A Perfect Match: Fast and Truly Random Copolymerization of Glycidyl Ether Monomers to Thermoresponsive Copolymers

Abstract

Thermoresponsive and highly biocompatible poly(glycidyl ether) copolymers of glycidyl methyl ether (GME) and ethyl glycidyl ether (EGE) with adjustable molecular weight and defined end groups are synthesized by a monomer-activated anionic ring-opening polymerization with NOct 4 Br as initiator and i-Bu 3 Al as activator. In contrast to a conventional oxyanionic (nonactivated) copolymerization, higher molecular weights and a truly random incorporation of the monomers are accomplished. The monomer reactivity ratios were determined by the Kelen−Tudos approach to be r GME = 0.98 and r EGE = 0.95. The thermoresponsive properties of these copolymers with varying molecular weight were characterized by UV−vis transmittance and dynamic light scattering. Conformational changes of the copolymer during the phase transition on the molecular level were studied by 1 H and 13 C NMR spectroscopy in D 2 O and revealed only a partial dehydration during the collapse of the copolymer affecting both side chains and polymer backbone.

Fast and solvent‐free microwave‐assisted synthesis of thermoresponsive oligo(glycidyl ether)s

“…This effect is more pronounced for lower molecular weight 1 kDa OGEs than for the 3 kDa OGEs which is in line with recent reports on higher molecular weight copolymers with a GME/EGE ratio of 1:3 [Fig. S7(a)] . Thus, CPTs determined from normalized cooling curves between concentrations of 1 and 20 mg mL −1 span ranges of ΔCPT = 16 and 15 °C for the 1 kDa polymers 6 (1:3) and 7 (1:5), respectively, whereas they are markedly lower with ΔCPT = 7 °C for both 3 kDa polymers 9 (1:3) and 10 (1:5) in this concentration range.…”

“…Over the past years, the monomer‐activated anionic ROP applying triisobutylaluminum as activator and tetraalkylammonium salts as initiator at lower temperature has rapidly gained in importance . Although the monomer‐activated method usually leads to less side reactions, it is not the ideal choice when targeting oligomers due to large amounts of concomitantly formed tetraalkylammonium salts after quenching which are hard to separate from the product …”

“…In this work, we report the gram‐scale microwave‐assisted synthesis of thermoresponsive oligo(glycidyl ether)s (OGEs). PGEs have shown to exhibit a phase transition temperature in aqueous solution which is dependent on their molecular weight, copolymer composition and polymer concentration . These polymers have also demonstrated to be suitable materials for functional, thermoresponsive surface coatings which have been applied in cell culture for the nondestructive, temperature‐triggered recovery of confluent cell sheets .…”

Thermoresponsive Poly(glycidyl ether) Brush Coatings on Various Tissue Culture Substrates—How Block Copolymer Design and Substrate Material Govern Self-Assembly and Phase Transition

“…Therefore, two BP monomers with different linker chemistry between the photo-reactive BP and the polymerizable glycidyl ether moiety or, alternatively, post-modification of a short allyl-precursor block have been applied. According to our previously established synthesis strategy for PGE-X-BP block copolymers, the sequential MA-AROP yields PGE block copolymers with a random [ 39 ], high-molecular-weight, thermoresponsive GME/EGE block and a short, rather hydrophobic, photo-reactive BP-based anchor block [ 16 ]. In the PGE-X-BP nomenclature X indicates the spacer between the polymer backbone and the BP unit.…”

Double thermoresponsive block–random copolymers with adjustable phase transition temperatures: From block‐like to gradient‐like behavior

“…For a sharp transition, however, a composition drift along the chain should be minimized. This makes a random‐like copolymerization of the different thermoresponsive building blocks and therefore the knowledge of the copolymerization kinetics mandatory . In that sense, the use of chemically similar comonomers with similar reactivities toward radicals is advantageous.…”