A hybrid methodology is used to combine the favorable properties of non‐isocyanate polyurethanes (NIPUs) in the side chains with poly(methacrylates) as the backbone into thermoset hybrid resins with hydroxyurethane linkages (HNIPU)s. Using NIPUs linkages avoids the use of toxic isocyanates in the poly(urethane) segments. The backbone is synthesized from cyclic carbonated copolymer templates derived from atom transfer radical polymerization (ATRP) of an alkyl methacrylate (C13MA with average side‐chain length of 13)/glycidyl methacrylate (GMA) mixtures (initial GMA mol fraction = 0.1–0.4). The resulting flexible resins with pendent epoxy functional groups were subsequently carbonated and then reacted with 1,10‐diaminodecane (90°C, 24 h) to form rigid side chains via hydroxyurethane linkages. Manipulating template functionality (2–11 urethane linkages out of 35 backbone units) yielded crosslinked networks with Young's moduli from 0.1 to 71.9 MPa while decreasing tensile elongation at break from 105% to 10%. Swelling ratios (SR) of the networks in tetrahydrofuran (THF) decrease as urethane linkage concentration increases, indicating tighter networks, consistent with the rheologically obtained molecular weight between crosslinks. Gel content indicated less than 15% of the networks are soluble in THF. The HNIPU networks derived show their ready tunability by simply changing the precursor functionality.

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.

Hybrid non‐isocyanate poly(urethanes) (HNIPUs) are designed from a precursor whose carbonate functionality is derived from epoxy‐functional statistical copolymers. Specifically, a bio‐based diene (β‐myrcene) is copolymerized via conventional free radical polymerization with glycidyl methacrylate (GMA) at different molar ratios, producing flexible copolymers with epoxy pendant groups, which are then reacted with carbon dioxide to yield the precursors with cyclic carbonate functionality. Subsequent addition of an amine‐terminated telechelic poly(propylene glycol) (PPG) forms urethane linkages in the side chains, whose concentration is tuned by varying the GMA initial molar fraction. The NIPUs are end‐capped with silanes to enable moisture curing, resulting in HNIPUs with elongations at break up to 150%, and relatively low elastic moduli varying from 32 kPa to 50 kPa as the number of urethane side linkages increases from 6 to 22. The swelling ratio of the NIPUs is also measured in tetrahydrofuran (THF). As the number of urethane side chains increases, the swelling ratio of the NIPUs decreases (710% to 620%), indicating a higher crosslinking density. All samples have gel contents higher than 50% in THF, indicating non‐crosslinked species in the hybrid samples which confirms the relatively low reported tensile moduli.

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