CO2 -Induced Morphological Transition of Co-Assemblies from Block-Random Segmented Polymers

Abstract

The co-assembly process is an effective approach to construct hierarchically nanostructured soft materials, but morphological transition of co-assemblies upon external stimuli, particularly the "green" trigger CO₂ , is not unraveled yet. Here, a segmented copolymer, poly(styrene)-block-poly[(4-vinyl pyridine)-random-((2-(diethylamino)ethyl methacrylate)] (P1), is used to co-assemble in the mixed solvent of dimethyl formamide and water with poly(ethylene oxide)-block-poly[(4-vinyl pyridine)-random-((2-(diethylamino)ethyl methacrylate)] (P2) and poly(ethylene oxide)-block-poly(acrylic acid) (P3), respectively. It is found that Janus micelles are generated from the P1-P2 pair in the presence of ferric ion, while wormlike micelles are formed from the P1-P3 duad. Upon stimulation with CO₂ , Janus and wormlike aggregates are transferred into core-shell and spherical micelles, respectively.

Keywords: CO2-sensitivity; co-assembly process; morphological transition; segmented copolymers.