Effects of polybutadiene-g-SAN impact modifiers on the morphology and mechanical behaviors of ABS blends

A series of PB-g-SAN impact modifiers with different ratio of PB to SAN ranging from 20.6/79.4 to 91.9/8.1 were synthesized by seeded emulsion polymerization. ABS blends were prepared by blending these PB-g-SAN impact modifiers and SAN resin. The rubber concentration of these ABS blends was kept at a constant value of 15 wt%. The influences of different impact modifier on the mechanical behavior and morphology of ABS blends have been investigated. The dynamic mechanical analysis on ABS blends shows that T_g of the rubbery phase shifts to a lower temperature, (tan δ)_max of the rubbery phase increases and then decreases with the increase of PB concentration in PB-g-SAN impact modifier. A uniform dispersion of rubber particles in the matrix can be observed when PB/SAN ratio in PB-g-SAN impact modifier is in the range from 20.6/79.4 to 71.7/28.3. When it exceeds 71.7/28.3, an agglomeration of rubber particles occurs. The mechanical tests indicate that the ABS blend, in which PB/SAN ratio in the impact modifier is 71.7/28.3, has the maximum impact strength and yield strength.     

Highly efficient non-doped blue fluorescent OLEDs with low efficiency roll-off based on hybridized local and charge transfer excited state emitters

Designing a donor–acceptor (D–A) molecule with a hybridized local and charge transfer (HLCT) excited state is a very effective strategy for producing an organic light-emitting diode (OLED) with a high exciton utilization efficiency and external quantum efficiency. Herein, a novel twisting D–π–A fluorescent molecule (triphenylamine–anthracene–phenanthroimidazole; TPAAnPI) is designed and synthesized. The excited state properties of the TPAAnPI investigated through photophysical experiments and density functional theory (DFT) analysis reveal that its fluorescence is due to the HLCT excited state. The optimized non-doped blue OLED using TPAAnPI as a light-emitting layer exhibits a novel blue emission with an electroluminescence (EL) peak at 470 nm, corresponding to the Commission International de L''Eclairage (CIE) coordinates of (0.15, 0.22). A fabricated device termed Device II exhibits a maximum current efficiency of 18.09 cd A⁻¹, power efficiency of 12.35 lm W⁻¹, luminescence of ≈29 900 cd cm⁻², and external quantum efficiency (EQE) of 11.47%, corresponding to a high exciton utilization efficiency of 91%. Its EQE remains as high as 9.70% at a luminescence of 1000 cd m⁻² with a low efficiency roll-off of 15%. These results are among the best for HLCT blue-emitting materials involved in non-doped blue fluorescent OLEDs. The performance of Device II highlights a great industrial application potential for the TPAAnPI molecule.

A new pure fluorescent blue HLCT-emitter was designed and synthesized. Highly efficient non-doped blue OLEDs with low efficiency roll-off were achieved.     

含一价铜配合物的新型双金属钼氧簇合物[5-(4-Br-Ph)-2,4'-Hbpy]2·[CuⅠ(5-(4-Br-Ph)-2,4'-bpy)2]2[Mo8O26]的水热合成及晶体结构

采用水热法合成出一种含一价铜配合物的新型双金属钼氧簇合物[5-(4-Br-Ph)-2,4'-Hbpy]2[Cu(5-(4-Br-Ph)-2,4'-bpy)2]2[Mo8O26],并通过X射线单晶结构分析、红外光谱分析、元素分析以及X射线粉末衍射分析对该化合物的结构进行了表征.结果表明,该化合物属单斜晶系,P21/c空间群,晶胞参数a=1.4411(3)nm,b=1.3924(3)nm,c=2.5183(5)nm,β=99.06(3)°,V=4.990(17)nm3,Z=2;该化合物是由一价铜配合物{Cu(5-(4-Br-Ph)-2,4'-bpy)2}+与{β-Mo8O26}4-簇通过共价配位键连接形成的新型多金属钼酸盐,其中游离的质子化配体作为抗衡阳离子.     

酶促开环聚合与自缩合乙烯基共聚合相结合制取超支化聚合物

在Novozyme 435脂肪酶催化下, 甲基丙烯酸羟乙酯(HEMA)引发己内酯(ε-CL)开环聚合反应, 得到一端为双键, 另一端为羟基的直链聚己内酯(PCL)产物; 将其端羟基官能化得到大分子AB*型单体, 与苯乙烯以原子转移自由基聚合(ATRP)反应形式进行自缩合乙烯基共聚合, 得到超支化结构聚苯乙烯-b-聚己内酯产物.     

The effect of methyl group on the mechanical properties of hydrophobic association hydrogel

Hydrophobic association hydrogels were fabricated via micellar copolymerization of acrylamide and hydrophobic monomers lauryl (meth)acrylate (LA or LMA) in an aqueous solution of sodium dodecyl sulfate. The effect of methyl groups of hydrophobic monomers on the crosslinking network structure and mechanical behavior of the gels was investigated on the basis of rubber elastic theory. It was found that the LMA-gel exhibited higher effective crosslink density and elastic modulus. The methyl groups of hydrophobic monomers limited the flexibility of the methacrylate backbone in the association domain, which resulted in the increment of chains constraints. With the increase of stretch rate, the dissipated energy of LMA-gel increased more highly than that of LA-gel. In addition, the methyl group hindered the movement of polymer chains, leading to the lower recovery efficiency of dissipated energy for LMA-gel. In contract, the LA-gel exhibited a rapid response to external force, and possessed better elasticity and self-recovery property. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1505–1512     

Evaluation of calcipotriol transdermal permeation through pig,rat and mouse skin using liquid chromatography–tandem mass spectrometry

A rapid and sensitive liquid chromatography–tandem mass spectrometric method to evaluate the permeation and retention of calcipotriol in excised samples of pig, rat and mouse skin after application of a calcipotriol ointment has been developed and validated. After sample preparation of ointment, skin homogenate and receptor medium by liquid–liquid extraction, chromatography was performed on an Extend‐C₁₈ column using isocratic elution. Detection was by electrospray ionization in the negative ion mode using multiple‐reaction monitoring of the precursor to product ion transitions of calcipotriol at m/z 411.1 → 393.5, and of lovastatin (internal standard) at m/z 403.2 → 101.2. The assay was linear in all matrices with LLOQs of 1, 0.5 and 40 ng/mL for skin homogenate, receptor medium and ointment samples respectively. In terms of the permeation profiles, it was found that calcipotriol permeated through all skins to only a limited extent over 20 h after application but was efficiently retained in all skins at a level at 20 h of between 40% (pig) and 60% (rat and mouse) of the applied dose. This indicates that calcipotriol ointment has the potential to provide sustained therapeutic benefit in the treatment of psoriasis with minimal systemic side effects. Copyright © 2013 John Wiley & Sons, Ltd.     

Photoluminescent chiral carbon dots derived from glutamine

The integration of luminescence and chirality in carbon dots (CDs) encourages candidates to explore novel functions and applications of CDs, however, the preparation of chiral CDs is very limited. Herein, we report a hydrothermal method to fabricate chiral CDs by utilizing amino acid enantiomers as the precursors. LGln-CDs or DGln-CDs with uniform size of 3–4 nm show excitation-dependent blue fluorescence in solutions. Circular dichroism measurement confirms the opposite optical rotation of chiral CDs in the region from 200 nm to 300 nm, and the signals can be regulated by concentrations of CDs solution. Time-dependent density functional calculation reveals that polypeptides may exist on the surface of CDs due to the polycondensation of L/DGln at high temperature, and the optical activity of CDs originates from the stacking of neighboring carbonyl groups. The facile synthetic methodology proposed will provide potential opportunities for the preparation and application of chiral and chiroptical CDs-based materials.