Synthesis and Application Development of Oxygen (O2) and Carbon Dioxide (CO2) Switchable Polymer

Abstract

Stimuli-responsive polymers have attracted great attention due to their unique responses in physicochemical properties to changes in external environment and stimuli variations (e.g. pH, thermo, light, electric and magnetic field, etc.). Introduction of gas triggers has greatly expanded the family of stimuli-responsive polymers since the first work on a CO2-switchable polymer was reported in 2006. Although significant progresses have been achieved over the past decade, studies on gas-switchable polymers are still at an early stage, with many challenges in both fundamental and application areas remaining to be tackled.

This thesis focuses on synthesis and application development of O2 and CO2 switchable polymers. The thesis starts from investigating O2-switchable thermo-responsive fluorinated monomers and their linear random copolymers, which undergo LCST shifting induced by O2 treatment. It provides good insight and general guidance for design and screening of monomer candidates for the synthesis of O2-switchable polymers. The second part of the thesis presents development of the first O2 and CO2 dual gas-switchable microgel system and building of the microgel-colloidosomes with O2 and CO2 tailored shell permeability. The latter is evaluated as microcapsules for hierarchical control-release of water-soluble cargo molecules upon respective O2 and CO2 treatment. The last part of the thesis explores preparation of various porous polymer systems from high internal phase emulsion (HIPE) templates. In particular, a highly porous polyHIPE membrane with "open-cell" structure exhibiting CO2-switchable surface wettability is promising for smart separation applications. This thesis represents a significant progress and a solid step forward in the development of gas-switchable polymers from monomer design, polymer preparation, and advanced application of polymer systems.