Abstract
The spontaneous polymerization of 4-vinylpyridine (VP) in aqueous solutions ([VP] = 1 mole/1) in the presence of low molecular weight (mol.wt.) acids or poly-acids was found to take place in 3 directions yielding polymeric products of differing compositions, i.e. ionene (at pH > 1·.1), polyvinylpyridine (at pH < 0·.4) and the ion-enepolyvinylpyridine copolymer (0·4 < pH < 1·1). The direction of the reaction depends on the acidity of the medium; that for VP to ionene has a stepwise zwitter-ionic mechanism, that for the poly-VP a zwitter-ionic chain mechanism. The 3 differing polymer structures form through the same intermediate reaction centre, i.e. the zwitter ion. The change of the mechanism of VP plymerizatien as a result of increase in acidity is explained by associations of the monomer. The zwitter ion is notsubject to termination on the proton, and the process takes place by a chain mechanism. The associations of the monmer molecules can be produced also at higher pH by adding to the polymerization medium some non-polymerizing low mol.wt. salts, e.g. Na 2SO 4.
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