Reactive Extrusion Synthesis of Biobased Isocyanate-Free Hydrophobically Modified Ethoxylated Urethanes with Pendant Hydrophobic Groups

Abstract

Development of hydrophobically modified ethoxylated urethane (HEUR) rheology modifiers enabled the widespread application of waterborne paints and coatings, replacing their environmentally burdening solvent-based predecessors. However, the diisocyanates, required for the conventional synthesis of HEURs, pose severe eco-sustainability threats. In this paper, we demonstrate an innovative approach to avoiding toxic components in the preparation of rheology modifiers by obtaining a new class of water-soluble isocyanate-free hydrophobically modified ethoxylated poly(hydroxy-urethane)s (IFHEURs). The first step in the synthetic pathway was the preparation of CO 2 -based five-membered poly(ethylene glycol) bis(cyclic carbonate) and its subsequent aminolysis using 4,7,10-trioxa-1,13-tridecanediamine, yielding poly(hydroxy-urethane) (PHU) prepolymers terminated with cyclic carbonate groups. The PHU prepolymers were further extended in a reactive extrusion (REX) synthesis using biobased hydrophobic diamine PRIAMINE 1075. The REX technique made it possible to overcome the typical limitations of the aminolysis reaction and to reach the desired conversion within a moderate reaction time. IFHEURs have been structurally elucidated using FT-IR and NMR spectroscopy techniques, MALDI-ToF mass spectrometry, and SEC analysis and applied as rheology modifiers. The study of their associative behavior in aqueous solutions confirmed that the architectural flexibility of the obtained IFHEURs, containing terminal and pendant hydrophobic groups, opens a perspective for tuneable thickening performance.

Poly(Urea-Urethane) Elastomers with Fire-Retardant and Tensile Properties Enhanced by a Built-In Phosphorus Derivative

“…The mechanism of the addition of oxiranes to phosphoric acids and the kinetics of the addition of activated ethylene oxide molecules to various OH groups present in these systems have been subjects of previous studies. 62−64 The synthesis scheme is shown in Scheme 1, while the results of FTIR, 1 H NMR, and 31 Based on spectral data, the general structure of the obtained product was confirmed. In the FTIR spectrum of the PPEG1 derivative, the signals from the terminal hydroxyl groups (3403 cm −1 ) and the P�O group (1249 cm −1 ) from the core are visible.…”

“…However, this analysis does not allow us to estimate the average chain length correctly since it does not account for the possibility of PPEG1 being a mixture of mono-, di-, and/or triesters of H 3 PO 4 . In fact, its 31 P NMR spectrum reveals the presence of two populations of magnetically distinct phosphorus nuclei, whose chemical shifts have values typical for noncyclic, alkyl esters of phosphoric acid. The main population (ca.…”

“…The products were collected into two big batches: PPEG1 and PPEG2, which were used to synthesize PUR and PUUR, respectively. These batches were characterized by 1 H NMR, 31 P NMR, FTIR, and L OH by titration analysis (ASTM E1899-16).…”

One-Step versus Two-Step Synthesis of Hydrophobically Modified Ethoxylated Urethanes: Benefits and Limitations

“…26,27 Efforts have also been made to explore the use of the reactive extrusion (REX) technique to overcome the kinetic limitations associated with the aminolysis of cyclic carbonates. 28,29 While this method shows promise to increase the reactivity and molar mass of PHUs, further studies are needed to optimize this method and make it a viable alternative for large-scale PHU production. Despite the promising future of PHUs and NIPUs, HEURs, made with diisocyanates, are still necessary in various applications.…”

“…However, the use of isocyanates in this process poses significant health and environmental risks, and alternative approaches have been sought. − Among the various synthetic routes to non-isocyanate polyurethanes (NIPUS), the polyaddition of cyclic carbonates with amines has emerged as a promising method to produce polyhydroxyurethanes (PHUs). , Despite the potential benefits of this technology, including the elimination of isocyanate-related hazards, there are challenges that hinder its broad adoption and industrial scaling-up. The limitations include low reactivity of the cyclic carbonate/amine reaction and limited degree of polymerization at room temperature, resulting in low molar mass PHUs. , Efforts have also been made to explore the use of the reactive extrusion (REX) technique to overcome the kinetic limitations associated with the aminolysis of cyclic carbonates. , While this method shows promise to increase the reactivity and molar mass of PHUs, further studies are needed to optimize this method and make it a viable alternative for large-scale PHU production. Despite the promising future of PHUs and NIPUs, HEURs, made with diisocyanates, are still necessary in various applications .…”