Non‐isocyanate Polyurethanes from 1,1′‐Carbonyldiimidazole: A Polycondensation Approach

Abstract

1,1′‐Carbonyldiimidazole (CDI) provides a platform to generate high molecular weight polyurethanes from industrially relevant diols and diamines. CDI, which is described in the literature for its use in amidation and functionalization reactions, enables the production of well‐defined and stable polyurethane precursors, thus eliminating the need for isocyanates. Herein, the functionalization of 1,4‐butanediol with CDI yields an electrophilic biscarbamate, bis‐carbonylimidazolide (BCI), which is suitable for further step‐growth polymerization in the presence of amines. Elevated reaction temperatures enable the solvent‐, catalyst‐, and isocyanate‐free polycondensation reaction between the BCI monomer and various diamines. The thermoplastic polyurethanes produced from this reaction demonstrate high thermal stability, tunable glass transition temperatures based on incorporation of flexible polyether segments, and mechanically ductile thin films. CDI functionalized diols will allow the preparation of diverse polyurethanes without the use of isocyanate‐containing monomers.

Carbamate thermal decarboxylation for the design of non-isocyanate polyurethane foams

“…Synthesis of 1,4-butyl(bis-carbonylimidazolide) (BBCI), 1b, and 1,4-cyclohexanedimethyl(bis-carbonylimidazolide) (CHDMBCI), 1a Synthesis followed from our previous literature (Scheme S1 †). 28 1,4-Butanediol (27.04 g, 0.3 mol) was added to a three-necked, 1 L round-bottomed flask outfitted with a magnetic stir bar, nitrogen inlet, nitrogen outlet, and rubber septa. The butanediol was dissolved in ethyl acetate (600 mL) at 25 °C for 10 min under a nitrogen purge.…”

“…27 Our previous work demonstrated the synthesis of NIPU using carbonyldiimidazole (CDI) functionalized bis-carbonylimidazolide (BCI) monomers. 28 This BCI pathway exhibited greater versatility compared to previous NIPU pathways due to increased compositional diversity compared to cyclic carbonate and isocyanate approaches. [29][30][31][32] BCI monomers provided an isocyanate-free pathway to a highly versatile platform for the future synthesis of polyurethanes.…”

Synthesis of non‐isocyanate polyurethanes with high‐performance and self‐healing properties

“…33 Polycondensation is also a significant route considering non-isocyanate and nonsolvent procedure. [34][35][36] NIPUs synthesized by polycondensation have identical structures and characteristics to conventional PUs, and this method is a solvent-free and more environmentally friendly route. Following this strategy, elastomeric PUs are synthesized by substituting dimethyl carbonate for diisocyanate.…”

Straightforward synthesis of aliphatic polydithiocarbonates from commercially available starting materials

“…15 1,1′-Carbonyldiimidazole (CDI, also known as Staab's reagent) 16 has been employed for various applications in organic chemistry, 17,18 and quite recently for polymer synthesis by virtue of its reactivity with various nucleophiles (carboxylic acids, alcohols, and amines) as shown in Scheme 1D. 19,20 Moreover, CDI is safe, cheap (3 € per gram), and easy to handle, compared to the commonly used toxic phosgene or chloroformates. In fact, Malkoch 20 and colleagues reported the detailed phosgene-free synthesis of aliphatic polycarbonates with a broad range of properties.…”

“…1,1′-Carbonyldiimidazole ( CDI , also known as Staab's reagent) 16 has been employed for various applications in organic chemistry, 17,18 and quite recently for polymer synthesis by virtue of its reactivity with various nucleophiles (carboxylic acids, alcohols, and amines) as shown in Scheme 1D. 19,20…”