Constructing conductive titanium carbide nanosheet (MXene) network on polyurethane/polyacrylonitrile fibre framework for flexible strain sensor.

Hypothesis: MXenes (two-dimensional early transition metal carbides and carbonitrides) possess both excellent conductivity and surface hydrophilicity, enabling more diverse potential applications. However, in flexible strain sensors, the flexible substrates are usually composed of hydrophobic elastomers such as thermoplastic polyurethane (TPU). To enhance the interactions between MXenes and hydrophobic.

Novel Hybrid Biomass Anti-Aging Filler for Styrene-Butadiene Rubber Composites with Antioxidative and Reinforcing Properties.

Antioxidants are normally utilized to extend the service life of polymers due to the strong reducibility of the phenolic hydroxyl group of the hindered phenol structure. Inspired by this characteristic, we have introduced green tea polyphenol (TP) supported on a silica surface containing considerable phenolic hydroxyl groups to obtain a novel biomass anti-aging filler (BAF, denoted as silica-s-TP) to reinforce and improve the anti-aging property of rubber composites. The applying of silica-s-TP to enhance the thermal-oxidative stability and ultraviolet light (UV) aging resistance of styrene-butadiene rubber (SBR) was evaluated.

Electrostatic wrapping of eupatorium-based botanical herbicide with chitosan derivatives for controlled release.

To avoid the negative effects of chemical herbicides and prepare herbicide with long-term efficacy, the active ingredients of eupatorium adenophorum spreng (AIEAS, negatively charged) were used as a botanical herbicide, and based on electrostatic attraction, the self-assembled hydroxyl isopropyl chitosan (HPCTS, positively charged) and carboxymethyl chitosan (CMC, with good water solubility) were successfully employed as degradable and water-soluble carrier for AIEAS to realize its controlled release. The release of AIEAS from the chitosan carrier in water could be divided into two stages. In the first stage, a fast release of AIEAS was detected and the total amount of the released AIEAS reached 41.

The Synergistic Effect of Ionic Liquid-Modified Expandable Graphite and Intumescent Flame-Retardant on Flame-Retardant Rigid Polyurethane Foams.

In this study, a nitrogen-phosphorus intumescent flame-retardant 3-(N-diphenyl phosphate) amino propyl triethoxy silane (DPES), the ionic liquid (IL) of 1-butyl-3-methyl-imidazole phosphate, and a phosphorous-containing ionic liquid-modified expandable graphite (IL-EG), were synthesized, and their molecular structures were characterized. The flame-retardant rigid polyurethane foams (RPUFs) were compounded with synergistic flame-retardant IL-EG/DPES to study the effects of the combination IL-EG and DPES on the pore structure, mechanical properties, thermal decomposition behavior and thermal decomposition mechanism of RPUF. The results showed that IL-EG/DPES had good thermal stability, and an excellent expansibility and char yield.

A Robust and Versatile Continuous Super-Repellent Polymeric Film for Easy Repair and Underwater Display.

Functionalized super-repellent polymeric materials play important roles in academic and industrial fields. In this work, a versatile continuous super-repellent polymeric film (CSPF) integrating reversible wettability with design manipulation was synthesized. On the basis of the optimal combination of a polyurethane acrylate (PUA)/precipitated silica particle (PSP)/ethanol suspension, covalently cross-linking networks and hierarchical topography were constructed in a polymer skeleton, endowing the CSPF with solid mechanical strength (B hardness).

TiC MXene as a new nanofiller for robust and conductive elastomer composites.

Ti3C2 MXene with a layered 2D structure was applied as a novel functional filler in rubber for the first time. A facile and green method was proposed to fabricate rubber/Ti3C2 nanocomposites via a freeze-drying & mechanical mixing process. It was found that Ti3C2 with ∼1 nm thickness fabricated by etching Al from Ti3AlC2 phases can be dispersed in styrene-butadiene rubber (SBR) evenly in a single-layered state.

Functionalized Halloysite Nanotubes⁻Silica Hybrid for Enhanced Curing and Mechanical Properties of Elastomers.

Vulcanization and reinforcement are critical factors in governing the ultimate practical applications of elastomer composites. Here we achieved a simultaneous improvement of curing and mechanical properties of elastomer composites by the incorporation of a functionalized halloysite nanotubes-silica hybrid (HS-s-M). Typically, HS-s-M was synthesized by 2-mercapto benzothiazole (M) immobilized on the surface of halloysite nanotubes-silica hybrid (HS).

Immobilization of rubber additive on graphene for high-performance rubber composites.

It is still a challenge to achieve simultaneous improvements in aging resistance, mechanical strength, thermal conductivity and dielectric constant of rubber composites via incorporation of graphene obtained by conventional methods. Herein, an effective and green method was proposed to simultaneously reduce and functionalize graphene oxide (GO) with 2-mercaptobenzimidazole (antioxidant MB) via a one-pot method. GO was successfully reduced by MB which was also chemically grafted on the reduced GO (G-MB).

Structure and Flame-Retardant Actions of Rigid Polyurethane Foams with Expandable Graphite.

In this paper, rigid polyurethane foams that were filled with expandable graphite (RPUF/EG) composites were prepared by the liquid blending method, and then the structure and flame retardancy performance of materials were investigated through optical microscope, scanning electron microscope, limit oxygen index, cone calorimeter, thermogravimetric analysis coupled to fourier transform infrared spectrum, and X-ray photoelectron spectroscopy. The results showed that a large number of EG could be good to the exhibition of flame retardancy of RPUF, where the optimal material was found at loading 15 phr EG that showed an increased limit oxygen index value and a decreased calorific or fuming value. TGA coupled FTIR and XPS revealed that EG could disassembled before RPUF under heating treatment, and it could form a pyknotic and enahnced residual carbon layer on RPUF surface after the fire, which restricted the transfer of gas, like oxygen or heat into PU matrix, finally resulting in the promotion of flame retardancy of RPUF.

Inorganic and Organic Hybrid Nanoparticles as Multifunctional Crosslinkers for Rubber Vulcanization with High-Filler Rubber Interaction.

Improving the interfacial interaction between rubber and silica nanoparticles, and simultaneously reducing free sulfur and preventing migration and volatilization of a rubber vulcanizing agent, commercial sulfur compound aliphatic ether polysulfide (VA-7) was chemically attached to the silica surface to obtain a functionalized nanoparticle (silica-s-VA7). Functional nanoparticles can not only effectively crosslink rubber without sulfur as a novel vulcanizator, but are also evenly dispersed in the rubber matrix and improve the dispersion of the remaining pristine silica as an interfacial compatibilizer. In addition, the thicker immobilized polymer layer and prominent crosslinking density of SBR nanocomposites simultaneously demonstrate that the novel vulcanizing agent silica-s-VA7 gives rise to significant improvement on the rubber⁻filler interfacial adhesion on account of the covalent linkages of organic and inorganic interfaces between elastomer and nanofillers.

Halloysite Tubes as Nanocontainers for Herbicide and Its Controlled Release in Biodegradable Poly(vinyl alcohol)/Starch Film.

Commercial herbicide atrazine (AT) was first loaded into the lumen of halloysite nanotubes (HNTs) in the amount of 9 wt %, and then the AT-loaded HNTs (HNTs-AT) were further incorporated into poly(vinyl alcohol)/starch composites (PVA/ST, with the weight ratio of 80/20) to construct a dual drug delivery system. AT loaded in nanotubes displayed much slower release from PVA/ST film in water than free AT; for example, the total release amount of AT from PVA/ST film with loaded AT was only 61% after 96 h, while this value reached 97% in PVA/ST film with free AT. The release behavior of AT from PVA/ST film with HNTs-AT was first dominated by the mechanism of matrix erosion and then by the mechanism of Fickian diffusion.

Elastomer Reinforced with Regenerated Chitin from Alkaline/Urea Aqueous System.

Novel hybrid elastomer/regenerated chitin (R-chitin) composites were developed, for the first time, by introducing chitin solution (dissolved in alkaline/urea aqueous solution at low temperature) into rubber latex, and then cocoagulating using ethanol as the cocoagulant. During the rapid coprecipitation process, the chitin solution showed rapid coagulant-induced gelation and a porous chitin phase was generated, and the rubber latex particles were synchronously demulsificated to form the rubbery phase. The two phases interlaced and interpenetrated simultaneously to form an interpenetrating polymer network (IPN) structure, which was evidenced by SEM observation.

Advances in rubber/halloysite nanotubes nanocomposites.

The research advances in rubber/halloysite nanotubes (rubber/HNTs) nanocomposites are reviewed. HNTs are environmentally-friendly natural nanomaterials, which could be used to prepare the rubber-based nanocomposites with high performance and low cost. Unmodified HNTs could be adopted to prepare the rubber/HNTs composites with improved mechanical properties, however, the rubber/HNTs nanocomposites with fine morphology and excellent properties were chiefly prepared with various modifiers by in situ mixing method.

Preparation and characterization of silicone rubber/nano-copper nanocomposites for use in intrauterine devices.

In this work, a novel silicone rubber/nano-copper nanocomposite for use in intrauterine devices (IUDs) was developed. Moreover, the release rate of Cu2+ ions and the water absorption of the prepared nanocomposite were investigated in detail. The results indicate that the release rate of Cu2+ ions and water absorption capability of the silicone rubber/nanocopper nanocomposite increase as the nano-copper content increases.

Styrene-butadiene rubber/halloysite nanotubes composites modified by epoxidized natural rubber.

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.

High performance light-colored nitrile-butadiene rubber nanocomposites.

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.

Tailoring the wettability of polypropylene surfaces with halloysite nanotubes.

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.

Evaluation of new tri-methacrylates as a reactive diluent in root canal sealant.

In this work, a novel tri-methacrylate oligomer, GPTEMA, with three long-branched chain structures was synthesized through the reaction of glycerol propoxylate triglycidyl ether (GPTE) and methacrylic acid. The structure of GPTEMA was confirmed by FT-IR, (1)H-NMR, gel-permeation chromatography (GPC) and element analysis. The GPTEMA was used to partially or completely replace TEGDMA as reactive diluent and applied in a root canal sealant system containing Bis-GMA.

Synthesis, characterization and photopolymerization of a new dimethacrylate monomer based on (alpha-methyl-benzylidene)bisphenol used as root canal sealer.

Methacrylate resin-based sealers have attracted wide attention because of their easy handling, superior aesthetic qualities, good mechanical properties and excellent adhesive ability with dentin. 2,2-Bis[4-(2'-hydroxy-3'-methacryloyloxypropoxy)-phenyl]-propane (Bis-GMA) is the main component of the newly developed commercial root canal sealer 'Epiphany', which is one of the methacrylate resin-based sealers. In order to further reduce the polymerization volume shrinkage of Bis-GMA, 4,4'-(alpha-methylbenzylidene)-bis(2'-hydroxy-3'-methacryloyloxy-propoxy)benzene (4,4'-AMBHMB) with higher molecular weight and larger molecular volume was synthesized to replace Bis-GMA as one of the components of the root canal sealer used in this study.

[Preparation and characterization of polyurethane/polyethylene glycol/copper nanocomposite].

A novel Cu-IUDs material, PU/PEG/Cu nanocomposite, was prepared by melt blending method with thermoplastic polyurethane (PU) as the matrix, with polyethylene glycol (PEG) as a hydrophilic modifier, and with nanometer particles of copper as active matter instead of copper wire or copper tube. The structure, morphology, mechanical properties, thermal stability and water absorption were investigated by using FT-IR, XRD, SEM and so on. The results indicated that the nanometer particles of copper were uniformly dispersed in the matrix in PU/PEG/ Cu nanocomposites.

Synthesis and characterization of a new dimethacrylate monomer based on 5,50-bis(4-hydroxylphenyl)-hexahydro-4,7-methanoindan for root canal sealer application.

In this study, a new dimethacrylate monomer 5,5'-bis[4-(2'-hydroxy-3'-methacryloyloxy-propoxy)-phenyl]-hexahydro-4,7-methan-oindan (5,5'-BHMPHM) with molecular weight of 640 and large molecular volume was designed and synthesized. The structure of monomer 5,5'-BHMPHM was confirmed by FT-IR, 1H-NMR and elemental analysis. Degree of double bond conversion, volume shrinkage, contact angle, water sorption and solubility, diffusion coefficient value, flexure strength and modulus of 5,5'-BHMPHM/tri(ethylene glycol) dimethacrylate (TEGDMA) based resin were measured.

Poly(vinyl alcohol)/halloysite nanotubes bionanocomposite films: Properties and in vitro osteoblasts and fibroblasts response.

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.

Synthesis and characterization of a new trimethacrylate monomer with low polymerization shrinkage and its application in dental restoration materials.

In this study, a new trimethacrylate monomer alpha,alpha,alpha'-tri[4-(2'-hydroxy-3'-methacryloyloxy-propoxy)phenyl]-1-ethyl-4-isopropylbenzene (alpha,alpha,alpha'-THMPEIB) with a molecular weight of 850 and a large molecular volume was designed and synthesized. The structure of monomer alpha,alpha,alpha'-THMPEIB was confirmed by FT-IR, (1)H NMR, and elemental analysis. Degree of double-bond conversion, volume shrinkage, water sorption and solubility, diffusion coefficient value, and flexure strength of alpha,alpha,alpha'-THMPEIB/tri(ethylene glycol) dimethacrylate- (TEGDMA) based resin were measured.

Interactions between halloysite nanotubes and 2,5-bis(2-benzoxazolyl) thiophene and their effects on reinforcement of polypropylene/halloysite nanocomposites.

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.

Synthesis and characterization of dimethacrylate monomer with high molecular weight for root canal filling materials.

A new dimethacrylate monomer 9,9'-bis[4-(2'-hydroxy-3'-methacryloyloxy-propoxy)phenyl] fluorene (3) with a molecular weight of 634 was synthesized in 51.4% yield by addition of a glycidyl ether group to 9,9'-bis(4-hydroxyphenyl) fluorene (1) by the reaction of compound 1 with epichlorohydrin, and then introducing the methacrylate moiety by the reaction of the epoxy group with methacrylic acid. The structure of monomer 3 was confirmed by FT-IR, (1)H-NMR, mass spectra and elemental analysis.