Xiaoming Yang

•Hollow carbon spheres (HCSs) are synthesized based on the one-step carbonization.•Three morphologies of HCSs with hierarchical pore structures are obtained.•High specific surface areas and heteroatoms content are generated in the HCSs.•Ultrahigh specific capacitance with superior rate performance is achieved.Hollow carbonaceous spheres (HCSs) have been extensively investigated due to their valuable potentials in the applications of energy storage devices such as solar cells, fuel cells, and supercapacitors. It is highly desirable to develop abundant pore structures and introduce heteroatoms in the resultant HCSs to improve capacitance of the devices. Herein, N-, and O-doped HCSs with macro/micro/mesoporous structures are successfully prepared by one-step carbonization of polypyrrole coated polystyrene nanoparticles followed by chemical activation with KOH. The huge specific surface area (up to 935 m2 g−1) and hierarchical porous structures can effectively facilitate the transportation and exchange of ions and electrons. Besides, high heteroatom content (∼30%) are believed to provide pseudocapacitance contributed from the redox faradic reactions of these electrochemically active functional groups. The as-prepared activated HCSs possess a high capacitance of 535 F g−1 at a current density of 0.2 A g−1, and maintains 55% of the highest capacitance even at a current density of 10 A g−1. The newly prepared HCSs thus show great potential as the electrode materials of supercapacitors.Download high-res image (232KB)Download full-size image

A one pot facile synthesis of Poly(butylene terephthalate)-block-poly(tetramethylene oxide) alternative multiblock copolymers via PROP method

Co-reporter:Jianying Chen, Dongxue Chen, Weichun Huang, Xiaoming Yang, Xiaohong Li, Yingfeng Tu, Xiulin Zhu

Polymer 2016 Volume 107() pp:29-36

Publication Date(Web):19 December 2016

DOI:10.1016/j.polymer.2016.11.001

•A polycondensation-coupling ring-opening polymerization (PROP) method is developed.•(PBT-b-PTMO-b-PBT)n multiblock copolymers were synthesized by the PROP method.•The multiblock copolymers show better thermal stability than PTMO homopolymers.A novel polycondensation-coupling ring-opening polymerization (PROP) method is utilized to synthesize poly(butylene terephthalate)-block-poly(tetramethylene oxide) alternative multiblock copolymers (PBT-b-PTMO-b-PBT)nvia the one pot melt polymerization of cyclic oligo(butylene terephthalate)s (COBTs) and dihydroxy end-functional PTMO (macroinitiator). The proton peaks in 1H NMR spectra corresponding to each block segments, the segmental ends connecting with different blocks, and copolymer chain ends, are assigned by the 1H-1H gCOSY 2D NMR spectra, respectively. The number-average molecular weights of multiblock copolymers and each segment are revealed by an improved quantitative 1H NMR spectra. The results show the molecular weights of the multiblock copolymers increase linearly with reaction time, while the molecular weights for each block segment remain the same, following the PROP mechanism, i.e., the ring-opening polymerization of COBTs by PTMO macroinitiator to form PBT-b-PTMO-b-PBT triblock copolymers at the first stage (short and quickly), then coupling with the condensation polymerization of triblock copolymers to form (PBT-b-PTMO-b-PBT)n alternative multiblock copolymers at the second stage. The mechanism is also supported by GPC results. These multiblock copolymers show improved thermal stability compared with PTMO homopolymers.

From ultratough artificial nacre to elastomer: Poly(n-butyl acrylate) grafted graphene oxide nanocomposites

Co-reporter:Yanhong Wu, Rui Cao, Gaoxiang Wu, Weichun Huang, Ze Chen, Xiaoming Yang, Yingfeng Tu

Composites Part A: Applied Science and Manufacturing 2016 Volume 88() pp:156-164

Publication Date(Web):September 2016

DOI:10.1016/j.compositesa.2016.05.028

A biologically inspired, multilayer laminate structural design is deployed into composite films of poly(n-butyl acrylate) (PBA) graft graphene oxide (GO) synthesized by Ce(IV)/HNO3 redox system in aqueous solution. Artificial hybrid films are fabricated by vacuum-assisted filtration macroscopic assembly method. Using nacre as the brick-and-mortar model construct free-standing membranes, here GO is similar to brick and PBA acts as mortar revealing the similar function of biopolymers in the natural nacre. Owing to the low Tg of PBA, the polymer chains could move freely at room temperature, enhancing the extensibility and flexibility. Meanwhile, the chemical structure of free-standing membranes was studied by Raman spectrum and XPS. The morphologies were charactered by XRD, SEM and TEM which are compact with the mechanical properties of the films. Interestingly, by tuning grafted PBA contents from 3.5 wt% to 77 wt%, quite wide range of mechanical properties (tensile strength from 20 to 180 MPa, Young’s modulus from 0.1 to 7 GPa, toughness from 0.8 to 4.3 MJ/m3, elongation from 1.2 to 24.5%) were obtained. At the same time, we found that the nanocomposite membranes can be adjusted from mimic nacre-liked film with high strength to a homogenous dispersed elastomer.

Synergistic toughening of bioinspired artificial nacre by polystyrene grafted graphene oxide

Co-reporter:Yanhong Wu, Rui Cao, Liangliang Ji, Weichun Huang, Xiaoming Yang and Yingfeng Tu

RSC Advances 2015 vol. 5(Issue 36) pp:28085-28091

Publication Date(Web):12 Mar 2015

DOI:10.1039/C5RA03074A

A biologically inspired, multilayer laminate structural design is deployed in composite films of polystyrene (PS) grafted graphene oxide (GO) synthesized by a Ce(IV)/HNO3 redox system in aqueous solution. Artificial hybrid films are fabricated using a vacuum-assisted filtration macroscopic assembly method, using nacre as the structural model, GO as the inorganic building blocks and PS as glue. The resulting multilayer structure and the mechanical properties of the nanopaper were studied by scanning electron microscopy, X-ray diffraction and stress–strain measurements. The resulting multilayer GO–PS films with low polymer content (<15 vol%) show greatly enhanced mechanical properties compared to pure GO films. It is interesting that the mechanical properties of the nacre-like films can be varied with the volume fraction of the polymer.

Influence of liquid crystalline formation on the phase behavior of side-chain liquid crystalline block copolymers

Co-reporter:Liangliang Ji, Xiaofang Chen, Yanhong Wu, Xiaoming Yang, Yingfeng Tu

Polymer 2015 Volume 61() pp:147-154

Publication Date(Web):20 March 2015

DOI:10.1016/j.polymer.2015.01.077

•Different morphologies are observed in the liquid crystalline block copolymers.•In major LC block weight fraction range, lamella morphology dominates.Order-order transition and lamella to modified layer structure change were observed.A series of narrowly distributed diblock copolymers composed of amorphous components and side-chain liquid crystalline (LC) polymer, poly (butyl acrylate)-block-poly [8-(4-cyano-4′-biphenyl)-1-octanoyl acrylate] (PBA-b-PCBOA), with side-chain LC block weight fraction (fw,PCBOA) ranging from 25% to 87%, were synthesized by atom transfer radical polymerization (ATRP). Their thermal property, LC behavior, bulk phase behavior and thin film morphology were studied by differential scanning calorimetry (DSC), polarizing optical microscope (POM), small-angle X-ray scattering (SAXS) techniques and atomic force microscopy (AFM), respectively. The results show the diblock copolymers with different composition could present sphere, lamellar and cylinder morphologies before the order–disorder transition. As the mesogen units self-organize to form smectic phase, the lamellar morphology dominates during the majority LC block weight fraction range (fw,PCBOA = 46%–77%) to minimized the surface energy. Interestingly, for spin-coated thin film, the lamella phase separation size decreased with increasing annealing time. For the copolymer with fw,PCBOA of 67%, a thermoreversible order–order transition (OOT) and lamella to lamella/modified layer (L/ML), were observed.

Crystallization behavior of spray-dried and freeze-dried graphene oxide/poly(trimethylene terephthalate) composites

Co-reporter:Chengxin Guo;Liangliang Ji;Yaowen Li, ;Yingfeng Tu

Journal of Applied Polymer Science 2014 Volume 131( Issue 11) pp:

Publication Date(Web):

DOI:10.1002/app.40332

ABSTRACT

Two types of graphene oxide (GO) powders were prepared by freeze-drying or spray-drying method, and their composites with poly(trimethylene terephthalate) (PTT) were prepared by melt blending. The influence of GO powders' type and content on crystallization behavior of PTT was investigated by differential scanning calorimeter (DSC) and polarized optical microscopy (POM). DSC results indicated that the overall crystallization rate of PTT was accelerated by well-dispersed GO material which acts as a heterogeneous nucleation agent, since the Avrami parameter obtained is near 3. On the contrary, large GO aggregates which is in the minority will hinder the nucleation. Interestingly, large and well-defined PTT spherulites instead of tremendous stunted spherulites were observed from POM, which means only a small portion of GO powders was acted as nucleation agent. Meanwhile, GO powders had no effect on PTT spherulites growth rate. In addition, the band spacing of PTT spherulites became weaker and wider with increasing GO content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40332.

Synthesis and characterization of well-defined poly(l-lactide) functionalized graphene oxide sheets with high grafting ratio prepared through click chemistry and supramolecular interactions

Co-reporter:Weichun Huang, Sheng Wang, Chengxin Guo, Xiaoming Yang, Yaowen Li, Yingfeng Tu

Polymer 2014 Volume 55(Issue 18) pp:4619-4626

Publication Date(Web):2 September 2014

DOI:10.1016/j.polymer.2014.07.014

Two simple and effective methods, “click” chemistry and supramolecular interactions, are demonstrated here to synthesize well-defined poly(l-lactide) (PLLA) functionalized graphene oxide (GO) sheets. We provide a simple method to introduce azide groups on GO sheets by the ring opening reaction of sodium azide with the epoxide groups of GO. The GO-N3 sheets can easily undergo “click” reaction with alkyne-terminated PLLA by “grafting onto” method to produce GO/PLLA composites with high grafting ratio and exfoliated structure. Interestingly, GO-N3 can be grafted with oxygen-containing polymers such as PLLA, polymethyl methacrylate (PMMA) or polyethylene oxide (PEO) via supramolecular interactions between the azide groups and these oxygen atoms on polymers, producing GO/polymer composites with low grafting ratio and intercalated structure. These “grafting onto” methods are useful to produce a variety of GO/polymer composites with different structure via “click” reaction or supramolecular interactions, which have potential applications in material science.

Layer-structured poly(vinyl alcohol)/graphene oxide nanocomposites with improved thermal and mechanical properties

Co-reporter:Xiaoming Yang;Songmin Shang;Liang Li

Journal of Applied Polymer Science 2011 Volume 120( Issue 3) pp:1355-1360

Publication Date(Web):

DOI:10.1002/app.33279

Abstract

Layer-structured poly(vinyl alcohol)/graphene oxide nanocomposites in the form of films are prepared by simple solution processing. The structure and properties of these nanocomposites are studied using X-ray diffractions, scanning electron microscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The results indicate that graphene oxide is dispersed on a molecular scale and aligned in the poly(vinyl alcohol) matrix, and there exists strong interfacial interactions between both components, which are responsible for the significant improvement in the thermal and mechanical properties of the nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Water-based amorphous carbon nanotubes filled polymer nanocomposites

Co-reporter:Xiaoming Yang;Liang Li;Songmin Shang;Xiao-ming Tao

Journal of Applied Polymer Science 2011 Volume 122( Issue 3) pp:1986-1992

Publication Date(Web):

DOI:10.1002/app.34072

Abstract

A novel method of making water-based amorphous carbon nanotubes (ACNTs) for advanced polymer nanocomposites is presented. In this approach, sodium dodecyl sulfate (SDS) is introduced onto the amorphous carbon nanotubes to improve the solubility in water and the dispersion in polyvinyl alcohol [PVA] matrix. As a result, the addition of 0.6 wt % ACNTs in the polymer resulted in the significant improvement (167.5 and 175.8%) in the tensile strength and modulus of the polymer, respectively. The improved mechanical property could be ascribed to the load transfer to the nanotubes in the composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

One-step synthesis of reduced graphite oxide–silver nanocomposite

Co-reporter:Chunhua Dai, Xiaoming Yang, Hongde Xie

Materials Research Bulletin 2011 46(11) pp: 2004-2008

Publication Date(Web):

DOI:10.1016/j.materresbull.2011.07.013

Polypyrrole nanofibers synthesized via reactive template approach and their NH3 gas sensitivity

Co-reporter:Xiaoming Yang, Liang Li

Synthetic Metals 2010 Volume 160(11–12) pp:1365-1367

Publication Date(Web):June 2010

DOI:10.1016/j.synthmet.2010.04.015

The synthesis of polypyrrole (PPy) nanofibers has been achieved via a simple reactive template approach. The reactive template of FeCl3 and methyl orange (MO) leads to the formation of uniform PPy nanofibers. Moreover, the fabrication of PPy nanofibers with high yield is realized, suggesting that this methodology is appropriate for the large-scale production of the corresponding nanomaterials. In contrast to the NH3 gas sensor based on bulk PPy, the gas sensor based on the as-prepared PPy nanofibers exhibits greatly improved performances.

Ag/AgCl-decorated polypyrrole nanotubes and their sensory properties

Co-reporter:Xiaoming Yang, Liang Li, Ye Zhao

Synthetic Metals 2010 Volume 160(17–18) pp:1822-1825

Publication Date(Web):September 2010

DOI:10.1016/j.synthmet.2010.06.018

A facile method to prepare Ag/AgCl-decorated polypyrrole nanotubes (PPy/Ag–AgCl nanocomposites) has been demonstrated. PPy nanotubes were assembled on the reactive self-degraded template of a fibrillar complex of FeCl3 and methyl orange (MO). By introducing PPy nanotubes into AgNO3 solution, Ag and AgCl nanoparticles could be uniformly decorated onto the PPy nanotube surface in situ by the reaction of PPy and AgNO3. The morphology and structure of the nanocomposites were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The possible application of PPy/Ag–AgCl nanocomposites as a vapor sensor has also been reported. The responses of these nanocomposites were observed to be reversible by monitoring the change in the resistance of the nanocomposites upon exposure to ammonia vapor. PPy/Ag–AgCl composite nanotubes sensors showed enhanced chemiresistor sensitivity compared with PPy nanotubes.

Erratum to: One-Step UV-Induced Synthesis of Polypyrrole/Ag Nanocomposites at the Water/Ionic Liquid Interface

Co-reporter:Yuyan Wei;Liang Li;Guoliang Pan;Guoping Yan

Nanoscale Research Letters 2010 Volume 5( Issue 10) pp:

Publication Date(Web):2010 October

DOI:10.1007/s11671-010-9759-y

Polypyrrole/silver composite nanotubes for gas sensors

Co-reporter:Xiaoming Yang, Liang Li, Feng Yan

Sensors and Actuators B: Chemical 2010 Volume 145(Issue 1) pp:495-500

Publication Date(Web):4 March 2010

DOI:10.1016/j.snb.2009.12.065

A simple strategy for synthesizing well-defined polypyrrole (PPy) nanotube, which can be used for loading silver nanoparticles without prior PPy nanotube functionalization under mild conditions is demonstrated. It is found that Ag nanoparticles could uniformly decorate onto the PPy nanotube surface in the presence of polyvinylpyrrolidone (PVP) to form PPy/Ag composite nanotubes. Transmission electron microscopy (TEM) images give evidence of the decoration of Ag nanoparticles on the surface of PPy nanotubes. Fourier transform infrared (FTIR) spectra reveal the structure of PPy/Ag composite nanotubes and X-ray diffraction (XRD) directly shows the presence of Ag nanoparticles. The as-prepared PPy/Ag composite nanotubes are applied to the detection of ammonia vapor. Compared with PPy nanotubes, the introduction of metal onto PPy nanotubes is effective in promoting the chemiresistor response to ammonia. Moreover, the response behaviors of PPy/Ag composite nanotubes depend on the distribution of Ag nanoparticles in the nanocomposites.

One-Step UV-Induced Synthesis of Polypyrrole/Ag Nanocomposites at the Water/Ionic Liquid Interface

Co-reporter:Yuyan Wei;Liang Li;Guoliang Pan;Guoping Yan

Nanoscale Research Letters 2010 Volume 5( Issue 2) pp:

Publication Date(Web):2010 February

DOI:10.1007/s11671-009-9501-9

Polpyrrole (PPy)/Ag nanocomposites were successfully synthesized at the interface of water and ionic liquid by one-step UV-induced polymerization. Highly dispersed PPy/Ag nanoparticles were obtained by controlling the experimental conditions. The results of Fourier-transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy revealed that the UV-induced interface polymerization leaded to the formation of PPy incorporating silver nanoparticles. It was also found that the electrical conductivity of PPy/Ag nanocomposite was about 100 times higher than that of pure PPy.

Precisely controlled growth of poly(ethyl acrylate) chains on graphene oxide and the formation of layered structure with improved mechanical properties

Co-reporter:Rui Cao, Ze Chen, Yanhong Wu, Yingfeng Tu, Gaoxiang Wu, Xiaoming Yang

Composites Part A: Applied Science and Manufacturing (February 2017) Volume 93() pp:

Publication Date(Web):February 2017

DOI:10.1016/j.compositesa.2016.11.019

A biologically inspired, multilayer laminate structural design is realized by using hybrid films of poly(ethyl acrylate) (PEA) graft graphene oxide (GO) synthesized by Ce(IV)/HNO3 redox system in aqueous solution. Due to the moderate activity of ethyl acrylate (EA) monomers, the added amount of monomers exhibits a linear relationship with the grafted content of PEA on the GO surface. This indicates that the grafting process of PEA chains on the GO surface is well-controlled. Then, hybrid films with layered structures are fabricated by the vacuum-assisted filtration macroscopic assembly method, and the mechanical properties of the formed hybrid structures are investigated. The fracture stress of the film are significant improved to 83.92 MPa with even a low content of PEA (3.46 wt%). The mechanism of the enhanced mechanical property is related to its unique composite microstructures similar to the brick-and-mortar system in natural nacre.