In-situ controllable synthesis of carbon dots for patterned fluorescent wood films rapid fabrication strategy

Fluorescent-patterned materials are widely used in information storage and encryp-tion.However,preparing a patternedfluorescent display on a matrix currently requires a time-consuming(hours or even days)and complex multi-step process.Herein,a rapid and mild technique developed for the in-situ controllable synthe-sis offluorescent nitrogen-doped carbon dots(NCDs)on eco-friendly transparent woodfilms(TEMPO-oxidized carboxyl woodfilm[TOWF])within a few min-utes was developed.A wood skeleton was employed as the carbon precursor for NCD synthesis as well as the matrix for the uniform and controlled distribution of NCDs.Moreover,the in-situ synthesis mechanism for preparing NCDs in TOWF was proposed.The resultingfluorescent woodfilms have excellent tensile strength(310.0015.57 MPa),high transmittance(76.2%),high haze(95.0%),UV-blocking±properties in the full ultraviolet(UV)range,andfluorescent performance that can be modified by changing the heating parameters.Fluorescent patterning was sim-ply achieved by regulating the in-situ NCD synthesis regions,and thefluorescent patterns were formed within 10 s.Thesefluorescent-patterned woodfilms can effec-tively store and encrypt information,and they can interact with external information through a transparent matrix.This work provides a green and efficient strategy for fabricatingfluorescent information storage and encryption materials.

Lanthanide coordinated multicolor fluorescent polymeric hydrogels for bio-inspired shape/color switchable actuation through local diffusion of Tb^(3+)/Eu^(3+)ions

Lanthanide coordinated multicolor fluorescent polymeric hydrogels(MFPHs)are quite promising for various applications because of their sharp fluorescence bands and high color purity.However,few attempts have been carried out to locally regulate their fluorescence switching or shape deforming behaviors,but such studies are very useful for patterned materials with disparate functions.Herein,the picolinate moieties that can sensitize Tb^(3+)/Eu^(3+)luminescence via antenna effect were chemically introduced into interpenetrating double networks to produce a robust kind of lanthanide coordinated MFPHs.Upon varying the doping ratio of Tb^(3+)/Eu^(3+),fluorescence colors of the obtained hydrogels were continuously regulated from green to orange and then red.Importantly,spatial fluorescence color control within the hydrogel matrix could be facilely realized by controlled diffusion of Tb^(3+)/Eu^(3+)ions,producing a number of 2D hydrogel objects with local multicolor fluorescent patterns.Furthermore,the differential swelling capacities between the fluorescent patterned and non-fluorescent parts led to interesting 2D-to-3D shape deformation to give well-defined multicolor fluorescent 3D hydrogel configurations.Based on these results,bio-inspired synergistic color/shape changeable actuators were demonstrated.The present study provided a promising strategy to achieve the local fluorescence and shape control within lanthanide coordinated hydrogels,and is expected to be expanded for fabricating useful patterned materials with disparate functions.