Core-crosslinked diblock terpolymer micelles – taking a closer look on crosslinking efficiency†
Herein, we present the synthesis, characterization and micellization of amphiphilic diblock terpolymers. Poly(ethylene oxide)-block-poly(allyl glycidyl ether-co-tert-butyl glycidyl ether) PEO-b-P(AGE-co-tBGE) and poly(ethylene oxide)-block-poly(furfuryl glycidyl ether-co-tert-butyl glycidyl ether) PEO-b-P(FGE-co-tBGE) with hydrophobic blocks of different molar masses containing 10 wt% of a crosslinkable monomer were synthesized by anionic ring opening polymerization (AROP) starting from a PEO macroinitiator. Micelles were formed and crosslinked in aqueous solution via either a Diels–Alder reaction or thiol–ene chemistry, respectively. Different amounts of crosslinker were used and advanced HR-MAS 1H NMR spectroscopy allowed subsequent semi-quantitative evaluation of the crosslinking reactions occurring. Hereby, crosslinking and monoaddition of the respective crosslinker to the diblock terpolymer side chain as well as the identification of any unreacted crosslinker within the micellar core allowed the evaluation of the reaction efficiency. Structural stability of the micelles in non-selective solvents was demonstrated using DLS measurements. Such in-depth analysis of crosslinking reactions may allow the fine-tuning of crosslinking processes in nanostructured materials to control swelling abilities or uptake and release of guest molecules in the future.