A 3D printable self-healing composite conductive polymer for sensitive temperature detection

Recent development of self-healing material has attracted tremendous attention,owing to its biomimetic ability to restore structure and functionality when encountering damages.Here,we develop a threedimensional(3D)printable self-healing composite conductive polymer by mixing hydrogen-bond-based supramolecular polymer with low-cost carbon black.It has a room-temperature self-healing capability in both conductivity and mechanical property,while its shear-thinning behavior enables fabrication of a self-healable circuit by 3D printing technology.As an application,the circuit shows an excellent temperature-dependent behavior of the resistance,indicating its great potential fo r practical application in the artificial intelligence field.     

A highly stretchable and self-healing hydroxy-terminated polybutadiene elastomer

The damage such as microcracks limits the application of hydroxy-terminated polybutadiene (HTPB) elastomer. Here, hydroxy-carboxy-terminated polybutadiene (HCTPB) and Fe³⁺ selected to facilitate ionic bonds (COO⁻⋯Fe³⁺) formation is proposed as a strategy to alleviate the intrinsic self-healing problem for HTPB elastomer. In typical HTPB polyurethane elastomer, the elongation at break is 997.3% while the tensile strength is 1.83 MPa, the damage cannot repair by intrinsic covalent or non-covalent, resulting in permanent damage. In contrast, HCTPB is able to offer COO⁻, entailing a COO⁻⋯Fe³⁺ ionic bonds. Incorporated 6 wt% HCTPB and Fe³⁺ into the HTPB elastomer elevates the tensile strength to 5.2 MPa, reducing the elongation at break in 877.8%. HCTPB and Fe³⁺ enhance the self-repair rate reaches up to 92% after repairing at 80 °C for 10 h after cutting for HTPB elastomer. This strategy has immediate implications for using COO⁻⋯Fe³⁺ ionic bonds to improve the performance of HTPB polyurethane elastomer devices.     

Green solvent approach for printable large deformation thermoplastic elastomer based piezoresistive sensors and their suitability for biomedical applications

Composites based on biocompatible thermoplastic elastomer styrene‐ethylene/butylene‐styrene (SEBS) as matrix and multi‐walled carbon nanotubes (MWCNT) as nanofillers show excellent mechanical and piezoresistive properties from low to large deformations. The MWCNT/SEBS composites have been prepared following a green solvent approach, to extend their range of applicability to biomedical applications. The obtained composites with 2, 4, and 5 wt % MWCNT content provide suitable piezoresistive response up to 80% deformation with a piezoresistive sensibility near 2.7, depending on the applied strain and MWCNT content. Composite sensors were also developed by spray and screen printing and integrated with an electronic data acquisition system with RF communication. The possibility to accurately control the composites properties and performance by varying MWCNT content, viscosity, and mechanical properties of the polymer matrix, shows the large potential of the system for the development of large deformation printable piezoresistive sensors. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2092–2103     

Development of A New Silicone Base Transdermal System: III. Study of thermal properties of silicone elastomers containing liquid ingredients

In present work we have investigated the commonly used base silicone elastomers namely cured poly-dimethyl-siloxanes and the change of the inner polarity of silicone elastomers containing various amounts of polar liquid ingredients and trifunctional silicone additives. It was shown that the polarity of the inside of the matrix is related to the diffusion properties of model substances and thermal properties of silicone elastomers. The ingredients used have changed the matrix framework, that was influenced by the type of trifunctional additive too. These properties show large dependence on the timing of the measurement. Measurements carried out after 48 hour of the production of the polymer showed reproducible properties, indicating that the final structure of the polymer has been formed.These results show that the ingredients influence the properties of the silicone matrices considerably, thus the characteristics of the drug release of pharmaceutical forms can be varied too.This revised version was published online in November 2005 with corrections to the Cover Date.     

Design and synthesis of self-healing polymers

Self-healing polymers represent a class of materials with built-in capability of rehabilitating damages. The topic has attracted increasingly more attention in the past few years. The on-going research activities clearly indicate that self-healing polymeric materials turn out to be a typical multi-disciplinary area concerning polymer chemistry, organic synthesis, polymer physics, theoretical and experimental mechanics, processing, composites manufacturing, interfacial engineering, etc. The present article briefly reviews the achievements of the groups worldwide, and particularly the work carried out in our own laboratory towards strength recovery for structural applications. To ensure sufficient coverage, thermoplastics and thermosetting polymers, extrinsic and intrinsic self-healing, autonomic and non-autonomic healing approaches are included. Innovative routes that correlate materials chemistry to full capacity restoration are discussed for further development from bioinspired toward biomimetic repair.     

Synthesis and characterization of a novel biodegradable,thermoplastic polyurethane elastomer

A series of biodegradable, thermoplastic polyurethane elastomers poly(?‐caprolactone‐co‐lactide(polyurethane [PCLA–PU] were synthesized from a random copolymer of L ‐lactide (LA) and ?‐caprolactone (CL), hexamethylene diisocyanate, and 1,4‐butanediol. The effects of the LA/CL monomer ratio and hard‐segment content on the thermal and mechanical properties of PCLA–PUs were investigated. Gel permeation chromatography, IR, ¹³C NMR, and X‐ray diffraction were used to confirm the formation and structure of PCLA–PUs. Through differential scanning calorimetry, tensile testing, and tensile‐recovery testing, their thermal and mechanical properties were characterized. Their glass‐transition temperatures were below ?8 °C, and their soft domains became amorphous as the LA content increased. They displayed excellent mechanical properties, such as a tensile strength as high as 38 MPa, a tensile modulus as low as 10 MPa, and an elongation at break of 1300%. Therefore, they could find applications in biomedical fields, such as soft‐tissue engineering and artificial skin. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5505–5512, 2006     

Sorbitol-based supramolecular organogelators with effective phase-selective gelation and significant self-healing property

Several effective phase-selective gelators (PSGs) have been developed from a series of cheap and easy-to-make sorbitol-based compounds for the removal of many oils from their biphasic mixtures with water. The dominant factors that drive gelation have been studied using FTIR and temperature-dependent ¹H NMR spectra. Additionally, the case of PSGs exhibit significant self-healing properties that can recover the gelatin block and hence provide a more flexible approach for oil-spill recovery. The highly effective phase-selective performance and self-healing properties of these organogelators indicate the potential and promising applicability in oil-spill recovery.     

Synthesis and properties of room-temperature self-healing polyurethane elastomers

Two kinds of polyurethane elastomers were synthesized. One containing acylhydrazone bonds was named TPIA. The other containing both acylhydrazone and disulfide bonds was named TPID. Self-repairable ability and reprocessability of these two elastomers were studied. The results show that: The polyurethane elastomer TPIA can automatically repair damage to it under acidic conditions. After self-healing for 24 h, the strength and the elongation value at break recovered to 32% and 55% of the originality, respectively. The polyurethane elastomer TPID can automatically repair damage to it under visible light at room temperature. After 24 h of self-healing time, 75% of the original strength and 100% of the original elongation values at break were obtained. These two polyurethane elastomers can be reprocessed in their cured state by just applying temperature and pressure.     

Toughness mechanism in polypropylene composites: Polypropylene toughened with elastomer and calcium carbonate

Polypropylene (PP) was modified with elastomer or CaCO₃ particles of two different sizes (1 μm and 50 nm) in various volume fractions. The dispersion morphology and mechanical properties of the two systems were investigated as functions of the particle size and volume fraction of the modifier. The brittle‐to‐tough transition occurred when the matrix ligament thickness was less than the critical ligament thickness, which was about 0.1 μm for the PP used here, being independent of the type of modifier. At the same matrix ligament thickness, the improvement of the toughness was obviously higher with the elastomer rather than with CaCO₃, but adding CaCO₃ increased the modulus of PP. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1656–1662, 2004     

Film morphology and orientation of N‐cyclohexyl‐γ‐aminopropyl polydimethylsiloxane

A novel polysiloxane softener bearing N‐cyclohexyl‐γ‐aminopropyl side groups (ASO‐702) is synthesized by copolymerization of octamethylcyclotetrasiloxane with N‐cyclohexyl‐γ‐aminopropyl methyldimethoxylsilane and hexamethyldisiloxane. Chemical structure and film morphology of the synthesized polysiloxane are characterized and investigated by IR, ¹H NMR, ¹³C NMR, SEM and atomic force microscope (AFM). The results of the experiment indicate that ASO‐702 can form a hydrophobic film on both a cotton fiber and a silicon‐wafer surface. At scales > 100 nm, the ASO‐702 shows a relative smooth‐resin film on the treated fabric/fiber surface. But as the observation rule decreases to 2 nm, the molecular scale, the ASO‐702 film exhibits an inhomogeneous structure and uneven morphology in its AFM images. There are many low or high peaks in ASO‐702 topography. Consequently in 2 µm² scanning field, the root mean square roughness of ASO‐702 film is 0.246 nm, which is 3.05 times rougher as compared with that of polydimethylsiloxane (PDMS) film. Copyright © 2008 John Wiley & Sons, Ltd.     

Magnetically tunable transparency for magnetorheological elastomer films consisting of polydimethylsiloxane and Fe3O4 nanoparticles

In this research, we demonstrate magnetically tunable transmittance for the magnetorheological elastomer films comprised of polydimethylsiloxane and Fe₃O₄ nanoparticles. The films bearing anisotropic and isotropic microtexture were prepared with and without magnetic field, respectively. The usage of toluene as diluent during the film preparation process leads to the increased tunable range of the magnetically induced transparency in comparison with our previous results. For the anisotropic film containing 1 wt% Fe₃O₄ nanoparticles, an increase of 23.01% in film transparency was observed at the wavelength of 600 nm with a magnetic field of B = ~ 80 mT applied, which is 2.67 times greater than the maximum change achieved in our previous research. The variation in transparency caused by the external magnetic field has been tentatively assigned to magnetostrictive effect. And the film microtexture might have a great influence upon the way an external magnetic field alters film transmittance.     

Synthesis and characterization of semicrystalline triblockcopolymers of isotactic polystyrene and polydimethylsiloxane

iPS‐b‐PDMS‐b‐iPS triblock copolymers were prepared by hydrosilylation of vinyl‐terminated isotactic polystyrenes (iPS) with α,ω‐bis(dimethylsilane)‐terminated poly(dimethylsiloxane)s (PDMS). As a function of the molecular weights of the two components, the triblock copolymer composition was varied between 9.0 and 98 wt % iPS. The resulting triblock copolymers remained soluble during block copolymer synthesis due to slow iPS crystallization in solution. At iPS content exceeding 31 wt %, the iPS crystallization was achieved by postpolymerization annealing and melt processing. The triblock copolymers melted above 200 °C with melting temperatures very similar to those of the corresponding iPS homopolymers. Nanostructure and microstructure formation of both amorphous and semicrystalline triblock copolymers were examined by means of light microscopy, atomic force microscopy, and TEM measurements. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Phosphorescent self-healing composites containing Re(I) complexes: preparation and properties

Abstract

To obtain self-healing phosphorescent composites, four Re(I) complexes, Re-Ura-a (a?=?1–4) with uracil group were synthesized. The ultraviolet-visible (UV-Vis) absorption spectra of Re-Ura-a (a?=?1–4) are mainly comprised of the π→π* transitions (200–400?nm) and the metal-to-ligand charge transfer transitions (400–450?nm). The photoluminescence (PL) spectra of Re-Ura-a (a?=?1–4) peaking at 576–584?nm possess the biexponential excited-state decay lifetimes (τ) of 0.19–0.43 μs. The PL spectra of Re-Ura-a@PAA (a?=?1–4, PAA?=?polyacrylic acid) gel blocks redshift to ca. 600?nm with τ values of ca. 0.33 μs. The Re-Ura-1(0.6?wt%)@PAA gel blocks could bear maximum stress of 0.191?MPa and maximum strain of 525%, and they could be ca. 40% self-healed in 5?min after being severed. Finally, the energies of the H-bonds between the carboxylic group of PAA and different parts of Re-Ura-1 were theoretically simulated to investigate the intermolecular interactions between Re-Ura-1 and PAA.     

自修复有机硅材料的制备策略

近年来,通过仿生生命体自我修复损伤这一现象而研制的自修复材料,可有效延长材料的使用寿命、提高材料的使用安全性、降低资源浪费,具有巨大的发展潜力。其中,自修复有机硅材料因兼具自我修复的功能和有机硅材料的优异性能,已成为当下的研究热点。由于外界刺激条件如紫外光、温度等是材料实现损伤自我修复的外在驱动力,在很大程度上影响着材料的修复效能,且不同的刺激条件具有不同的优缺点和应用领域。因此,本文将基于自修复过程中外界刺激因素的不同,对自修复有机硅材料尤其是近五年来的最新研究成果进行综述,从外援型和本征型自修复有机硅材料两方面入手,以本征型自修复有机硅材料为重点,并对自修复有机硅材料今后的发展进行了分析展望。     

Synthesis and characterization of in-chain silyl-hydride functional SBR and self-crosslinking elastomer

Functional in-chain silyl-hydride(Si-H) SBR copolymers of 4-vinyiphenyldimethylsilanol(VPDMS) and butadiene were synthesized by living anionic polymerization,in which active group Si-H was not lost and its content was controllable. Corresponding self-crosslinking elastomers were obtained by hydrosilation of Si-H group with vinyl bonds in chain.The copolymers and elastomers were characterized by ~1H NMR,size exclusion chromatography(SEC),Fourier transform infrared (FTIR) spectroscopy,differential scanning calorimetry(DSC),and thermogravimetry analysis(TGA) techniques.     

A fast on-demand preparation of injectable self-healing nanocomposite hydrogels for efficient osteoinduction

Injectable hydrogels have been considered as promising materials for bone regeneration,but their osteoinduction and mechanical performance are yet to be improved.In this study,a novel biocompatible injectable and self-healing nano hybrid hydrogel was on-demand prepared via a fast(within 30 s) and easy gelation approach by reversible Schiff base formed between-CH=O of oxidized sodium alginate(OSA) and-NH_2 of glycol chitosan(GCS) mixed with calcium phosphate nanoparticles(CaP NPs).Its raw materials can be ready in large quantities by a simple synthesis process.The mechanical strength,degradation and swelling behavior of the hydrogel can be readily controlled by simply controlling the molar ratio of-CH=O and-NH_2.This hydrogel exhibits pH responsiveness,good degradability and biocompatibility.The hydrogel used as the matrix for mesenchymal stem cells can significantly induce the proliferation,differentiation and osteoinduction in vitro.These results showed this novel hydrogel is an ideal candidate for applications in bone tissue regeneration and drug delivery.     

Applications of α, ω‐telechelic polydimethylsiloxane as cross‐linkers for preparing high‐temperature vulcanized silicone rubber

Multiamino‐terminated telechelic polydimethylsiloxane (MATTPS) was synthesized via aza‐Micheal reaction and amidation reaction and subsequently employed as cross‐linkers of polysiloxane containing γ‐chloropropyl groups (CPPS) for preparing a series of high‐temperature vulcanized silicone rubber (MCSR/MATTPS). The curing, mechanical, and thermal properties of MCSR/MATTPS were studied through rheometry, mechanical testing, and thermogravimetric analysis (TGA). MCSR/MATTPS exhibits optimal mechanical properties with a tensile strength of 9.52 MPa and tear strength of 45.4 kN/m when the molar ratio of [N–H]/[CH₂CH₂CH₂Cl] is of 1, which is attributed to the formation of concentrative cross‐linking in the three‐dimensional polymer networks. The thermal behaviors of MCSR/MATTPS display a two‐step weight loss process by heating in nitrogen whereas more than two weight loss process in air. TGA results indicate that the introduction of aliphatic long chain and carbonyl groups in the structure of MATTPS has little negative effect on the thermal stability of MCSR/MATTPS.     

Easy-handling and low-leaching heterogeneous palladium and platinum catalysts via coating with a silicone elastomer

We have developed a practical protocol for coating of commercial Pd/Al₂O₃ and Pt/Al₂O₃ catalysts in micro-powders with a silicone elastomer. Compared to original catalysts, the treated catalysts are easier to weight and transfer, and they are easier to recover by simple filtration. More importantly, the metal leaching of treated catalysts was significantly reduced. The treated catalysts worked very well in diverse hydrogenation reactions.     

Sunlight helps self-healing of liquid-crystalline gels of lignin-graft PMMA doped with GO and azobenzene

ABSTRACT

Self-healing soft matters have attracted much attention because of their extraordinary performance for extending working life of materials. To utilise sunlight to help self-healing of liquid-crystalline gels composed of one low-mass liquid crystal (5CB) and one hyperbranched polymer (lignin-graft-PMMA), a low content of graphene oxide (GO) and one azobenzene compound are doped as photoresponsive additives. Upon irradiation of UV light, the azobenzene can induce gel-sol transition due to the photoinduced molecular cooperative motion, thus surface dents can be repaired. On the other hand, GO functions as the nanoscale heat source because of the photothermal effect under exposure of visible (VIS) or NIR light, heating the gel to undergo gel-sol transition for mending surface cracks. In addition, the mechanical properties of the gels are also improved by addition of GO. This NIR-VIS-UV light responsive liquid-crystalline gel shows highly effective gel-sol transition upon direct solar radiation because of the coexistence of both photochemical and photothermal effect. Furthermore, these sunlight-assistant self-healing gels also show anisotropy and orientation just like other liquid-crystalline materials, enabling them to find various advanced applications with longer service life.