Towards non-traditional intrinsic luminescence luminogens from polystyrene derivative C5 skeletal polymers and ladder polymers with well-regulated microstructures

With the emergence of new emissive species in many nonconjugated structures, how to efficiently design and manipulate non-traditional intrinsic luminescence luminogens (NTILgens) is of academic importance but a dramatic challenge. As the carbon skeletons in olefin polymers have diverse microstructures that mainly affect molecular packing, the construction of the carbon skeletons is required to regulate the performances of luminescent materials. Our group previously reported the C5 skeletal P-CPVB and its ladder polymer (C-PCPVB) through the anion migrated ring -opening polymerization (AMROP) of 1-cyclopropylvinylbenzene (CPVB) and the cationic cyclization of P-CPVB. Unexpected, after the rigid seven membered rings were constructed among the phenyl rings, the NTIL was observed of the nonconjugated C-PCPVB in the aggregate state under UV light irradiation. The results inspired us to design the polymer luminogens through the construction of carbon skeletons. In present work, the P-CPVBs and their ladder polymers (C-PCPVBs) with different degree of polymerization (DPs) are prepared. Unexpected, P-CPVBs with different DPs were non -emissive in dilute solution but highly emissive with the visible light in the solid state under the UV light irradiation. As predicted, C-PCPVBs with different DPs fluoresced blue emission in the aggregation state. All the P-CPVBs in the solid state showed much higher absolute quantum yields (QY) values than C-PCPVB analogues did. The bright blue emissions in the aggregate state of both C-PCPVBs bearing nonconjugated groups and P-CPVBs bearing poorly conjugated groups could be attributed to the clusterization-triggered emission (CTE), but the mechanisms to generate NTIL were different due to the difference of the carbon skeletons, where the through -spacing conjugation (TSC) and through -spacing interactions (TSI), respectively, contributed to the NTIL of C-PCPVBs and P-CPVBs. In perspective of the property -oriented designability, their derivatives with different electron -donating and -withdrawing substituents (P-CPVB-OCH3/TPSE/yne, C-PCPVB-OCH3/TPSE/yne) when the DPs were fixed at 24 were synthesized and characterized. All the substituted P-CPVBs/C-PCPVBs were demonstrated with the aggregationinduced emission (AIE) effect and blue fluorescence as the unsubstituted P-CPVBs/C-PCPVBs. As desired, the electronic effect of carbon skeletons and their cyclization can affect their maximum emission wavelengths (lambda em) and the QY. All the lambda em values were red -shifted whether the carbon skeletons were cyclic or substituted. More importantly, the glass temperature (Tg) and decomposition temperature (Td) of P-CPVB were dramatically improved by the substituents and cyclization analogues. The seven -membered ring and the crosslinking networks of the yne group in the warming up can significantly improve the stability of polymers, contributing to the higher Td value. It should be noted that P-CPVB-yne and C-PCPVB-yne exhibited the much higher Td values, and they showed the higher carbonization yield of 49.78% and 45.25% at 800 celcius, respectively, which would broaden their applications of these nonpolar polymers.