Mechanically Robust and Chemically Recyclable Polyhydroxyurethanes from CO₂-Derived Six-Membered Cyclic Carbonates

Abstract

In the current context of sustainable chemistry development and new regulations, aminolysis of cyclic carbonate is one of the most promising routes to nonisocyanate polyurethanes, also called polyhydroxyurethanes (PHU). In this study, a new kind of shape memory PHU vitrimers with outstanding mechanical properties and chemical recyclability is prepared. The monomer employed for aminolysis to form the PHUs is bis(six-membered cyclic carbonate) of 4,4′-biphenol (BCC-BP), which is synthesized by bi(1,3-diol) precursors and CO 2 . The synthetic strategy, isocyanate-free and employing CO 2 as a building block, is environmentally friendly and suits the concept of carbon neutrality. The thermal properties, mechanical properties, and dynamic behaviors of the PHUs are explored. The maximum breaking strength and elongation at break of the resultant PHUs reach 65 MPa and 452%, respectively, exceeding other reported PHU-based materials in combined performance. Such a PHU material can also lift up a load 4700 times heavier than its own weight by a shape recovery process. Finally, the bi(1,3-diol) can be regenerated through the alcoholysis of PHUs to realize chemical recycling. This work provides a feasibility study for a green synthetic approach and for designing a novel PHU material with outstanding properties.

Biobased, Reprocessable Non-isocyanate Polythiourethane Networks with Thionourethane and Disulfide Cross-Links: Comparison with Polyhydroxyurethane Network Analogues

“…Finally, in one important way, the reprocessability of NIPTU networks is like that of PHU networks but unlike that of conventional PTU networks and PU networks. When PHU network reprocessabilty with full cross-link density recovery has been demonstrated, it was generally with networks that were synthesized at stoichiometric balance. ,,− That is also the case for the two NIPTU networks studied here. Stoichiometric balance is important in achieving the highest possible conversion of functional groups which in turn is needed for the most robust network structure formation.…”

“…Many research studies have focused on developing reprocessable PHU networks made at stoichiometric balance, some with highly successful outcomes. − ,,,,− A number of studies have focused on developing reprocessable conventional polythiourethane (PTU) networks. − However, none of those studies − was successful in demonstrating full cross-link density or related property recovery after reprocessing when the PTUs were synthesized at stochiometric balance. One of the studies was successful in recovering cross-link density after reprocessing when the PTU networks were synthesized at slightly off-stoichiometric conditions .…”

Chemically recyclable and mechanically robust non-isocyanate polyurethanes from resveratrol

“…2d). 8,10,12,15,19,20,[31][32][33][34] This was not only related to the high crosslink density of the material but also to the structure of resveratrol. The rigid aromatic ring structure of resveratrol in the main chain gave the polymer significant rigidity, which greatly increased the mechanical properties of NIPUs.…”

“…The exchangeable reaction between hydroxyls and carbamates results in covalent adaptable networks (CANs), which can be remolded after cross-linked NIPU molding. [8][9][10] Notably, the exchangeable reaction between hydroxyls and carbamates is catalyst-free. Accordingly, use of the dynamic network can avoid drawbacks such as catalyst compatibility and premature aging of the vitrimers after several recycling/reshaping cycles.…”

Biobased, Biodegradable, and Water-Soluble Amine-Functionalized Non-Isocyanate Polyurethanes for Potential Home Care Application

“…In general, NIPUs have 15–35 times higher water absorption capacity compared to conventional PUs owing to the hydrogen-bonding interaction between the primary/secondary hydroxyl groups on the polymer side chain and water. , However, the water solubility and dispersibility of NIPU are highly dependent on the structures of cyclic carbonate and amine monomers used for their synthesis and the hydrophilicity of functional groups present in the NIPU main chain or side chain. , Other than the functionalization of hydroxyl groups on the NIPU side chain, a potential way to introduce hydrophilic functionalities in NIPUs would be by the use of polyamines as monomers. Indeed, a number of publications ,,− reported the utilization of polyamine monomers for the synthesis of NIPUs. However, their water solubility/dispersibility were either not investigated thoroughly or they were insoluble due to the use of long-chain/aromatic bis–/polycyclic carbonate monomers.…”