In this research, Ag-NPs/Tb-complex/PLLA composite fibers with diameters of around 250 nm were successfully obtained by the electrospinning and characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and fluorescence spectra. The influence of localized surface plasmon resonance (LSPR) of silver nanoparticles (Ag-NPs) on the fluorescence of Tb(acac)3phen/poly-L-lactic acid (Tb-complex, acac = acetylacetone; phen = phenanthroline, PLLA = poly-L-lactic acid) fibers was mainly investigated. It is found that Tb-complex dispersed in the fibers in the form of nanoclusters. The local field surrounding of Tb3+ ions was affected by the neighboring Ag-NPs. As a result of the LSPR effect of Ag-NPs, the fluorescence intensity, quantum efficiency of Tb-complex in the composite fibers with the Ag/Tb ratio of 4 : 1, were simultaneously improved compared with the composite fibers without Ag-NPs.

In this work, we fabricated novel poly(urethane–urea) (PUU)-based dielectric elastomers using a hydroxyl-terminated butadiene–acrylonitrile copolymer (HTBN) as the soft segment and hexamethylene diisocyanate (HDI) and 3,3′-dimethyl-4,4′-diamino dicyclohexyl methane (DMDC) as hard segments. The effect of hard segment (HS) content on the hard domain (HD) structure, morphology, dielectric and mechanical properties was investigated with Fourier transform infrared spectroscopy (FTIR), small/wide angle X-ray scattering (SAXS/WAXS), broadband dielectric spectroscopy and mechanical testing methods. Our results indicated that the hard domain structure units of PUUs such as degree of hydrogen bonding, size and crystallinity played an important role in the dielectric and mechanical properties. The dielectric constant of PUUs was significantly decreased with increasing HS content, whereas the breakdown strength and Young's modulus of PUUs were significantly increased. The relationship between multi-length scale structure and dielectric constant and breakdown strength properties of PUUEs were discussed. Our results can provide a new insight for optimization of dielectric and mechanical properties of PUU-based dielectric elastomers.

Exploring novel dielectric polymer materials with high dielectric performance would play a crucial role in the high energy density capacitor applications. In this work, novel polyurethanes (PUs) for high dielectric performance were fabricated using containing polar nitrile group (–C ≡ N) of hydroxyl-terminated polybutadiene–acrylonitrile copolymer (HTBN) as soft segment and the hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI) as hard segment component. Effect of diisocyanate chemical structure on microphase separation, crystallization, dielectric property and mechanical properties of HTBN-based PUs, and the relationship between structure and dielectric property of HTBN-based PUs were investigated. The HTBN-based PUs showed high dielectric constant (>6.4) and low dissipation factor (<0.077) at the frequency range from 1 to 106 Hz. The crystallinity, degree of microphase separation and dielectric constant of HDI-/HTBN-based PU showed higher than that of MDI/HTBN and TDI-/HTBN-based PUs. Our results indicated that the dielectric constant and dissipation factor of PUs are not only dependent on the dipole orientation of hard and soft segments, but also strongly dependent on their microstructure including degree of microphase separation and crystallinity.

The toughening of semi-crystalline polymers with inorganic nanofiller is very important in the practical applications of such polymers. In this study, we successfully fabricated the surface attaching silica nanoparticles of silica nanofibers (SiO2@SNFs) from the calcination of electrospun poly(vinyl pyrrolidone)/tetraethyl orthosilicate/silica nanoparticle (PVP/TEOS/SiO2) nanofibers for the toughening of polypropylene (PP). The SiO2@SNFs had a nanoprotrusion structured surface, and the degree of surface nanoprotrusion of the silica nanofibers (SNF) can be adjusted via the incorporated SiO2 nanoparticle content of the SiO2@SNFs. The effects of the SiO2 content of the SiO2@SNFs on the crystallization behavior, relative β-form crystal content, and mechanical properties of PP were investigated with polarized optical microscopy, X-ray diffraction and notched Izod impact test methods. By comparison with SNF, the SiO2@SNFs showed greater improvements in the impact strength and heterogeneous crystal nucleation of PP at the same loading content of filler. The impact strength of PP/SiO2@SNFs at a loading of 2 wt% of SiO2@SNFs with 9 phr (SiO2/TEOS = 9/100) of SiO2 nanoparticles was improved by about 1.9 and 1.4 times that of neat PP and PP/SNFs composite (2 wt% of SNFs), respectively. However, the crystallinity, relative β-form crystal content, and tensile strength of PP/SiO2@SNFs were almost independent of the SiO2 nanoparticle content of the SiO2@SNFs. Our results demonstrated that these nanoprotrusion surface structured silica nanofibers can be used as a novel nanofiller for improving the toughening of PP.

Supported catalysts are an increasingly popular research area because supported catalysts are highly efficient and the catalyst particles can be recovered. In this study, a new silica-supported palladium (Pd/SiO2) nanofiber catalyst was developed. Pd/SiO2 nanofibers were prepared by the electrospinning of a solution mixture of poly(vinyl pyrrolidone) (PVP), TEOS gel, and PdCl2 nanoparticles, followed by the calcination of PdCl2/PVP/TEOS nanofibers at a high temperature and the reduction of PdO/SiO2 nanofibers in a H2 atmosphere. The results showed that the prepared Pd/SiO2 nanofibers had an average diameter of 500 nm. Pd nanoparticles with a diameter of 20–30 nm were uniformly dispersed on the surface of SiO2 nanofibers. The composite nanofibers had high Brunauer–Emmett–Teller (BET) specific surface area. The hydrogenation reaction for acrylic acid showed that the hydrogenation efficiency was 93.48% in the presence of 0.1 g of Pd/SiO2 nanofibers. These nanofibers could be easily recycled. These features make the Pd/SiO2 nanofibers promising in a wide range of applications in the catalyst industry.

•Tb(acac)3phen/PLLA//Ag-NPs/PVP core–sheath nanofibers were prepared.•Ag and Tb(acac)3phen uniformly dispersed in outer and inner layers, respectively.•The outer Ag-NPs improved the fluorescence of the inner Tb(acac)3phen.•The novel core–sheath nanofibers showed excellent fluorescence properties.Silver nanoparticles (Ag-NPs) were used to enhance the fluorescence properties of nanofibers containing the Tb(acac)3phen (Tb = terbium, acac = acetylacetone, phen = 1,10-phenanthroline) complex. Tb(acac)3phen/PLLA//Ag-NPs/PVP (PLLA = polylacticacid, PVP = polyvinylpyrrolidone) core–sheath fluorescence nanofibers were prepared by coaxial electrospinning. SEM images demonstrated that the fibers had an average diameter of 550 nm. TEM images illustrated that the Ag-NPs and Tb(acac)3phen were uniformly dispersed in the outer and inner fibrous layers in the form of nanoparticles and molecular clusters, respectively. The fluorescence intensity of the Tb(acac)3phen/PLLA//Ag-NPs/PVP core–sheath nanofibers with a molar ratio Ag/Tb of 1 increased by 69%, the quantum efficiency increased by 53%, and the fluorescence lifetime increased by 4% over those of the fibers without Ag-NPs because of the localized surface plasmon resonance (LSPR) effect of Ag-NPs. The prepared fibers with a core–sheath structure have great potential in a wide range of fluorescence applications.

A facile and efficient approach was developed to simultaneously functionalize and tune the reduction state of graphene oxide (GO) with γ-aminopropyl triethoxysilane (APTES) aided by NH3 solution. X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy indicated that many surface groups of GO sheets were removed, and APTES were successfully functionalized onto GO sheets. The APTES-functionalized GO sheets (GO-APTES) were dispersed in water and further incorporated into nitrile butadiene rubber (NBR) by latex co-coagulation to form GO-APTES/NBR composites. These composites featured high degrees of exfoliation and intercalation of GO-APTES sheets throughout the NBR matrix. More significantly, the GO-APTES/NBR composites exhibited a relatively high dielectric constant (∼30.8) and a small loss factor (<0.04) at 1.0 kHz, combining with a good insulating property. The unique dielectric responses of GO-APTES/NBR composites open up the potential applications of these materials in resistive and capacitive field grading materials.

Evolutions of chemical cross-linking and filler networks during sinusoidal small-strain (10%) shear loading (fatigue) process were studied in pure (unfilled) and silica-filled natural rubbers. The experimental results of dynamic mechanical analysis (DMA) and nuclear magnetic resonance (NMR) of pure natural rubber (PNR) indicated that the fatigued PNR has a more homogeneous cross-linking network than that of the virgin one, which can lead to a slight increase of the storage modulus; however, the change of cross-linking density and its effect on the viscoelastic properties of PNR are very limited. By analyzing the variation of storage and loss moduli and the transmission electron microscopy (TEM) images of silica-filled natural rubber (SFNR) during the cyclic loading process, we found that the loosely packed agglomerates were first disrupted, and then the closed ones could also be gradually broken down. Such a filler network evolution process also can be seen from our non-equilibrium molecular dynamics (NEMD) simulation results.

The modified silica at different temperature (MSaDT) with bis(3-triethoxysilylpropyl)tetrasulfide (TESPT), and MSaDT filled solution styrene butadiene rubber (SSBR) composites were prepared to investigate the effect of temperature on surface modification of silica. The results showed that TESPT was successfully bonded on the surface of silica by chemical bonds. The grafting degree (K) of MSaDT of 50 °C was 62.2% and higher than that at the other temperatures. The thermal weight loss and the size distribution of MSaDT showed that the silanol of TESPT hydrolysates reacted with the surface hydroxyl groups of silica, decreasing the average size and agglomeration of modified silica. For 50 °C modified silica/SSBR composite, the static mechanical properties and rubber–filler interaction of the composite were better than those of the others. As far as dynamic mechanical properties are concerned, the 50 °C modified silica/SSBR composite owned a best combination of low rolling resistance and high wet skid resistance.

The traditional method for directly compounding rubber, silica, and bis(3-triethoxysilylpropyl)tetrasulfide (TESPT) by shear force, which we called it One-Step Method (OSM), results in a modification of uncertain mechanism: it is not clear whether chemisorption or physisorption is involved. In addition, OSM leads to large processing energy consumption (PEC). In view of these issues, we used a novel method (Two-Step Method, TSM) to investigate the modification process in detail. The TSM modification indicated that the TESPT hydrolyzed firstly to generate the silanol (Si–OH), and the silanol reacted with the hydroxyl groups on the surface of silica, which characterized by FTIR. The properties of modified silica were studied. Furthermore, the SSBR nanocomposites filled with modified silica by TSM and OSM were prepared and the properties comparisons were carried out. The obtained results exhibited the advantages of TSM, and also revealed that 8% TESPT amount was suitable than 12% and 15% TESPT amount.

•In situ self-polymerization of unsaturated metal methacrylate was investigated mainly by the thermal effect.•UMM with low melting point can self-polymerize to a large extent.•The fine dispersion phase is composed of poly(UMM) nanoparticles formed by in situ self-polymerization in the rubber matrix.•The UMM crystals in the presence of peroxide and rubber undergo the processes of melting, diffusion, polymerization, and phase separation in this order.Unsaturated metal methacrylate (UMM) as one kind of functional filler has played an important role in reinforcing rubber materials. The in situ self-polymerization of UMM in UMM/rubber composite leads to the uniform dispersion of poly(UMM) in the rubber matrix, while the crosslinking of rubber and grafting between UMM and rubber chains occur simultaneously, making it difficult to clarify the effect of the in situ polymerization on the dispersion of poly(UMM) in the rubber matrix. In this work, we investigated the dispersion mechanism of UMM without rubber matrix for the first time using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. Three types of UMMs including zinc methacrylate (Zn(MA)2), sodium methacrylate (Na(MA)) and samarium methacrylate (Sm(MA)3) were chosen to investigate the in situ self-polymerization of UMM. Based on DSC results, we conclude that the crystals with low melting point tend to self-polymerize first and generate a large amount of heat in the presence of peroxide. The high heat of reaction can melt the crystals with high melting point, and more UMM molecules are dissolved in the rubber matrix, thus increasing the extent of the in situ polymerization. Hence, the UMM with low melting point can self-polymerize to a large extent. Our findings provide in-depth understanding of the dispersion mechanism of UMM in rubber.

In this work, nonequilibrium molecular dynamics simulations were performed to investigate the dispersion and spatial distribution of spherical nanoparticles (NPs) in polymer matrix under oscillatory shear flow. We systematically analyzed the influences of four important factors that consist of NP–polymer interfacial strength, volume fraction of NPs, shear conditions, and polymer chain length. The simulation results showed that the oscillatory shear can greatly improve the dispersion of NPs, especially for the polymer nanocomposites (PNCs) with high NP–polymer interfacial strength. Under specific shear conditions, the NPs can exhibit three different spatial distribution states with increasing the NP–polymer interfacial strength. Interestingly, at high interfacial strength, we observed that the NPs can be distributed on several layers in the polymer matrix, forming the PNCs with sandwich-like structures. Such well-ordered nanocomposites can exhibit a higher tensile strength than those with the NPs dispersed randomly. It may be expected that the information derived in present study provides a useful foundation for guiding the design and preparation of high-performance PNCs.

•Irradiated CBs had more oxygen-containing groups than original CBs.•Irradiated CBs had smaller particle sizes than original CBs.•NR filled with irradiated CBs has lower abrasion than NR filled with untreated CBs.•NR filled with irradiated CBs has lower rolling resistance than NR filled with untreated CBs.In this work, carbon black particles (CBs) were modified by high-energy electron beam (EB) irradiation at different doses. The influence of EB irradiation on the surface and particle size of CBs was investigated. Then, the CBs were compounded with natural rubber (NR), and the mechanical properties and dynamic properties of CBs/NR composite were further researched. The results showed that the irradiated CBs had more oxygen-containing groups and smaller particle sizes than original CBs. After irradiation, the content of bound rubber around the irradiated CBs increased, and the mechanical properties of CBs/NR composite were improved. Most importantly, NR filled with irradiated CBs has lower abrasion, higher wet skid resistance, and lower rolling resistance than NR filled with untreated CBs.