Functionalized graphene oxide nanosheets with unique three-inone properties for efficient and tunable antibacterial applications

Developing antibiotics-independent antibacterial agents is of great importance since antibiotic therapy faces great challenges from drug resistance.Graphene oxide(GO)is a promising agent due to its natural antibacterial mechanisms,such as sharp edgemediated cutting effect.However,the antibacterial activity of GO is limited by its negative charge and low photothermal effect.Herein,the amino-functionalized GO nanosheets(AGO)with unique three-in-one properties were synthesized.Three essential properties(positive charge,strong photothermal effect,and natural cutting effect)were integrated into AGO.The positive charge(30 mV)rendered AGO a strong interaction force with model pathogen Streptococcus mutans(330 nN).The natural cutting effect of 100 ng·mL^(-1)AGO caused 27%loss of bacterial viability after incubation for 30 min.Most importantly,upon the near-infrared irradiation for just 5 min,the three-in-one properties of AGO caused 98%viability loss.In conclusion,the short irradiation period and the tunable antibacterial activity confer the three-in-one AGO a great potential for clinical use.

Annealing Induced Microstructure and Mechanical Property Changes of Impact Resistant Polypropylene Copolymer

The effects of annealing on microstructure and mechanical properties of an impact resistant polypropylene copolymer （IPC） were investigated. Different annealing temperatures ranging from 80 ℃ to 160 ℃ were selected. The phase reorganization of IPC during annealing process was studied through morphological characterization technologies, including scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The crystalline structure changes in the IPC sample, including the iPP matrix and PE component, were investigated using wide angle X-ray diffraction （WAXD） and differential scanning calorimetry （DSC）. Dynamic mechanical analysis （DMA） was used to analyze the relaxation extent of 1PC before and after annealing. The results showed that annealing induced phase reorganization in IPC and the degree of phase reorganization depended on annealing temperature. The annealed IPC samples exhibited largely increased crystallinity compared with the unannealed one. Intensified damping peak with increased molecular chain mobility was achieved for the annealed IPC samples. At an appropriate annealing tem. perature （140 ℃）, largely enhanced impact strength was achieved for the annealed IPC sample. The toughening mechanisms were analyzed based on the phase reorganization and relaxation behavior.

Size Distribution and Anisotropy of the Minor Phase Droplets in Polypropylene/Ethylene-Octene Copolymer Blends: Effects of Shear and Component Miscibility

In this work, polypropylene （PP）/octene-ethylene copolymer （POE） blends were injection-molded using the so- called dynamic packing injection technique, which imposed oscillatory shear on the gradually cooling melt during the packing solidification stage. In this way, the effect of shear on the size distribution and anisotropy of the minor phase droplets could be investigated. Besides, by using two kinds of POE with different octene contents, the effect of component miscibility was also studied. The results show that the droplet size is mainly determined by composition and miscibility, and droplet anisotropy is mainly determined by droplet size and shear. Most importantly, under the same processing condition, droplet anisotropy increases with droplet size, and there seems a linear fit between them, disregarding the miscibility factor. These results may provide guidance for preparing polymer blends with desired properties by tailoring their phase morphologies.

Reversely Swellable Porphyrin-linked Microporous Polyimide Networks with Super-adsorption for Volatile Organic Compounds

A series of microporous polyimide networks with porphyrin units （Pr-MPIs） were facilely synthesized through a one-step solution polymerization process. Of particular interest is that Pr-MPI-1 containing distorted spirobisindane unit revealed the highest BET surface area （953 m^2/g）, total pore volume （0.75 cma/g）, and extreme hysteresis between the N2 adsorption and desorption isotherm. Further study revealed the prepared Pr-MPI-1 exhibited a synergistic structural effect on exceptional uptake of volatile organic compounds （VOCs） due to the high porosity and highly distorted spirobisindane structure enabled large interface and the swellability. This new approach would open up a facile approach toward the preparation of highly swellable high performance polymeric microporous materials, which are deeply wanted for environment-related applications such as VOCs adsorption and oil/water separation.

Green Synthesis of Polyimides and Their CNT Based Nanohybrid ShishKebabs through Reaction-induced Crystallization of Nylon-salt-type Monomers in Glycerol

A green approach to the synthesis and morphological control of high performance polyimides and their nanohybrid shish-kebabs in glycerol through reaction-induced crystallization of nylon-salt-type monomers was reported. Crystalline polyimide nanoplates can be observed by direct polycondensation of pyromellitic acid with various kinds of aliphatic or aromatic diamines. With the existence of carbon nanotuhes, the polyimides can be successfully decorated on the surface of CNTs through a reaction-induced hetero-epitaxial crystallization process, and resulted in novel polyimide/CNT nanohybrid shish-kebabs （NHSKs） structures. The morphologies of the NHSKs can be fine-tuned through changing the concentration of monomers or the reaction temperature, especially through the introduction of dynamic imine chemistry, the formation process of NHSKs can be attributed to a soft epitaxy mechanism. Thus a green approach for the synthesis of high performance polyimides and their CNT based nanohybrid structures was explored, which should be of great value for their applications in high performance reinforced nanocomposites.