One-pot synthesis of amphiphilic multiblock poly(2-oxazoline)s via para-fluoro-thiol click reactions

Abstract

A clickable initiator, pentafluoro benzyl bromide, has been investigated for the cationic ring opening polymerization of poly(2-oxazolines). Additionally, the clickable alpha end group was then utilized in a para-fluoro-thiol click reaction to synthesise linear diblock, tetrablock, multiblock copolymers as well as star shaped poly(2-oxazoline)s using dithiol compounds as terminating agents. Thus, a one-pot approach combining the para-fluoro-thiol click reaction and direct termination of the poly(2-oxazoline) living chain end with 4,4-thiobisbenzenethiol has been performed to prepare multiblock copolymers of poly(2-ethyl-2-oxazoline) (PEtOx) and poly((2-ethyl-2-oxazoline)-b-(2-methyl-2-oxazoline) (PEtOx-mb-PMeOx). All obtained polymers were characterized by Size Exclusion Chromatography (SEC), ¹H Nuclear Magnetic Resonance (NMR) and Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-ToF) mass spectrometry. Last but not least, the self-assembly properties of prepared amphiphilic polymers were studied with DLS and TEM. Nanoparticles with a diameter ranging from 184 nm to 250 nm were observed in TEM for PEtOx-mb-PMeOx copolymers.