A high humidity-resistant,dual mechanical responsive,and reversible mechanochromic wrinkling system based on a VHB 4910-polydimethylsiloxane(PDMS)substrate with a thin film consisting of 90 wt%poly(vinyl butyral)(PVB)...A high humidity-resistant,dual mechanical responsive,and reversible mechanochromic wrinkling system based on a VHB 4910-polydimethylsiloxane(PDMS)substrate with a thin film consisting of 90 wt%poly(vinyl butyral)(PVB)and 10 wt%hydroxypropyl cellulose(HPC)has been reported.The wrinkling system exhibited significant optical tuning from transparent to opaque states with 50%changes in transmittance,which was achieved through the dual mechanical modes of pre-stretching and releasing processes or bending.Upon exposure to ethanol vapor or a re-flattening process,wrinkles can be erased,yielding a transparent state.Consequently,the wrinkling system could be reversibly switched between transparency and opacity for 1000 cycles with marginal changes in the optical performance.Owing to the insolubility of PVB in water,the wrinkling patterns exhibited excellent durability in high-humidity environments(relative humidity(RH)=99%).Furthermore,the smart encryption device is also demonstrated via mechano-controlled surface topography by patterning the wrinkling system,suggesting potential applications of the designed structure in smart windows,anti-counterfeiting,dynamic display,optical information encryption,and rewritable surfaces.展开更多
Mechanochromic polyolefins represent a novel class of functionalized polyolefins,which still remains significant challenges.Pd(II)-catalyzed coordination-insertion copolymerization is a feasible method for achieving t...Mechanochromic polyolefins represent a novel class of functionalized polyolefins,which still remains significant challenges.Pd(II)-catalyzed coordination-insertion copolymerization is a feasible method for achieving this kind of polymers,yet with linear microstructures.Ringopening metathesis polymerization(ROMP)offers another promising avenue for affording functionalized polyolefins.This method exhibits high polar group tolerance and the ability to precisely regulate polymer branches.In this study,we report the method for producing mechanochromic branched polyethylenes via ROMP.By employing the terpolymerization of a well-designed monomer containing the mechanochromic group,NB-ABF,with cyclooctene(COE)and long-chain 5-hexylcyclooctene(COE-C6),following by hydrogenation process,we synthesized a range of functionalized branched polyethylenes characterized by varied branching density and polar monomer incorporation.These polymers bear a structural resemblance to functionalized ethylene-octene copolymers.After crosslinking,mechanochromophores are generated,and mechanochromism is achieved in uniaxial tensile testing.A comprehensive assessment reveals that both the incorporation of polar monomers and variations in branching density significantly influence their mechanical properties.Notably,upon stretching,these materials display pronounced visible color change,confirming the successful development of mechanochromic branched polyethylenes.展开更多
Mechanochromic organic materials are a typical class of stimuli materials that has response to external physical stimuli such as shearing,grinding,and compressing etc.Organic compounds with mechanochromic characters i...Mechanochromic organic materials are a typical class of stimuli materials that has response to external physical stimuli such as shearing,grinding,and compressing etc.Organic compounds with mechanochromic characters in solid forms have attracted significant attention in the past decades due to their potential applications in sensors and memory devices.Diamond anvil cell is an emerging technology that can provide isotropic pressure in a tiny place.Thus a new stimuli method can be applied in investigating optical variation of mechanochromic materials.In this review,we focus on mechanoluminescence systems that are responsive to isotropic compression under high pressure and summarize the recent advances on organic materials studied by the diamond anvil cell.展开更多
Mechanochromic hydrogels, a new class of stimuli-responsive soft materials, have potential applications in a number of fields such as damage reporting and stress/strain sensing. We prepared a novel mechanochromic hydr...Mechanochromic hydrogels, a new class of stimuli-responsive soft materials, have potential applications in a number of fields such as damage reporting and stress/strain sensing. We prepared a novel mechanochromic hydrogel using a strategy that has been developed to prepare dual-network(DN) hydrogels. A hydrophobic rhodamine derivative(Rh mechanophore) was covalently incorporated into a first network as a cross-linker. This first network embedded with Rh mechanophore within the DN hydrogel was pre-stretched. This guaranteed that the stress could be transferred extensively to the Rh-crosslinked first network once the hydrogel was under an applied force. Interestingly, we found that the threshold stress required to activate the mechanochromism of the hydrogel was less than 200 kPa, and much less than those in previous reports. Moreover, because of the excellent sensitivity of the hydrogel to stress, the DN hydrogel exhibited reversible freezing-induced mechanochromism. Benefiting from the sensitivity of Rh mechanophore to both p H and force, the DN hydrogel showed p H-regulated mechanochromic behavior. Our experimental results indicate that the preparation strategy we used introduces sensitive mechanochromism into the hydrogel and preserves the advantageous mechanical properties of the DN hydrogel. These results will be beneficial to the design and preparation of mechanochromic hydrogels with high stress sensitivity, and foster their practical applications in a number of fields such as damage reporting and stress/strain sensing.展开更多
Photophysical properties of organic and organometallic luminophors are closely related with their molecular packings, enabling the exploitation of stimuli-responsive functional luminescent molecules.Mechanochromic mol...Photophysical properties of organic and organometallic luminophors are closely related with their molecular packings, enabling the exploitation of stimuli-responsive functional luminescent molecules.Mechanochromic molecules, which can change their luminescence characteristics after mechanical stimulus, have received an increasing interest due to their promising applications in multifunctional sensors and molecular switches. During the past two decades, the development of gold(Ⅰ) chemistry has been attracting the attention of plenty of researchers. Indeed, a variety of gold(I) complexes with fascinating photophysical behaviors have been discovered. This review focuses on the research progress in the different types of mechanoluminochromic gold(Ⅰ) complexes, including mono-, bi-and multi-nuclear gold(Ⅰ)systems. Their interesting luminescence behaviors of these gold(Ⅰ)-containing luminogens upon mechanical stimulus and the proposed mechanisms of their observed mechanochromic luminescence are summarized systematacially. Moreover, this review will put forward an outlook about the possible opportunities and challenges in this significative scientific field.展开更多
Two functional tetraphenylethylene derivatives modified by vinylpyridine and vinylnitrobenzene,respectively,were synthesized by Heck coupling reaction.Their optical behaviors were investigated.The results showed they ...Two functional tetraphenylethylene derivatives modified by vinylpyridine and vinylnitrobenzene,respectively,were synthesized by Heck coupling reaction.Their optical behaviors were investigated.The results showed they had AIE activity in solution.The property in solid state displayed that both of them had reversible mechanochromism.Upon grinding,their fluorescence spectra showed around 13–40nm red-shift,and could return to the original state after solvent fuming.We believe that this work will be helpful for the design of stimuli-responsive materials in future.展开更多
An unexpected bistricyclic aromatic ene AF was synthesized in a tin(Ⅱ)chloride-mediated reductive aromatization reaction.The obtained AF showed a highly overcrowded structural conformation as revealed by X-ray crysta...An unexpected bistricyclic aromatic ene AF was synthesized in a tin(Ⅱ)chloride-mediated reductive aromatization reaction.The obtained AF showed a highly overcrowded structural conformation as revealed by X-ray crystallography.Interestingly,AF exhibited reversible high-contrast mechanochromism and thermochromism between pale and red color.The obvious chromism is likely ascribed to the conformation transformation and trace amount of diradical species formation upon stimulus.展开更多
In this study,a new twisting gold（Ⅰ） isocyanide complex based on tetraphenylethene（TPE）,TPE-NC-Au.was designed and synthesized.It exhibits aggregation induced phosphorescence（AIP） characteristics,owing to the i...In this study,a new twisting gold（Ⅰ） isocyanide complex based on tetraphenylethene（TPE）,TPE-NC-Au.was designed and synthesized.It exhibits aggregation induced phosphorescence（AIP） characteristics,owing to the incorporation of Au moiety and conformation rigidification in the aggregated states.Moreover,the emission color of the crystalline solid of TPE-NC-Au changes from blue（454 nm） to green（500 nm） in response to mechanical grinding,due to the combined effects of conformation planarization,enhanced π…π stacking,as well as the emergence of aurophilic interactions in the ground amorphous state.Notably,the emission color can be restored upon solvent fuming,associating with the reconstruction of crystalline lattices.The AIP and switchable mechanochromism of TPE-NC-Au make it suitable for potential applications in bioimaging,sensing,and optoelectronic devices.展开更多
Smart materials with tunable multiple-color emissions have been widely investigated in the fields of bioimaging,display,and information encryption.Herein,multicolor emissive molecules with hydrazone bridged triphenyla...Smart materials with tunable multiple-color emissions have been widely investigated in the fields of bioimaging,display,and information encryption.Herein,multicolor emissive molecules with hydrazone bridged triphenylamines and pyridinium groups are reported.The protonation of the pyridine subunit by various acids leads to aggregation-induced emission with broad emission colors ranging from blue to red in multiple states and spectra ofλPL,dichloromethane solution=463±584 nm,λPL,powder=455±620 nm,andλPL,crystal=485±657 nm,respectively.Upon grinding or heating,hydrazone with CF_(3)COO−exhibit blueshift emissions from red to yellow due to weakened molecular packing and conformational rigidity.In contrast,hydrazone with(CF_(3)SO_(2))_(2)N−exhibited redshift emission from green to yellow due to the decreased electron-donating ability of the triphenylamine unit upon transformation from a rigid pyramidal shape to a planar structure.These are rare,charged organic examples exhibiting predictable mechanochromic and thermochromic strong emissions through facile anion exchanges,potentially providing new insights into the design of smart materials.展开更多
We report a remarkable thickness-dependent wrinkling behavior of oxygen plasma-treated polydimethylsiloxane(PDMS)flms,in which an energy barrier separates the wrinkling mechanics into two regimes.For thick films,the f...We report a remarkable thickness-dependent wrinkling behavior of oxygen plasma-treated polydimethylsiloxane(PDMS)flms,in which an energy barrier separates the wrinkling mechanics into two regimes.For thick films,the film wrinkles with a constant periodicity which can be precisely predicted by the classic nonlinear finite mechanics.Reducing the film thickness below 1 mm leads to nonuniform wrinkles with an increasing periodicity which gives rise to random scattering and transparency changes under mechanical strains.By tuning the flm thickness,we were able to control both the quality and size of the periodic wrinkles and further design mechanochromic devices featuring briliant structural colors and programmable colorimetric responses.This work sheds light on the fundamental understanding of the wrinkling mechanics of bilayer systems and their intriguing mechanochromic applications.展开更多
Simultaneously introducing mechanochromic and self-healing properties into polymers is almost a field unexplored,and the integration of these capabilities in one material has important theoretical and substantial sign...Simultaneously introducing mechanochromic and self-healing properties into polymers is almost a field unexplored,and the integration of these capabilities in one material has important theoretical and substantial significance.In this paper,a mechanochromic poly(dimethylsiloxane)(PDMS)elastomer with self-healing ability and superior mechanical properties is first reported.Spiropyran mechanophore and reversible hydrogen bonds are incorporated into the system to realize multi-stimuliinduced color change and self-healing ability,respectively.Upon uniaxial stretching,heating or UV irradiation,the elastomer exhibits a reversible color variation from yellow to purple,which can recover rapidly by white light illumination.Its excellent tensile strength(10.5 MPa)and elongation at break(785%)are distinctive among PDMS elastomers with no fillers.After heat treatment at 60℃for 24 h,the self-healing efficiency of strength can achieve 92.1%.This novel robust PDMS elastomer holds great promise for applications in visualized stress/strain sensing,self-healing biomaterials and wearable devices.展开更多
In this work,we synthesize two luminescent Pt(Ⅱ)complexes using differentπ-conjugated bidentate ligands.Both complexes are assembled into three-dimensional(3D)networks through non-classical intermolecular interactio...In this work,we synthesize two luminescent Pt(Ⅱ)complexes using differentπ-conjugated bidentate ligands.Both complexes are assembled into three-dimensional(3D)networks through non-classical intermolecular interactions in the crystal state.Unexpectedly,substituting pyridine with the more extensivelyπ-conjugated quinoline significantly increases the dihedral angles between the phenyl and quinolyl groups of the bidentate ligands.This alteration disrupts theπ-πinteractions between molecules,resulting in distinct optical properties upon exposure to external stimuli.By integrating these complexes into polymers,we fabricate electrospun films containing luminescent nanofibers that exhibit reversible optical changes.These findings have paved the way for the development of high-performance optical encryption and anti-counterfeiting materials,achieved through the employment of simple chromophores.展开更多
Mechanochromic materials respond to external stimuli and provide early warnings of material damage.Perylene diimide(PDI)-based materials have attracted attention because of their outstanding fluorescence performance.H...Mechanochromic materials respond to external stimuli and provide early warnings of material damage.Perylene diimide(PDI)-based materials have attracted attention because of their outstanding fluorescence performance.However,the application of PDI in mechanochromism is limited by the difficulty for mechanical forces to disrupt the aggregation of PDI and its derivatives,as well as the fluorescence quenching caused by continuousπ-πstacking between PDI molecules.To eliminate the fluorescence quenching effect caused by the aggregation of PDI and broaden its application fields,polyhedral oligomeric silsesquioxane(POSS)-PDI-POSS(PPP)was screened as PDI doping.The photophysical properties of PPP in both monomeric and aggregated states in different solvents were studied.Then,PPP and styrene-butadiene-styrene block copolymer(SBS)were mixed to prepare the PPP/SBS film.The mechanochromic properties of PPP/SBS film were explored.The fluorescence emission spectra confirmed that when the PPP mass fraction increased to 0.30%,the PPP/SBS film exhibited mechanochromic behavior under uniaxial deformation due to the changes in the molecular packing.展开更多
A series of cholesterol-appended quinacridone (QA) derivatives 1a-1d have been synthesized,in which 1b and 1c could form stable organogels in a wide range of organic solvents upon ultrasound irradiation.Field emission...A series of cholesterol-appended quinacridone (QA) derivatives 1a-1d have been synthesized,in which 1b and 1c could form stable organogels in a wide range of organic solvents upon ultrasound irradiation.Field emission scanning electronic microscope (FESEM) and transmission electron microscopy (TEM) of xerogels or precipitates indicated that 1b and 1c formed 1D fibrous nanostructure,while 1a assembled into 3D flower-like microstructures.The ultrasound-induced organogel process was characterized by kinetic UV-vis and photoluminescence spectroscopic methods suggesting the formation of ?-? aggregates in the gel state.Experimental results demonstrated that the ultrasound could promote molecules to contact frequently in the solution and induce semistable initial aggregates,which propagate to form nano/micro superstructures.The aggregation model was optimized by semiempirical AM1 calculation suggesting the hierarchical self-assembly process.In addition,the formed xerogel film exhibited mechanochromic property,and the phase transition process was accompanied by the fluorescence changes between yellowish green and orange.展开更多
High-contrast mechanochromic(MC)materials are prominent candidates for sensor,security,and memory applications;however,the development of materials with a large luminescence change(Δλem>100 nm)under external stim...High-contrast mechanochromic(MC)materials are prominent candidates for sensor,security,and memory applications;however,the development of materials with a large luminescence change(Δλem>100 nm)under external stimuli is challenging.Considering that polymorphic molecules usually exhibit reversible mechanochromism,polymorph prediction is adopted for thefirst time to guide the design of high-contrastMC materials in this study.We designed and synthesized a series of donor–π–acceptor pyran derivatives bearing different electron donors and acceptors as model systems.The polymorph prediction indicated that 4-dicyanomethylene-2,6-distyryl-4H-pyran and 4H-pyran-4-one derivatives had the potential to crystallize in both monomer andπ-dimer aggregates,while barbituric acid-based compound tended to pack tightly in all aggregated states.The experimental results agreed well with the prediction that the derivatives potentially possessing both monomer andπ-dimer aggregate structures exhibit excellent MC behavior,whereas the fluorescence difference for the barbituric acid-based compounds is minimal.Moreover,a compound with an excellent fluorescence difference of three colors during reversible mechanochromism was chosen as the candidate for an optical recording material and security ink.This work proposes an effective method to guide the design of stimuli-responsive materials,which may open promising avenues for the development of high-contrast MC molecules.展开更多
Understanding the relationship between structure and properties is critical to the development of solidstate luminescence materials with desired characteristics and performance optimization. In this work, we elaborate...Understanding the relationship between structure and properties is critical to the development of solidstate luminescence materials with desired characteristics and performance optimization. In this work, we elaborately designed and synthesized a pair of mononuclear iridium(Ⅲ) complexes with similar structures but different degrees of cationization. [Ir2-f][2PF_(6)] with two counterions is obtained by simple Nmethylation of the ancillary ligand of [Ir1-f][PF_(6)] which is a classic cationic iridium(Ⅲ) complex. Such a tiny modification results in tremendously different optical properties in dilute solutions and powders.[Ir1-f][PF_(6)] exhibits weak light in solution but enhanced emission in solid-state as well as poly(methyl methacrylate) matrix, indicative of its aggregation-induced emission(AIE) activity. On the sharp contrary, [Ir2-f][2PF_(6)] is an aggregation-caused quenching(ACQ) emitter showing strong emission in the isolated state but nearly nonemissive in aggregation states. Benefiting from the appealing characteristics of mechanochromic luminescence and AIE behavior, [Ir1-f][PF_(6)] has been successfully applied in reversible re-writable data recording and cell imaging. These results might provide deep insights into AIE and ACQ phenomenon of iridium(Ⅲ) complexes and facilitate the development of phosphorescent materials with promising properties.展开更多
Mechanochromophores based on bichromic molecular switches,such as bis-naphthopyanes,allow multimodal mechanochromic behavior beyond the typical binary response from single chromophores,which is important for distingui...Mechanochromophores based on bichromic molecular switches,such as bis-naphthopyanes,allow multimodal mechanochromic behavior beyond the typical binary response from single chromophores,which is important for distinguishing between multiple stress states through discrete changes in color.Spontaneously generated persistent and distinguishable multi-colors from activated bis-naphthopyanes remain challenging.And the versatility of bis-mechanophore design for advanced optical molecular systems and the fundamental insights into the corresponding mechano-reactivity are not enough.Here,we identify a dihydroanthracene bridged bis-naphthopyrans as a multimodal mechanochromophore in polymers.Bridging two pyrans with the sterically constrained dihydroanthracene is helpful to control the steric effect for the favorable formation of a distinctly appreciable bis-merocyanine(bis-MC)product.By varying the length of the polymer chains,the force delivered to the mechanophore is modulated,resulting in a gradient change in the relative distribution of two distinctly colored MC products and a multicolor mechanochromism.Mechanical activation of this bis-naphthopyanes proceeds via a mechanistically distinct pathway compared to the photochemical process.In addition,the bulk films can also achieve pronounced color changes when subjected to mechanical force.This study thus further expands the molecular diversity of mechanochromophores and tune the multimodal switch properties of bis-naphthopyrans based polymers.展开更多
Triphenylamine(TPA)-containing 2-(2-hydroxyphenyl)benzoxazoles(2a-2c)have been synthesized via a highly efficient rhodium-catalyzed C–H/C–H cross-coupling reaction.Compound 2a is a novel mechanofluorochromic materia...Triphenylamine(TPA)-containing 2-(2-hydroxyphenyl)benzoxazoles(2a-2c)have been synthesized via a highly efficient rhodium-catalyzed C–H/C–H cross-coupling reaction.Compound 2a is a novel mechanofluorochromic material with blue-shifted mechanochromic properties.Compounds 2b and 2c presented opposite mechanochromic trends.For 2b,the enol-form emission enhanced,and the ketoform emission blue-shift after grinding.In contrast,2c exhibited the weak enol-form emission disappeared and the keto-form emission slightly red-shift after grinding treatments.The estrone-containing2b-based water-dispersed nanoparticles(NPs)exhibit apparent dual-emission and were applied for fluorescence images.In addition,bis(TPA)-containing 2c-based devices exhibit dual-emission with good performance and a singlet exciton yield of 92%,which breaks through the theoretical upper limit of 25%in conventional fluorescent OLEDs.This is one of the highest exciton utilization values recorded for the ESIPT molecules with a dual emission system.展开更多
A polymer （poly（9,10）anthracenevinylene-alt-4,4＇-（9,9-bis（4-（4＇-（1,2,2＇-triphenyviny）phenoxy）butyl）-9H- fluorene-2,7-diyl） dibenzaldehyde）, P1） was successfully synthesized through the Wittig-Horner re...A polymer （poly（9,10）anthracenevinylene-alt-4,4＇-（9,9-bis（4-（4＇-（1,2,2＇-triphenyviny）phenoxy）butyl）-9H- fluorene-2,7-diyl） dibenzaldehyde）, P1） was successfully synthesized through the Wittig-Horner reaction by employing fluorene and 9,10-distyrylanthracene moieties as building blocks for backbone and tetraphenylethenes as pendant groups. Photophysical and thermal properties of the resulting polymeric emitter were fully characterized by ultraviolet-visible （UV- Vis） absorption and photoluminescence （PL） spectra, thermogravimetric analysis （TGA） and differential scanning calorimetry （DSC）. While P1 emits an orange-light centered at 567 nm in dilute tetrahydrofuran （THF） solution, the solid powder of the polymer exhibits strong yellow emission peaked at 541 nm. It is also found that the as-synthesized polymer shows unique property of aggregation-enhanced emission （AEE）. In addition, P1 possesses high thermal stability with a decomposition temperature （Td,5%） of 430 ℃ and high morphological stability with a glass transition temperature （Tg） of 171℃. Under the stimulus of mechanical force, the emission of P1 can be changed from yellow to red （△λmax = 61 rim）, showing a remarkable mechanochromism. The results from XRD analysis suggest that such mechanochromic phenomenonof PI is probably caused by the destruction of crystalline structure, which leads to the conformational planarization of the distyrylanthracene moieties forming by the polymerization and the increase of molecular conjugation of the backbone.展开更多
Visualization and quantitative evaluation of covalent bond scission in polymeric materials are critical in understanding their failure mechanisms and improving the toughness and reliability of the materials. Mechano-r...Visualization and quantitative evaluation of covalent bond scission in polymeric materials are critical in understanding their failure mechanisms and improving the toughness and reliability of the materials. Mechano-responsive polymers with the ability of molecular-level transduction of force into chromism and luminescence have evoked major interest and experienced significant progress. In the current review, we highlight the recent achievements in covalent mechanochromic and mechanoluminescent polymers, leading to a bridge between macroscopic mechanical properties and microscopic bond scission events. After a general introduction concerning polymer mechanochemistry, various examples that illustrate the strategies of design and incorporation of functional and weak covalent bonds in polymers were presented, the mechanisms underlying the optical phenomenon were introduced and their potential applications as stress sensors were discussed. This review concludes with a comment on the opportunities and challenges of the field.展开更多
基金supported by the Science and Technology Development Fund(FDCT),Macao SAR(No.0149/2022/A),and(No.0046/2024/AFJ)Guangdong Science and Technology Department(No.2023QN10C305)。
文摘A high humidity-resistant,dual mechanical responsive,and reversible mechanochromic wrinkling system based on a VHB 4910-polydimethylsiloxane(PDMS)substrate with a thin film consisting of 90 wt%poly(vinyl butyral)(PVB)and 10 wt%hydroxypropyl cellulose(HPC)has been reported.The wrinkling system exhibited significant optical tuning from transparent to opaque states with 50%changes in transmittance,which was achieved through the dual mechanical modes of pre-stretching and releasing processes or bending.Upon exposure to ethanol vapor or a re-flattening process,wrinkles can be erased,yielding a transparent state.Consequently,the wrinkling system could be reversibly switched between transparency and opacity for 1000 cycles with marginal changes in the optical performance.Owing to the insolubility of PVB in water,the wrinkling patterns exhibited excellent durability in high-humidity environments(relative humidity(RH)=99%).Furthermore,the smart encryption device is also demonstrated via mechano-controlled surface topography by patterning the wrinkling system,suggesting potential applications of the designed structure in smart windows,anti-counterfeiting,dynamic display,optical information encryption,and rewritable surfaces.
基金supported by the National Natural Science Foundation of China(No.U23B6011)the Jilin Provincial Science and Technology Department Program(No.20230101347JC)。
文摘Mechanochromic polyolefins represent a novel class of functionalized polyolefins,which still remains significant challenges.Pd(II)-catalyzed coordination-insertion copolymerization is a feasible method for achieving this kind of polymers,yet with linear microstructures.Ringopening metathesis polymerization(ROMP)offers another promising avenue for affording functionalized polyolefins.This method exhibits high polar group tolerance and the ability to precisely regulate polymer branches.In this study,we report the method for producing mechanochromic branched polyethylenes via ROMP.By employing the terpolymerization of a well-designed monomer containing the mechanochromic group,NB-ABF,with cyclooctene(COE)and long-chain 5-hexylcyclooctene(COE-C6),following by hydrogenation process,we synthesized a range of functionalized branched polyethylenes characterized by varied branching density and polar monomer incorporation.These polymers bear a structural resemblance to functionalized ethylene-octene copolymers.After crosslinking,mechanochromophores are generated,and mechanochromism is achieved in uniaxial tensile testing.A comprehensive assessment reveals that both the incorporation of polar monomers and variations in branching density significantly influence their mechanical properties.Notably,upon stretching,these materials display pronounced visible color change,confirming the successful development of mechanochromic branched polyethylenes.
基金supported by the National Natural Science Foundation of China(No.91333201)
文摘Mechanochromic organic materials are a typical class of stimuli materials that has response to external physical stimuli such as shearing,grinding,and compressing etc.Organic compounds with mechanochromic characters in solid forms have attracted significant attention in the past decades due to their potential applications in sensors and memory devices.Diamond anvil cell is an emerging technology that can provide isotropic pressure in a tiny place.Thus a new stimuli method can be applied in investigating optical variation of mechanochromic materials.In this review,we focus on mechanoluminescence systems that are responsive to isotropic compression under high pressure and summarize the recent advances on organic materials studied by the diamond anvil cell.
基金financially supported by the National Natural Science Foundation of China (No. 51273189)the National Science and Technology Major Project of the Ministry of Science and Technology of China (No. 2016ZX05016)the National Science and Technology Major Project of the Ministry of Science and Technology of China (No. 2016ZX05046)
文摘Mechanochromic hydrogels, a new class of stimuli-responsive soft materials, have potential applications in a number of fields such as damage reporting and stress/strain sensing. We prepared a novel mechanochromic hydrogel using a strategy that has been developed to prepare dual-network(DN) hydrogels. A hydrophobic rhodamine derivative(Rh mechanophore) was covalently incorporated into a first network as a cross-linker. This first network embedded with Rh mechanophore within the DN hydrogel was pre-stretched. This guaranteed that the stress could be transferred extensively to the Rh-crosslinked first network once the hydrogel was under an applied force. Interestingly, we found that the threshold stress required to activate the mechanochromism of the hydrogel was less than 200 kPa, and much less than those in previous reports. Moreover, because of the excellent sensitivity of the hydrogel to stress, the DN hydrogel exhibited reversible freezing-induced mechanochromism. Benefiting from the sensitivity of Rh mechanophore to both p H and force, the DN hydrogel showed p H-regulated mechanochromic behavior. Our experimental results indicate that the preparation strategy we used introduces sensitive mechanochromism into the hydrogel and preserves the advantageous mechanical properties of the DN hydrogel. These results will be beneficial to the design and preparation of mechanochromic hydrogels with high stress sensitivity, and foster their practical applications in a number of fields such as damage reporting and stress/strain sensing.
基金financial support from the National Natural Science Foundation of China (Nos. 22061018, 21702079 and 21772054)the startup funding from South-Central University for Nationalities (No. YZZ19005)。
文摘Photophysical properties of organic and organometallic luminophors are closely related with their molecular packings, enabling the exploitation of stimuli-responsive functional luminescent molecules.Mechanochromic molecules, which can change their luminescence characteristics after mechanical stimulus, have received an increasing interest due to their promising applications in multifunctional sensors and molecular switches. During the past two decades, the development of gold(Ⅰ) chemistry has been attracting the attention of plenty of researchers. Indeed, a variety of gold(I) complexes with fascinating photophysical behaviors have been discovered. This review focuses on the research progress in the different types of mechanoluminochromic gold(Ⅰ) complexes, including mono-, bi-and multi-nuclear gold(Ⅰ)systems. Their interesting luminescence behaviors of these gold(Ⅰ)-containing luminogens upon mechanical stimulus and the proposed mechanisms of their observed mechanochromic luminescence are summarized systematacially. Moreover, this review will put forward an outlook about the possible opportunities and challenges in this significative scientific field.
基金financially supported by the National Natural Science Foundation of China(Nos.21676113,21402057,21772054)Distinguished Young Scholar of Hubei Province(No.2018CFA079)+5 种基金Youth Chen-Guang Project of Wuhan(No.2016070204010098)the 111 Project(No.B17019)the Ministry-Province Jointly Constructed Base for State Key Lab-Shenzhen Key Laboratory of Chemical Biology(Shenzhen),the State Key Laboratory of Materials-Oriented Chemical Engineering(No.KL17-10)the Open Project Fund of Key Laboratory of Natural Resources of Changbai Mountain&Functional Molecules,Yanbian University,Ministry of Education(No.NRFM201701)the Foundation of Key Laboratory of Synthetic and Biological Colloids,Jiangnan University,Ministry of Education(No.JDSJ2017-07)Self-determined Research Funds of CCNU from the Colleges’Basic Research and Operation of MOE(No.CCNU18TS012)
文摘Two functional tetraphenylethylene derivatives modified by vinylpyridine and vinylnitrobenzene,respectively,were synthesized by Heck coupling reaction.Their optical behaviors were investigated.The results showed they had AIE activity in solution.The property in solid state displayed that both of them had reversible mechanochromism.Upon grinding,their fluorescence spectra showed around 13–40nm red-shift,and could return to the original state after solvent fuming.We believe that this work will be helpful for the design of stimuli-responsive materials in future.
基金Innovation Program of Shanghai Municipal Education Commission(No.2019-01-07-00-05-E00012)Program for Changjiang Scholars and Innovative Research Team in University for financial support+1 种基金the financial supports sponsored by Shanghai Sailing Program(No.19YF1412900)the Fundamental Research Funds for the Central Universities。
文摘An unexpected bistricyclic aromatic ene AF was synthesized in a tin(Ⅱ)chloride-mediated reductive aromatization reaction.The obtained AF showed a highly overcrowded structural conformation as revealed by X-ray crystallography.Interestingly,AF exhibited reversible high-contrast mechanochromism and thermochromism between pale and red color.The obvious chromism is likely ascribed to the conformation transformation and trace amount of diradical species formation upon stimulus.
基金financially supported by the National Natural Science Foundation of China(No.51473092)the Shanghai Rising-Star Program(No.15QA1402500)
文摘In this study,a new twisting gold（Ⅰ） isocyanide complex based on tetraphenylethene（TPE）,TPE-NC-Au.was designed and synthesized.It exhibits aggregation induced phosphorescence（AIP） characteristics,owing to the incorporation of Au moiety and conformation rigidification in the aggregated states.Moreover,the emission color of the crystalline solid of TPE-NC-Au changes from blue（454 nm） to green（500 nm） in response to mechanical grinding,due to the combined effects of conformation planarization,enhanced π…π stacking,as well as the emergence of aurophilic interactions in the ground amorphous state.Notably,the emission color can be restored upon solvent fuming,associating with the reconstruction of crystalline lattices.The AIP and switchable mechanochromism of TPE-NC-Au make it suitable for potential applications in bioimaging,sensing,and optoelectronic devices.
基金financially supported by the National Natural Science Foundation of China (U20041101, 21772034, and 22305070)Top-Notch Personnel Fund of Henan Agricultural University (30500418 and 30501032)Scientific and Technological Project of the Henan Province of China (222102240043)。
文摘Smart materials with tunable multiple-color emissions have been widely investigated in the fields of bioimaging,display,and information encryption.Herein,multicolor emissive molecules with hydrazone bridged triphenylamines and pyridinium groups are reported.The protonation of the pyridine subunit by various acids leads to aggregation-induced emission with broad emission colors ranging from blue to red in multiple states and spectra ofλPL,dichloromethane solution=463±584 nm,λPL,powder=455±620 nm,andλPL,crystal=485±657 nm,respectively.Upon grinding or heating,hydrazone with CF_(3)COO−exhibit blueshift emissions from red to yellow due to weakened molecular packing and conformational rigidity.In contrast,hydrazone with(CF_(3)SO_(2))_(2)N−exhibited redshift emission from green to yellow due to the decreased electron-donating ability of the triphenylamine unit upon transformation from a rigid pyramidal shape to a planar structure.These are rare,charged organic examples exhibiting predictable mechanochromic and thermochromic strong emissions through facile anion exchanges,potentially providing new insights into the design of smart materials.
文摘We report a remarkable thickness-dependent wrinkling behavior of oxygen plasma-treated polydimethylsiloxane(PDMS)flms,in which an energy barrier separates the wrinkling mechanics into two regimes.For thick films,the film wrinkles with a constant periodicity which can be precisely predicted by the classic nonlinear finite mechanics.Reducing the film thickness below 1 mm leads to nonuniform wrinkles with an increasing periodicity which gives rise to random scattering and transparency changes under mechanical strains.By tuning the flm thickness,we were able to control both the quality and size of the periodic wrinkles and further design mechanochromic devices featuring briliant structural colors and programmable colorimetric responses.This work sheds light on the fundamental understanding of the wrinkling mechanics of bilayer systems and their intriguing mechanochromic applications.
文摘Simultaneously introducing mechanochromic and self-healing properties into polymers is almost a field unexplored,and the integration of these capabilities in one material has important theoretical and substantial significance.In this paper,a mechanochromic poly(dimethylsiloxane)(PDMS)elastomer with self-healing ability and superior mechanical properties is first reported.Spiropyran mechanophore and reversible hydrogen bonds are incorporated into the system to realize multi-stimuliinduced color change and self-healing ability,respectively.Upon uniaxial stretching,heating or UV irradiation,the elastomer exhibits a reversible color variation from yellow to purple,which can recover rapidly by white light illumination.Its excellent tensile strength(10.5 MPa)and elongation at break(785%)are distinctive among PDMS elastomers with no fillers.After heat treatment at 60℃for 24 h,the self-healing efficiency of strength can achieve 92.1%.This novel robust PDMS elastomer holds great promise for applications in visualized stress/strain sensing,self-healing biomaterials and wearable devices.
基金supported by the National Natural Science Foundation of China(Nos.22201057 and 22472044)Zhejiang Provincial Natural Science Foundation of China(Nos.LR22B010001 and LQ23B010001)。
文摘In this work,we synthesize two luminescent Pt(Ⅱ)complexes using differentπ-conjugated bidentate ligands.Both complexes are assembled into three-dimensional(3D)networks through non-classical intermolecular interactions in the crystal state.Unexpectedly,substituting pyridine with the more extensivelyπ-conjugated quinoline significantly increases the dihedral angles between the phenyl and quinolyl groups of the bidentate ligands.This alteration disrupts theπ-πinteractions between molecules,resulting in distinct optical properties upon exposure to external stimuli.By integrating these complexes into polymers,we fabricate electrospun films containing luminescent nanofibers that exhibit reversible optical changes.These findings have paved the way for the development of high-performance optical encryption and anti-counterfeiting materials,achieved through the employment of simple chromophores.
基金Yunfu 2023 Innovation Team Project,China(CYRC202305)。
文摘Mechanochromic materials respond to external stimuli and provide early warnings of material damage.Perylene diimide(PDI)-based materials have attracted attention because of their outstanding fluorescence performance.However,the application of PDI in mechanochromism is limited by the difficulty for mechanical forces to disrupt the aggregation of PDI and its derivatives,as well as the fluorescence quenching caused by continuousπ-πstacking between PDI molecules.To eliminate the fluorescence quenching effect caused by the aggregation of PDI and broaden its application fields,polyhedral oligomeric silsesquioxane(POSS)-PDI-POSS(PPP)was screened as PDI doping.The photophysical properties of PPP in both monomeric and aggregated states in different solvents were studied.Then,PPP and styrene-butadiene-styrene block copolymer(SBS)were mixed to prepare the PPP/SBS film.The mechanochromic properties of PPP/SBS film were explored.The fluorescence emission spectra confirmed that when the PPP mass fraction increased to 0.30%,the PPP/SBS film exhibited mechanochromic behavior under uniaxial deformation due to the changes in the molecular packing.
基金supported by the National Natural Science Foundation of China (50773027 and 50733002)the National Basic Research Development Program (2009CB939700)111 Project (B06009)
文摘A series of cholesterol-appended quinacridone (QA) derivatives 1a-1d have been synthesized,in which 1b and 1c could form stable organogels in a wide range of organic solvents upon ultrasound irradiation.Field emission scanning electronic microscope (FESEM) and transmission electron microscopy (TEM) of xerogels or precipitates indicated that 1b and 1c formed 1D fibrous nanostructure,while 1a assembled into 3D flower-like microstructures.The ultrasound-induced organogel process was characterized by kinetic UV-vis and photoluminescence spectroscopic methods suggesting the formation of ?-? aggregates in the gel state.Experimental results demonstrated that the ultrasound could promote molecules to contact frequently in the solution and induce semistable initial aggregates,which propagate to form nano/micro superstructures.The aggregation model was optimized by semiempirical AM1 calculation suggesting the hierarchical self-assembly process.In addition,the formed xerogel film exhibited mechanochromic property,and the phase transition process was accompanied by the fluorescence changes between yellowish green and orange.
基金This research was made possible as a result of a generous grant from National Natural Science Foundation of China(nos.21472111 and 21877013)the 111 Project(no.D20015).
文摘High-contrast mechanochromic(MC)materials are prominent candidates for sensor,security,and memory applications;however,the development of materials with a large luminescence change(Δλem>100 nm)under external stimuli is challenging.Considering that polymorphic molecules usually exhibit reversible mechanochromism,polymorph prediction is adopted for thefirst time to guide the design of high-contrastMC materials in this study.We designed and synthesized a series of donor–π–acceptor pyran derivatives bearing different electron donors and acceptors as model systems.The polymorph prediction indicated that 4-dicyanomethylene-2,6-distyryl-4H-pyran and 4H-pyran-4-one derivatives had the potential to crystallize in both monomer andπ-dimer aggregates,while barbituric acid-based compound tended to pack tightly in all aggregated states.The experimental results agreed well with the prediction that the derivatives potentially possessing both monomer andπ-dimer aggregate structures exhibit excellent MC behavior,whereas the fluorescence difference for the barbituric acid-based compounds is minimal.Moreover,a compound with an excellent fluorescence difference of three colors during reversible mechanochromism was chosen as the candidate for an optical recording material and security ink.This work proposes an effective method to guide the design of stimuli-responsive materials,which may open promising avenues for the development of high-contrast MC molecules.
基金financial support from the National Natural Science Foundation of China(Nos.22175033 and 51902124).
文摘Understanding the relationship between structure and properties is critical to the development of solidstate luminescence materials with desired characteristics and performance optimization. In this work, we elaborately designed and synthesized a pair of mononuclear iridium(Ⅲ) complexes with similar structures but different degrees of cationization. [Ir2-f][2PF_(6)] with two counterions is obtained by simple Nmethylation of the ancillary ligand of [Ir1-f][PF_(6)] which is a classic cationic iridium(Ⅲ) complex. Such a tiny modification results in tremendously different optical properties in dilute solutions and powders.[Ir1-f][PF_(6)] exhibits weak light in solution but enhanced emission in solid-state as well as poly(methyl methacrylate) matrix, indicative of its aggregation-induced emission(AIE) activity. On the sharp contrary, [Ir2-f][2PF_(6)] is an aggregation-caused quenching(ACQ) emitter showing strong emission in the isolated state but nearly nonemissive in aggregation states. Benefiting from the appealing characteristics of mechanochromic luminescence and AIE behavior, [Ir1-f][PF_(6)] has been successfully applied in reversible re-writable data recording and cell imaging. These results might provide deep insights into AIE and ACQ phenomenon of iridium(Ⅲ) complexes and facilitate the development of phosphorescent materials with promising properties.
基金financially supported by the National Natural Science Foundation of China(Nos.22275068 and 21975178)the Fundamental Research Funds for the Central Universitiesthe Open Project of the State Key Laboratory of Supramolecular Structure and Materials.
文摘Mechanochromophores based on bichromic molecular switches,such as bis-naphthopyanes,allow multimodal mechanochromic behavior beyond the typical binary response from single chromophores,which is important for distinguishing between multiple stress states through discrete changes in color.Spontaneously generated persistent and distinguishable multi-colors from activated bis-naphthopyanes remain challenging.And the versatility of bis-mechanophore design for advanced optical molecular systems and the fundamental insights into the corresponding mechano-reactivity are not enough.Here,we identify a dihydroanthracene bridged bis-naphthopyrans as a multimodal mechanochromophore in polymers.Bridging two pyrans with the sterically constrained dihydroanthracene is helpful to control the steric effect for the favorable formation of a distinctly appreciable bis-merocyanine(bis-MC)product.By varying the length of the polymer chains,the force delivered to the mechanophore is modulated,resulting in a gradient change in the relative distribution of two distinctly colored MC products and a multicolor mechanochromism.Mechanical activation of this bis-naphthopyanes proceeds via a mechanistically distinct pathway compared to the photochemical process.In addition,the bulk films can also achieve pronounced color changes when subjected to mechanical force.This study thus further expands the molecular diversity of mechanochromophores and tune the multimodal switch properties of bis-naphthopyrans based polymers.
基金Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology(No.BM2012110)the fundamental research funds for the central universities(No.2023CDJYGRH-YB17)+4 种基金the Venture&Innovation Support Program for Chongqing Overseas Returnees(No.cx2022061)the Natural Science Foundation of Chongqing(No.CSTB2022NSCQ-MSX1123)the Chongqing Talents:Exceptional Young Talents Project(No.cstc2021ycjh-bgzxm0067)Changzhou University,Advanced Catalysis and Green Manufacturing Collaborative Innovation Center(No.ACGM2022–10–10)National Natural Science Foundation of China(Nos.21702019,62174160)for financial support。
文摘Triphenylamine(TPA)-containing 2-(2-hydroxyphenyl)benzoxazoles(2a-2c)have been synthesized via a highly efficient rhodium-catalyzed C–H/C–H cross-coupling reaction.Compound 2a is a novel mechanofluorochromic material with blue-shifted mechanochromic properties.Compounds 2b and 2c presented opposite mechanochromic trends.For 2b,the enol-form emission enhanced,and the ketoform emission blue-shift after grinding.In contrast,2c exhibited the weak enol-form emission disappeared and the keto-form emission slightly red-shift after grinding treatments.The estrone-containing2b-based water-dispersed nanoparticles(NPs)exhibit apparent dual-emission and were applied for fluorescence images.In addition,bis(TPA)-containing 2c-based devices exhibit dual-emission with good performance and a singlet exciton yield of 92%,which breaks through the theoretical upper limit of 25%in conventional fluorescent OLEDs.This is one of the highest exciton utilization values recorded for the ESIPT molecules with a dual emission system.
基金financially supported by the National Natural Science Foundation of China(Nos.51473185,51603233 and 21672267)863 Program(No.SS2015AA031701)+1 种基金the Fundamental Research Funds for the Central UniversitiesGuangdong Science and Technology Plan(Nos.2015B090913003 and 2015B090915003)
文摘A polymer （poly（9,10）anthracenevinylene-alt-4,4＇-（9,9-bis（4-（4＇-（1,2,2＇-triphenyviny）phenoxy）butyl）-9H- fluorene-2,7-diyl） dibenzaldehyde）, P1） was successfully synthesized through the Wittig-Horner reaction by employing fluorene and 9,10-distyrylanthracene moieties as building blocks for backbone and tetraphenylethenes as pendant groups. Photophysical and thermal properties of the resulting polymeric emitter were fully characterized by ultraviolet-visible （UV- Vis） absorption and photoluminescence （PL） spectra, thermogravimetric analysis （TGA） and differential scanning calorimetry （DSC）. While P1 emits an orange-light centered at 567 nm in dilute tetrahydrofuran （THF） solution, the solid powder of the polymer exhibits strong yellow emission peaked at 541 nm. It is also found that the as-synthesized polymer shows unique property of aggregation-enhanced emission （AEE）. In addition, P1 possesses high thermal stability with a decomposition temperature （Td,5%） of 430 ℃ and high morphological stability with a glass transition temperature （Tg） of 171℃. Under the stimulus of mechanical force, the emission of P1 can be changed from yellow to red （△λmax = 61 rim）, showing a remarkable mechanochromism. The results from XRD analysis suggest that such mechanochromic phenomenonof PI is probably caused by the destruction of crystalline structure, which leads to the conformational planarization of the distyrylanthracene moieties forming by the polymerization and the increase of molecular conjugation of the backbone.
基金financially supported by the National Natural Science Foundation of China(Nos.21522405 and 51503142)the Thousand Youth Talents Planthe Natural Science Foundation of Tianjin(No.15JCYBJC52900)
文摘Visualization and quantitative evaluation of covalent bond scission in polymeric materials are critical in understanding their failure mechanisms and improving the toughness and reliability of the materials. Mechano-responsive polymers with the ability of molecular-level transduction of force into chromism and luminescence have evoked major interest and experienced significant progress. In the current review, we highlight the recent achievements in covalent mechanochromic and mechanoluminescent polymers, leading to a bridge between macroscopic mechanical properties and microscopic bond scission events. After a general introduction concerning polymer mechanochemistry, various examples that illustrate the strategies of design and incorporation of functional and weak covalent bonds in polymers were presented, the mechanisms underlying the optical phenomenon were introduced and their potential applications as stress sensors were discussed. This review concludes with a comment on the opportunities and challenges of the field.
