(Acid-Base)-Dependent Globular Structures of Partially N-Alkylated Poly(Tertiary Amines)

Summary

A new type of bifunctional polybase is presented which is obtained by partial N-alkylation of poly(tertiary amines) with pendant amino groups. The ability of partially N-methylated poly[thio-l-(N-N-diethyl- aminomethyl)ethylenes], Q-P(TDAE)X, to form hydrophobic microdomains in aqueous medium is discussed in regard to the amounts of N-alkylated repeating units and to acid-base reactions at residual tertiary amine sites. Emphasis is on deprotonated compounds with low contents of quaternary ammonium groups, as they can take on polysoap-like globular structures, thus explaining the difference between N-alkylation and N-protonation to form water soluble poly(tertiary amine) macromolecules. The acid-base dependency of these globular structures is discussed and it is shown that cooperative chemical and conformational transitions can be observed for some compounds. The effect of the nature of polymer backbones is investigated by comparing two polymers with the same degree of N-methylation but different polymer backbones, of the poly(thioether) and the poly(olefin) types, respectively. Potentiometric, viscometric and polarimetric titrations, and solubilization of progesterone, (a lipophilic water—insoluble compound), are used to characterize the physico—chemical states of these bifunctional polybases in water.