Jie Yin

Facile Synthesis of Soluble Graphene via a Green Reduction of Graphene Oxide in Tea Solution and Its Biocomposites

The chemical reduction of graphene oxide (GO) typically involves highly toxic reducing agents that are harmful to human health and environment, and complicated surface modification is often needed to avoid aggregation of the reduced GO during reduction process. In this paper, a green and facile strategy is reported for the fabrication of soluble reduced GO. The proposed method is based on the reduction of exfoliated GO in green tea solution by making use of the reducing capability and the aromatic rings of tea polyphenol (TP) that contained in tea solution. The measurements of the resultant graphene confirm the efficient removal of the oxygen-containing groups in GO. The strong interactions between the reduced graphene and the aromatic TPs guarantee the good dispersion of the reduced graphene in both aqueous and a variety of organic solvents. These features endow this green approach with great potential in constructing of various graphene-based materials, especially for high-performance biorelated materials as demonstrated in this study of chitosan/graphene composites.

Boron nitride nanosheets: large-scale exfoliation in methanesulfonic acid and their composites with polybenzimidazole

Boron nitride n nanosheets (BNNSs) are two dimensional crystals composed of boron and nitrogen atoms covalently bonded in a hexagonal manner with exceptional physiochemical properties. However, the researches on BNNS are rather limited due to the lack of an efficient method to prepare BNNS. In this study, we report a facile and efficient method for the fabrication of BNNS through liquid-phase exfoliation of hexagonal boron nitride particles (h-BNs) in methanesulfonic acid. The resultant BNNS can be readily disperse in a number of organic solvents, such as N-methyl-2-pyrrolidone. Transmission electron microscopy and atomic force microscopy confirms that the obtained BNNSs are mainly single or few-layered with a thickness less than 3 nm. X-Ray photoelectron and infrared spectroscopy reveal that almost no compositional change occurred in BNNS during the superacid-assistant exfoliation process. The BNNS holds great promise in a number of important applications as demonstrated in this study of poly [2,2′-(p-oxydiphenylene)-5,5′-bibenzimidazole] (OPBI)/BNNS composites. The OPBI/BNNS composites showed superior mechanical and thermal properties as compared to neat OPBI and h-BN reinforced ones.

Responsive fluorescent core-crosslinked polymer particles based on the anthracene-containing hyperbranched poly(ether amine) (hPEA–AN)

We here demonstrated a novel multistimuli responsive core-crosslinked polymer particle with fluorescence. These polymer particles with uniform size in the range of 100–300 nm were fabricated by self-assembly of the anthracene-containing amphiphilic hyperbranched poly(ether amine) (hPEA–AN) in water, followed by UV-light induced crosslinking of the core through the photodimerization of anthracene. The obtained hPEA–AN particles exhibited high fluorescence, and their size and fluorescence were responsive to external stimuli such as temperature and pH. The size, as well as the fluorescence, of the hPEA–AN particles decreased with an increase in temperature and pH. Moreover, the hPEA–AN particles can encapsulate both the hydrophobic guest molecule distytyl pyridine (DSP) and the hydrophilic guest molecule methyl orange (MO) in water, and their fluorescence can be gradually quenched after encapsulation of these guest molecules and then recovered after these guest molecules are released. Based on these characteristics of the hPEA-AN particles, we tried to develop an attractive concept in the field of drug delivery: the controlled release of guest molecules monitored by the fluorescence changes of the hPEA-AN particles.

Multi-responsive polymer nanoparticles from the amphiphilic poly(dimethylsiloxane) (PDMS)-containing poly(ether amine) (PDMS-gPEA) and its potential application for smart separation

We report here a novel amphiphilic PDMS-containing poly(ether amine) (PDMS-gPEA) synthesized through one-pot condensation polymerization of commercial di-epoxy and amine monomers. The obtained PDMS-gPEA could be dispersed directly in aqueous solution to form stable uniform-sized nanoparticles with a diameter of about 16 nm, whose aggregation is responsive to temperature, pH and ionic strength with tunable cloud point (CP). The whole process for the responsive aggregation of PDMS-gPEA nanoparticles was revealed by transmission electron microscope (TEM) and dynamic light scattering (DLS), and was intensively studied by UV-vis spectra. The responsive nanoparticles of PDMS-gPEA possessed the unique selective encapsulation of water-soluble dye, which provides potential applications in smart separations.

Stimuli-responsive microgels formed by hyperbranched poly(ether amine) decorated with platinum nanoparticles

We report novel multistimuli responsive microgels based on coumarin-containing hyperbranched poly(ether amine) (hPEA-EC). hPEA-EC could be dispersed directly in aqueous solution as polymer particles, whose cores were crosslinked through the photodimerization of coumarin moieties to form microgels with size of about 150 nm in diameter. The obtained microgels (hPEA-diEC) exhibited good stability in aqueous solution and possessed sharp response to temperature, pH and ionic strength with tunable cloud point (CP). Simultaneously, hPEA-diEC microgels decorated with platinum nanoparticles (Pt@hPEA-diEC) were investigated as microreactors for reduction of aromatic nitro compounds. Pt@hPEA-diEC exhibited interesting catalytic activities for the reduction of nitrophenol, which is obviously faster at lower temperature. Compared with the reduction of 4-nitrophenol (Nip), Pt@hPEA-diEC is more efficient in catalytic activity for reduction of the hydrophobic 4-nitro-3-(trifluoromethyl)phenol (CF3Nip), which is probably ascribed to the encapsulation of CF3Nip in hPEA-diEC microgels. These characteristics give hPEA-diEC microgels potential as intelligent materials for the controlled reduction of nitro compounds in water.

Polymeric vesicles with well-defined poly(methyl methacrylate) (PMMA) brushes via surface-initiated photopolymerization (SIPP)

We describe a novel and general approach to fabricate polymeric vesicles with well-defined PMMA brushes by using silica particles as template through surface-initiated photopolymerization (SIPP). The crosslinked PDMAEMA layer was immobilized on the surface of silica particles, and then photoinitiated polymerization of methyl methacrylate (MMA) was used to generate PMMA brushes in the presence of thioxanthone (TX). Polymeric vesicles with well-defined PMMA brush were obtained after removing silica cores. The whole process was well traced and confirmed by TEM, SEM, FT-IR and TGA. To the best of our knowledge, this is the first report the fabrication of polymer brush on the surface of polymeric vesicles through SIPP. This robust approach is expected to have potential in fabrication and modification of polymer vesicles with different sizes and functions.

Amphiphilic Zwitterionic Poly(dimethylsiloxane) (PDMS)-Contained Poly(Ether amine) (Z-SiPEA) as the Responsive Polymeric Dispersant

We demonstrated here a novel concept of the responsive dispersant based on the amphiphilic zwitterionic poly(ether amine) (Z-SiPEAs), which can control the dispersion of dyes and pigments in water. Z-SiPEAs are composed of short poly (dimethylsiloxane) (PDMS) chain in the backbone and Jeffamine L100 as graft chain. The amino groups in the backbone and carboxyl groups grafted to the backbone make the obtained Z-SiPEAs zwitterionic. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) results revealed that the obtained Z-SiPEAs can self-assemble into nanoparticles in water, which possessed sharp response to temperature, pH, and ionic strength with the tunable clouding point (CP). In the presence of Z-SiPEAs, not only hydrophobic dyes such as Nile Red can be dispersed in water, but the hydrophilic dye Rose Bengal (RB) can be dispersed in unpolar solvents. Further more, Z-SiPEAs can enhance the dispersion of inorganic pigments Titanium White, Iron Red and Chrome Yellow very efficiently in most solvents. It should be noted that the dispersion of organic dyes and inorganic pigments in water can be controlled by temperature in the presence of Z-SiPEAs. ¹H NMR and FT-IR revealed the strong coordination between carboxyl groups in Z-SiPEAs and metal atoms of inorganic pigments. These characteristics will give Z-SiPEAs potential as the novel responsive polymeric dispersant.