The Construction Of Multicolor Fluorescent Polymeric Hydrogel Based On Aggregation Induced Emission And Lanthanide Coordination Mechanisms

Fluorescent polymeric hydrogels（FPHs）are polymeric soft materials with tunable luminous features.As a marriage of polymeric hydrogels and fluorescent materials,FPHs integrate the merits of both materials,including intrinsic soft wet mature,multi-stimuli-responsiveness of hydrogels and high sensitivity,high selectivity of fluorochrome.FPHs demonstrate promising application in smart display,bio-inspired soft actuators,information encryption fields.To date,introducing organic fluorophores,lanthanide complexes and luminescent nanoparticles into polymeric hydrogel matrix by physical or chemical method is the common method to prepare FPHs.However,it is still challenging to endow FPHs with full spectrum fluorescence emission and self-healing property to satisfy the demand under different scenes and extend the service life.To solve the abovementioned problem,the main work of this thesis can be listed as follows:1.The naphthalimide（NI）was modified by nucleophilic substitution of phenol to get aggregation-induced-blue-light-emitting molecular 4-phenoxy-N-allyl-1,8-naphthalimide（Ph AN）.Then Ph AN was radically copolymerized with hydrophilic hydroxyethyl methacrylate（HEMA）and N-isopropyl acrylamide（NIPAM）to produce thermal responsive blue-light emitting linear polymer Poly（Ph AN-NIPAM-HEMA）.Blue-light-emitting polymeric hydrogels with semi-interpenetrated network were prepared by introducing Poly（Ph AN-NIPAM-HEMA）into PNIPAM network with chemical crosslinking.When the temperature was higher than lower critical solution temperature（LCST）of PNIPAM,the shrinking of PNIPAM network caused aggregation of Ph AN among Poly（Ph AN-NIPAM-HEMA）and blue fluorescence enhanced furtherly.The anisotropic bilayer actuator was produced by interfacial composition between blue-light-emitting polymeric hydrogels and pan paper.Taking advantage of mismatch of thermoregulated swelling ratio and modules of bilayers and fluorescence performance of hydrogel,the reversible shape-morphing accompanying with simultaneous optical change were realized.2.N-acryloyl glycinamide（NAGA）consisting of two amides was synthesized firstly.Then the NAGA was copolymerized with 6-acrylamidopicolinate（6APA）consisting pyridine carboxylic acid ligand in the presence of Poly（Ph AN-NIPAM-HEMA）to prepare physical crosslinked hydrogel with semi-interpenetrated network.The pyridine carboxylic acid ligand can coordinate with lanthanide Eu³⁺or Tb³⁺ions to emit red or green fluorescence respectively through antenna effect.The Poly（Ph AN-NIPAM-HEMA）in the hydrogel can emit blue fluorescence owing to the existence of Ph AN.By adjusting the ratio of Eu³⁺and Tb³⁺and the concentration of Poly（Ph AN-NIPAM-HEMA）,the ratio of red,green,blue fluorescence were also changed to realize full spectrum fluorescence emission.The coordination between organic ligand and lanthanide ions belongs to supramolecular interaction and it was easily dissociated in alkaline solution.Utilizing this feature,p H responsive fluorescence performance was realized.In addition,two amides groups play two roles in hydrogel.For one thing,they can form hydrogen bond as physical crosslinker;for another,the dynamic nature of hydrogen bond endows the hydrogel with self-healing property.Camouflage skin was prepared using the as-prepared multicolor fluorescence polymeric hydrogel.It demonstrated excellence camouflage ability in complicated surrounding and paved the ways for the design and development of camouflage skin in the future.In summary,this thesis has done the research about the construction of multicolor fluorescent hydrogel and its functional synergy.By introducing fluorescent chromophores of red,green and blue into polymeric hydrogel,full spectrum fluorescence emission was realized by adjusting the ratio of different colors.By adjusting the supramolecular interaction,the synergy of multicolor fluorescence performance and p H responsive color changing and self-healing property were in reality,which demonstrate potential application in camouflage skin.