Guangming Chen

Convenient construction of poly(3,4-ethylenedioxythiophene)–graphene pie-like structure with enhanced thermoelectric performance

A novel strategy via the convenient construction of a pie-like structure has been developed to prepare a poly(3,4-ethylenedioxythiophene)–reduced graphene oxide (PEDOT–rGO) nanocomposite with a greatly enhanced thermoelectric performance. Via a template-directed in situ polymerization, thick and uniform coatings of PEDOT layers were conveniently grown on both sides of the rGO nanosheet surfaces due to a strong π–π interfacial interaction. The nanocomposite exhibited a significantly enhanced thermoelectric performance at room temperature with a power factor of 5.2 ± 0.9 × 10−6 W m−1 K−2, greater than 13.3 times that of the PEDOT.

Preparation, stability and rheology of polyacrylamide/pristine layered double hydroxide nanocomposites

Novel polyacrylamide (PAM)/pristine layered double hydroxide (LDH) nanocomposites have been prepared by a facile solution dispersion procedure, and their stability and rheological properties have been studied. The pristine LDHs without any surface organo-modification (LDH_NO3), synthesized by co-precipitation procedure, are dramatically exfoliated and uniformly dispersed in formamide. Subsequently, PAM/LDH_NO3 nanocomposites are prepared by a convenient solution dispersion procedure, wherein the dispersion structure of LDH_NO3 in PAM was studied by X-ray diffraction, size distribution measurements and Tyndall effect. The nanocomposites exhibit excellent stabilities toward various environmental conditions such as heating, centrifugation and salt-tolerance. Moreover, in the whole process of drying and after the re-dissolution, the nanocomposites kept a uniform dispersion structure without any precipitation formation. Finally, the dynamic and steady rheological investigations were conducted. Nanoscale LDH_NO3 particles and layers were found to have drastic effects on the PAM solution rheological behaviour with an obvious gel-formation process at a low LDH content, and strong frequency dependence of viscosity at low frequencies.

Template‐Directed In Situ Polymerization Preparation of Nanocomposites of PEDOT:PSS‐Coated Multi‐Walled Carbon Nanotubes with Enhanced Thermoelectric Property

A template-directed in situ polymerization preparation of nanocomposites of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-coated multi-walled carbon nanotubes (MWCNTs) with greatly enhanced thermoelectric property is presented. The results reveal that monomeric 3,4-ethylenedioxythiophene was successfully polymerized, enwrapping the surfaces of dispersed MWCNTs (templates) with the aid of PSS. The coated morphology was directly observed by high-resolution transmission electron microscopy. The coated layer was further characterized by energy-dispersive X-ray spectroscopy and X-ray diffraction. In addition, the interfacial interaction between PEDOT:PSS and MWCNTs was studied by Fourier transform infrared spectroscopy. Finally, the thermoelectric measurements show that the obtained PEDOT:PSS/MWCNT nanocomposites exhibited greatly enhanced electrical conductivities, Seebeck coefficients, and power factors when compared with those of neat PEDOT:PSS.

Enhanced thermoelectric property by the construction of a nanocomposite 3D interconnected architecture consisting of graphene nanolayers sandwiched by polypyrrole nanowires

A new strategy, i.e. interfacial adsorption-soft template polymerization, is developed to enhance polymer thermoelectric property. The obtained nanocomposite 3D interconnected architecture consisting of reduced graphene oxide (rGO) nanolayers sandwiched by polypyrrole (PPy) nanowires is directly confirmed by scanning and transmission electron microscopies. Moreover, the nanocomposites reveal significantly enhanced thermoelectric performance. At rGO:PPy ratio of 50 wt%, the nanocomposite power factor reaches ∼476.1 times that of pure PPy nanowires. Our results suggest that a greatly enhanced thermoelectric property for polymer nanocomposites can be achieved by a complex morphology design.

Poly(ethylene terephthalate) nanocomposites with a strong UV-shielding function using UV-absorber intercalated layered double hydroxides

A novel strategy has been developed to prepare poly(ethylene terephthalate) nanocomposites with a strong UV-shielding function. The nanoscale dispersion of UV-absorber intercalated layered double hydroxides (LDHs), and a combination of the chemical absorption and physical blocking of UV rays may account for the greatly enhanced UV-shielding ability, which remarkably depends on the interlayer anions, the content and the platelet size of the LDHs.

In Situ Chemical Oxidative Polymerization Preparation of Poly(3,4‐ethylenedioxythiophene)/Graphene Nanocomposites with Enhanced Thermoelectric Performance

Three different in situ chemical oxidative polymerization routes, that is, (A) spin-coating and subsequent liquid layer polymerization, (B) spin-coating followed by vapor phase polymerization, and (C) in situ polymerization and then post-treatment by immersion in ethylene glycol (EG), have been developed to achieve poly(3,4-ethylenedioxythiophene)/reduced graphene oxide (PEDOT/rGO) nanocomposites. As demonstrated by scanning electron microscopic and energy-dispersive X-ray spectroscopic techniques, PEDOT has been successfully coated on the surface of the rGO nanosheets by each of the three preparation routes. Importantly, all of the nanocomposites display a greatly enhanced thermoelectric performance (power factors) relative to those of the corresponding neat PEDOT.

Aqueous dispersions of layered double hydroxide/polyacrylamide nanocomposites: preparation and rheology

Water was used to replace the toxic organic solvent of formamide in preparation of the aqueous dispersions of layered double hydroxide/polyacrylamide (LDH/PAM) nanocomposites, which exhibited greatly enhanced rheological properties when compared to those of the neat PAM. First, the nanocomposite dispersions were prepared via a convenient in situ polymerization or solution mixing method, using water to exfoliate the LDH particles instead of formamide as used in the pioneer investigation. The LDH dispersion structure in the nanocomposite dispersion was demonstrated by X-ray diffraction and direct observation. Then, the rheological investigations including sol → gel transition, dynamic oscillatory frequency sweep and steady shear measurements were carried out. Subsequently, the rheological properties for the aqueous nanocomposite dispersions prepared by the two methods were compared. Finally, the mechanism of the enhancement of rheological properties (the moduli and viscosities) was discussed based on the LDH dispersion microstructure, network formation as well as interfacial interactions between PAM chains and LDH nanoparticles.

Tuning thermoelectric performance by nanostructure evolution of a conducting polymer

The thermoelectric performance of a conducting polymer is conveniently and effectively tuned by nanostructure evolution. The electrical conductivity, Seebeck coefficient and power factor follow the same sequence of bulk poly(3,4-ethylenedioxythiophene) (PEDOT) < globular nanoparticle < nanorod or ellipsoidal nanoparticle < nanotube < nanofibre. The molecular mechanism is studied by carrier mobility and concentration, the ordered structure of polymer chains, and the levels of doping and oxidation of PEDOT.

Recent advances in organic polymer thermoelectric composites

Thermoelectric materials can realize the direct energy conversion between heat and electricity, having diverse applications in energy harvesting (especially for waste heat and low-grade heat) and local cooling and sensing. In recent years, organic polymer thermoelectric composites have received extensive attention and have experienced a rapid development because of their low densities, low thermal conductivities, high flexibilities, and the synergistic combination of the advantages of both constituents. This review covers the recent advances in organic polymer thermoelectric composites. Herein, their preparation strategies have been discussed. In addition, the non-conducting polymer-based composites, ternary composites, and the devices have also been discussed. Finally, an outlook on future investigations is provided.

Morphology and thermoelectric properties of graphene nanosheets enwrapped with polypyrrole

With the help of sodium dodecyl sulfate (SDS), uniform polypyrrole (PPy) coatings were conveniently grown on both sides of reduced graphene oxide (rGO) nanosheet surfaces via a template-directed in situ polymerization. The rGO/PPy composites exhibited greatly enhanced thermoelectric performance with a power factor at room temperature of up to 3.01 μW m−1 K−2, which is 84 times greater than that of the pure PPy.