The Design,Synthesis And Properties Investigation Of Aggregation-Induced Emission Polysiloxanes

Luminescent materials have been widely used in traditional agriculture,industry and modern medical science.As for traditional luminescent materials,the fluorescence intensity will decrease or even quench in the aggregate state because of the aggregation-caused quenching(ACQ)effect,which limits its application as a solid state device.Since the concept of aggregation induced emission(AIE)has been put forward in 2001,the traditional luminescent materials' shortcoming that the light emission will be quenched in aggregate state has been partially addressed.The phenomenon of aggregation-induced emission(AIE)is exactly opposite to the ACQ phenomenon,which means non-emissive luminogens are induced to emit by the aggregate formation.In this paper,we designed and synthesized aminopropyl terminated polydimethylsiloxane and side-chain aminopropyl polydimethylsiloxane modified with tetraphenylethylene(TPE)derivative respectively,and further studied the properties of the modified products.The reaction condition of tetraphenylethylene derivative(TPE-20(CH2)2Br)was optimized via McMurry reaction,aminopropyl terminated polydimethylsiloxanes(ATP)with different molecular weights were synthesized and then aminopropyl terminated polydimethylsiloxane modified with tetraphenylethylene derivative(TPE-ATP)was obtained via a simple and facile way.The structures of the obtained products were characterized and analyzed by 1H NMR,13C NMR,MS and IR spectra.DSC and TGA were employed to study its thermodynamic properties.The results showed that the reaction was carried out successfully,and the obtained product had excellent thermodynamic stability compared with TPE derivative.According to fluorescence spectrophotometer analysis,either the value of the time-resolved fluorescence decay constant(?)or quantum yields(?F)of TPE-20(CH2)2Br had been improved by knitted to the ATP.The emission intensity of the product increased at first but it would suddenly decrease upon gradually increasing the concentration because of the inner filter effect(IFE).The fluorescence behaviors in mixed solvents were studied in dilute concentration.The results confirmed that the products had a typical AIE behavior.We further designed and synthesized new TPE derivative(n-TPE)substituted with donor(D)and acceptor(A)moieties.The TPE-pendent polymers(n-TPE-AP-PDMS 2%and n-TPE-AP-PDMS 10%)were synthesized via aza-Michael reaction of TPE derivative(n-TPE)and side-chain aminopropyl polydimethylsiloxane with different amino contents(AP-PDMS).Their structure,surface morphology and thermodynamic properties were characterized by 1H NMR,13C NMR,MS,IR spectra,SEM and TGA analysis.The results showed that the fluorescence polymers were successfully prepared,and the TPE derivative(n-TPE)was dispersed uniformly in side-chain aminopropyl polydimethylsiloxane and the thermal decomposition temperature was increased significantly.By fluorescence analysis,the obtained products showed aggregation emission enhanced effect in THF/n-hexane mixtures.Compared with TPE derivative(n-TPE),the introduction of side-chain aminopropyl polydimethylsiloxane(AP-PDMS)raised n-TPE monomer's fluorescence response to non-solvents.The TPE-pendent polymers had good film-forming ability and its fluorescence response of n-TPE-AP-PDMS 2%in detecting nitrobenzene was investigated.The fluorescence of the obtained film was quenched by 53 ± 2%at the exposure time of 600s.The n-TPE-AP-PDMS 2%film also had good reversibility,indicating ideal practical applications.