The Construction Of Supramolecular Polymeric Materials Via Non-covalent Interactions

The development of supramolecular chemistry has enabled scientists to construct a variety of supramolecular polymer materials with novel properties different from traditional polymer materials through various non-covalent interactions.Supramolecular polymer materials are novel materials based on various non-covalent interactions,which show dynamic reversibility and various environmental stimuli responsiveness.Due to these unique properties,supramolecular polymer materials are expected to be good degradable materials with responsiveness to external stimuli.It is always the direction for scientists to construct novel and unique supramolecular polymer materials through different non-covalent interactions.This thesis is a supramolecular polymer material that uses a variety of different non-covalent bond interactions to construct new functions.The main content of the thesis mainly includes the following four parts:In the first part,we prepared a novel multiple-responsive supramolecular polymer constructed by crown ether-based molecular recognition and disulfide bond connection.This linear supramolecular polymer is assembled from two monomers:a bis(benzo-21-crown-7)-based AA monomer containing a disulfide bond and a bis(dialkylammonium salt)-based BB monomer.Due to the fact that the complexation between the benzo-21-crown-7 unit and the dialkylammonium salt moiety can be controlled by adjusting the solution pH and the addition of ion,this linear supramolecular polymer has ion and pH responsivenesses.Moreover,because of the dynamic nature of disulfide bond,this supramolecular polymer is endowed with redox and light responsivenesses.Interestingly,different from most previous studies about multiple-responsive supramolercular polymers,here we provide a new strategy to fabricate a multiple-responsive supramolercular polymer whose responsivenesses are not only from the stimuli-responsive non-covalent interactions but also from the stimuli-responsive functional group.In the second part,we prepared a novel yet facile approach to prepare white fluorescent polymeric hydrogel based on the aggregation of a single fluorescent chromophore,which is favored by self-assembly of a polymer through intermolecular quadruple hydrogen bonding.This advanced material is an ideal candidate to construct intelligent information display/storage devices.A protected quick response code was fabricated by using this white fluorescent supramolecular gel.which hides the information under natural light yet displays it under UV light.Therefore,the code is protected and only readable under a specific condition.Furthermore,due to the dynamic nature of hydrogen bonds,the supramolecular polymer gel and the resulting quick response code have self-healing ability,which is crucial for the application.The information of a damaged quick response code is incomplete and can not be read out under UV light irradiation,whereas the code is healable based on the interracial self-assembly of gels through multiple hydrogen bonding,resulting in the recovery of protected information.In the third part,by the electrostatic interactions between poly(sodium p-styrenesulfonate)and tetraphenylethene(TPE)derivative containing two quaternary ammonium cations,a novel bioresponsive supramolecular fluorescent hydrogel was constructed.This self-assembly process led to the aggregation of TPE,a typical chromophore with aggregation-induced emission(AIE)property,thereby endowing this hydrogel with the AIE fluorescence property.Moreover,this supramolecular fluorescent hydrogel was responsive to biomolecue.When ATP was added to this system,it interacted with TPE derivative stronger than poly(sodium p-styrenesulfonate).Correspondingly,the network structure of the hydrogel was destroyed and the aggregation extent of TPE derivative was decreased,which induced the transition from gel to sol and decreased the fluorescence intensity of the hydrogel at the same time.Subsequently,after phosphatase ATPase was added into the solution,ATP was decomposed and the electrostatic interactions between poly(sodium p-styrenesulfonate)and TPE derivative were rebuilt,transforming sol into gel and recovering the fluorescence intensity of the hydrogel.Therefore,the fluorescent supramolecular hydrogel was bioresponsive.Simultaneously,this fluorescent supramolecular hydrogel could cross over cell membrane and enter cytoplasm,which could be applied in the cell imaging.In the last part,we described a novel ionically conductive supramolecular hydrogel with reversible photoconductive properties in which the azobenzene motif,a-cyclodextrin(?-CD)and ionic liquid are grafted onto the gel matrix.Host-guest interactions with different association constants between a-CD and azobenzene or the anionic part of the ionic liquid can be readily tuned by photoinduced trans-cis isomerization of the azobenzene unit.When irradiated by 365 nm light,?-CD prefers to form a complex with the anionic part of the ionic liquid,resulting in decreased ionic mobility and thus high resistance of the hydrogel.However,under 420 nm light irradiation,a more stable complex is again formed between ?-CD and trans-azobenzene,thereby releasing the bound anions to regenerate the low-resistive hydrogel.As such,remote control of the ionic conductivity of the hydrogel is realized by simple host-guest chemistry,which makes the resultant smart material stand out from traditional hydrogels with only separated photoresponsiveness and ion-conducting ability.With the incorporation of a logic gate,this hydrogel is able to reversibly switch an electric circuit on and off by light irradiation with certain wavelengths.The concept of photoswitchable ionic conductivity of a hydrogel mediated by competitive molecular recognition is potentially promising toward the fabrication of optoelectronic devices and applications in bioelectronic technology.