Photoconductive polyimides derived from a novel imidazole-containing diamine

Abstract

A new diamine containing an imidazole structure, 4,4′-(4,5-diphenyl-1H-imidazole-1,2-diyl)dianiline (DIMA), was synthesized to prepare photoconductive polyimides (PIs) with four types of dianhydrides such as 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxyduphthalic anhydride, 4,4′-(hexafluoroisopropylidene) diphthalic anhydride, and cyclobutane-1,2,3,4,-tetracarboxylic dianhydride, based on the fact that the imidazole ring is a useful n-type block with high electron-donating property and good thermal stability. The imidazole-containing diamine possesses high electron-donating properties due to the lone pair electrons at nitrogen, which affords a high hole-transport property. All the PIs prepared from DIMA were amorphous due to the large side group and kink structure of the diamine, optically transparent (transmittances of 92–98% at 450 nm), and exhibited high thermal stability (10% weight loss temperatures ranged 453–558°C).

High Performance Biomass-Based Polyimides for Flexible Electronic Applications

“…The results are in good agreement with the trend in ρ values of the film. Besides, the disparity in electron affinity ( E A ) between aliphatic CBDA (0.54 eV) and aromatic BPDA (2.55 eV) may affect the individual or disordered interchain packing of the polymer chain and result in inferior mechanical properties. − Collectively, the biobased PIs studied possess conspicuous thermal resistance ( T d > 400 °C and T g > 250 °C), dimensional stability ( CTE < 50 ppm K –1 ), and durable mechanical properties, which is superior to most of the reported biopolymers. , The prepared bioderived PIs with high thermal and mechanical robustness are favorable for flexible and sustainable electronic applications. Therefore, PI­(ISBA-C95B5) with high biomass content was selected as the substrate and dielectrics materials for the application in flexible OFET in a later discussion.…”

“…In comparison, PI­(ISBA-BPDA) exhibits lower T 400 and higher YI values than does PI­(ISBA-CBDA), but a much higher T 400 value than that of PI­(ISBA-PMDA). The strong CT interaction in the high electron-withdrawing ability of PMDA, which has a higher E A of 2.62 eV as compared to that of BPDA (2.52 eV), causes the resulting PI with the higher YI and lower T 400 values. Besides, a relatively higher T 400 of PI­(ISBA-BPDA) is probably due to the smallest ρ observed in the PIs studied .…”

Soluble and transparent polyimides with high Tgs from a new semi-aliphatic diamine with cyclohexyl and ortho-methyl groups

“…This is ascribed to the trifluoromethyls in 6FDA, which provide steric hindrance and high electronegativity of C-F bonds to inhibit the formation of CTC. 6,13 On the contrary, PI-H1 and PI-L1 possessed the lowest average transmittance (80%) due to the most rigid dianhydride PMDA, but still better than that of Kapton (69%). 16 The optical photographs of the resulting PI films (Thickness: 55-65 mm) were shown in Figure 7.…”

“…In addition, it is easy to form intramolecular and intermolecular charge-transfer complex (CTC) that usually causes the low transparency and deep color of PI films. [5][6][7][8][9][10] These two drawbacks impede the applications of PIs in microelectronic and optoelectronic engineering. 11,12 Therefore, lots of efforts have been made to overcome above-mentioned problems through the design and modification of PI molecular structures, 13 including introduction of bulky pendent groups (e.g., cyclobutyl and cyclohexyl) to decrease close-packing and intermolecular CT interactions, [14][15][16] flexible linkages (e.g., -O-, -CH 2 -and -S-) to provide kinks in the polymer backbones, [17][18][19] noncoplanar structures to reduce crystallinity and hinder interactions, [20][21][22] and fluorine substituents like trifluoromethyl or perfluoro groups to weaken intermolecular cohesive force and reduce CTC formation.…”

New fluorinated polyimides based on 1,2-bis(4-aminophenyl)-4,5-bis(4-trifluoromethylphenyl)-1H-imidazole

“…29,30 In previous work, some aromatic PIs and poly(ether imide)s containing di-and triarylimidazolyl units into the polymer backbone or as bulky pendant groups have been reported. [31][32][33][34][35][36][37][38][39] In this paper, with an aim to develop high performance and processable PIs, a new kind of unsymmetrical diamine containing tetraarylimidazolyl and trifluoromethyl groups, 1,2diphenyl-4,5-bis(4-trifluoromethylphenyl)-1H-imidazole, has been synthesized successfully. Meanwhile, a new series of fluorinated imidazolyl-containing PIs were synthesized derived from the resulting diamine monomer.…”