Inspired by filler effects, a strategy to enhance the mechanical properties of TPU elastomers by designing segments arrangement is presented.

Polyurethanes with covalent adaptive network (CAN) have received widespread attention due to their recyclability and self-healing properties. The strategy of regulating the dynamic network rearrangement kinetics through varying the monomer structure is particularly interesting. Herein, based on the phenol–carbamate dynamic bond, we design a strategy to regulate the rearrangement kinetics of the dynamic covalent network by adjusting the chemical structure of aliphatic isocyanates with the same initial cross-linking degree. Temperature-varying FTIR and stress relaxation experiments prove the feasibility of this strategy from the perspective of thermodynamics and kinetics. For the studied isocyanates, greater steric hindrance or attachment of benzyl groups can promote the rearrangement of CAN. The two factors can reduce the relaxation time by one order of magnitude, and the relaxation activation energy can be reduced by over 20 kJ mol⁻¹. Regardless of the network rearrangement kinetics, all polyurethane samples show good self-healing and reprocessing performance. In addition, the mechanical properties and stability in a hot air environment also vary with the chemical structure of the isocyanates, e.g., the isocyanates with alicyclic structure can improve the thermal stability, and the mechanical properties are almost unchanged after 24 h of treatment at 100 °C under air conditions, while the other polyurethanes show obvious softening. The method to regulate the rearrangement kinetics of phenol–carbamate CAN via changing the chemical structure of the monomers would be beneficial for developing self-healing and recyclable cross-linked polyurethanes with variable properties synthesized from industrial chemical feedstocks.

One material, multiple functions. Thermal and UV-adaptive self-healable polyurethanes as flexible substrates for patternable printed electronic circuits were synthesized, using dihydroxybenzophenone as the key monomer.

A novel biobased and biodegradable polyester, i.e., poly(butylene succinate-co-butylene 2-methylsuccinate) (P(BS-BMS)) was synthesized by succinic acid (SA), 2-methylsuccinic acid (MSA), and 1,4-butanediol (BDO) via a typically two-step esterification and polycondensation procedure. The chemical structure and macromolecular weight of obtained copolymers were characterized by ¹H NMR, ¹³C NMR, and GPC. The melting temperature and degree of crystallinity were also studied by DSC, and it was found that the values were gradually decreased with increasing of MSA content, while the thermal stability remained almost unchanged which was tested by TGA. In addition, the biodegradation rate of the P(BS-BMS) copolymers could be controlled by adjusting the ratio of SA and MSA, and such biodegradability could make P(BS-BMS) copolymers avoid microplastic pollution which may be brought to the environment for applications in agricultural field. When we applied P(BS-BMS) copolymers as pesticide carriers which were prepared by premix membrane emulsification (PME) method for controlling Avermectin delivery, an improvement of dispersion and utilization of active ingredient was obviously witnessed. It showed a burst release process first followed by a sustained release of Avermectin for a long period, which had a great potential to be an effective and environmental friendly pesticide-release vehicle.

The integration of high strength, super toughness, damage resistance, body-temperature shape memory, and biosafety into a single skin-mimic material system has been a notable challenge in the realm of material science and biomedical applications. In this study, “Lego-like” polyurethane (PU) was selected to amalgamate multiple properties through the design of multilevel structures. By comprehensively designing the chemical and sequence structures of blocks, coordinating weak/strong hydrogen bonds, and achieving rational microphase separation and crystallization, an elastomer was obtained with an exceptional true tensile strength of 1.42 gigapascal, a high fracture energy of 384.7 ± 18.9 kJ/m ² , and a skin-like nonlinear mechanoresponse. The coordination of crystallization and physical cross-linking also guaranteed excellent body-temperature shape memory properties, which are applicable in 4D printing. Moreover, the obtained elastomer is biosafe and has the potential to promote cell proliferation and DNA repair, which will find wide applications in the biomedical field including minimally invasive surgery.