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Graphical abstract Highlights • A novel hydrothermal self-assembled strategy is proposed for constructing 3D segregated graphene network in polymer matrix. • The shape of the products can be controlled by changing the types of reactors. • The nanocomposites present unique mechanical properties and competitive electrical conductivity. • The post-impregnation process can significantly improve the electrical conductivity of the nanocomposites. Abstract Constructing three-dimensional segregated graphene (3DG) network in polymer matrix is very effective in fabricating highly conductive polymer composites. However, it remains challenging to control the distribution of graphene with a concise and efficient method though the past efforts have been made. In this contribution, we propose a novel hydrothermal self-assembled strategy in combination of the post-impregnation process to prepare highly conductive polymer/graphene composites. Specifically, styrene-butadiene rubber/graphene nanocomposites with a three-dimensional graphene network (3DG-SBR) were prepared by employing the hydrothermal self-assembling, followed by impregnating by silver nitrate. The resultant graphene/styrene-butadiene rubber/silver particle (3DG-SBR-Ag) nanocomposite with 1.66 vol% of graphene exhibits the conductivity of 512 S m−1, which is competitive to those prepared by template-guided assembly strategy. Impressively, the polymer composite possesses mechanical robustness due to the strong interfacial reaction between graphene and polymer matrix. This synthetic approach for graphene-based nanocomposites is generic, scalable, flexibility in complex geometry and cost-effective. The as-prepared products could potentially be applied as competitive candidates for practical application in electromagnetic wave absorption and electromagnetic interference shielding. [ABSTRACT FROM AUTHOR]

Abstract A combination of malleability, supramechanical properties and multi-stimuli response into catalyst-free and commercially available polymer-based networks is particularly attractive to extend the realm of thermally malleable polymers. Toward this goal, herein we demonstrated a paradigm by introducing dynamic imine bonds into styrene-butadiene rubber (SBR)/graphene composites. SBR was firstly grafted with aldehyde groups and then cross-linked with p -phenylene diamine and it-modified graphene through imine condensation between aldehyde and amino groups. The crosslinked networks were able to alter their topologies via imine exchange reactions in both the bulk network and SBR-graphene interphase in the absence of catalyst, enabling them to be recycled and reshaped under heating or IR irradiation. The incorporation of graphene led to spectacular improvements on the mechanical properties of vitrimer composites, and the mechanical properties could be tuned through solid-state drawing. The relationships between morphological structure and dynamic properties as well as mechanical properties of the vitrimer composites were addressed. [ABSTRACT FROM AUTHOR]

Abstract Covalently cross-linked elastomers with high elasticity are widely found in daily life and high-tech areas. However, the irreversibility of the crosslinked networks hinders the rubber products from reprocessing or recycling, causing a major environmental problem. Recently developed vitrimer chemistry provides fantastic avenues for cross-linked elastomers to achieve full reprocessability and recyclability. Herein, we disclose a novel C N transalkylation of pyridinium by model studies and implant this chemistry into the interfaces of an elastomeric composite. As a proof of concept, (3-bromopropyl)trimethoxysilane modified silica was used to crosslink butadiene-styrene-vinylpyridine rubber, forming pyridiniums in the interfaces. The composites were prepared by straightforward mechanical compounding and subsequent hot-pressing. Because of the covalent interfacial bridges and excellent dispersion of silica, the composites possess robust mechanical properties. Furthermore, the C N transalkylation reactions of pyridiniums at elevated temperature endows the composites with vitrimer properties, such as malleability and reprocessability. As the pyridine moieties can be easily introduced into a great variety of commercial polymers, we envision this newly demonstrated C N transalkylation of pyridinium possesses significant potential in broadening the gallery of vitrimer materials. [ABSTRACT FROM AUTHOR]

• The morphology of CoP/CC can be adjusted with appropriate ammonium citrate. • The change of morphology increased the electrochemically active surface area. • Ammonium citrate can regulate the electronic structure of CoP/CC. • The HER performance of the catalyst was significantly improved. The development and improvement of new transition metal-based catalysts to replace Pt/C electrodes in electrolytic water hydrogen evolution has attracted much attention. In this work, we used ammonium citrate as additive, mixed with cobalt nitrate, through hydrothermal and phosphating methods to get supported on carbon cloth catalyst with new morphology (referred to as E380-CoP/CC, E380 stands for ammonium citrate). Benefit from the dense and fine nanosheet structure, compared with cobalt phosphating alone, the catalyst E380-CoP/CC has a significant improvement in hydrogen evolution performance. In 1 M KOH, the overpotential is 57 mV at the current density of 10 mA cm−2, and the Tafel slope is only 40 mV dec-1, which is very close to the hydrogen evolution performance of Pt/C electrode. In addition, the catalyst has favorable stability and superior hydrogen evolution performance after undergoing CV 2000 cycles and 48 h i- t test. This work offers a reliable idea for realizing electrolytic water hydrogen evolution technology with high efficiency and energy saving. [ABSTRACT FROM AUTHOR]

The SiO 2 insulating layer was prepared on the FeSiCr powders successfully by one-step dumping sol-gel method and ammonia was used as the catalyst. It is found that the growth of SiO 2 layer can be tuned by the ammonia concentration. Within the reaction time of 0.5 h, SiO 2 grows with heterogeneous nucleation when the ammonia concentration is 0.08–0.16 ml/g, and SiO 2 coating layer was relatively uniform. With a high ammonia concentration of 0.20–0.24 ml/g, SiO 2 grows with both heterogeneous and homogeneous nucleation, and SiO 2 particles gathered and grew. The saturation magnetization and effective permeability of FeSiCr@SiO 2 SMCs gradually decrease with the increase of ammonia concentration, while the specific resistance, quality factor and DC-bias property increase. With the ammonia concentration of 0.12 ml/g, the thickness of SiO 2 insulating layer was about 30–60 nm. The annealed FeSiCr@SiO 2 soft magnetic composite shows good soft magnetic performance with effective permeability and core loss of 45.52 and 418.32 kW/m3 at 0.05 T and 100 kHz, respectively, and the quality factor of 76.5 at 1 MHz. • FeSiCr@SiO 2 soft magnetic composites were prepared by one-step dumping sol-gel method. • The growth of SiO 2 insulation layer on magnetic powders can be tuned by the ammonia concentration. • SiO 2 grows with heterogeneous nucleation when the ammonia concentration is 0.08–0.16 ml/g. • With the ammonia concentration of 0.12 ml/g, the thickness of SiO 2 insulating layer was ∼30–60 nm. • μ e and P cv were 45.52 and 418.32 kW/m3 at 0.05T and 100 kHz, respectively, and Q was 76.5 at 1 MHz. [ABSTRACT FROM AUTHOR]

Inverse vulcanization provides a facile but effective methodology to create sulfur-based polymers with diverse applications by utilization of element sulfur, a massive waste product from petroleum industry. An integration of functional groups into sulfur-based polymers may inject new vitality for the traditional discipline of rubber composites, though the examples remain limited. Herein, we reported the synthesis of polysulfur copolymers (STs) via one- or two-step methods by inverse vulcanization of sulfur and triethoxyvinylsilane (TEVS) and their function mechanism in silica-filled diene rubber composites. Owing to the presence of polysulfide and multiple alkoxysilyl moieties, STs could provide two functions of vulcanizator and interfacial modifier through the reaction with the rubber chains and silica, enabling the crosslinking of rubber and uniform dispersion of silica. Importantly, ST -modified composites exhibited more uniform silica dispersion and stronger interfacial interaction than sulfur cross-linked BR/silica composites modified with conventional coupling agents, thus leading to more enhancements of the mechanical properties. Moreover, the mechanism of ST copolymers in the silica filled diene rubber composites was proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

Covalent bonds mediated interfaces are generally favorable for transferring interfacial stress and hence rationalizing the mechanical properties of the filled elastomeric composites. Aiming at reprocessable yet robust elastomeric composites, in this contribution, exchangeable interfacial crosslinks are introduced into the interfaces between epoxidized natural rubber (ENR) and multi-walled carbon nanotubes (MWCNTs). This is accomplished by functionalizing MWCNTs with carboxyl groups through diazo-coupling reaction and then incorporating the modified MWCNTs into diacid-cured ENR. Accordingly, covalent β -hydroxy ester bonds result in the interfaces between ENR and MWCNTs. The formation of covalent interfaces enables much uniform dispersion of MWCNTs and stronger interfacial adhesion. Comparing to the ENR filled with pristine MWCNTs, the modified composites exhibit much improved mechanical performance. Importantly, the exchangeable nature of interfacial β -hydroxy ester bonds has promoted effect on the reprocessibility of epoxy-MWCNTs vitrimers. Overall, we envision this interfacial strategy can provide an alternative avenue towards reprocessable yet robust elastomeric composites. [ABSTRACT FROM AUTHOR]

It remains a huge challenge to realize the homogeneous graphene dispersion in elastomer matrix by a simple and general compounding method. Herein, we develop a straightforward slurry compounding method for preparation of rubber/graphene composites with well-dispersed graphene. Specifically, TPG (tea polyphenol reduced graphene)/ethanol slurry was first collected by solvent exchange after the reduction of graphene oxide by tea polyphenol and then directly melt compounded with chlorosulfonated polyethylene (CSM) in a two-roll mill to produce the composites. As revealed by the XRD and morphological studies, TPG homogeneously dispersed in CSM matrix, which together with the strong interfacial interaction between TPG and CSM contribute to the remarkable improvement in mechanical properties of the resulted composites. We envision that the present work offers a straightforward yet effective methodology for preparing high-performance elastomer/graphene composites via conventional melt compounding. [ABSTRACT FROM AUTHOR]

The exploitation of generic strategy for preparation of conductive elastomer composites with interconnected filler network is of significant scientific and technical interests. Herein, we report a novel, green and effective strategy to prepare conductive natural rubber (NR) composites with interconnected graphene network structure. It is found that the Pickering emulsion template is effective in constructing 3D interconnected graphene oxide (GO) networks while the thermal treatment during hot pressing step is able to convert GO to conductive thermal reduced graphene (TRG). This strategy does not rely on the toxic and corrosive reducing agents and the adopted solvents in Pickering emulsions can be recycled and reused, which makes the process environmentally friendly. As a result, interconnected graphene network is well constructed within NR matrix, which significantly enhances the electrical conductivity, mechanical properties and lowers the percolation threshold of the resulted composites. Specifically, with the incorporation of 1.90 vol% TRG, the electrical conductivity of NR composites with interconnected graphene network structure is more than 7 orders of magnitude higher than that of NR composites with uniform graphene dispersion. More intriguingly, this GO stabilized Pickering emulsion template strategy can also be used to realized the selective distribution of carbon nanotubes and assemble them into interconnected network structure, further facilitating the conductivity improvement of the resulted composites. Overall, we envision that the present work offers new insights into the design of conductive elastomer composites. [ABSTRACT FROM AUTHOR]

The (Bi 0.5 Nb 0.5 ) x Ti 1- x O 2 (BNTO, 0 ≤ x ≤ 0.05) ceramics were synthesized by a standard conventional solid-state reaction. The effects of sintering temperature and composition x on the crystal structure, microstructure, and dielectric properties of BNTO ceramics were investigated. A pure rutile phase is achieved as x ≤ 0.01, and secondary phase Bi 1.74 Ti 2 O 6.624 is detected as x ≥ 0.025. BNTO ceramic with x = 0.025 shows a high dielectric constant (155.1 k) and low dielectric loss (0.042) at 1 kHz (room temperature). Colossal permittivity is primarily related to Maxwell-Wagner effect, electron-pinned defect-dipoles or weak-binding electron. The low dielectric loss is argued to Bi ions which are doped into TiO 2 lattice and the formation of Bi 1.74 Ti 2 O 6.624 phase. [ABSTRACT FROM AUTHOR]

Ruthenium (Ru) is considered as a promising element for constructing alkaline hydrogen evolution (HER) catalysts due to its rapid water dissociation kinetics and low-cost advantages than Pt. Alloying can optimize the electrochemical performance of metals and reduce the usage of the noble metal. Herin, RuCo alloy nanoparticles were grown in-situ on N-doped carbon nanofibers (RuCo/NCNF) by electrospinning and graphitization. Under thermodynamic driving force, the Ru and Co elements formed RuCo alloys. It is worth noting that the Ru not only improved the catalytic performance, but also reduced the nanoparticle size and exposing more active sites. Moreover, N-doped carbon nanofiber was not only used to load RuCo alloy nanoparticle, but also as a good substrate for the HER reaction. Therefore, the RuCo/NCNF had fabulous catalytic activity in alkaline media. Furthermore, the in-situ growth also endowed the RuCo/NCNF with excellent stability, HER performance was not significantly reduced even after 40 h stability test. And when the Ru:Co = 1:8, RuCo/NCNF had the excellent HER catalytic performance. Only 41 mV was required to drive a current density of 10 mA cm−2, with Tafel Slope as low as 64.8 mV dec−1. • RuCo alloy nanocrystals were growing in-situ on N-doped carbon nanofibers. • The strong synergetic behavior between Ru and Co via alloying improved and optimized the electrochemical performance of catalysts. • RuCo alloy nanocrystals anchored on N-doping carbon nanofibers exhibit exceedingly low overpotentials and small Tafel slopes in alkalinemV. • It presents superb conductivity and durable stability with the existence and protection of carbon. [ABSTRACT FROM AUTHOR]

New temperature stable 4 wt% LiF-doped (1− x )Li 2 Mg 3 TiO 6 - x Ca 0.8 Sr 0.2 TiO 3 (LMT-CST, x = 0.10, 0.15, 0.20, 0.25) composite ceramics were fabricated by solid-state reaction for developing ultra-low temperature (≤800 °C) sintering microwave dielectric ceramics. Sintering temperatures of LMT-CST ceramics were successfully lowered to 725 °C due to LiF liquid-phase sintering and well-densified microstructures were obtained at 800 °C. Excellent microwave dielectric properties of ε r = 18.8, Q × f = 48200 GHz (at 8.2 GHz), τ f = 0.3 ppm/°C was obtained at 800 °C for 0.8 LMT-0.2CST-4wt% LiF ceramics. Such sample was compatible with Ag electrodes, which suggests suitability of the developed material for LTCC applications. [ABSTRACT FROM AUTHOR]

• Ce-doping results in the unique nested-like morphology. • Ce-CoP NWs/CC was prepared via hydrothermal and phosphorization method. • Ce-CoP NWs/CC exhibits excellent HER and OER activity in 1 M KOH. • It demands 1.506 and 1.624 V to deliver j 10 and j 50 , respectively. The development of efficient electrocatalyst is one of the effective ways to speed up the efficiency of water electrolysis. In this work, we prepared a nested-like Ce-doped CoP nanowires catalytic material on carbon cloth by simple hydrothermal and phosphating methods. After adjusting the doping ratio of Ce, the doping ratio (Ce/W = 6 %) with the best performance is obtained and named as Ce-CoP NWs/CC. The Ce-CoP NWs/CC exhibits preeminent electrocatalytic activity with low overpotentials with 80 and 290 mV at 10 mA cm−2 for HER and OER, respectively. Moreover, the Ce-CoP NWs/CC electrocatalyst also exhibits excellent electrochemical performance in overall water splitting with a low voltage of 1.506 V at 10 mA cm−2, outperforming many reported electrocatalysts. This work provides a feasible electrocatalytic material for the introduction of rare earth elements into water electrolysis. [ABSTRACT FROM AUTHOR]

The filler dispersion and network in rubber composites are critical factors in determining the properties of the composites. In this study, we incorporate a graphene-like layered material, molybdenum disulfide (MoS 2 ), to partly substitute carbon black (CB) in styrene butadiene rubber/CB composites, and primarily focus on the filler dispersion and network as well as their effects on the mechanical properties of the composites. With the addition of MoS 2 , the dispersion of CB is greatly improved and the CB agglomerates are suppressed. When MoS 2 substitution content is less than 1 phr, the modulus and strength of the composites are slightly decreased due to the release of trapped rubber from CB agglomerates, while the dynamic mechanical properties are significantly improved. At higher MoS 2 substitution loading, MoS 2 and CB form a denser and continuous hybrid filler network, which shows remarkable synergistic effects in improving the both static and dynamic mechanical properties of the composites. For example, the addition of 3 phr MoS 2 leads to a 50% increase in the tensile modulus and 10 °C decrease in the heat build-up of the composite. [ABSTRACT FROM AUTHOR]

The energy loss of tires during service is closely related to the hysteresis of tire tread, which is governed by the dispersion and interface of the elastomer nanocomposites. However, traditional undeformable spherical fillers have approached a bottleneck in regulating the viscoelasticity and lowering the hysteresis loss. Herein, the designed covalent interface in the graphene/elastomer nanocomposite maximizes the reinforcement of the nanomaterial as well as minimizes the dynamic energy loss. The reinforced interfacial interaction, an ultralow percolation threshold of tensile strength and high reinforcement synergistically benefit these nano-organized rubber nanocomposites. The energy losses under dynamic loading are largely suppressed in this material, due to the reduced nano-scale frictions. The developed graphene/elastomer nanocomposites are applied to typical dynamic rubber product - auto tires, and the tests indicate that these tires possess energy efficiency close to the highest “A-grade”, which gave great economic and environmental improvements. The critical role of interface structure in the performance of the elastomer nanocomposites was revealed and new design strategy for low dynamic energy losses in rubber products was suggested. [ABSTRACT FROM AUTHOR]

In order to simulate the effect of non-rubber components on strain-induced crystallization (SIC) in natural rubber (NR), sacrificial metal-ligand bonds are incorporated, for the first time, into cis -1,4 polyisoprene cured by sulfur. The incorporation of sacrificial bonds is found to bring in much smaller onset strain for SIC and higher crystallinity compared with the cis -1,4 polyisoprene with sulfide crosslinks only. Accordingly, the striking improvements in tensile modulus and fracture toughness are achieved. The present work contributes to significant insights for mimicking NR outstanding properties in synthesized cis -1,4 polyisoprene and affords new technological route in improving the mechanical properties of synthesized polyisoprene alternative to the nanofilling. [ABSTRACT FROM AUTHOR]

Low-fired Li 2 SnO 3 ceramics co-doped with MgO–LiF were fabricated by a conventional solid-state route, and their sinterability, microwave dielectric properties were investigated. With increasing MgO content, a novel phase Li 2 Mg 3 SnO 6 was formed. A near-zero τ f value was obtained at 1325 °C for Li 2 SnO 3 -8 wt% MgO ceramics. Furthermore, LiF addition not only successfully lowered the sintering temperatures to 880 °C but also promoted formation of Li 2 Mg 3 SnO 6 . The microwave dielectric properties of Li 2 SnO 3 -8 wt% MgO ceramics were further optimized with increasing Li 2 Mg 3 SnO 6 content. The excellent microwave dielectric properties ( ε r = 14.7, Q × f = 78,400 GHz, and τ f = −0.9 ppm/°C) were achieved at 880 °C for Li 2 SnO 3 -8 wt% MgO-2 wt% LiF ceramics, which is compatible with Ag electrodes and suitable for the low-temperature co-fired ceramics (LTCC) applications. [ABSTRACT FROM AUTHOR]

Li 2 MnO 3 ceramics co-doped with 2 wt% LiF and x wt% TiO 2 ( x =0, 3, 5, 7, 10) were prepared by solid-state reaction for low-temperature co-fired ceramics (LTCC) applications. The sintering temperatures of Li 2 MnO 3 ceramics were successfully lowered to 925°C due to the formation of a LiF liquid phase. Their temperature stability was improved by doping with TiO 2 . A typical Li 2 MnO 3 -2 wt% LiF-5 wt% TiO 2 sample with well-densified microstructures displayed optimum dielectric properties ( ε r =13.8, Q × f = 23,270 GHz, τ f =1.2 ppm/°C). Such sample was compatible with Ag electrodes, which suggests suitability of the developed material for LTCC applications in wireless communication systems. [ABSTRACT FROM AUTHOR]

So far, most of the preparation methods for polymer/boron nitride nanosheets (BNNSs) composites are not suitable for mass production. Here, cost-effective and environmentally friendly water/ethanol were selected as the solvents to prepare BNNSs slurry on large scale by liquid exfoliation/solvent exchange. The slurry was then compounded with styrene-butadiene rubber (SBR) to form the rubber/BNNSs composites via conventional two-roll milling. The sulfide-containing silane was introduced to modify the interface between BNNSs and the rubber. The silane modified BNNSs (Si-BNNSs) has been characterized by FTIR, XPS and TGA. It is found that, with in situ modification of the silane, the rubber/BNNSs composites exhibited significantly improved thermal conductivity. With 10.5 vol% Si-BNNSs incorporated, the thermal conductivity of the composites is increased by 253%, comparing to the neat SBR. Meanwhile, the mechanical properties of the composites are simultaneously largely enhanced. The scalable yet environmentally-friendly slurry approach paves the way for industrial-scale utilization of BNNSs in thermally conductive polymer composites. [ABSTRACT FROM AUTHOR]

The dispersion of nanofiller in polymer composites is critical in governing the ultimate performances. Present study aimed to improve the dispersion of silica in elastomeric materials based on natural rubber (NR) composites using the nanoplatelets of molybdenum disulfide (MoS 2 ), a graphene-like layered inorganic. NR latex was co-coagulated with MoS 2 suspension to form NR/MoS 2 compounds (1∼5 phr). Then silica (30 phr) was incorporated into NR/MoS 2 compounds, followed by curing with sulfur, to obtained NR/MoS 2 /silica composites. The dispersion state of silica in the composites was examined by TEM and the effects of MoS 2 on the performance of the composites were investigated. It was found that a small amount of MoS 2 nanoplatelets significantly improved the silica dispersion. Consequently, the static and dynamic mechanical properties of the crosslinked natural rubber materials were greatly enhanced. The improved dispersion of silica is associated with charge transfer interaction, giving rise to electrostatic repulsion among silica. [ABSTRACT FROM AUTHOR]

The incorporation of interfacial modifiers into silica-filled rubber composite is necessary to optimize the composite properties because abundant silanol groups on silica surface make it essentially incompatible with non-polar rubbers. The modification of silica-filled composites with the commonly used silanes generally causes many constraints such as excessive silane dosage, high temperature compounding, volatile organic compound emission, and loss of toughness of the composite. In this contribution, we reported the use of naturally small molecule thioctic acid (TA) as an intelligent interfacial modifier for silica-filled styrene-butadiene rubber (SBR) composite. The carboxyl group of TA can interact with silica through hydrogen bonds, meanwhile the disulfide bond of TA can be cleaved to generate sulfur radicals and then couple with SBR macroradicals during compounding and curing, making TA a bridge between silica and SBR matrix. In the TA-modified composite, silica dispersion is greatly improved and hydrogen bond-mediated interface is constructed. When comparing with the most widely used bis-(γ-triethoxysilylpropyl)-tetrasulfide, TA-modified composites exhibit simultaneously improved strength, modulus, toughness and tear strength, which is on account of the reversible energy-dissipating mechanism of the hydrogen bond-mediated interfaces. [Display omitted] • Thioctic acid as an interfacial bridge constructs hydrogen bond-mediated interface in silica-filled rubber composites. • Silica dispersion is improved and interfacial adhesion is strengthened in the composites upon modifying with thioctic acid. • The modified composites exhibit simultaneously improved tensile strength, modulus, toughness and tear strength. • Breaking-reformation of hydrogen bonds facilitates energy-dissipating and chain orientation for reinforcing and toughening. [ABSTRACT FROM AUTHOR]

Carbon black (CB) is an irreplaceable filler in the rubber industry, due to its unparalleled cost performance. Nevertheless, the poor CB dispersion in the rubber matrix significantly compromises the overall performance of the composites, especially in the aspect of hysteresis loss. Herein, a novel adamantyl-based imine (DADI) was synthesized and then adopted as the interfacial mediator of natural rubber/CB composites. As demonstrated, the imine moieties on the DADI skeleton are capable of capturing the macroradicals generated by the scission of rubber chains during compounding, followed by stabilizing inside the adamantyl functionalities. These DADI-capped macroradicals can further transfer to the energy traps on the CB surface through electron cloud sharing, which enables strong interfacial adhesion between rubber matrix and CB and hence improves the dispersion state of CB particles. Consequently, with the incorporation of 1phr DADI, the resulting composite achieves remarkable decreases of approximately 6 °C in heat generation and 21% in energy loss. Besides, the aging resistance of the resulting samples is also considerably improved due to the capability of DADI to wipe out reactive radicals. We envisage that the synthetic DADI has great potential to prepare high-performance tire products in terms of low energy loss and superior aging resistance. [Display omitted] • A brand-new adamantyl imine, as the seminal interfacial mediator rubber/carbon black composites, was synthesized. • The interfacial adhesion and filler dispersion of composites were greatly improved. • The resultant composite shows superior energy-saving capability and aging resistance. [ABSTRACT FROM AUTHOR]

Constructing segregated structure in polymer composites is a particularly effective strategy to improve electrical conductivity by selectively distributing fillers in the interstitial space among isolated polymer domains. However, the segregated composites generally suffer from inferior mechanical properties because the fillers at the interfaces hinder chain diffusion and leads to weak interfacial adherence or defects. In this contribution, we present a facile method to fabricate segregated composites with improved electrical conductivities and mechanical properties by creating molecular bridges across the interfaces among the segregated domains. Specifically, β-hydroxyl ester-crosslinked epoxidized natural rubber (ENR) granules were compounded with the master batch of carboxylated nitrile rubber (x NBR) and carbon nanotubes (CNTs), followed by compression molding. In the resultant composites, CNTs embedded in x NBR phase are distributed along the boundaries of ENR domains, and x NBR can act as binder to bridge the crosslinked ENR granules through the reaction of carboxyl groups with the epoxy groups and β-hydroxyl esters on ENR granule surfaces. As a consequence, the segregated composites exhibit greatly improved electrical conductivity and mechanical properties when comparing to their randomly dispersed counterparts. In addition, the segregated network is able to endure deformations and heal damage without significant loss of the electrical conductivity. The conductive and mechanical properties of the composites are found to be closely related to the morphologies of segregated structure and CNT concentration in the continuous x NBR phase. [Display omitted] • Segregated rubber composites with excellent interfacial adherence are prepared by creating molecular bridges among the segregated domains. • The segregated composites exhibit remarkably improved conductive and mechanical properties, and can heal damage. • The properties are closely related to the morphologies of segregated structure and CNT concentration in the continuous phase. [ABSTRACT FROM AUTHOR]

It is well-accepted that thermoplastic vulcanizates (TPVs) integrate the fascinating recyclability of thermoplastics and the mechanical robustness comparable to nano-filled elastomers, deriving from the particular heterogeneous network structure. However, the elasticity of TPVs is inferior to covalently cross-linked elastomers, since the irreversible deformation or even collapse of plastic phases of TPVs will certainly give rise to considerable hysteresis loss and therefore deteriorate the elasticity. Herein, we proposed a facile network design strategy toward covalently cross-linked elastomer with mechanical robustness and recyclability by engineering heterogeneous blend networks into diene-rubber system. Specifically, two conventional diene-rubbers, ethylene propylene diene terpolymer (EPDM) and styrene-butadiene rubber (SBR), were adopted as thermodynamic incompatible pair and then directly admixed. Due to the significant difference in the cross-linking reactivity between the pair, the resulting system assembled into a microphase-separated structure with strong interfacial adhesion upon in situ co-cross-linking. Upon deformation, the overall chain orientation of the networks is promoted by the efficient interfacial stress transfer and a striking reinforcement of the networks is achieved accordingly. More importantly, by virtue of the slightly cross-linking attribute of EPDM component, the resulting system featured with desirable recyclability and high elasticity in comparison with conventional TPVs. We envisage that this work will provide important inspiration for the non-filling reinforcement of elastomers and the development of a new generation of thermoplastic vulcanizates with considerably low hysteresis through manipulating the covalent network heterogeneity. [Display omitted] ● A novel design strategy toword heterogeneously cross-linked rubbers was proposed. ● A heterogenous blend network with strong interfacial adhesion was achieved in situ. ● Striking reinforcement and recyclability were enabled to the resulting systems. ● The covalently cross-linked nature afforded the systems with superior elasticity. [ABSTRACT FROM AUTHOR]

The transfer of vitrimer concept to diene-rubber materials can enable these thermosets with thermo-activated malleability and reprocessability. However, there are still significant gaps in the knowledge of introducing dynamic covalent bonds-based networks directly into rubber matrix without the need for elaborated modification of the molecular architecture. Herein, we demonstrate a one-pot approach to prepare covalently cross-linked diene-rubbers by engineering dynamic silyl ether linkages into the networks. Specifically, based on a thermally initiated thiol-ene reaction, silyl ether-based networks were directly achieved through incorporating silyl ether-containing multifunctional thiols (SE-T x ) into commercially available diene-rubber. The mechanical and dynamic behaviors of the resulting networks can be rationally tuned upon the regulation of the content and functionality of SE-T x cross-linkers. In addition, by virtue of the thermal stability of silyl ether linkages, the resulting networks feature with superior creep resistance at moderate temperatures, while the corresponding network rearrangement ability at elevated temperatures is barely affected, enabling the networks with malleability and recyclability. [Display omitted] • Silyl ether-based multi-thiols (SE-Tx) were synthesized to cross-link diene rubber. • Dynamic silyl ether architecture were directly introduced into elastomer matrix. • The content and functionality of SE-Tx regularly affect the propery of the system. • The systems feature with superior creep resistance at moderate temperatures. [ABSTRACT FROM AUTHOR]

Recent progress in introducing elegant dynamic covalent bonds into covalently crosslinked networks enabled the trade-offs between chemical crosslinking and recycling. Thus far, continuous efforts are made to exploit new dynamic chemistries to address the constrains of intricate preparation procedures and need of catalyst additives in creating dynamic covalent networks. In this work, we report an industrially feasible process to prepare catalyst-free malleable elastomers by engineering dithioacetals as the dynamic motifs into a commercial diene rubber. Specifically, a dithioacetal-containing diacid (BTA) is synthesized and used as a novel crosslinker for epoxidized natural rubber (ENR), by which dynamic dithioacetals are introduced into the elastomeric networks. Small molecule model study shows that dithioacetal exchange can be conducted at elevated temperature without catalyst. In the BTA crosslinked ENR, the thermoactivated dithioacetal exchange reactions can alter its network topologies in an associative pathway and confer it with remarkable reprocessability. The mechanical properties and relaxation rate of the networks can be readily manipulated by varying the dithioacetal concentration. Catalyst-free recyclable elastomers are prepared by incorporating dithioacetals as the dynamic motifs using an industrially feasible process. [Display omitted] • Small molecule model study indicates the dithioacetal exchange without catalyst. • Dithioacetal-containing diacid is used as a crosslinker for epoxidized rubber. • Dynamic dithioacetal motif is incorporated into crosslinked rubber networks. • Dithioacetal exchanges impart the crosslinked networks with reprocessability. • The network properties can be readily manipulated by varying crosslinking density. [ABSTRACT FROM AUTHOR]

Most elastomeric vitrimers suffer from mechanical weakness in practical applications. Inspired by the development of strong and tough biomaterials relying on sacrificial bond-detachment mechanisms, herein we describe the biomimetic design of elastomeric vitrimers with mechanical robustness, preservable malleability, and recyclability by engineering sacrificial metal-ligand coordination bonds into exchangeable networks. In particular, we use a commercially available metal complex, aluminum acetylacetonate (Al(acac) 3), to catalyze cross-linking based on the silylation reaction between hydroxylated natural rubber and hydrosilanes, thus introducing dynamic silyl ether-based architectures into the rubber matrix. At the same time, the Al3+ ions can interact with the free oxygen-containing moieties on the rubber skeleton, enabling labile Al3+ O coordination bonds in the covalent framework to substantially dissipate mechanical energy through reversible bond detachment/reattachment upon deformation. As the organic acetylacetonate ligands of Al(acac) 3 can facilitate the dispersion of Al3+ ions in the matrix, incorporating a small amount of organometallic complex (0.68 wt% of elastomer matrix) achieves an unparalleled improvement of the strength, modulus, and toughness of the resulting vitrimers. Moreover, due to their temperature-dependent nature, the Al3+ O coordination bonds will partially dissociate at elevated temperatures, which only slightly compromises the topological rearrangements of the silyl ether-based network, but barely affects the reprocessability. Unlabelled Image • Dynamic silyl ether linkages are introduced into hydroxylated elastomer through silylation reaction with hydrosilanes. • An organometallic complex is employed as both catalyst for cross-linking and coordinative center for elastomeric matrix. • The metal-ligand coordination bonds undergo reversible bond breaking/reforming to dissipate energy upon deformation. • Introducing 0.68 wt% organometallic complex achieved an unparalleled reinforcement of the vitrimers. • The incorporation of metal-ligand coordination bonds has only a small impact on the network relaxation rate. [ABSTRACT FROM AUTHOR]

• Magnetic Fe cores with varied secondary particle size distributions are prepared. • Size distribution and size ratio greatly affect density and magnetic properties. • Real permeability is inversely proportional to the mean diameter of particles. • Minimum loss factor is obtained at coarse/fine particles mixing ratio of 7:3. The effects of secondary particle size distribution on the electromagnetic properties of the carbonyl iron powder cores have been investigated in this work. For preparing the cores, the iron powders were firstly undergone insulation treatments including phosphorization and organic coating. After granulation, the secondary particles with different size distributions were molded into the final shape and cured at 200 °C. The results show that for the secondary particles with unimodal size distribution, the real part of the complex magnetic permeability of the powder core is in inverse proportion to the particle size. For the cores prepared from the secondary particles with bimodal size distribution, the effects of the size ratio and volume ratio of the coarse particle/fine particle on the magnetic properties are discussed. It is found that the permeability increases with the increasing volume of fine secondary particles. The minimum magnetic loss factor value is obtained at the coarse/fine secondary particles volume ratio of 7:3. The density and magnetic properties including complex permeability and magnetic loss of the cores prepared with coarse/fine particles size ratio of ~3 and ~7 are both in inverse proportional to the volume fraction of coarse secondary particles. The present work indicates that a reasonable size distribution of the secondary particles is required to improve the magnetic properties of the soft magnetic powder cores. [ABSTRACT FROM AUTHOR]

The development of biobased polymers from renewable resources offers a solution to the growing environmental concerns and scarcity of fossil feedstock. The synthesized biobased polymers, especially for biobased elastomers, are mechanically weak, which greatly restricts their applications. In the present work, we demonstrate that the integration of transient and sacrificial quadruple H-bonding motifs into as-synthesized biobased elastomer can enhance the mechanical properties and bestow it with adaptive performance. Specially, the biobased elastomer was synthesized through melting poly-condensation using biobased di-acids and diols as the starting materials. The biobased elastomer is covalently crosslinked and grafted with ureido-pyrimidinone (UPy) containing acrylate through thiol-ene click reaction by using pentaerythritol tetra(3-mercaptopropionate) as the linkers. Under external load, UPy aggregations based on H-bonding can function as sacrificial units through reversible rupture and re-formation events, leading to significant improvements on the modulus and strength of the biobased elastomer while maintaining the extensibility. In addition, the dissociation and re-formation of H-bonding under thermal stimuli impart the elastomer with thermo-activated shape memory behavior. The incorporation of transient and sacrificial quadruple H-bonding motifs into bio-based elastomer that is synthesized from bio-based di-acids and diols can enhance the mechanical properties and bestow it with adaptive recovery. Image 1 • Quadruple H-bonding motifs are introduced into as-synthesized biobased elastomer through thiol-ene click reaction. • UPy aggregations based on H-bonding can act in sacrificial manner to improve modulus and tensile strength of the elastomer while maintaining the extensibility. • Dynamic nature of H-bonding allows the elastomer to access thermo-activated shape memory behavior. • The structure-property relationships of the resulted elastomer materials are studied. [ABSTRACT FROM AUTHOR]

The dispersion of filler and properties of elastomer composites are always the focus in the rubber researching. In this work, RGO/SiO 2 nanocomposites were obtained by self-assembling of silica nanoparticles (SiO 2) and reduced graphene oxide (RGO), which were used to manufacture RGO/SiO 2 -SSBR/BR composites by means of compounding with solution-polymerized styrene butadiene rubber/butadiene rubber (SSBR/BR). The structure and morphology characterization showed that SiO 2 nanoparticles were homogeneously distributed on RGO. With the adding of RGO, the mechanical properties were enhanced and the RGO/SiO 2 -SSBR/BR with 1% weight percentage of RGO possessed the optimal wet skid resistance and rolling resistance compared with commercialized Zeosil 1165 MP highly-dispersed nano-SiO 2 (Zeosil 1165 MP)-SSBR/BR (tan δ is 16.8% higher at 0 °C and 50.0% lower at 60 °C). In addition, the heat build-up exhibited considerable decrease with low RGO weight percentage, and wear resistance considerably enhanced. The reinforced integrated performances provide a potential application of RGO/SiO 2 for green tires. [ABSTRACT FROM AUTHOR]

Microwave dielectric ceramics of Mg 4 Nb 2 O 9 with various excess Mg(OH) 2 were synthesized by the reaction-sintering process method. The effects of excess Mg(OH) 2 on the sintering behavior, phase composition, microstructures and microwave dielectric properties were investigated. XRD patterns show that Mg(OH) 2 as raw materials is more beneficial to obtain the pure Mg 4 Nb 2 O 9 phase than that of MgO. The microwave dielectric properties of Mg 4 Nb 2 O 9 ceramics strongly depended on the sintering temperature, microstructures and secondary phase MgO. With 0.03 M excess Mg(OH) 2 addition, the Mg 4 Nb 2 O 9 /MgO composite ceramics sintered at 1400 °C have excellent microwave dielectric properties of ε r =12.6, Q × f =196,700 GHz and τ f =−47 ppm/°C. [ABSTRACT FROM AUTHOR]

The microstructures, phase compositions and microwave dielectric properties of (1− x )SiO 2 − x TiO 2 (0≤ x ≤0.20) composite ceramics prepared by a conventional oxide mixing method were investigated. XRD patterns conformed that SiO 2 and TiO 2 phases co-existed as a two-phase system and some Ti 4+ ions entered the SiO 2 lattice. Addition of TiO 2 eliminated the formation of tridymite phase. As TiO 2 content x increased, the ε r and τ f values increased gradually, while the Q × f values declined inversely. Under the same amount of TiO 2 content, the ε r and Q × f values increased initially and then decreased slightly with increasing the sintering temperature, whereas the τ f values increased slowly. The 0.84SiO 2 –0.16TiO 2 ceramics sintered at 1275 °C for 3 h possess good dielectric properties of ε r =5.91, Q × f =39,680 GHz (measured at 12.52 GHz), and τ f =−4.53 ppm/°C. [ABSTRACT FROM AUTHOR]

Roxadustat (FG-4592) is a hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) prescribed to patients with low hemoglobin associated with chronic kidney disease. Due to the various HIF-mediated adaptive responses, FG-4592 has attracted significant interest for therapeutic use against various diseases. However, the clinical application of Roxadustat remains limited due to a lack of understanding of its underlying mechanisms. Herein, we performed label-free quantitative liquid chromatography with tandem mass spectrometry (LC-MS-MS) proteomics and un-targeted metabolomics to study the protein and metabolite alterations in the urine of renal anemia patients before and after Roxadustat therapy. The results were validated by parallel reaction monitoring (PRM). A total of 46 proteins (including 15 upregulated and 31 downregulated proteins) and 207 metabolites were significantly altered after Roxadustat treatment in urine samples obtained from renal anemia patients. Then, the altered proteins were further validated by PRM. Finally, proteomics combined with metabolomics analysis revealed that the Ras signalling pathway, cysteine and methionine metabolism, arginine and proline metabolism, and cholesterol metabolism were the main pathways altered by Roxadustat treatment. The multi-omics analysis revealed that Roxadustat could alter the protein expression and reverse the potential metabolic changes to exert hypotensive, lipid metabolic regulation, and renoprotective effects in clinical practice.

Upcycling of cross-linked rubbers is pressing. The introduction of dynamic covalent bonds into the networks is a popular tactic for recycling thermosetting polymers, but it is very challenging to integrate engineering performance and continuous yet stable reprocessability. Based on traditional rubber formulations, herein, a straightforward strategy is presented for constructing a skeletal network (SN) through interfacial crosslinking and percolation of rubbery granules in a rubber matrix. Rapid exchange reactions involving dynamic interfacial sulfides realize repeated "fragmentation and healing" in the solid-state and consequent reconfiguration of the SN topology of the elastomer, thus endowing the resultant SN elastomer with continuous yet stable re-extrudability. These SN elastomers with hierarchical structures exhibit high gel contents, high resilience, low creep, and reinforcibility competitive to traditional vulcanizates. Specifically, SN elastomers exhibit better overall performance than commercial thermoplastic vulcanizates (TPVs) materials. Overall, a new concept of thermoplastic vulcanizates is proposed, which will promote the sustainable development of rubbers., (© 2023 Wiley-VCH GmbH.)

Polydopamine (PDA) is a natural melanin derived from marine mussels that has good biocompatibility, biodegradability, and photothermal conversion ability. As a new coating material, it offers a novel way to modify the surface of various substances. The drug loading capacity and encapsulation efficiency of PDA are greatly improved via the use of mesoporous materials. The abundant pore canals on mesoporous polydopamine (MPDA) exhibit a uniquely large surface area, which provides a structural basis for drug delivery. In this review, we systematically summarized the characteristics and manufacturing process of MPDA, introduced its application in the diagnosis and treatment of cancer, and discussed the existing problems in its development and clinical application. This comprehensive review will facilitate further research on MPDA in the fields of medicine including cancer therapy, materials science, and biology.

Background: Roxadustat is a new oral anti-renal anemia medication that works by stabilizing hypoxia-inducible factor (HIF) which can activate the expression of more than 100 genes in addition to genes related to anemia. However, the more potential molecular targets of roxadustat are not completely clear. Therefore, it is essential to further reveal its molecular targets to guide its clinical applications., Methods: We performed label-free quantification and LC-MS/MS to study the proteomic alterations in serum exosome of renal anemia patients before and after roxadustat therapy. Results were validated by PRM., Results: A total of 30 proteins were significantly changed after treatment with roxadustat. Among these proteins, 18 proteins were up-regulated (and 12 were down-regulated). The results are statistically significant (P < 0.05). Then, we validated the result by PRM, the results confirmed that TFRC, HSPA8, ITGB3, COL1A2, and YWHAZ were markedly upregulated, while ITIH2 and CFH were significantly downregulated upon treatment with roxadustat., Conclusions: TFRC and HSPA8 could be an important target of the action of roxadustat, and roxadustat may increase cardiovascular risk through its influence on platelet activation. Our results provide a theoretical basis for its wider clinical application and preventing expected side effects., (© 2022. The Author(s).)

It remains challenging to simultaneously realize mechanical robustness, malleability, and functionality in elastomers via facile yet efficient methods. Herein, a simple strategy for the biomimetic heterogeneous design is proposed to achieve mechanically strong, malleable, and functionalized elastomers. We demonstrate the strategy by straightforward mechanical mixing of a highly cross-linked vitrimeric elastomer with a homogeneous gum and subsequent curing, resulting in heterogeneous vitrimeric elastomers (hetero-VEs). The hetero-VEs comprise two phases: a hard phase with dense cross-links and a soft matrix with few cross-links, with excellent interface between the two phases. The hard phases can be deformed upon loading, dissipating energy, which significantly improves the overall mechanical performance of the hetero-VEs. When conductive fillers are incorporated into the soft matrix, due to the volume exclusion effect of the hard phases, the resultant hetero-VEs exhibit high conductivity with a small fraction of fillers. In view of the facile and generic preparation process, this strategy should be a promising way to reinforce and functionalize many vitrimeric elastomer systems.

S-rich MoS2-NCNF hybrid nanomaterials exhibiting extraordinary HER activity, with a very low onset potential of 30 mV and a small Tafel slope of 38 mV per decade, were successfully fabricated by combining N-doped carbon nanofibers and single-layered MoS2 nanostructures with abundant edge active sites.

For the purpose of preparing liquefied graphene oxide (GO), a process consisting of sulfonation with sodium sulfanilic acid and ionization with bulky amine-terminated Jeffamine® was designed and performed. The obtained hybrid fluid is actually a supramolecular ionic liquid (SIL) with sulfonated GO as the central anions and the terminal ammonium groups of Jeffamine® as the surrounding cations. The successful grafting of the GO sheets with Jeffamine®via an ionic structure was verified and the morphology of the SIL was characterized. The SIL based on GO (GO-SIL) exhibits excellent solubility and amphiphilicity. The rheological measurements confirm the essential viscoelasticity and the liquid-like behavior of GO-SIL. The present GO based SIL suggests promising applications in the fabrication of various GO or graphene based composite materials. In addition, the new functionalization method may guide the future work on acquiring derivatives with tunable properties by simply changing the bulky canopy.

High mechanical performance nitrile-butadiene rubber (NBR) with light color was fabricated by the method of in situ formation of zinc disorbate (ZDS) or magnesium disorbate (MDS). The in situ formed ZDS and its polymerization via internal mixing was confirmed by X-ray diffaraction. The mechanical properties, ageing resistance, morphology and the dynamic mechanical analysis were fully studied. It was found that with increasing loading of metallic disorbate both the curing rate and the ionic crosslink density was largely increased. The modulus, tensile strength and tear strength were largely increased. With a comparison between internal mixing and opening mixing, the mechanical performance for the former one was obviously better than the latter one. The high performance was ascribed to the finely dispersion nano domains with irregular shape and obscure interfacial structures. Except for the NBR vulcanizate with a high loading of MDS, the others' ageing resistance with incorporation of these two metallic disorbate was found to be good. Dynamic mechanical analysis (DMA) showed that, with increasing loading of metallic disorbate, the highly increased storage modulus above -20 degrees C, the up-shifted glass transition temperature (Tg) and the reduced mechanical loss were ascribed to strengthened interfacial interactions.

The reinforcement effects of halloysite nanotubes on styrene-butadiene rubber and the modification effect of epoxidized natural rubber on styrene-butadiene rubber/halloysite nanotubes composites were studied. The structure, morphology and properties of styrene-butadiene rubber/halloysite nanotubes composites before and after the incorporation of epoxidized natural rubber were investigated. The results indicated that epoxidized natural rubber can promote the dispersion and orientation of halloysite nanotubes in styrene-butadiene rubber matrix at nanoscale and strengthen interfacial combination between halloysite nanotubes and styrene-butadiene rubber by the formation of covalent bonds and hydrogen bonds between epoxidized natural rubber and halloysite nanotubes. Consequently epoxidized natural rubber can improve the mechanical properties of the vulcanizates of styrene-butadiene rubber/halloysite nanotubes composites. Besides epoxidized natural rubber can decrease the rolling resistance of the vulcanizates and increase the wet grip property of the vulcanizates.

From the point of better biocompatibility and sustainability, biobased shape memory polymers (SMPs) are highly desired. We used 1,3-propanediol, sebacic acid, and itaconic acid, which have been industrially produced via fermentation or extraction with large quantities as the main raw materials for the synthesis of biobased poly(propylene sebacate). Diethylene glycol was used to tailor the flexibility of the polyester. The resulted polyesters were found to be promising SMPs with excellent shape recovery and fixity (near 100% and independent of thermomechanical cycles). The switching temperature and recovery speed of the SMPs are tunable by controlling the composition of the polyesters and their curing extent. The continuously changed switching temperature ranging from 12 to 54 °C was realized. Such temperature range is typical for biomedical applications in the human body. The molecular and crystalline structures were explored to correlate to the shape memory behavior. The combination of potential biocompatibility and biodegradability of the biobased SMPs makes them suitable for fabricating biomedical devices.

In this contribution, halloysite nanotubes (HNTs), a kind of natural hydrophilic nanoclay, are incorporated into polypropylene (PP) for tailoring the surface microstructures of the composites prepared by solution casting. HNTs act as heterogeneous nuclei for PP, which leads to the change of phase separation process during drying of the composites and consequently the microstructures of composite surfaces. Micro-papilla like hybrid spherulites with nanostructures are formed on the PP/HNTs composite surfaces. The rough surfaces demonstrate superhydrophobicity with a maximum water contact angle as nearly 170 degrees and sliding angle of about 2 degrees. The spherulites size, surface roughness, and wetting property of PP can be tuned by HNTs. HNTs can significantly improve the thermal degradation behavior of the composites which is attributed to the well-dispersed HNTs and the improved interfacial interactions by the nucleation effect. The present work provides an alternative routine for preparing polymer superhydrophobic surfaces via tailoring the surface microstructures by adding nanoparticles in a solution process., (Copyright 2010 Elsevier Inc. All rights reserved.)

In this study, transparent poly(vinyl alcohol) (PVA) and PVA/halloysite nanotubes (HNTs) bionanocomposite films were prepared by solution casting and glutaraldehyde (GA) crosslinking. The surface topography and chemistry of the films were characterized by atomic force microscopy (AFM) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, respectively. Blending with HNTs induced changes in nanotopography and surface chemistry of PVA films. The mechanical properties of PVA were enhanced by the incorporated HNTs. The stain-induced crystallization was confirmed by DSC after tensile test. MC3T3-E1 osteoblast-like and NIH 3T3 fibroblast cells were cultured on neat PVA and PVA/HNTs films to evaluate the effects of surface nanotopography and composition on cell behavior. The observations indicated that MC3T3-E1 cell behavior strongly responded to surface nanotopography. On nanotube-dominant surface, cells exhibited a significantly higher level of adhesion than on neat PVA film, whereas neat PVA showed higher degree of osteoblast proliferation compared with PVA/HNTs. In vitro fibroblasts response demonstrated that both neat PVA and PVA/HNTs nanocomposite films were biocompatible and PVA/HNTs films favored to fibroblasts attach and growth below 7.5 wt % of HNTs incorporated. In summary, these results provided insights into understanding of PVA and PVA/HNTs bionanocomposite films in potential applications in bone tissue engineering and drug delivery systems., ((c) 2009 Wiley Periodicals, Inc.)

Many types of clay tend to absorb organics via electron transferring interactions between the clay and the organics. This may be utilized to design clay incorporated polymer composites with better interfacial properties. In the present paper, 2,5-bis(2-benzoxazolyl) thiophene (BBT), capable of donating electrons, is selected as the interfacial modifier for polypropylene (PP)/halloysite nanotube (HNTs) composites. The electron transfer between HNTs and BBT are confirmed. The mechanical properties and the unique morphology of the nanocomposites are examined. Formation of fibrils of BBT in the presence of HNTs is found in the nanocomposites. The chemical composition of the fibrils in the nanocomposites is found to be composed of largely BBT and a small amount of HNTs. The formation mechanism of BBT fibrils are elucidated to be the strong interactions between BBT and HNTs under melt shearing. The formation of the BBT fibrils leads to much higher crystallinity compared with previously reported PP nanocomposites. The nanocomposites with BBT show substantially increased tensile and flexural properties, which are attributed to the enhanced crystallinity of the nanocomposites.