A highly efficient and facile sensing system made of N-doped graphene quantum dots (N-GQDs)/poly(3,4-ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT–PSS) was fabricated by drop coating on interdigitated Au electrodes with high uniformity over a large area of silicon substrate, and was used to sense the vapors of volatile organic compounds (VOCs) for detection at room temperature. An innovative method was developed for the synthesis of N-GQDs through hydrothermal processing of citric acid. The N-GQDs obtained have a N to C atomic ratio of 0.058 and a diameter of 2–7 nm. The nanocomposite sensing system exhibits highly sensitive, selective, rapid, and reversible responses for the detection of 1–1000 ppm VOCs. The N-GQDs/PEDOT–PSS nanocomposite gas sensor has an enhanced methanol sensing property of 13 times the value for pristine PEDOT–PSS in a low concentration of 50 ppm methanol. Moreover, the gas sensor based on the nanocomposite has a fast response (ca. 12 s) and recovery (ca. 32 s) behavior, excellent room temperature selectivity and stability. The methanol-sensing mechanisms of the N-GQDs/PEDOT–PSS nanocomposite gas sensor, based on direct charge transfer and a swelling process, are highlighted.

We herein report an investigation of ultralarge graphene oxide (UL-GO) sheet/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin composite layers fabricated by spin coating on an indium–tin-oxide (ITO) anode as hole transport layer (HTL) in polymer light-emitting diodes (PLEDs), as well as polymer solar cells (PSCs). Monolayer UL-GOs were first synthesized based on a novel solution-phase method involving pre-exfoliation of graphite flakes which were then mixed into the PEDOT:PSS solution in various specific amounts. The PEDOT:PSS composite film mixed with 0.04 wt% UL-GO by weight exhibits a conductivity of 749.4 S cm⁻¹ and a transmittance of 88.6% at 550 nm. The PEDOT:PSS/GO HTL shows enhanced charge carrier transport because of improved conductivity by the weakening of the coulombic attraction between PEDOT and PSS by the functional groups on GO nanosheets, and the formation of an extended conductive network. Moreover, it can effectively block electrons and reduce resistance in the HTL, leading to better injection and transport of holes and lower turn-on voltage and resulting in a higher overall efficiency in PLEDs. Similarly, it remarkably increases the short circuit current (J_sc), and PSC efficiency because of a remarkable reduction of exciton quenching that results in higher charge extraction in PSCs. The optimized PLEDs and PSCs with a PEDOT:PSS/GO composite HTL layer show a maximum luminosity of 725.6 cd m⁻² (at 10.6 V) for PLEDs, as well as a power conversion efficiency of 3.388% for PSCs, which were improved by ∼11% and 12%, respectively, compared to reference PLEDs and PSCs with a PEDOT:PSS layer.

Here we present a highly efficient ammonia (NH₃) gas sensor made of copper(II) tetrasulfophthalocyanine supported on a three-dimensional nitrogen-doped graphene based framework (CuTSPc@3D-(N)GF)/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) nanocomposite sensing film with high uniformity over a large surface area. The NH₃ gas sensing performance of the nanocomposite was compared with those of sensors based on pure PEDOT-PSS and a pristine CuTSPc@3D-(N)GF. It was revealed that the synergistic behavior between both of these candidates allowed excellent sensitivity and selectivity for NH₃ gas in a low concentration range of 1–1000 ppm at room temperature. The CuTSPc@3D-(N)GF/PEDOT-PSS nanocomposite gas sensor exhibited a much better response (∼5 and 53 times, with a concentration of NH₃ gas at 200 ppm) to NH₃ gas than those of the pure PEDOT-PSS and pristine CuTSPc@3D-(N)GF gas sensors, respectively. The combination of the CuTSPc@3D-(N)GF and PEDOT-PSS facilitated the enhancement in the sensing properties of the final nanocomposite and paved a new avenue for the application of CuTSPc@3D-(N)GF/PEDOT-PSS nanocomposites in the gas sensing field.

In the present study poly (butylene sebacate-co-terephthalate)s having different compositions were synthesized with a high yield and a random distribution by thermal transesterification of poly (butylene sebacate) and poly (butylene terephthalate) homopolymers. The copolymer with the highest comonomer ratio was the least crystalline sample, although the melting peaks corresponding to both, sebacate and terephthalate-rich phases were still observable in calorimetric heating runs. This copolymer was associated with interesting thermal and mechanical properties, as the maximum melting point was higher than 100 °C and the storage modulus was also high (i.e. 1.1 × 109 N/m2 and 1.7 108 N/m2 were determined just before and after the main glass transition temperature of -12 °C).\ud \ud As all studied samples were thermally stable up to temperatures clearly higher than the fusion temperature, they could be easily processed. Increasing the terephthalate content of the copolymers resulted in higher hydrophobicity, which had a minor influence on cell adhesion and proliferation of both fibroblast-like and epithelial-like cells. Hydrolytic and enzymatic degradability were assessed and the effect of composition and crystallinity on the degradation rate was investigated. Molecular weight measurements during exposure to a hydrolytic media indicated a first order kinetic mechanism during the initial stages of degradation before reaching a limiting molecular size, which was indicative of solubilization. The most amorphous sample appears as a highly promising biodegradable material since it showed a significant weight loss during exposure to all selected degradation media, but also exhibited good performance and properties that were comparable to those characteristic of polyethylenePeer ReviewedPostprint (author's final draft

Biological materials employ a variety of dynamic interactions in sophisticated composite structures to function adaptively on different time and length scales. Inspired by such designs we develop a novel surface modification approach to promote dynamic interactions between nanoparticles and polymer chains in physical and double network hydrogels. Physical hydrogels are formed via reversible complexation of borate ions with poly(vinyl alcohol) (PVA) and chemical crosslinks are introduced by electron beam irradiation. Dopamine is used for surface modification of magnetic iron oxide nanoparticles (MNPs) in two different ways: the direct treatment results in anchoring via catechol groups, whereas the indirect method leaves the catechol group on the free surface of MNPs. Although the former particles show very good colloidal stability, they lower the network connectivity, which results in lower plateau modulus, faster terminal relaxation, and lower yield stress, presumably due to imposing an extra distance between PVA chains. In contrast to this passive design, the latter particles actively reinforce the network by forming clusters of physical bonds between catechol groups of the individual particles and the monodiol complexes of the borate ions and PVA chains. Moreover, the additional complexes formed upon the introduction of nanoparticles with active surfaces provide further energy dissipation potential and therefore enhance the toughness. This approach can help develop novel hydrogels with superior toughness and multiple stimuli-responsiveness.