A universal strategy for achieving dual cross-linked networks to obtain ultralong polymeric room temperature phosphorescence

Efficient polymeric room-temperature phosphorescence(PRTP)with excellent processability and flexibility is highly desirable but still faces formidable challenge.Herein,a general strategy is developed for efficient PRTP through photo-polymerization of phosphor monomers and N-isopropylacrylamide(NIPAM)spontaneously without a crosslinker.Remarkably ultralong lifetime of 3.54 s with afterglow duration time of 25 s and decent phosphorescent quantum efficiency of 13%are achieved.This efficient PRTP has been demonstrated to be derived from the synergistic effect of the covalent and hydrogen bonds networks formed through photo-polymerization of NIPAM.The electron paramagnetic resonance(EPR)spectra confirmed that methyl radicals are generated under the irradiation of ultraviolet light and promote the formation of covalent cross-linking networks.This strategy has also been proved to be generalizable to several other phosphor monomers.Interestingly,the polymer films display ultrahigh temperature resistance with long afterglows even at 140℃ and unexampled ultralong lifetime of 2.45 s in aqueous solutions.This work provides a simple and feasible avenue to obtain efficient PRTP.

Light-absorbing copolymers of polyimides as effi

Polyimide(PI),an important engineering polymer with a rigid chemical structure,readily has excellent chemical stability,heat resistance,and electrical insulation but lacks broadband photothermal properties.Herein,we design and synthesize PI copolymers that embrace intrinsic photothermal properties by using two diamine monomers of(Z)-2,3-bis(4-aminophenyl)acrylonitrile(CNDA)and 4,4-diphenyldiamine(NDA)with strong ultraviolet(UV),and near-infrared(NIR)absorption capabilities,respectively.Tuning the molar ratio of the two diamines can modulate UV and NIR light absorption and regulate the intrinsic photothermal properties of PIs.After condensation with pyromellitic dianhydride,the resulting PI-0.5 with a unit molar ratio of CNDA:NDA=1 shows the best photothermal efficiency.PI-0.5 is used to construct 3D steam generators with vertically dried channels by a freeze-drying method.The 3D steam generators show a good water evaporation rate and continuously operate with excellent stability under varying salinity and pH conditions.The synthetic design herein suggests that PI can be molecularly engineered to be intrinsic photothermal materials,expanding the properties and applications of existing PIs.

AIEgen containing side-chain liquid crystalline polymers: Photoluminecence or photothermal, which dominate?

Why many luminescent liquid crystalline polymers(LLCPs)containing aggregation-induced emission luminogen(AIEgen)show weak emission is a question still to be answered.Herein,a series of LLCPs(α-Pns,n=4,8,and 12)with polynorbornene as main chain and twoα-dicyanodistyrylbenzene(α-DCS)as side chain are successfully synthesized to solve this issue.Differential scanning calorimetry(DSC),polarized light microscopy(PLM),one-dimentional(1D),two-dimentional(2D)middle-angle and wide-angle X-ray scattering(MAXS and WAXS)results demonstrate that the polymers form smectic A(SmA)phase with the side chains interdigitated packed within the smectic layers.Meanwhile,the photophysical properties ofα-Pns were investigated by ultraviolet-visible(UV-vis)absorption,steady state and time-resolved spectroscopy,and photothermal effect.Results show that the polymers are AIE active,but emit weak emission.The emission peak ofα-Pns film red-shift from 473 to 531 nm,the quantum yield gradually increases from around 1.6%to 14.7%,and the photothermal conversion efficiency decreases from 39%to 19%with the alkyl tail length increased.The photothermal effect,but not photoluminescence,dominates the excited state relaxation.