of ionic and hydrogen bonds)63 is possible. It should be mentioned here that hydrophobic interactions play an important role in the stabilization of synthetic and natural polyelectrolyte complexes and also of complexes with hydrogen bonds. The contribution of either interactions may be different, depending on the chemical structure of the components of the polycomplex and the nature of the medium. 

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