Sugar-Based Thermoplastic Polyhydroxyurethanes: Effects of Sorbitol and Mannitol Diastereomers on Polymer Properties and Applications in Melt Blending

Abstract

Each of the three bio-sourced dicarbonates, sorbitol biscarbonate (SBC), mannitol biscarbonate (MBC), and diglycerol dicarbonate (DGC), is polymerized with 1,6-hexamethylenediamine (HMDA) or 1,10-diaminodecane (DAD) in dimethyl sulfoxide for 24 h at 100 °C to obtain highly crystalline (70–77%) thermoplastic polyhydroxyurethanes (TPHUs). Even though SBC and MBC are isomers, their respective TPHUs present similar (micro)­structural, thermal, and rheological properties. However, MBC reacts faster with amines at room temperature and induces more flexibility into the TPHU chains than SBC. The glass transition temperatures (T gs) of the MBC-based TPHUs are 7 °C lower than those of the SBC-based ones. Interestingly, the HMDA-based TPHUs exhibit liquid crystalline-like rheological behavior with their storage moduli increasing above their apparent melting points. Nevertheless, replacing SBC and MBC, whose structure contains a rigid furan ring, by DGC, a linear aliphatic dicarbonate, significantly alters the properties of the TPHUs, especially the rheological ones. The storage modulus of the DGC-DAD TPHU is ten-fold lower than those of the SBC and MBC analogues, when measured at similar conditions. MBC-HMDA, MBC-DAD, and DGC-DAD are then blended into poly­(lactic acid) (PLA) (20/80 wt%/wt%), and the blends are predicted to be miscible from the Hoftyzer–Van Krevelen group contribution method. While PLA/MBC-HMDA and PLA/MBC-DAD show one T g, the PLA/DGC-DAD presents two, despite the predicted miscibility of that blend. However, both T gs are shifted lower compared to the homopolymers, indicating that the components of that blend act as plasticizers of a two-phase morphology, as implied by droplets no more than 5 μm in diameter in the PLA matrix observed from SEM. Despite their miscibility with PLA, the TPHUs agglomerate into droplets inside the blends caused by significant intramolecular hydrogen bonding interactions between their chains. These results expand the application of TPHUs as nontoxic additives, for example, plasticizers, reinforcing agents, rubber tougheners, and composites into different polymer matrices.

Utilizing bio‐derived amine‐terminated thermoplastic polyhydroxyurethanes as crosslinkers for hybrid thermosets

“…The synthesis of DGC was performed using procedures reported elsewhere. 6,13 First, DIG (29.19 g, 0.175 mol), DMC at a 10:1 molar ratio of DMC:DIG (158.5 g, 1.75 mol) and potassium carbonate as a catalyst at 0.5 wt% of the DIG (0.14 g) were added to a 250-ml three-necked roundbottom flask equipped with a thermal well and a magnetic stir bar. The setup was placed on a heating mantle on a magnetic stirrer for mixing the mixture.…”

“…[9][10][11][12] Diglycerol dicarbonate (DGC) is derived from glycerol, a byproduct of biomass waste hydrolysis and biodiesel production. 13 On the other hand, D-mannitol biscarbonate (MBC) is obtained from sugars derived from glucose processing. 13,14 While thermoplastic NIPUs have a wide range of applications, thermoset NIPUs are required for specific applications such as coatings and sealants.…”

“…13 On the other hand, D-mannitol biscarbonate (MBC) is obtained from sugars derived from glucose processing. 13,14 While thermoplastic NIPUs have a wide range of applications, thermoset NIPUs are required for specific applications such as coatings and sealants. 15 However, their inability to be recycled due to the presence of permanent crosslinks is considered a negative feature.…”

Reprocessable, Bio-Based, Self-Blowing Non-Isocyanate Polyurethane Network Foams from Cashew Nutshell Liquid

“…Polyhydroxyurethane (PHU), synthesized from cyclic carbonate aminolysis, is a promising NIPU because of its benign precursors and the sequestering of CO 2 in the synthesis process. − Ultimately, the fabrication of PHU foams is needed for PHU to supplant isocyanate-based PU, which explains the increasing reports on methods to prepare PHU foams. − There has been significant study of cross-linked PHU network foams that exploits the elevated temperature, chemical, and dimensional stability of covalent networks. Creating more sustainable PHU foams by valorizing cheap and abundant waste biomass is highly favored to replace PUFs.…”

“…Creating more sustainable PHU foams by valorizing cheap and abundant waste biomass is highly favored to replace PUFs. Although there are numerous studies applying renewable precursors, such as sugar, ,, lignin, protein, vegetable oils, , and starch to develop PHU materials, they typically come with limitations of being either food-competitive or virgin feedstocks. Being a non-food-based biowaste-derived feedstock, cashew nutshell liquid (CNSL) is a renewable resource with immense potential stemming from its structural features, low cost, and availability. − For example, CNSL-based polyols have been used to manufacture rigid PU foams and CNSL-based epoxies were employed in bulk PHU synthesis .…”