Poly(2-ethyl-2-oxazoline-co-N-propylethylene imine)s by controlled partial reduction of poly(2-ethyl-2-oxazoline)

The partial reduction of poly(2-ethyl-2-oxazoline) was investigated. A series of poly(2-ethyl-2-oxazoline-co-N-propylethylene imine)s were synthesized by direct reduction using lithium aluminum hydride or borane/dimethylsulfide (BH₃/DMS), respectively. It is shown that the degree of reduction can be readily controlled either by the reaction time when using an excess of LiAlH₄ or by the stoichiometry of BH₃/DMS as was demonstrated by 1H-NMR spectroscopy. Differential scanning calorimetry revealed that the glass transition temperature of the products decreased with increasing degree of reduction up to 25% of reduction, above which no glass transition could be detected. This control over the reduction allows the tailor synthesis of partially cationic polymers, which, in combination over the hydrophilic/lipophilic balance through the side chain length allows a tight control over materials properties. Such materials may be interesting, inter alia, for biomaterials or organic electronics.