Tetraphenylethene-modified polysiloxanes: Synthesis, AIE properties and multi-stimuli responsive fluorescence

Herein, polysiloxane-based aggregation -induced emission (AIE) polymers and rubbers were prepared which display interesting multi -stimuli responsive fluorescence. TPE-modified polydimethylsiloxanes (PDMS-TPE) as polysiloxane-based AIE polymers were synthesized through Heck reaction of bromo-substituted tetraphenylethene (TPE-Br) and vinyl polysiloxanes. As expected, TPE moiety endows the modified polysiloxane with typical AIE behavior. However, limited by the long polymer chains, the aggregation process of PDMS-TPE shows obvious differences compared with the small molecule TPE-Br. The fluorescence of PDMS-TPE in THF/H 2 O starts to increase when the H 2 O fraction (f w ) is 70% while TPE-Br is nearly non -luminous until the f w is up to 99%. The fluorescence intensity ratio (I/I 0 ) of PDMS-TPE in the aggregated state and dispersed state is over 1300, greater than that of TPE-Br (I/I 0 = 380). More importantly, the exceptional thermal motion of Si-O-Si chains and AIE characteristic of TPE moiety work together, enabling PDMS-TPE to show specific temperature -dependent fluorescence with a wider response range of room temperature to 190 degrees C, which is distinguished from TPE-Br. And such fluorescence responsiveness possess good fatigue -resistance. Furthermore, fluorescent silicone rubbers, rPDMS-TPE were prepared by using PDMS-TPE as additive of the base gum. They display interesting solventcontrollable fluorescence and higher tensile strength (4.42 MPa) than the control sample without TPE component (1.96 MPa). Notably, a unique stretching -enhanced emission (SEE) phenomenon is observed from these TPE-modified silicone rubbers. When being stretched, the rubbers' fluorescent emission intensity could increase by 143%.