Shape amphiphiles with distinct shapes and amphiphilic properties can be used as fundamental building blocks in the fabrication of novel structures and advanced materials. In this research synthesis and selfassembly of monotethered single-chain nanoparticle shape amphiphiles are reported. Poly(2-(dimethylamino)ethyl methacrylate)-block-polystyrene (PDMAEMA-b-PS) was synthesized by two-step reversible addition− fragmentation chain transfer (RAFT) polymerization. The PDMAEMA blocks were intramolecularly cross-linked by 1,4-diiodobutane (DIB) at significantly low concentrations, and PS-tethered PDMAEMA single-chain nanoparticles were prepared. Gel permeation chromatograph, 1 H NMR and transmission electron microscopy results all indicated successful synthesis of the structures. The controlled self-assembly of the shape amphiphiles in selective solvents was investigated. Depending on the size of the single-chain nanoparticles, the shape amphiphiles self-assemble into strawberry-like micelles, a structure with single-chain nanoparticles in the corona and PS in the core, or vesicles in aqueous solutions. Similar to the self-assembled structures in aqueous solution, the morphology of the aggregates in methanol changes from micellar structure to vesicular structure with the decrease of the PDMAEMA single-chain nanoparticles size. In cyclohexane, the shape amphiphiles self-assemble into bunchy micelles with single-chain nanoparticles in the cores and linear PS in the coronae.

Carboxyl groups at the periphery of reduced graphene oxide (RGO) sheets are converted to amine groups by reaction with N-hydroxysuccinimide and 1,3-diaminopropane, and a free-radical polymerization initiator is anchored to the RGO sheets. Poly(acrylamide) (PAM) polymer brushes on RGO sheets (RGO/PAM) are synthesized by in situ free-radical polymerization. The heavy metals, Pb(II), and the benzenoid compounds, methylene blue, (MB) were selected and adsorbed by RGO/PAM composites, and the adsorption capacity of RGO/PAM for Pb(II) and MB was measured. The experimental data of RGO/PAM isotherms for Pb(II) and MB followed the Langmuir isotherm model. The RGO/PAM displays adsorption capacities as high as 1000 and 1530 mg/g for Pb(II) and MB, respectively, indicating RGO/PAM is a good adsorbent for the adsorption of Pb(II) and MB. The adsorption kinetics of Pb(II) and MB onto RGO/PAM can be well fitted to the pseudo-second-order model. The adsorption processes of Pb(II) and MB onto RGO/PAM are spontaneous at 298, 308, and 318 K.

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Ultrabroadband photodetection has been a hot topic with the rapid development of materials science and the application requirements for communication, imaging, and sensing. Photodetectors based on bandgap-independent bolometry are promising candidates for detection of light from the ultraviolet to the terahertz range. Here we report a photothermoelectric detector made of an alloy of EuBiSe3 single crystal. The device shows room-temperature self-powered photoresponse from ultraviolet (375 nm) to terahertz (163 μm) with nearly uniform sensitivity against wavelength and fast response speed. Thanks to the large thermoelectric power (Seebeck coefficient) of EuBiSe3, the photovoltage responsivity derived from the incident (not absorbed) power reaches as high as 1.69 V/W at 405 nm without any bias voltage and exceeds 0.59 V/W even at terahertz frequencies, with noise-equivalent power below 1 nW/ , which is 1–2 orders of magnitude lower than reported photothermoelectric detectors. The response time is around 200 ms, nearly 2 orders of magnitude faster than silicon-based heterojunction ultrabroadband photodetectors and on the same order as the millimetric-scale graphene- and carbon nanotube-based bolometric photodetectors. In addition, the as-grown EuBiSe3 crystal possesses a unique needle-like shape, intrinsically facilitating integration of the detector. Our work demonstrates that improved thermoelectric materials hold great promise for room-temperature, high-performance, broadband photodetection.

Three-dimensional microporous graphene (3DMG) possesses ultrahigh photon absorptivity and excellent photothermal conversion ability and shows great potential in energy storage and photodetection, especially for the not well-explored terahertz (THz) frequency range. Here, we report on the characterization of the THz thermal–electrical conversion properties of 3DMG with different annealing treatments. We observe distinct behavior of bolometric and photothermoelectric responses varying with annealing temperature. Resistance–temperature characteristics and thermoelectric power measurements reveal that marked charge carrier reversal occurs in 3DMG as the annealing temperature changes between 600 and 800 °C, which can be well explained by Fermi-level tuning associated with oxygen functional group evolution. Benefiting from the large specific surface area of 3DMG, it has an extraordinary capability of reaching thermal equilibrium quickly and exhibits a fast photothermal conversion with a time constant of 23 ms. In addition, 3DMG can serve as an ideal absorber to improve the sensitivity of THz detectors and we demonstrate that the responsivity of a carbon nanotube device could be enhanced by 12 times through 3DMG. Our work provides new insight into the physical characteristics of carrier transport and THz thermal–electrical conversion in 3DMG controlled by annealing temperature and opens an avenue for the development of highly efficient graphene-based THz devices.

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However, rare materials have the ability directly sensitive to light over a broad range of the electromagnetic spectrum from ultraviolet (UV) down to terahertz (THz) wavelengths, particularly at room temperature. For example, conventional semiconductors such as silicon [2] and transition metal dichalcogenides, [3] which have photo response properties cut off by the bandgap, are transparent to light below their bandgap, and therefore, transparent to THz photons. Recent studies on ultrabroadband photodetectors have mainly focused on fabricating devices using graphene owing to its gapless band structure. [4] However, a significant shortcoming of graphene-based photodetectors is their low optical absorption, which is a critical obstacle for efficient photodetection. [5] To overcome this drawback, researchers have fabricated graphene quantum dot arrays, [6] and heterostructures with silicon nanowire arrays, [7] as well as monolithically integrated graphene with a Fabry-Perot microcavity, [8] to improve the responsivities. However, all these devices share a common problem-namely the complex device fabrication processes involved. Other materials such as topological insulators (TIs), which benefit from their relativistic Dirac-dispersion of the surface state, are considered promising candidates for multiband photodetection, and have attracted considerable Ultrabroad spectrum detection has a wide range of photonic and optoelectronic applications, such as spectroscopy, optical communication, imaging, and sensing. 3D topological insulator candidates are promising materials for fast high-performance photodetectors owing to their linear dispersion band structure and high carrier mobility. In this study, an ultrabroadband photothermoelectric (PTE) self-powered detector based on the topological insulator candidate HfTe 5 is reported for the first time. The photosensitive properties are characterized in an ultrabroadband range from the ultraviolet (375 nm) to terahertz (118.8 µm) wavelengths, and the responsivities at all examined wavelengths are found to be greater than 1 V W −1 at room temperature. Owing to the Dirac band dispersion of HfTe 5 , the response time (τ) of the proposed detector is as short as ≈1 ms, which is 1-3 orders of magnitude faster than that of recently reported PTE detectors based on millimeter-scale graphene, 3D graphene, EuBiSe 3 single crystal, and SrTiO 3 crystal. Furthermore, the sensitivity of the HfTe 5 detector to the light intensity and direction of linearly-polarized light is demonstrated. Thus, the proposed device demonstrates outstanding flexibility, air stability, and long-term photostability as well, displaying high potential for practical applications in wearable optoelectronics.

An amphiphilic block copolymer comprising poly(ethylene glycol) (PEG) and poly(2-(methacryloyl)oxyethyl-2'-hydroxyethyl disulfide) (PMAOHD) blocks was synthesized by atom transfer radical polymerization (ATRP). Pyrenebutyric acid was conjugated to the block copolymer by esterification, and a block copolymer with pendant disulfide bonds and pyrenyl groups (PEG-b-P(MAOHD-g-Py)) was obtained. (1)H NMR and gel permeation chromatography (GPC) results demonstrated the successful synthesis of the block copolymer. The cleavage of the disulfide bonds and the degrafting of the pyrenyl groups were investigated in THF and a THF/methanol mixture. Fluorescence spectroscopy, GPC, and (1)H NMR results demonstrated fast cleavage of the disulfide bonds by Bu(3)P in THF. Fluorescence results showed the ratio of the intensity of the excimer peak to the monomer peak decreased rapidly within 20 min. GPC traces of the block copolymer moved to a long retention time region after addition of Bu(3)P, indicating the cleavage of the disulfide bonds and the degrafting of the pyrenyl groups. PEG-b-P(MAOHD-g-Py) can self-assemble into micelles with poly(MAOHD-g-Py) cores and PEG coronae in a mixture of methanol and THF (9:1 by volume). The dissociation of the micelles in the presence of Bu(3)P was investigated. After cleavage of the disulfide bonds in the micellar cores, a pyrene-containing small molecular compound and a block copolymer with pendant thiol groups were produced. Transmission electron microscopy (TEM), dynamic light scattering (DLS), and (1)H NMR were employed to track the dissociation of the polymeric micelles. All the techniques demonstrated the dissociation of the micelles and the fast release of pyrenyl groups from the micelles.