Synthesis of novel temperature/pH responsive polymer via oxyanionic polymerization

Hyperbranched poly(3-ethyl-3-oxetanemethanol)-graft-poly(2-dimethylaminoethyl methacrylate) (HP-g-DMA) with a three-demensional structure was synthesized via oxyanionic polymerization. The hydroxyl groups of hyperbranched poly (3-ethyl-3-oxetanemethanol) (HP) reacted with KH and conversed into potassium alcoholate macroinitiators with high initiating efficiencies. High monomer conversion (>95%) was obtained and no residual macroinitiators or monomer was observed. UV-visible spectra indicate that the aqueous solution of the HP-g-DMA exhibited the lowermost critical solution temperature (LCST). The LCST was influenced by the chain length of DMA and pH condition of solution. It is found that LCST decreased with increasing DMA chain length or increasing pH value of solution.