Synthesis and identification of organosoluble polyimides: thermal, photophysical and chemiluminescence properties

Abstract

Novel fluorescent polyimides (PIs) were prepared from a new diamine, 4-(4-(4-amino-2-(4,5-diphenyl-1H-imidazol-2-yl) phenoxy)phenoxy)-3-(4,5-diphenyl-1H-imidazol-2-yl)benzenamine, and three tetracarboxylic dianhydrides. The new symmetrical diamine was successfully synthesized by the nucleophilic substitution reaction of hydroquinone with 2-(2-chloro-5-nitrophenyl)-4, 5-diphenyl-1H-imidazole (I). The PIs synthesized here are amorphous and soluble in polar aprotic solvents and demonstrate the ability to form films; their inherent viscosities ranged from 43 to 82 ml g À1 . The PIs had suitable thermal stability and relatively high T g values (245-274 1C), 10% weight loss temperatures in excess of 500 1C and char yields at 600 1C in air up to 62%. The PIs show emission in the solid state and in dilute (0.20 g per 100 ml) N,N-dimethyl acetamide solution at 431-464 nm with photoluminescence (PL) quantum yields in the range of 11-25%. The chemiluminescence activity of PIs in the presence of peroxyoxalate was also investigated. Polymer Journal (2010) 42, 648-656; doi:10.1038/pj.2010.57; published online 30 June 2010Keywords: fluorescent; polyimides; solubility; synthesis; thermal stability INTRODUCTION Aromatic polyimides (Pls) generally possess excellent thermal, mechanical, electrical and chemical properties. Therefore, they have been used in many applications such as electronics, coatings and adhesives, composite materials and membranes. 1-3 However, these polymers are difficult to process because of their high glass transition temperatures (T g ) or high melting temperatures (T m ) and their limited solubility in organic solvents. 4,5 Considerable efforts have been made to improve the solubility and melting processability of PIs while maintaining their desired properties. 6-8 Significant synthetic efforts in the area of high-performance polymers have been focused on improving the processability and solubility of PIs through the design and synthesis of new monomers. Various structural modifications can be made to the PI backbone to modify the polymer properties, such as insertion of flexible linkages on the main chain, 9-13 use of noncoplanar 14 or asymmetric monomers [15][16][17][18][19] and incorporation of pendant groups in the polymer backbone, 20-29 with results including lower interchain interactions or a reduced polymer chain stiffness. Depending on the type and amount of structural modifications, melting temperatures can be lowered and solubility improved, resulting in processable materials. Introducing bulky pendant substituents and heteroaromatic rings into PI chains has been considered to be an efficient method to provide not only enhanced solubility but also good thermal and thermo-oxidative stability. 22 The rigidity based on the

Synthesis and characterization of trifluoromethylated poly(ether–imidazole–imide)s based on unsymmetrical diamine bearing carbazole and imidazole chromophores in ionic liquids: Study of electrochemical properties by using nanocomposite electrode

“…Among these approaches, introduction of bulky pendants and heteroaromatic rings into the polymer chains has provided not only enhanced solubility but also good thermal stability and processability [14][15][16][17][18][19][20][21]. There are reports of using imidazole and carbazole rings and their derivatives into polymeric frameworks to improve the solubility of the polymers, which have also been suggested as promising photoconductive and photorefractive materials [22][23][24]. PIs containing hexafluoroisopropylidene or trifluoromethyl groups are of special interest due to enhanced solubility and optical transparency together with a lower dielectric constant which were attributed to low polarizability of the C-F bond and increasing free volume.…”

Novel thermal stable organosoluble polyamides and polyimides based on quinoxalin bulky pendent group

“…2H c , J=1.5 Hz), 6.03 (t, 1H b , J=2Hz), 5.01 (s, 4H a , NH 2 ). 13 Polymer Synthesis. Polyamides Synthesis: General procedure for the preparation of polyamides is described as follows.…”

“…[1][2][3] Therefore the interest of the investigators was focused on the development of structurally modified aromatic PAs and PIs having increased solubility in order to improve their processability with retention of their thermal stability. These studies include introduction of bulky, packing-disruptive moieties, [4][5][6][7][8][9][10][11][12][13] flexible segments into the polymer chain, [14][15][16][17][18][19][20] alicyclic units, 21 and replacing symmetrical aromatic rings by unsymmetrical ones. 7,[22][23][24][25][26] Another approach employed to increase the solubility of rigid-rod PIs and PAs is by incorporation of the nonlinear moieties such as a bulky noncoplanar group in the polymer backbone.…”

Synthesis and characterization of novel organosoluble and thermally stable polyamides bearing triptycene in their backbones

“…Therefore, considerable effort has been made to increase the processability and solubility of aramids by structural modification. One of the most common approaches to increasing solubility and lowering T g and T s is the introduction of flexible bonds in the polymer backbone and/or bulky pendent groups along the main chain [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Soluble or thermoplastic aramids may broaden applications in films, separation membranes, coatings, polymer blends, and composites.…”