Although persistent room-temperature phosphorescence (RTP) emission has been observed for a few pure crystalline organic molecules, there is no consistent mechanism and no universal design strategy for organic persistent RTP (pRTP) materials. A new mechanism for pRTP is presented, based on combining the advantages of different excited-state configurations in coupled intermolecular units, which may be applicable to a wide range of organic molecules. By following this mechanism, we have developed a successful design strategy to obtain bright pRTP by utilizing a heavy halogen atom to further increase the intersystem crossing rate of the coupled units. RTP with a remarkably long lifetime of 0.28 s and a very high quantum efficiency of 5 % was thus obtained under ambient conditions. This strategy represents an important step in the understanding of organic pRTP emission.

Although persistent room-temperature phosphorescence (RTP) emission has been observed for a few pure crystalline organic molecules, there is no consistent mechanism and no universal design strategy for organic persistent RTP (pRTP) materials. A new mechanism for pRTP is presented, based on combining the advantages of different excited-state configurations in coupled intermolecular units, which may be applicable to a wide range of organic molecules. By following this mechanism, we have developed a successful design strategy to obtain bright pRTP by utilizing a heavy halogen atom to further increase the intersystem crossing rate of the coupled units. RTP with a remarkably long lifetime of 0.28 s and a very high quantum efficiency of 5 % was thus obtained under ambient conditions. This strategy represents an important step in the understanding of organic pRTP emission.

Organic mechanoluminochromic materials are mechano/piezo-responsive and promising for applications in sensors, displays, and data storage devices. However, their switching range of emission is seriously impeded by only one kind of emission (either a fluorescent or phosphorescent peak) in the spectrum of single organic compounds. This study presents a design strategy for pure organic compounds with excellent room-temperature fluorescent–phosphorescent dual-emission (rFPDE) properties, which combines the effective factors of dipenylsulfone group, crystalline state, and heavy atom effect. Following the principle of color mixing, myriad emission colors with a wide range from orange to purple and across white zone in a straight line in the chromaticity diagram of the Commission Internationale de l’Eclairage (CIE) can be obtained by simply mechanical grinding the compound. The unique properties could be concentrated on a pure organic compound through this design strategy, which provides a new efficient channel for the discovery of efficient mechano-responsive organic materials.

A novel white-light-emitting organic molecule, which consists of carbazolyl- and phenothiazinyl-substituted benzophenone (OPC) and exhibits aggregation-induced emission-delayed fluorescence (AIE-DF) and mechanofluorochromic properties was synthesized. The CIE color coordinates of OPC were directly measured with a non-doped powder, which presented white-emission coordinates (0.33, 0.33) at 244 K to 252 K and (0.35, 0.35) at 298 K. The asymmetric donor–acceptor–donor′ (D-A-D′) type of OPC exhibits an accurate inherited relationship from dicarbazolyl-substituted benzophenone (O2C, D-A-D) and diphenothiazinyl-substituted benzophenone (O2P, D′-A-D′). By purposefully selecting the two parent molecules, that is, O2C (blue) and O2P (yellow), the white-light emission of OPC can be achieved in a single molecule. This finding provides a feasible molecular strategy to design new AIE-DF white-light-emitting organic molecules.

A novel white-light-emitting organic molecule, which consists of carbazolyl- and phenothiazinyl-substituted benzophenone (OPC) and exhibits aggregation-induced emission-delayed fluorescence (AIE-DF) and mechanofluorochromic properties was synthesized. The CIE color coordinates of OPC were directly measured with a non-doped powder, which presented white-emission coordinates (0.33, 0.33) at 244 K to 252 K and (0.35, 0.35) at 298 K. The asymmetric donor–acceptor–donor′ (D-A-D′) type of OPC exhibits an accurate inherited relationship from dicarbazolyl-substituted benzophenone (O2C, D-A-D) and diphenothiazinyl-substituted benzophenone (O2P, D′-A-D′). By purposefully selecting the two parent molecules, that is, O2C (blue) and O2P (yellow), the white-light emission of OPC can be achieved in a single molecule. This finding provides a feasible molecular strategy to design new AIE-DF white-light-emitting organic molecules.

Organic mechanoluminochromic materials are mechano/piezo-responsive and promising for applications in sensors, displays, and data storage devices. However, their switching range of emission is seriously impeded by only one kind of emission (either a fluorescent or phosphorescent peak) in the spectrum of single organic compounds. This study presents a design strategy for pure organic compounds with excellent room-temperature fluorescent–phosphorescent dual-emission (rFPDE) properties, which combines the effective factors of dipenylsulfone group, crystalline state, and heavy atom effect. Following the principle of color mixing, myriad emission colors with a wide range from orange to purple and across white zone in a straight line in the chromaticity diagram of the Commission Internationale de l’Eclairage (CIE) can be obtained by simply mechanical grinding the compound. The unique properties could be concentrated on a pure organic compound through this design strategy, which provides a new efficient channel for the discovery of efficient mechano-responsive organic materials.

Compounds displaying delayed fluorescence (DF), from severe concentration quenching, have limited applications as nondoped organic light-emitting diodes and material sciences. As a nondoped fluorescent emitter, aggregation-induced emission (AIE) materials show high emission efficiency in their aggregated states. Reported herein is an AIE-active, DF compound in which the molecular interaction is modulated, thereby promoting triplet harvesting in the solid state with a high photoluminescence quantum yield of 93.3 %, which is the highest quantum yield, to the best of our knowledge, for long-lifetime emitters. Simultaneously, the compound with asymmetric molecular structure exhibited strong mechanoluminescence (ML) without pretreatment in the solid state, thus exploiting a design and synthetic strategy to integrate the features of DF, AIE, and ML into one compound.

A series of novel optically active poly(ester-imide)s (ter-PEIs) with high glass transition temperature (T_g), good thermal stability, and solubility were successfully designed and synthesized by direct polycondensation reactions, using p-hydroxybenzoic acid (PHB), 4,4’-dihydroxybenzophenone, and a chiral diacid, N,N'-(pyromellitoyl)-bis-L-phenylalanine diacid as monomers. The resulting terpolymers were characterized by¹H-NMR, FTIR, element analysis, thermogravimetric analysis, different scanning calorimeter and wide-angle x-ray diffraction, etc. The ter-PEIs are amorphous polymers with good heat resistance and high T_gs. They are soluble in many common polar organic solvents and show optically rotation property. The specific rotation values of the ter-PEIs increase with the molar ratio of the chiral diacid, and the rigid PHB monomer is beneficial to increase the T_gs of the polymers. Copyright © 2013 John Wiley & Sons, Ltd.

The synergistic effects of 4A zeolite (4A) on the thermal degradation, flame retardancy and char formation of a novel halogen-free intumescent flame retardant polypropylene composites (PP/IFR) were investigated by the means of limiting oxygen index (LOI), vertical burning test (UL-94), digital photos, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), cone calorimeter test (CCT), laser Raman spectroscopy (LRS) and X-ray photoelectron spectroscopy (XPS). It was found that a small amount of 4A could dramatically enhance the LOI value of the PP/IFR systems and the materials could pass the UL-94 V-0 rating test. Also, it could enhance the fire retardant performance with a great reduction in combustion parameters of PP/IFR system from CCT test. The morphological structures observed by digital and SEM photos revealed that 4A could promote PP/IFR to form more continuous and compact intumescent char layer. The LRS measurement, XPS and TGA analysis demonstrated that the compactness and strength of the outer char surface of the PP/IFR/4A system was enhanced, and more graphite structure was formed to remain more char residue and increase the crosslinking degree. Copyright © 2013 John Wiley & Sons, Ltd.

A simple diamine (TetraPEDA) containing rigid nonplanar conjugated tetraphenylethylene (TetraPE) moieties was designed and synthesized through Wittig–Horner and Suzuki coupling reactions. Four kinds of high-performance functional polyimides (PI) were thus prepared by the polymerization of TetraPEDA and four dianhydrides, respectively. Because of the introduction of the aromatic rigid nonplanar TetraPE structure, the PI exhibited special fluorescent characteristics, as the maximum fluorescence emission of the four PI was observed at 425–505 nm in NMP solution and at 470–491 nm in film state. Also these organo-soluble PI showed outstanding properties, such as low dielectric constant (even without fluorinated substituent), light color, high glass transition temperatures (382–443 °C) and thermal stability in air (T_d5% up to 565 °C), and excellent mechanical properties. The polymer memory devices with the configuration of indium tin oxide/PI/aluminum (ITO/PI/Al) exhibited distinct volatile memory characteristics of static random access memory, with an ON/OFF current ratio of 1 × 10⁴ to 1 × 10⁵. These functional PI showed attractive potential applications in the field of high performance flexible polymer photoconducting devices or fluorescent polymer memory devices. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

A novel charring agent (CNCA-DA) containing triazine and benzene ring, using cyanuric chloride, aniline, and ethylenediamine as raw materials, was synthesized and characterized. The effects of CNCA-DA on flame retardancy, thermal degradation, and flammability properties of polypropylene (PP) were investigated by limited oxygen index (LOI), vertical burning test (UL-94), thermogravimetric analysis (TGA), and cone calorimeter test (CCT). The TGA results showed that CNCA-DA had a good char forming ability, and a high initial temperature of thermal degradation; the char residue of CNCA-DA reached 18.5% at 800°C; Ammonium polyphosphate (APP) could improve the char residue of APP/CNCA-DA system, the char residue reached 31.6% at 800°C. The results from LOI and UL-94 showed that the intumescent flame retardant (IFR) containing CNCA-DA and APP was very effective in flame retardancy of PP. When the mass ratio of APP and CNCA-DA was 2 : 1, and the IFR loading was 30%, the IFR showed the best effect; the LOI value reached 35.6%. It was also found that when the IFR loading was only 20%, the flame retardancy of PP/IFR can still pass V-0 rating in UL-94 tests, and its LOI value reached 27.1%. The CCT results demonstrated that IFR could clearly change the decomposition behavior of PP and form a char layer on the surface of the composites, consequently resulting in efficient reduction of the flammability parameters, such as heat release rate (HRR), total heat release (THR), smoke production rate (SPR), total smoke production (TSP), and mass loss (ML). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

A series of polyureas were synthesized through the reaction of aniline trimer with toluene-diisocyanate, diphenylmethane-4,4′-diisocyanate, and hexamethylene-1,6-diisocyanate, respectively. The chemical structure of these polyureas was characterized and verified by FT-IR, ¹H NMR, elemental analysis, UV, XRD and CV. The conductivity of these polyureas ranged from 10⁻⁷ to 10⁻⁶ S/cm measured by four-point-probe instrument. Compared to the standalone aniline trimer, the stability (thermal stability and electrochemical stability), response range and sensitivity of these polyureas are enhanced. The sensitivity of these polyureas DMF solution to pH value is superior to that of the standalone aniline trimer. The color of the polyureas DMF solution is greatly depended on pH value and the color change process is reversible, whenever from base to acid or from acid to base. These enhancements may give these polyureas more opportunities in order to be used as sensor materials.

The phase stability and melting behavior of nylon 6 were studied by high-temperature wide-angle X-ray diffraction and differential scanning calorimetry (DSC). The results show that most of the α phase obtained by a solution-precipitation process [nylon 6 powder (Sol-Ny6)] was thermodynamically stable and mainly melted at 221°C; the double melting peaks were related to the melt of α crystals with different degrees of perfection. The γ phase formed by liquid nitrogen quenching (sample LN-Ny6) melted within the range 193–225°C. The amorphous phase converted into the γ phase below 180°C but into the high-temperature α phase at 180–200°C. Both were stable over 220°C. α- and γ*-crystalline structures were formed by annealing but were not so stable upon heating. Typical double melting peaks were shown on the DSC curve; melt recrystallization happened within the range 100–200°C. The peak at 210°C was mainly due to the melting of the less perfect crystalline structure of the γ phase and a fraction of the α phase; the one at 219°C was due to the high-temperature α- and γ-phase crystals. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

On the basis of the self-catalytic characteristic of α-aminomethyl triethoxysilanes, (diethyl) aminomethyl triethoxysilane, cyclohexylaminomethyl triethoxysilane, and anilinomethyl triethoxysilane were used as self-catalytic cross-linkers to prepare a series of environmental friendly, nano-CaCO₃ reinforced silicone sealants based on poly(dimethylsiloxane) (PDMS). The tensile properties, hardness, adhesive properties, hot-air aging resistance, and oil-resistance properties of these materials were studied by universal electronic tensile machine, scanning electron microscope, and atomic force microscopy, etc. Results show that the comprehensive properties of the self-catalytic cross-linking PDMS sealants are much better than that of the traditional ones. The chemical structure and reactivity of the α-aminomethyl triethoxysilanes have a great effect on the properties of PDMS sealants. The tensile strength of the reinforced sealants with 100 phr (100 parts per hundreds of PDMS) nano-CaCO₃ is about 4.4 times than that of the unreinforced ones, and the elongation at break is about three times. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Reinforcing and toughening effects on the thermoplastic poly(ether imide) (PEI) by a novel thermo tropic liquid crystalline poly(ester-imide-ketone) (TLCPEIK) with low content were studied in this work. The novel TLCPEIK with kink naphthalene structure in the backbone was synthesized in our laboratory. A series of in-situ composites (TLCPEIK/PEI) with a low concentration of TLCPEIK(≤5 wt%) were prepared by direct extrusion. Tensile strength, flexural strength, and flexural modulus of the composites increased with increasing TLCPEIK content. Impact strength and elongation at break of the composites were enhanced greatly when compared with that of pure PEI. To explain the simultaneously reinforcing and toughening effects on PEI by TLCPEIK, miscibility and morphology of the composites were studied by differential scanning calorimetry (DSC) and scanning electron microscopy. The experimental results suggest that good compatibility of the components is beneficial to improve the ultimate properties of TLCPEIK/PEI in-situ composites. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers.