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A new diamine containing pyridine and carbazole groups was synthesized via a Chichibabin reaction and subsequent reduction; this compound was then used in the preparation of organo-soluble aramides (PA-a–i). The resultant polymers had high glass transition temperatures, which fell within the ranges of 271–287 °C, and Td10 at 510–535 °C in a nitrogen atmosphere. The pristine PA-a exhibited the maximum value in the UV–vis absorption spectrum at 307 nm, and this value shifted to 394 nm after protonation by HCl. When the emission of the polymer in THF solution was observed, the intensity of the emission peak at 420 nm decreased and the intensity of a new emission peak at 552 nm increased as the acid concentration increased. Additionally, the color of the polymer solution changed from blue to yellow after protonation. The intensity of the emission at 552 nm based on excimers increased as MeOH content increased. The color of polymer films also changed irreversibly from yellow, which was indicative of the neutra...

Novel electrochromic polynorbornenes poly(NBPYTPAM) and poly(HNBPYTPAM), containing electroactive chromophores, were prepared via ring-opening metathesis polymerization (ROMP) from a new norbornene derivative (NBPYTPAM) using Grubbs’ catalyst and followed by hydrogen reduction. The glass transition temperatures (Tg) of poly(NBPYTPAM) and hydrogenated poly(HNBPYTPAM) were 190 and 175 °C, respectively. The cyclic voltammogram of the poly(HNBPYTPAM) film cast onto flexible graphene-coated polyethylene terephthalene (PET) substrates exhibited two reversible oxidation redox couples at 1.0 and 1.9 V. Flexible electrochromic devices were fabricated from the electroactive polymers and graphene-coated PET substrates. The electrochromic characteristics of poly(HNBPYTPAM) showed excellent stability and reversibility, with multistaged color changes from its yellow neutral form to green and then to dark-blue.

This work reports the synthesis and characterization of a series of functional aromatic polyimides (OXTA-PI)s containing triphenylamine and 1,3,4-oxadiazole moieties. All the polyimides exhibit high glass transition temperatures of 309−319 °C. A resistive switching device with the sandwich structure of indium−tin oxide/polymer/Al was fabricated using the soluble polyimide from 4,4′-hexafluoroisopropylidenediphthalic anhydride (OXTA-PIa). The device exhibits two conductivity states and can be switched from the initial low-conductivity (OFF) state to the high-conductivity (ON) state at the threshold voltages of 1.8 V under both positive and negative electrical sweeps, with an ON/OFF state current ratio in the order of 105. The ON state of the device is nonvolatile and can withstand a constant voltage stress of −1 V for 6 h and 108 pulse read cycles at −1 V under ambient conditions. Upon reversing the bias, the ON state cannot be reset to the initial OFF states. The nonvolatile and inerasable nature of the O...

A novel N,N,N′,N′-tetraphenyl-1,4-phenylenediamine (TPPA)-containing aromatic dibromide (3), N,N-bis(4-bromophenyl)-N′,N′-bis(4-(2,4,4-trimethylpentan-2-yl)phenyl)-1,4-phenylenediamine, was successfully synthesized. The novel conjugated polymer (4) having number-average molecular weight of 2.05 × 104 was prepared via Suzuki coupling from the dibromide (3) with 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester. The conjugated polymer (4) exhibited excellent solubility in common organic solvents such as N-methyl-2-pyrrolidinone (NMP), tetrahydrofuran, chloroform, and toluene at room temperature. The conjugated polymer (4) had useful levels of thermal stability associated with their relatively high glass transition temperature (Tg = 144 °C), 10% weight-loss temperatures (Td10) in nitrogen (Td10 = 445 °C), and char yields at 800 °C in nitrogen (59.0%). The hole-transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. Cyclic voltammograms o...

A new diamine containing a pyridine heterocyclic group and a pyrene substituent, 4-(1-pyrene)-2,6-bis(4-aminophenyl)pyridine (PBAPP), was synthesized and used in a preparation of poly(pyridine−imide) by direct polycondensation with 4,4‘-hexafluoroisopropylidenediphathalic anhydride (6FDA) in N-methyl-2-pyrrolidinone (NMP). The poly(pyridine−imide) derived from diamine (PBAPP) was highly soluble in several solvents such as THF, NMP, DMAc, DMF, pyridine, DMSO, and cyclohexanone at room temperature or upon heating at 70 °C and exhibited good thermal stability both in nitrogen and air (Td10>520 °C) and a high dielectric constant of 4.32 at 1 kHz. The poly(pyridine−imide) could be cast into a flexible and tough film from DMAc solution. The poly(pyridine−imide) film had a tensile strength of 118 MPa and a tensile modulus of 2.2 GPa. The optical properties exhibited the UV−vis absorption bands at the region of 200−400 nm and possessed strong orange fluorescent (560 nm) after protonated with protic acid.