Schizophrenic thermoresponsive block copolymer micelles based on LCST and UCST behavior in ethanol–water mixtures

Abstract

The development of responsive and multiresponsive polymers is gaining interest as they enable the development of more and more complex responsive materials. In this contribution, the synthesis and solubility behavior of well-defined poly(methyl acrylate) (PMA) and poly(diethylene glycol ethyl ether acrylate) (PDEGEA) homopolymers as well as PMA-block-PDEGEA block copolymers is reported. At first, a solubility screening of the homopolymers in ethanol–water solvent mixtures was performed in a high-throughput experimentation (HTE) manner using parallel turbidimetry, which revealed that in 35wt% ethanol PMA undergoes an upper critical solution temperature (UCST) phase transition while PDEGEA undergoes a lower critical solution temperature phase transition in this solvent mixture. Moreover, the thermoresponsive self-assembly of PMA-b-PDEGEA block copolymers in water and ethanol were investigated by turbidimetry and DLS revealing UCST-induced disassembly of the micelles in ethanol and LCST-induced clustering of the micelles in water. Finally schizophrenic behavior of the PMA-b-PDEGEA block copolymers in 35wt% ethanol is demonstrated.