Nowadays, polyurethanes with multifunctional and multiple shape memory effects, especially those without the use of toxic phosgene and isocyanate, have attracted significant attention. In this work, to prepare a kind of nonisocyanate polyurethane (NIPU) with triple shape memory effect, we introduced the behenic acid (BA) with good crystallinity into the NIPUs network, which combines glass transition of the cross-linked network and crystallization-melting of behenic acid, endowing the NIPUs with two independent transition temperatures: the glass transition temperature (T g ) and crystallization melting temperature (T m ). Specifically, the NIPUs were synthesized by the addition reaction of bi-functional cyclic carbonate and semicrystalline curing agent. The bi-functional cyclic carbonate was prepared by thiol-ene click reaction, and the BA was grafted onto polyethyleneimine to prepare semi-crystalline curing agent. By adjusting the ratio of BA to PEI and curing temperature, the crystallinity of NIPU can be tuned in a wide range, so that the NIPUs has tunable and superior triple shape memory performance, and the shape recovery rate is almost 100%.
Fast, reliable, and low-cost glucose detection methods are of great importance for the control of diabetes. In this study, Cu2O combined with Cu nanoparticles anchored on reduced graphene oxide (RGO), was synthesized to function as the electrode in a non-enzymatic glucose sensor. The synergistic effect between Cu nanoparticles and Cu2O, together with the high conductivity of RGO enabled considerably lower resistivity with greater glucose oxidation activity than pure Cu2O. The RGO@Cu2O@Cu electrode exhibited a high sensitivity of 1.112 mA mM−1 cm−2 with a detection limit of 0.019 μM, and the linear range is up to 4 mM. Additionally, the RGO@Cu2O@Cu electrode displayed good anti-interference performance within human blood and high stability while operating for a long duration. Significantly, the glucose detection capability of the as-designed electrode was comparable to commercial sensors, representing a valuable design for future non-enzymatic glucose sensing.
The low tensile strength of ethylene/α-octene co-polymer (POE) limits its application as high-strength materials. In this study, 3-amino-1,2,4-triazole (ATA) was grafted onto maleic anhydride functionalized POE (PM) by melt reaction to obtain side chains capable of forming hydrogen bonding and metal coordination bonding, and then ferric chloride hexahydrate and POE are blended with them to obtain composite materials with high strength and fracture energy. The introduction of iron-based coordination bonding and hydrogen bonding double dynamic crosslinking network endow thermoplastic elastomers with excellent mechanical strength and high toughness. Fourier transform infrared spectroscopy, rheological tests, and X-ray photoelectron spectroscopy reveal the existence of non-covalent crosslinking networks. Based on the strengthening and toughening of non-covalent dynamic crosslinking network, the tensile strength of the modified POE elastomer composites achieves 12.5 MPa along with the elongation at break of 3540%. In addition, the modified POE elastomer composites exhibit improved melt elasticity and thermal stability.
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