Synthesis of Polyurea Thermoplastics through a Nonisocyanate Route Using CO₂ and Aliphatic Diamines

Abstract

The transformation of CO2 can alleviate environmental problems and promote sustainable development. We prepared polyureas (PUas) from CO2 and diamines via an isocyanate-free route. PUas synthesized by the copolymerization of CO2 with 1,6-hexamethylene diamine (HMDA) and 1,12-diaminododecane (DAD) presented superior mechanical properties compared to the ones from CO2 with either DAD or HMDA alone. The PUas contained DAD and HMDA segments in the main polymer chains, and hydrogen bonds were formed between DAD and HMDA segments, in which the hydrogen bonds were distributed at regular and irregular intervals depending on the relative amounts of the two segments. For PUas synthesized from either DAD (x = 0) or HMDA (x = 100), hydrogen bonds were mostly present at regular distances, forming a regular hydrogen bond network and contributing to high crystallinity. For PUas of DAD100–x HMDA x (37 ≤ x ≤ 63), in contrast, irregular hydrogen bonds coexist with regular ones, so the crystallinity was lower compared to DAD100 and HMDA100. It is to note that the PUas synthesized are advantageous for postprocessing as their initial decomposition temperatures (T d,5% > 295 °C) are about 85 °C higher than the melting temperatures (T m , 116–207 °C). Furthermore, mechanical properties were optimized by varying the chain length of aliphatic diamine used. The PUas (DAD50HMDA50 and DAD37HMDA63) obtained show mechanical properties superior to those of the previously reported polymeric materials, such as CO2-based PUas, isocyanate-free polyhydroxyurethanes, CO2-sourced polycarbonates, polyamide 6, and traditional PUas from diisocyanates. Hence, the present CO2-sourced PUas will find industrial applications in different fields.

Bio-based Thermoplastic Polyhydroxyurethanes Synthesized from the Terpolymerization of a Dicarbonate and Two Diamines: Design, Rheology, and Application in Melt Blending

“… a Number average molecular weight and dispersities were estimated from SEC with the THF eluent at 40 °C relative to poly­(methyl methacrylate) standards. b The crystallinity X c was calculated from DSC by dividing Δ H m = 19.3 J/g with Δ H m,100% = 219 J/g of DAD as crystallinity was caused by the addition of DAD. The Δ H m,100% of DAD was estimated by interpolation from the Δ H m,100% of 1,12-diaminododecane and 1,6-hexamethylene diamine c The crystallinity X c was calculated from WAXS by using the deconvolution method to estimate the area of the amorphous and crystalline portions.…”

“… b The crystallinity X c was calculated from DSC by dividing Δ H m = 19.3 J/g with Δ H m,100% = 219 J/g of DAD as crystallinity was caused by the addition of DAD. The Δ H m,100% of DAD was estimated by interpolation from the Δ H m,100% of 1,12-diaminododecane and 1,6-hexamethylene diamine …”

A self-healing and recyclable poly(urea-imine) thermoset synthesized from CO2

“…When OUa, TA and TAEA reacted together, the absorption bands of the PUIs formed (OUa 3 -T 2 , OUa 1 -T 1 and OUa 2 -T 3 ) were similar to those of OUa 1 -T 0 . The broad N-H stretching vibrations indicated the wide distribution of ordered and disordered hydrogen bonds (difference in distance and geometry), 59,60 which was also confirmed by the broad band due to CvO stretching vibrations, including free urea bonds. In addition, the adsorption at 1633 cm −1 suggested that the hydrogen bonds were mostly in a disordered form in PUIs.…”

High‐performance thermoplastic polyureas via a non‐isocyanate route from urea and aliphatic diamines

“…Zhao and coworkers developed a catalyst‐free two‐step method to synthesize CO 2 ‐based PUrs to improve the properties 18 . Nevertheless, high pressure and long reaction time are required for this method, which hinders further development in the commecilization 19,20 . The synthetic method based on dicarbamates and diamine also seems quite attractive but catalysts are usually required 21 .…”

“…18 Nevertheless, high pressure and long reaction time are required for this method, which hinders further development in the commecilization. 19,20 The synthetic method based on dicarbamates and diamine also seems quite attractive but catalysts are usually required. 21 In this method, a two-step procedure is more favorable than a one-pot procedure.…”