By employing coarse-grained molecular dynamics simulation, we simulate the spatial organization of the polymer-grafted nanoparticles (NPs) in homopolymer matrix and the resulting mechanical performance, by particularly regulating the grafted chain length and flexibility. The morphologies ranging from the agglomerate, cylinder, sheet, and string to full dispersion are observed, by gradually increasing the grafted chain length. The radial distribution function and the total interaction energy between NPs are calculated. Meanwhile, the stress⁻strain behavior of each morphology and the morphological evolution during the uniaxial tension are simulated. In particular, the sheet structure exhibits the best mechanical reinforcement compared to other morphologies. In addition, the change of the grafted chain flexibility to semi-flexibility leads to the variation of the morphology. We also find that at long grafted chain length, the stress⁻strain behavior of the system with the semi-flexible grafted chain begins to exceed that of the system with the flexible grafted chain, attributed to the physical inter-locking interaction between the matrix and grafted polymer chains. A similar transition trend is as well found in the presence of the interfacial chemical couplings between grafted and matrix polymer chains. In general, this work is expected to help to design and fabricate high performance polymer nanocomposites filled with grafted NPs with excellent and controllable mechanical properties.
Realizing and manipulating a fine dispersion of silica nanoparticles (NPs) in the polymer matrix is always a great challenge. In this work, we first successfully synthesized N,N′-bis[3-(triethoxysilyl)propyl-isopropanol]-propane-1,3-diamine (TSPD), which was a new interface modifier, aiming to promote the dispersion of silica NPs. Through Fourier transform infrared spectroscopy, nuclear magnetic resonance analysis, and mass spectroscopy, we verified that TSPD contains together six ethoxy groups at its two ends. Then, we used this TSPD to modify the pure silica NPs, and this modified silica was abbreviated as D-MS, which is realized by the thermal gravimetric analysis examination, scanning electron microscopy analysis, and dynamic light scattering results. It was clearly observed that D-MS NPs are connected to one another but are not conglutinated tightly, exhibiting a novel predispersed structure with around 1–2 nm certain extent of interparticle distance. Next, we fabricated the following four elastomer nanocomposites such as pure silica/natural rubber (NR) composite (PS–NR), D-MS/NR composite (DMS–NR), bis-(γ-triethoxysilylpropyl)-tetrasulfide (TESPT)-modified silica/NR composite (TS-NR), and TESPT-modified D-MS/NR composite (T&DMS-NR) and found that the Payne effect is the smallest for T&DMS–NR via the combination use of the D-MS and the traditional coupling agent TESPT, which is attributed to its best dispersion state evidenced by the transmission electron microscopy results. Moreover, by measuring a series of other important mechanical performances such as the stress–strain curve, the dynamic strain dependence of the loss factor, and the heat build-up, we concluded that the T&DMS–NR system greatly exceeds those of the three other rubber composites. In general, this new approach provides a good opportunity to prepare a silica/rubber composite with excellent properties in mechanical strength and dynamic behavior by tailoring the fine dispersion of NPs.
Abstract Tunable circularly polarized luminescence (CPL) has attracted substantial research interest. Till date, the main methods for adjusting CPL is by changing the ratio of fluorescent components and/or regulating external stimuli. Although these adjustment methods have been demonstrated to be reliable, most of them show disadvantages including challenging molecular design, complicated and cumbersome material fabrication, and rigorous adjustment conditions. Herein, the “Surface‐Filming Assembly” (SFA) strategy for conveniently and efficiently modulating CPL by taking the perovskite/chiral helical polyacetylene system as a model is proposed and established. This strategy can facilely achieve multicolor CPL by simply changing the color (or number) of perovskite fluorescent layers and/or the attaching order of the perovskite layers in the assembled multilayer film. Compared with previously reported methods, the SFA strategy integrates the preparation process and adjustment in one single step, simplifying the preparation process (especially the preparation of perovskite with different ratios of halogen atoms) and making adjustment simple and efficient. The SFA strategy and different CPL generation mechanisms to achieve multicolor and white‐color emission with g lum up to 10 −2 are combined. Based on the CPL film and the solvent sensitivity of perovskite, a solvent‐responsive CPL‐emitting switch and further applied the CPL sample in multiple information displays and encryption are realized.
In this paper, the research progress of compounding method using pristine clay and commercialised rubber latex to produce rubber/layered silicate nanocomposites, namely, latex compounding method, is summarised. The properties of a series of rubber/clay nanocomposites prepared by latex compounding method are systematically presented. Latex compounding method is a low cost and easily controlled process, and quite promising to be industrialised. The resulting structure of the nanocomposites by latex compounding method is either 'separated structure' or 'intercalated structure'. The nanocomposites exhibited desirable properties, such as excellent tensile strength, superior gas barrier property, improved flame retardant property, outstanding antifatigue properties, etc. As a result, the first production line of kiloton clay/rubber nanocomposites materials in China was established and a 10 000 ton scaled production line is being constructed. The applications of the nanocomposites in tire inner tube, tire inner liner, off the road tire tread and conveyer belt are investigated and initially presented.
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