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To tune the photophysical properties of polyimides (PIs), a diamine containing naphthalene and triphenylamine units, N 1 -(4-aminophenyl)-N 1 -[(4-naphthalene-2-yloxy)phenyl]benzene-1,4-diamine (DA), was synthesized. A series of fluorescent electroactive new PIs from synthesized DA were prepared with conventional thermal imidization with dianhydride. The selected dianhydride were used to study and compare the effects of rigid planar phenyl, flexible phenoxy, and nonplanar flexible hexafluoroisopropyidene and carbonyl groups in the main polymer backbone on the optoelectronic properties and processability of materials. The structures of the synthesized diamine and its PIs were evaluated by spectral and CHNS elemental analysis. The optoelectronic and thermal properties of PIs revealed intense blue-light emission (428-477 nm), a low oxidation potential (0.3-1.3 V), and a lower highest occupied molecular orbital-lowest unoccupied molecular orbital gap (2.92-3.21 eV). The observed behavior and properties of our synthesized PIs suggest their potential as future hole-transport materials in optoelectronic applications. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44526.

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A series of poly(azomethine)s (PAMs) were synthesized from N-(4-aminophenyl)-N-(4-phenoxyphenyl)benzene-1,4-diamine (DA) and various dialdehydes to investigate the influence of structure of polymer chain and triphenylamine-based phenoxy pendant group on the optoelectronic properties. The structural characterization of the resulting poly(azomethine)s was carried out by solubility test, gel permeation chromatography, viscosity measurement, fourier transform infrared (FTIR) spectral and CHN elemental analysis. The photophysical and electrochemical properties of the materials were scrutinized by UV-vis, photoluminescence, time correlation photon counting spectral analysis (TCSP) and cyclic voltammetry. The thermal stability of the poly(azomethine)s was assessed by differential scanning calorimetry and thermogravimetric analysis found to be stable upto 300 °C. These polymers exhibit moderate inherent viscosity range from 0.99 to 1.15 g dL and appreciable organosolubility. The presence of triphenylamine and azomethine (CH = N) linkage in our synthesized materials rendered them fluorescent, emitting green light upon excitation at 375 nm with quantum efficiencies of 3.9-8.5%. The pendant phenoxy group at para-position in new poly(azomethine)s has also lowered the onset oxidation potentials and elevated the HOMO levels. Additionally, the presence of conjugation increases the fluorescence time of the excited state in conjugated polymers which was found in the range 9.22-11.17 ns, sufficient to be use in future optoelectronic applications.

A series of fluorescent donor- acceptor (D-A) alternating copolyimides (P1, P2, P3 and P4) with 4-quinolin-8-yloxy linked triphenylamine main polymer chain have been synthesized by conventional polycondensation. All the synthesized co-polyimides were characterized by elemental, gel permeation chromatography and FTIR spectral analysis. These newly prepared PIs possess HOMO energy levels in range of - 4.74 to - 4.78 eV and have medium optical band gaps. The photoluminescence spectral analysis revealed blue to violet emission with appreciable efficiency with lower onset oxidation potentials suitable for the facile hole injection materials. All the photophysical and electrochemical properties were also explored in context of effect of the pendant 4- quinolin-8-yloxy, indicating suitable combination of donor (TPA) on one hand and imide and pendant as acceptor on both ends.Graphical Abstract.

A trifunctional, triamine 4-(4-aminophenoxy)-4 0 ,4 00-diamino triphenylamine (A) was successfully synthesized by N-arylation in the presence of cesium fluoride, followed by catalytic reduction. A series of aromatic tree-shaped hyperbranched copolyimides (HBPIs, 1-4) was fruitfully synthesized by onepot polycondensation of a newly synthesized triamine monomer (A), difunctional monomer 4,4 0-dianiline, 4,4 0-oxydianiline (ODA) and a series of aromatic dianhydride monomers. The appropriate molar ratio of triamine, ODA to the dianhydride monomer B is 1:1:2.5 for HBPIs synthesis using the A 2 A 3 B 5 type copolymerization approach. The synthesized HBPIs exhibited a moderate number-average molecular weight (25,700-28,400 g/mol) and polydispersity in the range 2.6-3.0 as revealed by gel permeation chromatography measurement. The oxidative thermal degradation analyses of the HBPIs showed that the synthesized materials are thermally stable up to 500 C and glass transition temperature in the range 290-302 C. The elongation at break was found in the range 4.8%-8.1% as revealed by tensile measurement. Besides, good thermal stability the HBPIs exhibited excellent flow, appreciable organosolubility, easy processability, and noticeable mechanical stability, thus suggesting their use as thermally resistant, protective coatings for various devices and outdoor environment in the future.