查看更多>>摘要：Adhesives play an important role in modern society's production and daily life.Developing robust and sustainable adhesives remains a great challenge.Here we report a sustainable epoxy-vitrimer adhesive with high adhesive strength(about 10 MPa)and reusability(82％strength after 3 times).This adhesive can be fabricated from commercially available products through a straightforward hot-pressing method without the need of solvents.The adhesive process is also simple,requiring only 30 min at 180 ℃.In addition,the vitrimer adhesive has the advantages of both erasability for reuse and excellent water resistance.This work provides a facile strategy to fabricate high-strength adhesive that ensures reusability,recyclability,low cost of raw materials,and simple processing technology.Simultaneously,it expands the range of potential applica-tions for epoxy vitrimers.
查看更多>>摘要：Achieving versatile room temperature phosphorescence(RTP)materials,especially with tunable mechanical properties and shape memory is attractive and essential but rarely reported.Here,a strategy was reported to realize multi-functional RTP films with multicolor fluores-cence,ultralong afterglow,adjustable mechanical properties,and shape memory through the synergistic dynamic interaction of lanthanide(LnⅢ)-terpyridine coordination,borate ester bonds,and hydrogen bondings in a poly(vinyl alcohol)(PVA)matrix.By varying the amount of borax,the mechanical properties of the films could be finely controlled due to the change of crosslinking degree of dynamic borate ester bonds in PVA.The assembly and disassembly of borate ester bonds upon the trigger of borax and acid were applied as reversible linkage to achieve pro-grammable shape memory behavior.In addition,the films displayed both fascinating multicolor fluorescence and ultralong afterglow character-istics due to the presence of LnⅢ doping and confinement of terpyridine in PVA.This study provides a new avenue to impart modulable mechani-cal strength and shape memory to RTP materials.
查看更多>>摘要：The incorporation of molecular switches into polymer networks has been a powerful approach for the development of functional poly-mer materials that display macroscopic actuation and function enabled directly by molecular changes.However,such materials sometimes re-quire harsh conditions to perform their functions,and the design of new molecular photoswitches that can function under physiological condi-tions is highly needed.Here,we report the design and synthesis of a spiropyridine-based photoswitchable hydrogel that exhibits light-driven ac-tuation at physiological pH.Owing to its high pKa,spiropyridine maintains its ring-open protonated form at neutral pH,and the resulting hydro-gel remains in a swollen state.Upon irradiation with visible light,the ring closure of spiropyridine leads to a decrease in the charge and a reduc-tion in the volume of the hydrogel.The contracted gel could spontaneously recover to its expanding state in the dark,and this process is highly dynamic and reversible when the light is switched on and off.Furthermore,the hydrogel shows switchable fluorescence in response to visible light.Bending deformation is observed in the hydrogel thin films upon irradiation from one side.Importantly,the independence of this spiropyri-dine hydrogel from the acidic environment makes it biotolerant and shows excellent biocompatibility.This biocompatible spiropyridine hydro-gel might have important biorelated applications in the future.
查看更多>>摘要：Elastomers with high strength and toughness,excellent self-healing properties,and biocompatibility have broad application prospects in wearable electronics and other fields,but preparing it remains a challenge.In this work,we propose a highly adaptable strategy by introducing the small molecule crosslinking agent of triethanolamine(TEA)to the poly(thioctic acid)(PTA)chains and preparing the PAxEy elas-tomers using a simple synthesis step.This strategy stabilizes the PTA chains by constructing multiple non-covalent cross-linked dynamic net-works,endowing materials with excellent strength and toughness(tensile strength of 288 kPa,toughness of 278.2 kJ/m3),admirable self-healing properties(self-healing efficiency of 121.6％within 7 h at 70 ℃),and good biocompatibility.The PAxEy elastomers can also be combined with MWNTs to become flexible strain sensors,which can be used to monitor human joint movements with high sensitivity,repeatable responses,and stability.
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