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PubMed | Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, REPUBLIC RESOURCES and Beijing University of Chemical Technology
Type: Journal Article | Journal: Soft matter | Year: 2016

By adopting coarse-grained molecular dynamics simulation, we investigate the effects of end-functionalization and shear flow on the destruction and recovery of a nanorod conductive network in a functionalized polymer matrix. We find that the end-functionalization of polymeric chains can enhance the electrical conductivity of nanorod filled polymer nanocomposites, indicated by the decrease of the percolation threshold. However, there exists an optimal end-functionalization extent to reach the maximum electrical conductivity. In the case of steady shear flow, both homogeneous conductive probability and directional conductive probability perpendicular to the shear direction decrease with the shear rate, while the directional conductive probability parallel to the shear direction increases. Importantly, we develop a semi-empirical equation to describe the change of the homogeneous conductive probability as a function of the shear rate. Meanwhile, we obtain an empirical formula describing the relationship between the anisotropy of the conductive probability and the orientation of the nanorods. In addition, the conductivity stability increases with increasing nanorod volume fraction. During the recovery process of the nanorod conductive network, it can be fitted well by the model combining classical percolation theory and a time-dependent nanorod aggregation kinetic equation. The fitted recovery rate is similar for different nanorod volume fractions. In summary, this work provides some rational rules for fabricating polymer nanocomposites with excellent performance of electrical conductivity.


Li C.Y.,Beijing University of Chemical Technology | Wang W.C.,Key Laboratory of Carbon Fiber and Functional Polymers | Wang W.C.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | Xu F.J.,Beijing University of Chemical Technology | And 3 more authors.
Journal of Membrane Science | Year: 2011

A facile method to immobilize the initiators onto the substrate is desirable for surface initiated atom transfer radical polymerization (ATRP). In this work, a two-step process was first developed for covalent immobilization of ATRP initiators on the outside and inside surfaces of the porous nylon membrane. The nylon membrane was functionalized with poly(dopamine), and the bromoalkyl initiators were then immobilized on the poly(dopamine) functionalized nylon membrane surfaces in a two-step solid-phase reaction, followed by ATRP of acrylic acid (AAc), which was deprotonated by the addition of NaOH in an aqueous solution. The resulting nylon membranes with grafted poly(acrylic acid) (PAAc) side chains were characterized by X-ray photoelectron spectroscopy (XPS). The morphology of the nylon membranes was studied by scanning electron microscopy (SEM). The results indicated that the grafted PAAc polymers formed uniformly inside the pores throughout the entire membrane. With the increase of the polymerizing time, the average diameter of the pores became smaller. A kinetics study revealed that the chain growth from the membranes was consistent with a " controlled" process. The nylon-g-PAAc membranes exhibit rapid and reversible responses of the flux to the environmental pH varied from 3 to 8. Between pH 3.5 and 5.5, the membranes demonstrated a pH-valve function as the carboxyl group changed from neutral to charged states with a corresponding variation of chain configuration. © 2010 Elsevier B.V.


Liu J.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | Liu J.,Beijing University of Chemical Technology | Wu S.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | Zhang L.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | And 3 more authors.
Physical Chemistry Chemical Physics | Year: 2011

By employing an idealized model of a polymer network and filler, we have investigated the stress-strain behavior by tuning the filler loading and polymer-filler interaction in a broad range. The simulated results indicate that there actually exists an optimal filler volume fraction (between 23% and 32%) for elastomer reinforcement with attractive polymer-filler interaction. To realize this reinforcement, the rubber-filler interaction should be slightly stronger than the rubber-rubber interaction, while excessive chemical couplings are harmful to mechanical properties. Meanwhile, our simulated results qualitatively reproduce the experimental data of Bokobza. By introducing enough chemical coupling between the rubber and the filler, an upturn in the modulus at large deformation is observed in the Mooney-Rivlin plot, attributed to the limited chain extensibility at large deformation. Particularly, the filler dispersion state in the polymer networks is also characterized in detail. It is the first demonstration via simulation that the reinforcement mechanism stems from the nanoparticle-induced chain alignment and orientation, as well as the limited extensibility of chain bridges formed between neighboring nanoparticles at large deformation. The former is influenced by the filler amount, filler size and filler-rubber interaction, and the latter becomes more obvious by strengthening the physical and chemical interactions between the rubber and the filler. Remarkably, the reason for no obvious reinforcing effect in filled glassy or semi-crystalline matrices is also demonstrated. It is expected that this preliminary study of nanoparticle-induced mechanical reinforcement will provide a solid basis for further insightful investigation of polymer reinforcement.


Wang L.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | Zhao S.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | Zhao S.,Beijing University of Chemical Technology | Li A.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | And 2 more authors.
Polymer | Year: 2010

Solution polymerized styrene-butadiene rubber (SSBR) and SSBR with tert-Butylchlorodiphenylsilane (TBCSi, large-volume functional groups) at the two ends of macromolecular chains (T-SSBR) were prepared by anionic polymerization. The molecular structure parameters of T-SSBR and SSBR were characterized and the ratio of the amount of macromolecular chain ends connected with TBCSi to total macromolecular chain ends (i.e., end-capping efficiency) was calculated. The comprehensive properties of T-SSBR and SSBR composites filled with carbon black (CB) were investigated. The results showed that T-SSBR composites presented lower Payne effect (namely better CB dispersion) than those of SSBR composites, which led to decrease in hardness, internal friction, dynamic compression heat built-up and permanent set of T-SSBR composites, significant increase in tensile strength, elongation at break, tear strength and resilience of T-SSBR composites, and excellent balance between wet-skid resistance and rolling resistance. However, compared with SSBR composites, T-SSBR composites presented longer stress-relaxation time, bigger die-swell and higher apparent viscosity, as well as slightly inferior dynamic-cutting resistance. All the above, owing to the end-capping of TBCSi, which could immobilize the free chain ends of T-SSBR (i.e., to reduce the friction loss of molecular chains and create a greater degree of orientation in the force field), and adsorb CB, the comprehensive performances of T-SSBR were better than those of SSBR and T-SSBR terminated with styrene-TBCSi (TS-SSBR) were far superior to those of T-SSBR terminated with butadiene-TBCSi (TB-SSBR). Accordingly, the former was suitable for the tread of green tires. © 2010.


Liu J.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | Liu J.,Beijing University of Chemical Technology | Wu Y.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | Shen J.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | And 3 more authors.
Physical Chemistry Chemical Physics | Year: 2011

By tuning the polymer-filler interaction, filler size and filler loading, we use a coarse-grained model-based molecular dynamics simulation to study the polymer-filler interfacial structural (the orientations at the bond, segment and chain length scales, chain size and conformation), dynamic and stress-strain properties. Simulated results indicate that the interfacial region is composed of partial segments of different polymer chains, which is consistent with the experimental results presented by Chen et al. (Macromolecules, 2010, 43, 1076). Moreover, it is found that the interfacial region is within one single chain size (Rg) range, irrespective of the polymer-filler interaction and the filler size, beyond which the bulk behavior appears. In the interfacial region, the orientation and dynamic behaviors are induced by the interfacial enthalpy, while the size and conformation of polymer chains near the filler are controlled by the configurational entropy. In the case of strong polymer-filler interaction (equivalent to the hydrogen bond), the innerest adsorbed polymer segments still undergo adsorption-desorption process, the transport of chain mass center in the interfacial region exhibits away from the glassy behavior, and no plastic-like yielding point appears in the stress-strain curve, which indicates that although the mobility of interfacial polymer chains is restricted, there exist no "polymer glassy layers" surrounding the filler. In addition, it is evidenced that the filler particle prefers selectively adsorbing the long polymer chains for attractive polymer-filler interaction, validating the experimental explanation of the change of the bound rubber (BR). In short, this work provides important information for further experimental and simulation studies of polymer-nanoparticle interfacial behavior. © the Owner Societies 2011.


Fu Y.,State Key Laboratory of Organic Inorganic Composites | Fu Y.,Beijing University of Chemical Technology | Liu L.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | Liu L.,Beijing University of Chemical Technology | And 4 more authors.
ACS Applied Materials and Interfaces | Year: 2014

Using tetraethyl orthosilicate as a main raw material, silica nanofibers (SiNFs) were prepared through the combination of a sol-gel process and an electrospinning technique followed by pyrolysis. Surface modified electrospun SiNFs developed by self-polymerization of polydopamine on the surface (SiNFs-PDA) served as templates for the electroless plating of silver nanoparticles (Ag NPs), using glucose as a reducing agent. The electrical resistivity of silver coated SiNPs-PDA (SiNFs-PDA/Ag) was measured by the four-point probe method and was found to be as low as 0.02 mΩ·cm at room temperature. The morphology of SiNFs-PDA/Ag before and after the blending with silicon rubber indicated a strong interaction between the silver layer and the SiNFs-PDA. The electrical and mechanical properties of the silicon rubber filled with SiNFs-PDA/Ag were studied to demonstrate the conductive performance application of SiNFs-PDA/Ag. © 2014 American Chemical Society.


Zhu L.,Beijing University of Chemical Technology | Zhu L.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | Lu Y.,Beijing University of Chemical Technology | Lu Y.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | And 6 more authors.
Applied Surface Science | Year: 2012

Inspired by the bio-adhesive proteins secreted by mussels for attachment to almost all wet substrates, a facile method involving oxidative polymerization of dopamine was proposed to prepare highly hydrophilic carbon black (CB) particles. A self-assembled polydopamine (PDA) ad-layer was formed via the oxidative polymerization of dopamine on the surface of CB simply by dipping the CB into an alkaline dopamine solution and mildly stirring at room temperature. The process is simple, controllable, and environment-friendly. The surface composition and structure of the CB were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The surface morphology of the CB was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the PDA ad-layer was successfully deposited on the CB surfaces. The PDA-functionalized CB (CB-PDA) gave a stable colloidal dispersion in water. Contact angle measurement results indicated that the hydrophilicity of CB was significantly improved after dopamine modification. TGA results confirmed that the modified CB maintained good heat resistance. The method provided a facile route to prepare hydrophilic CB having terminal hydroxyl groups. © 2012 Elsevier B.V. All rights reserved.


Wang W.,Beijing University of Chemical Technology | Li R.,Beijing University of Chemical Technology | Tian M.,Key Laboratory of Carbon Fiber and Functional Polymers | Liu L.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | And 4 more authors.
ACS Applied Materials and Interfaces | Year: 2013

A facile method was developed to fabricate highly electrically conductive aramid fibers. The immobilization of silver nanoparticles on the surface of polymetaphenylene isophthamide (PMIA) fibers was carried out by the functionalization of the PMIA fibers with poly(dopamine), followed by electroless silver plating. The poly(dopamine) (PDA) layer was deposited on the PMIA surface by simply dipping the PMIA substrate into an alkaline dopamine solution. The silver ions can be chemically bound to the catechol and indole functional groups in PDA. The silver ions were reduced into silver nanoparticles by using glucose as the reducing agent, resulting in a distinct silver layer on the PMIA surface. The obtained silver deposit was homogeneous and compact. The chemical composition of the modified PMIA fibers was studied by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS), and the crystalline structure of the silver-coated PMIA fibers was characterized by powder X-ray diffraction (XRD). The topography of the modified PMIA fibers was investigated by scanning electron microscopy (SEM). The four-point probe resistivity meter was used to study the electrical resistivity of the silver-coated PMIA fibers, the results indicated that the electrical resistivity could be as low as 0.61 mΩ·cm, with a controllable silver content, and a satisfactory stability by ultrasonic treatment. © 2013 American Chemical Society.


Li Q.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | Zhao S.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials | Zhao S.,Beijing University of Chemical Technology | Pan Y.,Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials
Journal of Applied Polymer Science | Year: 2010

The vulcanization properties, mechanical properties of hydrogenated nitrile rubber (HNBR) filled with carbon black (N550), zinc dimethacrylate (ZDMA), SiO2 independently and two of three kinds of fillers together were investigated, respectively. The filler-dispersion was characterized by the transmission electron microscopy (TEM) and dynamic mechanical properties. The results showed that HNBR composite filled with SiO2 or ZDMA displayed high tensile strength, elongation at break and compression set. The HNBR composite filled with N550 displayed low compression set, tensile strength and elongation at break. The dispersion of SiO2 in HNBR compound was better than that in HNBR vulcanizates because of SiO2 particles self-aggregation in vulcanizing processing. ZDMA particles with micron rod-like and silky shape in HNBR compounds changed into near-spherical poly-ZDMA particles with nano size in HNBR vulcanizates by in situ polymerization reaction. The N550 particles morphology exhibited no much change between HNBR compounds and vulcanizates. N550/ZDMA have the most effective reinforcement to HNBR and the appropriate amount of ZDMA is about 25% of total filler amount by weights. The theory prediction for Payne effect (dispersion of the filler) shown by the dynamic properties is identical with actual state observed by TEM. © 2010 Wiley Periodicals, Inc.


Wang W.,State Key Laboratory of Organic Inorganic Composites | Wang W.,Beijing University of Chemical Technology | Cheng W.,State Key Laboratory of Organic Inorganic Composites | Cheng W.,Beijing University of Chemical Technology | And 8 more authors.
Electrochimica Acta | Year: 2012

A biomimetic method for the preparation of highly conductive silver-plated polyethylene terephthalate (PET) fiber was demonstrated. First, the PET fibers were functionalized with a bio-inspired polydopamine (PDA) coating, simply by being dispersed in a dopamine solution under mild stirring at room temperature. Electroless plating of silver was then carried out on the surface of the PET-PDA fiber. An aqueous solution of silver nitrate and glucose was used as silver precursor and reducing reagent, respectively. The overall procedure is fast, simple, efficient, nontoxic, as well as controllable. The PDA layer on the PET surface was characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and contact angle measurement. The crystalline structure of the modified PET fiber was studied by X-ray diffraction (XRD). The morphology of the PET-PDA and the PET-Ag fiber was observed by scanning electron microscopy (SEM). SEM results showed that the silver layer coated on PET-PDA was continuous, uniform, and compact. The as-prepared PET-Ag fibers have good electrical conductivity, with surface resistivity as low as 0.4 mΩ cm. The binding force between the silver layer and PET-PDA fiber was strong enough that the silver layer remained compact and continuous after the PET-PDA/Ag fiber was rinsed under ultrasound for 4 h. © 2012 Elsevier Ltd.

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