Stimuli-responsive OEG-based Dendronized Copolymers

Polymers with stimuli-responsive properties attract intensive research interest recent decades as they have potential applications in many areas from materials science to biomedicine. OEG-based dendronized polymers not only combine the specific structure of dendronized polymers and biocompatible property of OEG-based polymers, but also show unique thermoresponsive behaviors. In the present thesis, through copolymerization of OEG-based dendritic macromonomers with HEDTA monomers, a series of novel multi-responsive dendronized copolymers were prepared, their responsive behaviors and applications in smart separation were investigated.Four kinds of dendronized copolymers with different copolymerization ratio, molecular weight and dendron generation were efficiently synthesized through the copolymerization of OEG-based dendritic macromonomers with HEDTA monomer. Their structures and compositions were characterized by 1H NMR spectroscopy. Their molecular weights were characterized by GPC. These copolymers exhibit thermoresponsive behaviors which were firstly followed by UV/Vis spectroscopy. It was found that their thermally induced phase transitions were influenced by several parameters, including copolymerization ratios, salt, p H values, metal ions and dendron generations. Interestingly, the copolymer with second generation OEG dendritic units shows specific shielding effect to the protonation of HEDTA in aqueous solution at room temperature. This make it exhibit different p H responsive behavior compared to first generation copolymers. DLS measurement were then applied to investigate the thermally induced aggregation behavior of the copolymers. By virtue of the thermoresponsive property of OEG-based dendritic polymers and the multi-charged and chelating ability of HEDTA units, these copolymers are proved to be good candidates for separation of dyes and metal ions.