Conventional Oxyanionic versus Monomer-Activated Anionic Copolymerization of Ethylene Oxide with Glycidyl Ethers: Striking Differences in Reactivity Ratios

Abstract

Detailed understanding of the monomer distribution in copolymers is essential to tailor their properties. For the first time, we have been able to utilize in situ 1H NMR spectroscopy to monitor the monomer-activated anionic ring opening copolymerization (AROP) of ethylene oxide (EO) with a glycidyl ether comonomer, namely, ethoxy ethyl glycidyl ether (EEGE). We determine reactivity ratios and draw a direct comparison to conventional oxyanionic ROP. Surprisingly, the respective monomer reactivities differ strongly between the different types of AROP. Under conventional oxyanionic conditions similar monomer reactivities of EO and EEGE are observed, leading to random structures (r EO = 1.05 ± 0.02, r EEGE = 0.94 ± 0.02). Addition of a cation complexing agent (18-crown-6) showed no influence on the relative reactivity of EO and EEGE (r EO = r EEGE = 1.00 ± 0.02). In striking contrast, monomer-activated AROP produces very different monomer reactivities, affording strongly tapered copolymer structures (r EO = 8.00 ± 0.16, r EEGE = 0.125 ± 0.003). These results highlight the importance of understanding reactivity ratios of comonomer pairs under certain polymerization conditions, at the same time demonstrating the ability to generate both random and strongly tapered P­(EO-co-EEGE) polyethers by simple one-pot statistical anionic copolymerization. These observations may be generally valid for the copolymerization of EO and glycidyl ethers.

Design and synthesis of thermoresponsive aliphatic polyethers with a tunable phase transition temperature

“…Furthermore, the copolymerization of EO and substituted epoxides sometimes results in producing blocky copolymers with the EO-rich segment near from the initiation end, because of the appreciable difference in their reactivities. 15 Therefore, exploring an alternative aliphatic polyether system as tunable thermoresponsive materials is of great importance.…”

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

“…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 …”

“…[14][15][16] 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. 17,18 For the development of a simple, solvent-free method to prepare low-molecular weight thermoresponsive PGEs using alcoholate initiators, microwave heating represents a promising tool as it has shown to be a fast alternative to conventional heating. 19,20 During the past decades, microwave-assisted reactions have made their way in virtually all branches of polymer chemistry.…”

Glycidyltosylat: Die Polymerisation eines “nicht polymerisierbaren” Monomers ermöglicht eine universelle, polymeranaloge Funktionalisierung von Polyethern

“…[1,[5][6][7] Durch kontrollierte radikalische Copolymerisation ermçglichen sie einen einfachen Zugang zu funktionellen Poly(meth)acrylamiden. Basierend auf der monomeraktivierten ROPv on Epoxiden [9,10] entwickelten Carlotti und Deffieux eine Methode, [11] [13] Zusätzlich untersuchten wir die kürzlich von G. Zhang [14] und X.-H. Zhang [15] et al verçffentlichte Methode,d ie P 2 -t-Bu, B-(Et) 3 als Lewissäure und 2-(Benzyloxy)ethanol als Initiator nutzt, welche ebenfalls eine milde Methode zur Polymerisation von Epoxiden und Glycidylethern darstellt. Im Vergleich zu diesen hochentwickelten Polymer-Modifizierungsstrategien fürV inylpolymere bietet die Chemie der Polyether derzeit keine ähnlichen polymeranalogen Modifizierungsoptionen.…”

“…Die nukleophile Substitution der "Lehrbuch"-Abgangsgruppe Tosylat macht die Ringçffnung des Epoxids und die Polymerisation durch herkçmmliche alkoxidinitiierte Ringçffnungspolymerisation (ROP)u nmçglich. Basierend auf der monomeraktivierten ROPv on Epoxiden [9,10] entwickelten Carlotti und Deffieux eine Methode, [11] Struktur %GlyTs M n (g mol À1 ) T g T m P(PO 0,92 -co-GlyTs 0,08 )8 5800 1,9 À55 -P(PO 0,85 -co-GlyTs 0,15 )1 56 800 2,1 À43 -P(PO 0,84 -co-GlyTs 0,16 )1 64 400 1,8 À41 -P(PO 0,78 -co-GlyTs 0,23 )2 34 300 2,1 À35 -P(PO 0,75 -co-GlyTs 0,25 )2 53 000 2,1 À34 -P(EO 0,93 -co-GlyTs 0,07 )7 5500 1,6 À43 33 P(EO 0,92 -co-GlyTs 0,08 )8 4400 1,7 À45 29 P(EO 0,89 -co-GlyTs 0,11 )1 14 600 1,6 À47 18 P(EO 0,86 -co-GlyTs 0,14 )1 43 900 1,6 À45 -P(EO 0,82 -co-GlyTs 0,18 ) [13] Zusätzlich untersuchten wir die kürzlich von G. Zhang [14] und X.-H. Zhang [15] Zur nukleophilen Substitution wurden P(PO-co-GlyTs) Proben mit unterschiedlichen Mengen an GlyTs und zugesetztem Nukleophil in Acetonitril (bzw.D MF) gelçst, 16 h erhitzt und über Dialyse gegen Methanol aufgereinigt. Wiein Abbildung 3f ürd ie Substitution unter Verwendung von Dimethylamin gezeigt, finden sich im 1 H-NMR-Spektrum des substituierten Copolymers keine Signale der Tosylatgruppe, und die Methylprotonen der eingeführten Dimethylamingruppe kçnnen nachgewiesen werden.…”