| Stimuli-responsive luminescent materials are a kind of intelligent luminescent materials.Compared with traditional luminescent materials,the luminescent intensity and the color of stimuli-responsive luminescent materials will be changed when applied with stimulation.Due to their unique properties,stimuli-responsive luminescent materials have potential applications in the fields of fluorescent anti-counterfeiting materials,substance detections,detectors,drug controlled release and so on.At present,most of the reported stimulus-responsive luminescent materials only exhibit single stimulus response,such as temperature stimuli-responsive luminescent materials,UV irradiation stimuli-responsive luminescent materials,ionic strength stimuli-responsive luminescent materials,pH stimuli-responsive luminescent materials and so on.There are few reports about multistimuli-responsive luminescent materials,and most of the reported multistimuli-responsive luminescent materials were prepared by copolymerization.There is no report about the multistimuli-responsive luminescent homo-polymers.The cause lays in the difficulties combining different stimuli blocks and luminophores within one molecule.In this paper,a series of side chain polymers with multistimuli-responsive properties and luminescent properties were synthesized by combining the design ideas of luminescent materials and stimulus-responsive materials,and the effects of the chemical structures of side chain polymers on their luminescent properties and stimulus-responsive properties were also explored in detail.This research not only enriches the variety of multistimuli-responsive photoluminescent polymer materials,but also provides a new method to prepare multistimuli-responsive photoluminescent polymer materials.The main contents of this paper are described as follows:(1)A series of small molecules AIEE luminescent materials HPTEOmPA(m=l,2,3,m is the repetition number of ethylene oxygen chains)with multistimuli-responsive properties were designed and synthesized.The luminescent properties and their multistimuli-responsive properties were characterized in detail.Experimental results showed that HPTEOmPA behaved AIEE characteristics.HTPEO3PA and HPTEO2PA with long hydrophilic chains were thermosensitive,and the LCST of their aqueous solution increased with the increasing hydrophilic chains.The luminescence behavior of HPTEO3PA and HPTEO2PA aqueous solutions were also showed temperature stimuli-responsive.With the increasing temperature,the emission intensity kept unchanged at first,then increased and then decreased.HPTEO3PA and HPTEO2PA also possessed pH stimuli-responsive.In aqueous solution,the LCST value of HPTEO3PA aqueous solution first decreased and then increased with the increasing alkali content.The fluorescence intensity of HPTEO3PA increased slowly with the increase of alkali content in aqueous solution,while increased greatly with the addition of alkali in THF solution and the maximum luminescence wavelength exhibited different extent of red-shift with the addition of different alkali.Based on the stimuli-responsive properties of HPTEO3PA,we also developed a rewritable material with the advantages of simple preparation method,good visual effect and reusability.HPTEO3PA and HPTEO2PA are also showed UV irradiation stimuli-responsive.With the increasing UV irradiation time,the emission intensity of HPTE03PA aqueous solution increased while the luminescence intensity of HPTEO3PA THF solutions decreased.(2)A series of monomers(Z)-4-(1-cyano-2-(3,4,5-tri(2-(2-methoxyethoxy)ethoxy)phenyl)vinyl)phenoxymethacrylate(MOTEOmPVPCN,m=1,2,3)and their corresponding polymers(PMOTEOmPVPCN,m=1,2,3)were designed and synthesized.The luminescent properties and their multistimuli-responsive properties of monomers and polymers were also investigated in detail.The experimental results showed that both monomers and polymers exhibited obvious AIEE characteristics.MOTEO2PVPCN and MOTEO3PVPCN with long hydrophilic chains were thennosensitive,and the LCST value increased with the increasing of the hydrophilic chains length.PMOTEO3PVPCN also behaved temperature sensitivity,and the LCST value was higher than MOTEO3PVPCN.The luminescence behavior of thermosensitive monomers and polymers was also thermosensitive.With the increasing temperature,the luminescence intensity of monomers and polymer aqueous solutions kept basically unchanged at first,then increased,and then decreased.Thermosensitive monomers and polymer aqueous solutions also behaved UV irradiation stimuli-responsive.With the increasing UV irradiation time,the LCST value of monomers decreased,while the LCST value of polymers increased first and then decreased with the change of concentration.The fluorescence intensity of thermosensitive monomers and polymer aqueous solution increased with the increasing UV irradiation time,while in THF solution,the fluorescence intensity of monomers and polymer decreased.Thermosensitive monomers and polymer also showed obvious ionic strength stimuli-responsive.The change rule of LCST values of thermo sensitive monomers and polymers after adding different salts was consistent with Hofmeister Effect.(3)A series of luminescent monomers(Z)-(o-(4-(1-cyano-2-(3,4,5-tri(2-(2-(2-methoxyethoxy)ethoxy)phenyl)phenoxy)alkyl methacrylate(MmTEO3PVPCN,m=0,2,4,6)and corresponding polymers(PMmTEO3PVPCN,m=0,2,4,6)with different flexible spacer lengths were designed and synthesized.Their luminescent properties and multistimuli-responsive properties were studied in detail.The experimental results showed that all monomers and polymers with different flexible spacer length behaved AIEE characteristics.All monomers and polymers possessed temperature sensitivity,and the LCST values of monomers and polymers decreased with the increasing flexible spacer length.The luminescent behavior of monomers and polymers aqueous solution also showed thermosensitivity.With the increment of temperature,the luminescent intensity of monomers and polymer aqueous solutions kept basically unchanged,then increased,and then decreased.Monomers and polymers also exhibited UV irradiation stimuli-responsive.In aqueous solution,the LCST value of monomers aqueous solutions decreased after UV irradiation,and the change of LCST value of polymers aqueous solutions was related to their flexible spacer length.The fluorescent luminescence behavior of monomers and polymers aqueous solutions also showed UV irradiation stimuli-responsive.After UV irradiation,the fluorescence intensity of monomers and polymers aqueous solutions increased.The flexible spacer length also had great influence on their fluorescence luminescence behavior.For monomers,with the increment of spacer length,the emission peak of excimer appeared and enhanced.For polymers,the emission peak number did not change.However,the ratio of fluorescence intensity after and before UV irradiation increased with the increasing the flexible spacer length.Monomers and polymers with different flexible spacer lengths also exhibit obvious ionic strength stimuli-responsive,and the change rule of LCST values of monomers and polymers after adding different salts was consistent with Hofmeister Effect.The flexible spacer length of monomers and polymers had little influence on their ionic strength stimuli-responsive.(4)A series of copolymers PMOTEO3PVPCN(x)-co-PNIPAM(y)with different copolymerization ratios were synthesized,and the chemical structure of the copolymer was characterized by 1H NMR and GPC.The luminescent properties and multistimuli-responsive properties of copolymers were characterized by UV spectroscopy and fluorescence spectroscopy.The experimental results show that all copolymers behaved AIEE characteristics.The thermosensitivity of the copolymers was characterized by UV spectroscopy and fluorescence spectroscopy.The test results showed that the LCST value of the copolymers decreased first and then increased with the increasing PMOTEO3PVPCN molar content.All copolymers exhibited thermo-sensitive luminescence behavior.With the increment of temperature,the luminescence intensity of copolymers aqueous solution kept basically unchanged,then increased,and then decreased.The UV stimuli-responsive of the copolymers was characterized by UV spectroscopy and fluorescence spectroscopy.In THF solution,the fluorescence intensity of the copolymers decreased with the increasing UV irradiation time,while in aqueous solution,the fluorescence intensity of the copolymers increased with the increasing UV irradiation time.All copolymers also exhibited obvious ionic strength stimuli-responsive.After adding with different salts,the change rule of LCST value of copolymers was consistent with Hofmeister Effect. |
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