Enhancing Photoluminescence of Nonconventional Luminescent Polymers by Increasing Chain Flexibility

Abstract

Many nonconventional luminescent polymers are found to exhibit intrinsic photoluminescence and “aggregation‐induced emission” (AIE) behavior. Strong physical interactions among polymer chains and/or a rigid molecular conformation of polymer chains are thought to be beneficial to boost stronger emissions. The purpose of this work is to prove that increasing chain flexibility is, at least in some cases, beneficial to enhance the photoluminescence of nonconventional luminescent polymers. Poly(itaconic anhydride) (PITA) and poly[(1‐octene)‐co‐(itaconic anhydride)] (POITA) synthesized in this work are highly emissive in concentrated solutions and in solid state, exhibiting typical AIE characteristics, and very interestingly, the copolymer POITA exhibits stronger and red‐shifted emissions than the homopolymer PITA in both solutions and in the solid state. These results are explained by the increase of chain flexibility, which makes the nonconventional chromophores adopt proper conformations for strong intra‐ and/or interchain n‐π* and/or π–π* interactions. This study sheds some light on designing nonconventional luminescent materials with high emission efficiency and long wavelength emission.

Nontraditional Organic/Polymeric Luminogens with Red‐Shifted Fluorescence Emissions

“…In a subsequent work of Wang's group, they investigated the fluorescence behavior of poly(itaconic anhydride) (PITA) and poly(itaconic anhydride-1-octene) (POITA). [33] POITA exhibits slightly red-shifted emission than PITA due to the higher chain flexibility of POITA. The increase of chain flexibility makes the nonconventional chromophores adopt proper conformations for strong intra-and/or interchain n-𝜋 and/or 𝜋-𝜋 interactions.…”

“…The reported NTLs are mainly polymers, both naturally occurring and synthetic, and some small organic compounds. Based on the type of heteroatoms other than carbon and hydrogen atoms in the nonconventional chromophores, the NTLs can be roughly classified into following categories (Figure 1) 1) Oxygen-containing NTLs: alcohols (d-fructose, d-(+)-xylose, d-galactose, and pentaerythritol), [30] ethers [poly(ethylene glycol) (PEG), [31] and hyperbranched polyether epoxy (EHBPE)], [23] carboxylic acids [poly(acrylic acid) (PAAc)], [32] anhydrides [poly(itaconic anhydride) (PITA), [33] and poly(maleic anhydride)], [16,34] and esters [polycarbonate, [35] and poly(lactic acid) binary blends]. [36] 2) Nitrogen-containing NTLs: amines [poly(amido amine) (PAMAM), [37,38] hyperbranched poly(amino ester) (PAE), [39,40] and poly(amino ether ester)], [41] imines [linear or hyperbranched polyethyleneimine (PEI)], [42][43][44] oximes (hexanal oximes), [11] nitriles [polyacrylonitrile (PAN)], [17] amides [polyacrylamide (PAAm), [45] poly(N-isopropylacrylamide) (PNIPAM), [32] poly(ether amide) (PEA), [46] poly(esteramide-ether) (PEAE), [47] and poly(amido acids)], [48] imides (polysuccinimide), [20,22] polyurethane, [49,50] amino acids, [51,52] and lactams [polyvinylpyrrolidone (PVP), [53] and poly(Nvinylcaprolactam) (PNVCL)].…”

Multiring-induced multicolour emission: hyperbranched polysiloxane with silicon bridge for data encryption

“…Currently, despite the fact that a broad series of HBPSi have been obtained, compared with traditional conjugated luminescent polymers, 25 these HBPSi still have drawbacks such as short and narrow excitation wavelength in the ultraviolet region as well as monochromatic blue emission, which seriously restrict their application. Recently, some non-conjugated luminescent polymers have been reported to exhibit excitation-dependent properties such as poly[(1-octene)-co-(itaconic anhydride)], 26 poly(maleic anhydridealt-vinyl acetate) 27 and poly(maleic anhydride-alt-vinyl pyrrolidone), 28 which prompted us to design and synthesise novel hyperbranched polysiloxanes with strong and red-shifted fluorescence emission. Moreover, it will be also important to expand the HBPSi to novel applications.…”

Significantly Red‐Shifted Emissions of Nonconventional AIE Polymers Containing Zwitterionic Components

“…[12,13] Unsatisfactorily, most nonconventional AIE polymers show short wavelength emission. [14][15][16] For rigid polymers with limited conformations or lack of physical interaction, the formation of more extended conjugation is limited. Very recently, Wang and co-workers synthesized poly (itaconic anhydride-alt-vinyl pyrrolidone) (PIVP) with long-wavelength emission (620 nm).…”