单组分热温可逆感温变色涂料的制备

介绍一种以热塑性丙烯酸树脂为基料、添加感温粉,可用于ABS等塑胶底材的感温变色涂料;讨论了涂料各组分对涂料性能的影响及选用原则,并简单介绍了感温变色涂料的施工工艺及施工注意事项。     

Reversibly thermochromic micro-fibres by coaxial electrospinning

A ‘solvent facilitated’ coaxial electrospinning process was used to produce reversible narrow temperature gap thermochromic, core-shell fibres. A thermochromic composite composed of crystal violet lactone (the leuco dye), bisphenol A (the developer) and 1-dodecanol (the phase-change solvent) was entrained as core material inside poly(methyl methacrylate) shells. A mutual core and shell solvent (chloroform) was used to obtain low interfacial tension between the core and shell spinning solutions. This enabled room temperature entrainment of the low molecular weight, low viscosity core fluid. In order to minimize the effect of light scattering and subsequently produce fibres with visible colour transitions, the fibres were produced with external diameters of 3-8 μm and core diameters of 1.7-5.7 μm. In order to produce core-shell fibres with repeated, reversibly thermochromic behaviour and a stable colour developed state, it was necessary to entrain a dye composite that contained an excess developer, essentially making this composite non-thermochromic prior to entrainment. The fibres were analyzed using SEM and DSC.     

热致变色显温材料的研制

本文着重阐述了示温涂料的主要成分及其示范原理,并且着重介绍了无机热色性材料的研究情况及其变色机理。     

Dynamic colorimetric properties of mixed thermochromic printing inks

Leuco dye‐based thermochromic inks reversibly change from the coloured to the discoloured state in a defined, comparatively wide temperature region. Inside this region, the colour of a sample depends on the temperature and thermal history, which is known as the hysteresis effect. The colour of such a sample as a function of temperature has the shape of a hysteresis loop. Commercially available thermochromic inks have different loops, narrow or broad, and their shapes range from approximately symmetric to highly asymmetric. These properties are also important in mixtures of inks. The hysteresis loop of a mixture reveals its binary nature if the individual pure inks have well‐separated hysteresis. When inks with close‐separated loops, i.e. with similar activation temperatures, are mixed together, the loop of the mixture fuses together into an apparently single loop. Our research shows that some of their dynamic colour properties could be predicted in advance. However, optic and colorimetric properties of mixtures are not additive.     

The thermochromic properties of the ceramic colour standards

Thermochromism is a reversible change oftransmittance, reflectance, or absorptance induced by a change of temperature. Photochromism is the corresponding effect induced by optical radiation. These effects can occur in the use of reflectance standards, as they may undergo a considerable temperature rise when subjected to the polychromatic irradiation used by many measuring instruments. An investigation of any thermochromic (and photochromic) properties of the twelve Ceramic Colour Standards is described. It is shown that thermochromic effects are only significant to a very small extent in about half of the standards and not at all in the remainder, while there is no evidence of any photochromism.     

3D-printable thermochromic acrylic resin with excellent mechanical performance

This study demonstrated the feasibility of printing three-dimensional (3D) hybrid objects based on acrylic photocurable formulations, with an additional function of thermochromic (TC) performance. In fact, directly mixing TC pigments into an acrylic resin (AR), led to a decrease of the mechanical properties like tensile strength and elongation. In order to address this problem, TC was modified by γ-methacryloxypropyltrimethoxysilane before added into an AR (modified thermochromic [mTC] pigment). Compared with pure AR and TC/resin composite structures (TC/AR), the final mTC/acrylic resin (mTC/AR) exhibited a better performance of tensile strength and Young's modulus. Besides, they could be successfully fabricated into 3D structures by stereolithography method. More interestingly, mTC/AR 3D composite structures demonstrated a unique tunable TC property, which could be responsive to external temperature fields reversely. Thus, their TC property could find novel applications in smart temperature sensor technology, and other related technological applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48277.     

Preparation of reversible thermochromic building coatings and their properties

Thermochromic dyes reversible at normal ambient temperatures have been identified and microencapsulated using an emulsion polymerization process. By blending microencapsulated thermochromic dyes and nonthermochromic pigments with ordinary building coatings, thermochromic building coatings, in which colors change reversibly from warm tones to cool tones at about 18 °C have been obtained. The application and performance properties of the coatings were measured, and it was found that adding thermochromic dyes did not degrade the properties of coatings. The aging results showed that the aging properties of the coatings were not ideal; the reasons will be given in another paper. 1923 Siping Road, Shanghai, P. R. China. Project Supported by National Natural Science Foundation of China (59978036).     

可逆热致变色材料的变色机理及应用

本文介绍了热致变色材料的类别和发展趋势,着重介绍了可逆热致变色材料的变色机理及其应用。     

Study of thermochromic behaviour of some indolinobenzospiropyrans by infrared spectroscopy

The thermochromic behaviour of some indolinobenzospiropyrans was studied by heating solid compounds in K Br. Changes in i.r. spectra are interpreted as being due to the formation of a pseudoquinonic structure, ( V ).     

Imitation-mussel-based high-performance conductive coating on hydrophobic fabric for thermochromic application

On the basis of mussel inspiration, a common and low-cost method for preparing a high-performance poly-3,4-ethylene dioxythiophene (PEDOT) coating was proposed. First, cheap imitation-mussel tannin–iron materials with universal adhesion properties were used as a modified coating on hydrophobic polypropylene nonwoven fabric. Because of the excellent wettability and ion chelating properties of the modified coating, a high-performance PEDOT coating was successfully prepared later without complicated and expensive equipment. The PEDOT coating, with a conductivity of above 50 S/cm, could successfully realize the electric–thermal conversion at an appropriate current, and then, an obvious thermochromic effect on a pattern occurred; this is the key to achieving the functional textiles. The role of the artificial mussel adhesion materials in the modified coating were analyzed and are discussed. The results of this study provide new insight into preparing highly conductive coatings at low cost with potential practical applications in many fields. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47751.     

感温变色建筑涂料的制备及光谱反射性能实验研究

感温变色建筑涂料在降低建筑冷热负荷、改善城市热环境方面具有很大的应用潜力。为了探究感温变色材料光学性能的影响因素,优化材料配方,首先制备了12种不同配方,变色温度为31℃的感温变色涂料,并分析了金红石型TiO₂质量百分含量对涂料光谱反射率和太阳光反射比的影响,研究表明涂料光谱反射率均随着TiO₂含量的增加而提高,感温变色粉最佳质量分数5%,TiO₂的最佳质量分数应在5%~10%之间,此时浅色态的反射比比深色态高0.2以上。同时探究了TiO₂粒径对涂料在不同波段反射率的影响,结果表明,在紫外和除红光外的可见光波段,感温变色涂料的反射率基本上随TiO₂粒径的增大而减小;在红光和近红外波段,感温变色涂料反射率基本上随TiO₂粒径的增大而增大。     

Influence of stabilizer additives on thermochromic coating for temperature monitoring

Compounds based on smart materials are functional structures that can be used as thermochromic sensors for temperature monitoring in equipment such as pipelines, motors, and heat exchangers. We developed thermochromic coatings based on 1,3,3-trimethylindolino-β-naphthopyrylospiran acrylic polyurethane with and without 2-(2H-benzotriazol-2-yl)-4,6-ditertpentylphenol photostabilizer additives and antioxidant butylated hydroxytoluene and applied them on stainless-steel plates by the spray lay-up method. The samples were analyzed using a weathering chamber with UVA and UVB radiation to monitor their degradation process, revealing complete degradation of the coating without antioxidant and photostabilizer, leading to loss of its thermochromic characteristic.     

Realization of reversible thermochromic polydiacetylene through silica nanoparticle surface modification

The novel functionalized poly(silanization alcoholamine diacetylene)/silica nanoparticles (poly(SiDGADA)/SiO₂ nanoparticles) have been achieved for reversible thermochromism. The silanized alcoholamine diacetylenic monomer (SiDGADA) is condensed with the hydroxyl group of SiO₂ nanoparticle via hydrolysis of the SiDGADA siloxy group, followed by fixation after being polymerized upon UV light stimulation. The maximum thermal decomposition rate of the SiDGADA/SiO₂ nanoparticles is 0.65%/°C at 460°C, while the maximum thermal decomposition rate of the SiDGADA is 1.92%/°C at 400°C. Poly(SiDGADA)/SiO₂ nanoparticles appears a blue phase after photo polymerization and exhibits a distinctive red phase at the discoloration temperature of 65°C, which is 5°C higher than that of the pure poly(SiDGADA). It shows excellent reversible thermochromic properties, undergoing stable reciprocal blue-to-red conversion from 25 to 65°C, and returning to bluish violet after cooling. The extension of the SiDGADA alkyl chain length with formation of the covalent bond, to promote the interaction between the alkyl chains of polydiacetylene (PDA). This work provides a strategy to effectively improve the reversibility of thermochromic PDA.     

Colour in visual displays

Coloured display screens are now in widespread use in many workplaces and homes. So much so that we already take them for granted. Nevertheless, they are highly complex items that represent a considerable achievement for colour technology.     

Palladium-catalysed amination of bromofluorans and an investigation of their thermochromic behaviour

The palladium-catalysed amination of readily accessible bromofluorans and bromobenzo[a]fluorans has been accomplished with a series of anilines and morpholine. The resulting aminofluorans generated intense black shades upon formulation in methyl stearate containing bisphenol A. The route provides an alternative approach to various amino substituted fluorans without the need of a series of individual diphenylamine intermediates.     

Design of thermochromic polymer blends containing low‐mass compounds

We investigated the light transmittance of an immiscible polymer blend comprising a copolymer of ethylene and vinyl acetate (EVA) and a terpolymer of vinyl butyral, vinyl alcohol, and vinyl acetate (PVB). Both EVA and PVB are used in the interlayers of laminated glass. We found that the transparency of the blend depends on the ambient temperature. This can be attributed to the difference in the temperature dependence of the refractive index between EVA and PVB. The blend has good transparency at room temperature because the difference between the refractive indices of its components is minimal. At high or low temperatures, however, the blend becomes opaque owing to light scattering. The addition of a plasticizer favorably affects the temperature range over which the blend exhibits high transparency, because the refractive index and its temperature dependence are affected by the plasticizer. We also evaluated the interphase transfer of a plasticizer between EVA and PVB at various temperatures. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45927.