An amino-terminated poly(propylene glycol)-modified tetraaryl-buta-1,3-diene derivative (TABDAA) was introduced to synthesize polyurethanes with different ratios of soft/hard segments. A mixture of TABDAA and poly(tetrahydrofuran) 1000 as the soft segments was reacted with 4,4-diphenylmethane diisocyanate and 1,4-butanediol as the hard segments in molar ratios of 1 : 2 : 1, 2 : 3 : 1, and 3 : 4 : 1 to give the desired polyurethanes named TMPU-211, TMPU-321 and TMPU-431, respectively. The three polyurethanes exhibited different aggregation-enhanced emission (AEE) behaviors because of their different soft/hard segment ratios. The polyurethanes with a higher soft segment content tended to form bigger particles in a DMF/water mixture solution, thus causing a sharper increase in their fluorescence intensity. In addition, the polyurethane films exhibited different fluorescence intensities after different heat treatments. After a quenching treatment of the soft segments in the polyurethane films, the fluorescence intensity dropped greatly. When these quenched polyurethane films were thermally annealed at 60 °C for 24 hours, their fluorescence intensity exceeded the initial intensity of the as-prepared films. Differential scanning calorimetry results showed that the polyurethane films in the quenched condition did not present the endothermal melting peak of the soft segments, and the melting peaks appeared again after thermal annealing. AFM experiments showed that an ordered arrangement was achieved after the heat treatment of these AEE polyurethane films. These results demonstrated that the polymer structure had a significant effect on the AEE properties of the polyurethane films, and more importantly, it is of great significance in improving the fluorescence emission of the AEE polymers and also for their potential application in fluorescent probes, stimuli-responsive materials, PLED devices and so on.

AbstractA series of self-doped oligoaniline derivatives, that is, carboxyl-capped tetraaniline (HOOC-(Ani)4-COOH), carboxyl-capped pentaaniline (HOOC-(Ani)5-COOH), carboxyl-capped hexaaniline (HOOC-(Ani)6-COOH), and carboxyl-capped star-shaped tetraaniline (Tri-(Ani)4-COOH) in leucoemeraldine base state, were synthesized and characterized. The number of the aniline units was varied and a star-shaped structure was designed to detect the influence of the molecular architecture on the electrochromic properties. The introduction of carboxylic groups into oligoaniline derivatives produced intermolecular hydrogen bonds, which contributed to their self-doping capability. As a result, these oligoaniline derivatives presented reversible electrochromic properties at pH≥7, which could not be seen in pristine oligoanilines or polyanilines. Then, these oligoaniline derivatives were fabricated into electrochromic devices without an external acid dopant in the assembling process. Comprehensive electrochemical tests were conducted to investigate their electrochromic properties. The resulting devices showed good performances in spectroscopic, electrochemical, and in situ tests. Increasing the chain length contributed to an improved optical contrast, coloration efficiency, response time, and cycling stability. Meanwhile, introducing a star-shaped structure also led to a better electrochromic performance. Moreover, electrochemical impedance spectroscopy and AFM tests were used to explore the mechanism to understand how the star-shaped molecule facilitated the redox process.

A kind of amphiphilic rod-coil diblock copolymer consisting both of tetraaniline (TAni) and polyethylene glycol (PEG) blocks, TAni-b-PEG, was synthesized. The diblock copolymer shows excellent electrochromic properties, especially, in switching time and coloration efficiency compared with tetraaniline. TAni-b-PEG is able to self-assemble into spherical structure, which is attributed to the formation of conducting channels and increase of ion-exchange capacity of TAni-b-PEG, implying that a block copolymer with electrochromic block and high ionic conductive block simultaneously possesses improving electrochromic properties.

Pristine tetraaniline and three carboxyl-substituted tetraaniline derivatives, that is, tetraaniline ((Ani)4), carboxyl-capped tetraaniline ((Ani)4-COOH), amino/carboxyl-capped tetraaniline (NH2-(Ani)4-COOH) and carboxyl-capped star-shaped tetraaniline (Tri-(Ani)4-COOH) were synthesized, and the influence of substituent and molecular architecture on their electrochromic properties was investigated. Pristine (Ani)4 shows lowest electrochromic properties while the carboxyl-capped star-shaped Tri-(Ani)4-COOH possesses the best electrochromic properties with fast bleaching and coloring times of 2.04 s and 1.90 s, respectively, promising optical contrast of 74.2%, and improved coloration efficiency of 133.31 cm2C−1 at 750 nm. This enhanced electrochromic performance can be attributed to the introduction of carboxyl substituent and star-shaped molecular architecture, which are able to improve the interchain charge movement, electron movement between films and substrate and enhanced ion diffusion resulting from loosely packed molecular structure of films, and confirmed by cyclic voltammetry and atomic force microscope results, implying the introduction of special substituent and molecular architecture is an effective strategy to improve the electrochromic properties of aniline oligomers.

Three terpyridine (TPY)/diphenylamine (DPA) derivatives, with DPA functioning as the electron donor and TPY as the electron acceptor, were designed and synthesized. By switching the position of the nitrogen atom in the substituted pyridine of TPY acceptors, we can adjust the electron-drawing strength of the TPY group, and hence, further modify the fluorescence, lowest unoccupied molecular orbital energy levels, carrier transporting properties of three compounds, but barely influence triplet energy levels. Three compounds satisfy the requirements of multifunctional blue fluorophores and are successfully used as highly efficient blue fluorescent emitters and red phosphorescent hosts in organic light-emitting devices (OLEDs). Non-doped blue fluorescent OLEDs that use TPY22DPA, TPY33DPA, and TPY44DPA as emitters exhibit maximum external quantum efficiencies (EQEs) of 4.9%, 3.8%, and 2.7%, respectively. Meanwhile, red phosphorescent OLEDs that use TPY22DPA, TPY33DPA, and TPY44DPA as host materials exhibit maximum EQEs of 19.1%, 20.9%, and 17.2%, respectively. These results are among the best reported multifunctional blue fluorophore efficiencies.

Tetra- and tri-substituted m-phenylacetylene macrocycles with diethylene glycol monoethyl ether (DEG) phenylether peripheral side chains (PAM 1 and PAM 1′) were synthesized, and both of them could self-assemble into well-defined one-dimensional (1D) structures through two kinds of fabrication processing. The recrystallization approach led to similar microbelts for PAMs 1 and 1′ with hundreds of microns in length, 2–4 μm in width, and 200–300 nm in thickness. But AFM, XRD, and spectrum characterizations indicated that the microbelts of PAM 1′ had smaller intercolumnar distances and more favorable π–π stacking. Two different nanostructures were obtained through the other processing of solvent evaporation: nanobelts for PAM 1 and twisted nanorods for PAM 1′. The different molecular arrangement and nanostructures could be ascribed to the different molecular structures, especially the different positioning of the peripheral substituents. This research provides a potential control over the morphology and the structure of the 1D assembly by adjusting the molecular structure as well as the sample processing.Graphical abstractHighlights► Tetra- and tri-substituted phenylacetylene macrocycles (PAMs) were synthesized. ► Distinct 1D nanostructures were obtained from the self-assembly of the PAMs. ► The steric hindrance of the side chains played a crucial role on morphology control. ► PAM with less side chains could form more variable nanostructures.

Unusual flower-like patterns were observed for the first time in syndiotactic polystyrene/carbon nanotube nanocomposite films, which were prepared by simple hot-pressing using polyimide films or aluminium foils as supporting substrates.

The orientation structures of both carbon nanotubes (CNTs) and polymer molecular chains in the skin–core structure of polystyrene/multiwalled carbon nanotube (PS/MWCNT) nanocomposite melt-injection-molded pellets were examined. Scanning electron microscopic (SEM) and transmission electron microscopic (TEM) images clearly show the MWCNT preferred orientation along the melt shearing direction, while polarized Raman spectroscopy results consolidate the MWCNT preferred orientation in each of the skin, medium, and core layers of the injection-molded pellets. By infrared dichroism measurements, a preferred orientation of the PS side groups (phenyl rings) perpendicular to the melt shearing direction was deduced at all depths of the present injection-molded nanocomposite pellet. Meanwhile, the MWCNTs have little effect on the random orientation of the PS main chain (−CH2– groups) with a dichroic ratio near unity.

The effect of carbon nanotubes on polymer macromolecular orientation structure during stretching of syndiotactic polystyrene/carbon nanotube nanocomposite film was quantitatively studied for the first time by an infrared dichroism technique.

The response of organic–inorganic nanocomposites under deformation is important for fundamental science and practical applications. Here the orientation evolution of syndiotactic polystyrene (sPS) molecules and carbon nanotubes (CNTs) in uniaxially drawn sPS/CNT nanocomposite films were assessed by means of polarized Raman spectroscopy and infrared dichroism. The results demonstrate the preferred parallel orientation of the CNTs is along the uniaxial stretching direction in the stretched films. In addition, the presence of the CNTs has a hindrance effect on the preferred parallel orientation for the main chain (–CH2– segments) and the side groups (benzene rings) of the sPS macromolecules. The reason was attributed to the large sPS/CNT interface areas and the strong interactions (especially the π–π interactions between the benzene rings of sPS and the π electrons of the CNT sidewalls). Moreover, with the increase in the draw ratio, the degree of the sPS preferred orientation in the sPS/CNT nanocomposite films increases more slowly than that in pure sPS films.

A novel method was used to tune the morphologies and properties of conducting polyanilines. In the first time, sulfonic acid-containing Gemini surfactant 9BA-m-9BA (that is 6,6′-(alkyl-1,m-diylbis(oxy))bis(3-nonylbenzenesulfonic acid) with different alkyl spacer length m = 2, 3, 4, 6, respectively) was used in the preparation of conducting polyanilines at 0 °C in reverse emulsion system of ethyl acetate/water with the volume ratio of 10:1. Simply increasing the spacer length of 9BA-m-9BA from m = 2 and 3 to m = 4 and 6, the morphologies of resultant polyanilines were changed obviously from granular to fiber-like forms, while the intrinsic viscosity of resultant polyanilines increased dramatically from 49.3 to 119.5 ml/g but conductivity decreased from 1.0 to 0.1 S/cm.

High-performance one-dimensional polyaniline (PANI) nanostructures, i.e. nanotubes and nanofibers were synthesized in the presence of dodecylbenzene sulfonic acid (DBSA) and hydrochloric acid (HCl) aqueous solution, with ammonium peroxydisulfate (APS) as oxidant. And the resulting PANI nanotubes possessed the diameters of 350–650 nm and length up to tens of micrometers and PANI nanofibers with diameters of 120–160 nm, respectively. Especially, the PANI nanotubes had a very uniform structure (nearly 100% in nanotubes) and the reaction yield was about 110% (compared to the quantity of aniline in the reaction). The formation mechanism of 1D PANI nanostructures was also proposed. The guide effect of the initial “soft-template” formed by aniline and DBSA was greatly controlled by its content and chemical structures.

A facile method was developed for preparing uniform silver nanoparticles with small particle sizes of less than 10 nm at high concentrations, in which aniline was used to reduce silver nitrate (AgNO3) to silver nanoparticles in the presence of dodecylbenzenesulfonic acid (DBSA) as a stabilizer. Upon the addition of excess NaOH to the DBSA−aniline−AgNO3 (DAA) system, the formation of silver nanoparticles was almost complete in just 2 min at 90 °C (in 94% yield). The average size of those resultant silver nanoparticles was 8.9 ± 1.1 nm, and the colloids were stable for more than 1 year at ambient temperature. A possible mechanism for the formation of silver nanoparticles was proposed to be related to two factors: one was the mesoscopic structures of the DAA system in which silver ions were restricted in the dispersed phases composed of DBSA and aniline; the other was Ag2O nanocrystallites generated in situ that could be readily reduced by aniline to small silver nanoparticles at high concentrations.

Novel polyacrylamide (PAM)/pristine layered double hydroxide (LDH) nanocomposites have been prepared by a facile solution dispersion procedure, and their stability and rheological properties have been studied. The pristine LDHs without any surface organo-modification (LDH_NO3), synthesized by co-precipitation procedure, are dramatically exfoliated and uniformly dispersed in formamide. Subsequently, PAM/LDH_NO3 nanocomposites are prepared by a convenient solution dispersion procedure, wherein the dispersion structure of LDH_NO3 in PAM was studied by X-ray diffraction, size distribution measurements and Tyndall effect. The nanocomposites exhibit excellent stabilities toward various environmental conditions such as heating, centrifugation and salt-tolerance. Moreover, in the whole process of drying and after the re-dissolution, the nanocomposites kept a uniform dispersion structure without any precipitation formation. Finally, the dynamic and steady rheological investigations were conducted. Nanoscale LDH_NO3 particles and layers were found to have drastic effects on the PAM solution rheological behaviour with an obvious gel-formation process at a low LDH content, and strong frequency dependence of viscosity at low frequencies.

The polyanilines were synthesized via an inverse emulsion polymerization path at 0 °C or room temperature using ammonium peroxydisulfate (APS) as oxidant and dodecylbenzene sulfonic acid (DBSA) as surfactant and dopant simultaneously for the resulting polyanilines. The influence of polymerization temperature, organic continuous phase type (xylene or hexane) and APS/aniline molar ratio on the polyaniline properties was investigated. Polyaniline–DBSA precipitates prepared at 0 °C showed high conductivity in the range of 1.0–4.0 S/cm. Polyanilines in emeraldine base form prepared at 0 °C and APS/aniline molar ratio of 0.4 had high intrinsic viscosities of 191 and 202 ml/g using xylene and hexane as the organic continuous phase of emulsion system, respectively. The polyaniline–DBSA precipitates obtained from the polymerization system using xylene as the organic continuous phase possessed nice fibrillar morphology.

A new intercalated hybrid of polyacrylamide (PAM)/layered double hydroxide (LDH) prepared via in situ intercalative polymerization procedure is reported. LDH with counterion ion of nitrate or dodecyl sulfate anion was employed for comparison. The obtained PAM/LDH hybrid was characterized by X-ray diffraction, infrared spectra, differential scanning microcalorimetry and X-ray photoelectron spectrum. The results reveal that the LDH modified with dodecyl sulfate anion can be used to obtain an intercalated hybrid, whereas PAM polymer chains can not enter the interlayer space of LDH with nitrate anion as counterion ion.

The rheological properties of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA)-doped polyaniline (PAni) using dichloroacetic acid (DCA) as solvent were systematically studied using parallel-plate rotational rheometer. The influence of PAni/AMPSA concentration, PAni molecular weight, shear rate, temperature and time on the apparent viscosity was measured and analyzed. At certain shear rate (about 0.03–1 s−1, in the second region), PAni/AMPSA solution presents typical shear-thinning behavior, and PAni/AMPSA concentration and PAni molecular weight obviously affected the rheological behaviors of PAni/AMPSA solution. By temperature sweeps, it was found that the apparent viscosity of PAni/AMPSA solution decreased with the increase of temperature, and the solution became gel after 80–90 °C. More importantly, a predominant transition temperature at about 55 °C was observed in the PAni/AMPSA solutions, suggesting a structural transition at this temperature. The results of the rheological stability of PAni/AMPSA solution at different concentration and molecular weight by monitoring the viscosity change with the time at 30 and 60 °C verified that the higher temperature might be responsible for the quick gelation of the PAni solution. In addition, the non-Newtonian exponent and the apparent viscous flow activation energies of PAni/AMPSA solution has been calculated and discussed as well.

A novel interlamellar surface modification of layered double hydroxides (LDHs) via covalent bonding by toluene-2,4-di-isocyanate (TDI) has been successfully obtained, and poly(vinyl chloride) (PVC)/TDI-modified LDH nanocomposites have been prepared via solution intercalation process. After the interlamellar modification, TDI was grafted to the surface hydroxyl groups of LDHs with nitrate, dodecyl sulfate or stearate anion as counterion anion. The structures of the TDI-modified LDHs and the nanocomposites were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, and transmission electron microscopy (TEM) techniques. The enhanced thermal stability of PVC/TDI-modified LDH nanocomposites was confirmed by means of conventional Congo Red test and dynamic thermogravimetric analysis (TGA). In addition, the thermal degradation mechanism was briefly discussed on the basis of the above experimental results.

Four sulfonic acid-containing gemini surfactants 9BA-m-9BA (m = 2, 3, 4, 6), 6,6′-(ethane-1,2-diylbis(oxy)) bis(3-nonylbenzenesulfonic acid) (9BA-2-9BA), 6,6′-(propane-1,3-diylbis(oxy)) bis(3-nonylbenzenesulfonic acid) (9BA-3-9BA), 6,6′-(butane-1,4-diylbis(oxy)) bis(3-nonylbenzenesulfonic acid) (9BA-4-9BA), and 6,6′-(hexane-1,6-diylbis(oxy)) bis(3-nonylbenzenesulfonic acid) (9BA-6-9BA), were synthesized and characterized by Fourier transform infrared (FTIR), 1H NMR, elemental analysis, and melting temperature measurements. Their ability to lower the water surface tension and hexadecane/water interfacial tension was measured and correlated with the hydrophobicity and length of their alkyl spacer chain. Their aggregates in aqueous solutions were investigated using dynamic light scattering and transmission electron microscopy. Spherical vesicles could be found in aqueous solutions of four gemini surfactants with an apparent hydrodynamic radius (Rh) of ∼100 nm. The critical micelle concentration (cmc) of four gemini surfactants evaluated by surface tension measurements was 1 order of magnitude smaller than that of conventional single-chain surfactant sodium dodecylsulfonate (SDS). And their C20, the gemini surfactant concentration required for lowering the surface tension of water by 20 mN/m, was about 2 orders of magnitude smaller than that of SDS, showing excellent efficiency at reducing the surface tension of water. In addition, the hexadecane/water interfacial tension could be less than 1.0 mN/m after using pure 9BA-m-9BA in water. Using 9BA-6-9BA the hexadecane/water interfacial tension was reduced to 0.21 mN/m.

Highly crystalline polyanilines (PAni) with uniform rice-like nanostructures, ca. 50–130 nm in diameter and 130–260 nm in length were successfully prepared in the presence of dodecylbenzene sulfonic acid (DBSA) without stirring, and characterized by SEM, FTIR, UV–vis and XRD measurements. The formation of aniline/DBSA salts insoluble in reaction system without stirring is believed to be favorable for the formation of this uniform rice-like nanostructures.

The effect of carbon nanotubes on polymer macromolecular orientation structure during stretching of syndiotactic polystyrene/carbon nanotube nanocomposite film was quantitatively studied for the first time by an infrared dichroism technique.

Novel polyacrylamide (PAM)/pristine layered double hydroxide (LDH) nanocomposites have been prepared by a facile solution dispersion procedure, and their stability and rheological properties have been studied. The pristine LDHs without any surface organo-modification (LDH_NO3), synthesized by co-precipitation procedure, are dramatically exfoliated and uniformly dispersed in formamide. Subsequently, PAM/LDH_NO3 nanocomposites are prepared by a convenient solution dispersion procedure, wherein the dispersion structure of LDH_NO3 in PAM was studied by X-ray diffraction, size distribution measurements and Tyndall effect. The nanocomposites exhibit excellent stabilities toward various environmental conditions such as heating, centrifugation and salt-tolerance. Moreover, in the whole process of drying and after the re-dissolution, the nanocomposites kept a uniform dispersion structure without any precipitation formation. Finally, the dynamic and steady rheological investigations were conducted. Nanoscale LDH_NO3 particles and layers were found to have drastic effects on the PAM solution rheological behaviour with an obvious gel-formation process at a low LDH content, and strong frequency dependence of viscosity at low frequencies.

Three terpyridine (TPY)/diphenylamine (DPA) derivatives, with DPA functioning as the electron donor and TPY as the electron acceptor, were designed and synthesized. By switching the position of the nitrogen atom in the substituted pyridine of TPY acceptors, we can adjust the electron-drawing strength of the TPY group, and hence, further modify the fluorescence, lowest unoccupied molecular orbital energy levels, carrier transporting properties of three compounds, but barely influence triplet energy levels. Three compounds satisfy the requirements of multifunctional blue fluorophores and are successfully used as highly efficient blue fluorescent emitters and red phosphorescent hosts in organic light-emitting devices (OLEDs). Non-doped blue fluorescent OLEDs that use TPY22DPA, TPY33DPA, and TPY44DPA as emitters exhibit maximum external quantum efficiencies (EQEs) of 4.9%, 3.8%, and 2.7%, respectively. Meanwhile, red phosphorescent OLEDs that use TPY22DPA, TPY33DPA, and TPY44DPA as host materials exhibit maximum EQEs of 19.1%, 20.9%, and 17.2%, respectively. These results are among the best reported multifunctional blue fluorophore efficiencies.