Selective nucleophilic substitution reactions on poly(epichlorohydrin) using aromatic and aliphatic thiol compounds

Poly(epichlorohydrin) has been modified chemically using aromatic and aliphatic thiol compounds. The reactivity and kinetics of these modifiers with respect to substitution and elimination was studied. Therefore, the chemical structure of the reaction products was analysed using 13C NMR, 1H NMR and 13C-DEPT spectroscopies. It is shown that both, aromatic as well as aliphatic thiols, are highly selective with respect to nucleophilic substitution as reaction conditions can be found which allow one to achieve degrees of modification of up to 90% without any elimination side-reaction. As a consequence no degradative chain-scission takes place what has been confirmed by GPC analysis.A comparison between both types of thiol modifiers shows that aromatic ones react faster and that higher degrees of modification are reached than with their aliphatic homologues.