Chainlength effects on interactions of polyvinylpyrrolidone with low and high molecular compounds

Very narrow fractions of polyvinylpyrrolidone (PVP) for a range of low molecular weight from 20·10³ to $\text{\&{;10}{}^3$ were prepared by gel filtration using sephadex gel. Interactions between fractions of different M_n and small molecules (iodine and 1-anilinonaphthaline-8-sulphonate) and polymers (polymethacrylic and polyacrylic acids) were studied in aqueous solution. The ability of PVP to form complexes with low molecular weight compounds depends on chainlength. The greatest loss of the ability was observed for PVP with M_n on passing from 5·10³ to $\text{\&{;10}{}^3$. The chainlength effects for PVP are accounted for an unlike dehydration and unlike “local” link concentration near links for these macromolecules in water. For PAA and PMAA. the threshold values of M?_n, below which there is the beginning of weakening of complexation for PVP, are 6·10³ and 2.5·10³ respectively. The difference of the complex formation for these polyacids appears to be related to hydrophobic interactions between the χ-methyl groups of PMAA and nonpolar regions of PVP.