Solvent- and Catalyst-free Synthesis, Hybridization and Characterization of Biobased Nonisocyanate Polyurethane (NIPU)

Abstract

Nonisocyanate polyurethane (NIPU) is a research hotspot in polyurethane applications because it does not use phosgene. Herein, a novel method of solvent- and catalyst-free synthesis of a hybrid nonisocyanate polyurethane (HNIPU) is proposed. First, four diamines were used to react with ethylene carbonate to obtain four bis(hydroxyethyloxycarbonylamino)alkane (BHA). Then, BHA reacted with dimer acid under condensation in the melt to prepare four nonisocynate polyurethane prepolymers. Further, the HNIPUs were obtained by crosslinking prepolymers and resin epoxy and cured with the program temperature rise. In addition, four amines and two resin epoxies were employed to study the effects and regularity of HNIPUs. According to the results from thermal and dynamic mechanical analyses, those HNIPUs showed a high degree of thermal stability, and the highest 5% weight loss reached about 350 °C. More importantly, the utilization of these green raw materials accords with the concept of sustainable development. Further, the synthetic method and HNIPUs don’t need isocyanates, catalysts, or solvents.

Preparation and Evaluation of Glucose Based Non-Isocyanate Polyurethane Self-Blowing Rigid Foams

“…The wide peak around 3300 cm −1 is characteristic of the O–H and N–H groups [34], which is decreased in g-NIPU-MA and g-NIPU-G when compared with g-NIPU, this being so because maleic anhydride or glutaraldehyde react with the amine groups in g-NIPU to consume it. The sharp bands at 2860 and 2940 cm −1 are attributed to the –CH 2 – stretching vibration [35].…”

“…The sharp bands at 2860 and 2940 cm −1 are attributed to the –CH 2 – stretching vibration [35]. It is very clearly visible in the curves of g-NIPU and g-NIPU-G with signals appearing at 1700 and 1640 cm −1 , which are typical for carbonyl IR absorption of urethane groups and N–H deformation of the urethane group, respectively [4,34]. The peak at 1640 cm −1 has disappeared with the presence of maleic acid in the system of g-NIPU-MA and the foams g-NIPU-F, because of the reaction between the carboxyl and the amino groups to form amide bonds.…”

“…The peak at 1640 cm −1 has disappeared with the presence of maleic acid in the system of g-NIPU-MA and the foams g-NIPU-F, because of the reaction between the carboxyl and the amino groups to form amide bonds. Meanwhile, due to the hydrogen of the N–H bond in the urethane groups being replaced, the C=O vibration peak at 1700 cm -1 shifts to a lower wavenumber of 1681 cm −1 [34,36]. The absorption at peak 990 cm −1 in the curves of g-NIPU-MA and g-NIPU-F is attributed to the C=C linkages [34], which are present once maleic acid has been added.…”

“…Meanwhile, due to the hydrogen of the N–H bond in the urethane groups being replaced, the C=O vibration peak at 1700 cm -1 shifts to a lower wavenumber of 1681 cm −1 [34,36]. The absorption at peak 990 cm −1 in the curves of g-NIPU-MA and g-NIPU-F is attributed to the C=C linkages [34], which are present once maleic acid has been added. A sharp absorption peak at 3335cm −1 indicated the presence of N–H stretching vibration from amide bonds, which is possibly the result of the reaction of maleic acid with free hexamethylene diamine or amine groups in g-NIPU; this is confirmed by the structure analysis by MALDI-ToF which follows.…”

Bio-Based Polymers for Engineered Green Materials

“…Several interesting bio-based polymers from other resources and processes are also presented. Polyesters and NIPU were synthesized using vegetal oils, offering products with enhanced mechanical properties and high thermal stability, respectively [29,30]. Latex was exposed to photodegradation catalyzed by TiO 2 to obtain easy-to-manage low molecular weight rubber [31].…”