Optoeletronic properties of poly(N‐alkenyl‐carbazole)s driven by polymer stereoregularity

Abstract

Stereoregular polymers like isotactic poly(N‐butenyl‐carbazole) (i‐PBK), isotactic and syndiotactic poly(N‐pentenyl‐carbazole) (i‐PPK and s‐PPK), and poly(N‐hexenyl‐carbazole) (i‐PHK and s‐PHK) are synthesized using the stereospecific homogeneous “single site” Ziegler‐Natta (Z‐N) catalysts: rac‐dimethylsilylbis(1‐indenyl)zirconium dichloride (1)/methylaluminoxane (MAO) and diphenylmethylidene(cyclopentadienyl)‐(9‐fluorenyl)zirconium dichloride (2)/MAO. Catalytic activity is rationalized by density functional theory (DFT) calculations. All synthesized polymers are fully characterized by NMR, thermal, wide‐angle X‐ray diffraction, and fourier transform infrared spectroscopy analysis. Fluorescence measurements on isotactic and syndiotactic polymer films indicate that all polymers give rise to excimers, both “sandwich‐like” and “partially overlapping.” Excimer formation is essentially driven by the polymer tacticity. Isotactic polymers generate both sandwich‐like and partially overlapping excimers, while syndiotactic polymers give rise especially to partially overlapping ones. A theoretical combined molecular dynamics–time dependent DFT approach is also used to support the experimental results. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 242–251

Synthesis of Di-Block Copolymers Poly (Propylene oxide)-block-Poly (9-(2,3-epoxypropyl) Carbazole) via Sequential Addition of Monomers in One Pot

“…In our opinion, the broad band observed at 400 nm should be associated to excimer fluorescence, probably, to the low energy ''sandwich like" excimer fluorescence. As already reported for other polymers containing pendant carbazole groups [15,[18][19][20][21], these experimental results can be explained assuming that polymer chain conformational freedom in solution prevents excimer formation, while in the solid state, a reduced conformational freedom allows the excimer formation. reported in Figure 8A.…”

“…In our opinion, the broad band observed at 400 nm should be associated to excimer fluorescence, probably, to the low energy ''sandwich like" excimer fluorescence. As already reported for other polymers containing pendant carbazole groups [15,[18][19][20][21], these experimental results can be explained assuming that polymer chain conformational freedom in solution prevents excimer formation, while in the solid state, a reduced conformational freedom allows the excimer formation. Consistent with the literature concerning the PEPK homopolymer photoluminescent feature [1], the fluorescence spectra of diluted solutions of PPO-b-PEPK copolymers do not exhibit excimer emission (see Figure 8A): the observed bands at 354 and 375 nm, have to be associated to the isolated carbazole fluorescence of PEPK block.…”

“…In particular, it was reported that polymers with pendant carbazolyl groups do not exhibit excimer emissions in diluted solutions at room temperature, except when the carbazole chromophores are directly bound to the polymer backbone as in the case of PVK [ 1 , 40 , 41 , 42 , 43 ]. On the contrary, in the solid state, carbazole-containing polymers also present a short spacer between the polymer chain and the carbazole groups give rise to excimer fluorescence [ 1 , 2 , 15 , 18 , 19 , 20 , 21 , 40 , 41 , 42 , 43 ]. Moreover, it was reported that, depending on polymer chain conformation, two different excimer fluorescences can be generated: the low energy ‘‘sandwich like” excimer and/or the high energy ‘‘partially overlapping” excimer fluorescence (see Scheme 3 ) [ 2 , 15 , 18 , 19 , 20 , 21 , 40 , 41 , 42 , 43 ].…”

“…On the contrary, in the solid state, carbazolecontaining polymers also present a short spacer between the polymer chain and the carbazole groups give rise to excimer fluorescence [1,2,15,[18][19][20][21][40][41][42][43]. Moreover, it was reported that, depending on polymer chain conformation, two different excimer fluorescences can be generated: the low energy ''sandwich like" excimer and/or the high energy ''partially overlapping" excimer fluorescence (see Scheme 3) [2,15,[18][19][20][21][40][41][42][43]. Consistent with the literature concerning the PEPK homopolymer photoluminescent feature [1], the fluorescence spectra of diluted solutions of PPO-b-PEPK copolymers do not exhibit excimer emission (see Figure 8A): the observed bands at 354 and 375 nm, have to be associated to the isolated carbazole fluorescence of PEPK block.…”

“…The synthesis of polymers with pendant carbazolyl groups has attracted great academic and industrial interest thanks to the unique spectroscopic properties that they exhibit [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. Starting from polyvinylcarbazole (PVK) [ 8 ], different kinds of polymers with pendant carbazolyl groups, i.e., polyacrylate [ 9 , 10 ], polymethacrylate [ 11 , 12 , 13 , 14 ], polystyrene [ 15 , 16 , 17 ], and polyolefin [ 18 , 19 , 20 , 21 ] derivates, have been reported. Poly(9-(2,3-epoxypropyl) carbazole) (PEPK) has been widely studied because of its high carrier and hole drift mobility, too [ 22 , 23 , 24 , 25 , 26 ].…”