Hybrid polyhydroxyurethanes: How to overcome limitations and reach cutting edge properties?

Abstract

The restrictions on isocyanate substances have encouraged researchers to find alternative methods for the synthesis of Polyurethanes (PUs). New pathways have been designed with focus on non-hazardous and eco-friendly substances. The reaction of cyclic carbonates and amines has appeared as the most promising substitute for the synthesis of Non-Isocyanate Polyurethanes (NIPUs). The obtained Polyhydroxyurethanes (PHUs) have been deeply studied these last decades to offer the best solutions in the substitution of isocyanates in PUs synthesis. Strong efforts have been paid to understand key parameters for the synthesis of PHUs and to design new architectures. However, some limitations in terms of kinetics, conversion and molar masses still remain and impede PHUs expansion. Therefore, this review aims to detail the recent progress that has been made on a new strategy, the hybrid PHUs. The characteristics of additional reactants such as a high reactivity, a low viscosity or the ability to reach higher conversions can be combined with the properties of PHUs in hybrid networks. Other functional groups such as acrylates, methacrylates, epoxies, alkenes or siloxanes give access to new designs and materials with higher performances. Hence, the different strategies to perform hybrid PHUs are discussed and detailed. The main strategies employed are the co-polymerization in one-step, the synthesis of prepolymers with various architectures and the synthesis of organic/inorganic and composite PHUs. Furthermore, a short overview of reprocessable PHUs is given as another outlook for PHU development.

Synergetic Effect of Dopamine and Alkoxysilanes in Sustainable Non‐Isocyanate Polyurethane Adhesives

“…To surpass these limitations, one elegant approach focused on the design of hybrid formulations [ 15 ] including epoxies, alkoxysilane or acrylic that combine different curing chemistries to overcome some of the limitations of aminolysis. Addition of epoxies within NIPU formulations is very popular as it improved drastically the mechanical performances of the final polymer [ 16–18 ] while alkoxysilane chemistry [ 19,20 ] represented an alternative to endow materials with better properties or to speed up the curing process.…”

Moisture Curable Hybrid Polyhydroxyurethanes from Sugar‐Derived Dicarbonates

“…Hence, it was important to develop new hybrid PHUs (HPHUs) that would crosslink effectively at ambient conditions similarly to the conventional PU adhesives on the market. Recently, HPHUs have gained much attention, [ 32,33 ] especially the ones employing sol/gel crosslinking. [ 34–40 ] The studies by Kathelawar et al.…”

Enhanced aminolysis of cyclic carbonates by β-hydroxylamines for the production of fully biobased polyhydroxyurethanes

“…[8][9][10] Hence, the aminolysis of 5-membered cyclic carbonates, which yields polyhydroxyurethanes (PHUs), is nowadays the most promising and described route to non-isocyanate polyurethanes (NIPUs). [11][12][13][14] This route has the advantage that these carbonates are easily obtained by the carbonation of commercial epoxides. Moreover, this route valorizes CO 2 as a cheap, renewable and non-toxic resource, which makes this pathway the least toxic and most eco-friendly route to NIPU and PHUs.…”