Polymer dispersed liquid crystal device with integrated luminescent solar concentrator

Polymer dispersed Liquid crystal (PDLC) windows are regarded as a good choice for curtain-free windows. However, conventional PDLC needs external electricity to operate, which causes extra energy consumption. These devices cannot be combined with traditional solar cells for energy savings. In this study, a new design of luminescent solar concentrator (LSC)-based PDLC device is presented. In particular, we successfully demonstrate that the PDLC can be integrated with LSC as its back scatter and potentially contributes towards the enhancement of power output by minimising backside light losses. Multi-luminophore LSC is employed to increase the absorption of air mass 1.5 solar irradiance. The edge emission measurements show multiple-luminophore-based PDLC-LSC gives the maximum edge emission power which is 1.7 times more than that of single luminophore-based PDLC-LSC device. Photocurrent measurements are also performed as an additional evidence for the improved performance of PDLC-LSC device. Finally, the visual properties of PDLC-LSC devices are evaluated to realise the compatibility of using such devices in the built environment.     

Dispersion stabilization of antimony-doped tin oxide (ATO) nanoparticles used for energy-efficient glass coating

Nano-antimony-doped tin oxide (ATO) was synthesized using the sol–gel method. A colloidal dispersion of ATO nanoparticles in distilled water was achieved using a milling process in which different dispersants were studied. In this paper, different factors that affect the stability of ATO nanoparticles were discussed, such as zeta potential, dispersant, and pH value. Sodium polyphosphate was a suitable dispersant for stabilizing ATO nanoparticles in distilled water. A stable dispersion of ATO nanoparticles in distilled water was prepared. The stable dispersion of ATO nanoparticles was used to prepare nano-thermal insulation glass paint to block near-infrared rays of sunlight.     

POSS-based glycidyl methacrylate copolymer for transparent and permeable coatings

Polyhedral oligomeric silsesquioxane (POSS)-based glycidyl methacrylate (GMA) hybrid copolymers of P(GMA-MAPOSS) are prepared by methacrylisobutyl polyhedral oligomeric silsesquioxane (MAPOSS) and GMA via free radical polymerization used as coatings. Their morphologies and particle size distributions in CHCl₃ solution are characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The effect of MAPOSS content on surface wettability, transparency and permeability of casted films, the adhesive strength, and thermostability of hybrid copolymers are further characterized by scanning electron microscopy (SEM), static contact angle (SCA), UV-Vis, mercury porosimeter, mechanical testing, differential scanning calorimetry (DSC), and thermogravimetry (TGA). Compared with the homogeneous surface of PGMA film, the surface of P(GMA-MAPOSS) film exhibits heterogeneous morphology due to the bulky volume of MAPOSS tending to agglomerate onto the film surface. This micro-rough structure helps to enhance the surface hydrophobicity (100–112° water SCA). While the surface of cured P(GMA-MAPOSS) film obtains a very homogeneous micro-rough morphology without any agglomeration due to the restricted movements of MAPOSS by 250 nm core-shell particles in CHCl₃ solution. Therefore, the cured P(GMA-MAPOSS) film provides with superior luminousness (>98%), strong adhesive strength (748.2 Pa), and high thermostability (T_g = 115°C). Particularly, the chemically involved MAPOSS into PGMA can effectually improve the permeability of traditional epoxy resin. It is believed that the POSS-based GMA hybrid copolymers P(GMA-MAPOSS) will have great potential applications as transparent and permeable coatings.     

SnS and SnS2 thin films deposited using a spin‐coating technique from intramolecularly coordinated organotin sulfides

Synthesis and applications of organotin(II) sulfide ({2,6‐(Me₂NCH₂)₂C₆H₃}Sn)₂(μ‐S) ( 1 ), organotin(II) thiophenolate {2,6‐(Me₂NCH₂)₂C₆H₃}Sn(SPh) ( 2 ) and organotin(IV) heptasulfide {2,6‐(Me₂NCH₂)₂C₆H₃}₂Sn₂S₇ ( 3 ) as potential single‐source precursors (SSPs) for the deposition of SnS or SnS₂ thin films using a spin‐coating method are reported. Compounds 1 , 2 and 3 differ either by tin oxidation state or by Sn:S ratio (Sn:S = 2:1 in 1 , 1:1 in 2 and 2:7 in 3 ). It is shown that compound 1 is not a suitable SSP for thin‐film fabrication using the spin‐coating process because of its incomplete decomposition at annealing temperature. However, compounds 2 and 3 seem to be promising SSPs for spin‐coating of amorphous semiconducting thin films of SnS and SnS₂, respectively. Copyright © 2015 John Wiley & Sons, Ltd.     

Assessment of corrosion protection and performance of bio-based polyurethane acrylate incorporated with nano zinc oxide coating

In this study, a series of UV-curable anticorrosive PUA coatings embedded with varying concentrations of inorganic ZnO fillers have been successfully prepared from jatropha-based polyol. The electrochemical impedance spectroscopy (EIS) and Tafel polarisation analysis revealed that increasing fillers composition lead to the improvement of the anticorrosive property of the hybrid coatings. Meanwhile, the salt spray test results were found to correlate with the EIS of C_c (F cm⁻²) was 2.71 × 10⁻⁹, Bode plot - 10⁶ Ω cm² and Tafel polarisation results 7.56 × 10⁻⁶ MPY at 3 wt% of ZnO. Physical properties of 3 wt% loading of ZnO fillers in hardness test obtained 6H which was strongly attributed to the low interfacial interaction and poor dispersion of the fillers within the polymer matrix.     

Expedient Synthesis of Oxaboracyclic Compounds Based on Naphthalene and Biphenyl Backbone and Phase-Dependent Luminescence of their Chelate Complexes

The approach to a series of six- and seven-membered oxaboraheterocycles based on naphthalene or biphenyl backbones was developed. The key synthetic step involved Br/Li exchange in respective potassium (bromoaryl)trifluoroborates followed by quenching with selected electrophiles (CO₂, DMF, Me₂Si(H)Cl) and hydrolytic workup. Two ring-expanded benzoxaborole congeners were obtained by an additional reduction step with LiAlH₄ or NaBH₄. The obtained boracyclic compounds were characterized in detail by NMR spectroscopy and single-crystal X-ray diffraction. Specifically, biphenyl-based systems show dynamic behaviour interpreted in terms of inversion of non-planar seven-membered boraheterocycles. The acidity of the obtained compounds varies very strongly (pK_a ranges from 3.1–9.6) depending on their structure. Due to the enhanced boron Lewis acidity, selected compounds were used as a basis for luminescent complexes with 8-hydroxyquinoline. A strong phase-dependent variation of emission-band maximum (480–527 nm) and photoluminescence quantum yield (10–95 %) was observed, which was rationalized in terms of specific aggregation effects.     

Analyses of the surfaces of concrete by Raman and FT‐IR spectroscopies: comparative study of hardened samples after demoulding and after organic post‐treatment

Concrete surfaces were studied by two spectroscopic techniques, FT‐IR (in ATR mode) and Raman, to establish a nondestructive method to analyze the distribution of hydrated and organic phases. The surface composition of ordinary clinker, polished concrete, concrete after demoulding, and coated concrete as used in building construction was studied. The clinker's mineral phases and the polished concrete were first analyzed by Raman spectroscopy to determine a spectrum database of the specific phases located on the surface of the concrete. Then, both spectroscopic techniques were used to analyze, directly, the surface of hardened concrete after demoulding. No impact of roughness or porosity was highlighted using Raman spectroscopy; many cementitious, or hydrated phases (alite, belite, tricalcium aluminate, ferrite, portlandite and ettringite) were clearly identified. FT‐IR in ATR mode only identified some hydrated phases: portlandite and CaO? SiO₂? H₂O (C? S? H), but organic residues from the demoulding oil were characterized by this technique. Furthermore, the convenience of using these techniques together was tested by analyzing the composition of concrete surfaces coated by different organic post‐treatments. FT‐IR spectroscopy was useful to identify the main organic groups at the concrete surface, whereas Raman spectroscopy was especially able to characterize the mineral/hydrated phases under a thick post‐treatment layer (constituted of polyester varnish). Due to their own specificities, these complementary techniques should be used together to easily identify all the mineral phases and organic residues/coatings on concrete surfaces. Copyright © 2010 John Wiley & Sons, Ltd.     

涂层/基体材料界面结合强度测量方法的现状与展望

界面结合强度是涂层/基体材料体系中的一项重要力学性能指标.而表征与评价涂层/基体材料的界面结合强度又得依靠实验 方法的测定.由于涂层/基体材料体系的多样性与复杂性, 至今还没有形成适合于测量这类材料的界面结合强度的标准方法. 目前, 常用来测量涂层/基体材料的界面结合强度的方法有：拉伸法、剪切法、弯曲法、划痕法、压入法等.本文就目前表征 与评价涂层/基体材料界面结合强度的测量方法做了综述, 讨论了它们的适用范围, 比较了它们的优势与不足.     

功能梯度材料涂层平面裂纹分析

研究粘接于均质基底材料上功能梯度涂层平面裂纹问题. 假设功能梯度材料剪切模量的倒数为坐标的线性函数，而泊松比为常数. 采用Fourier变换和传递矩阵法将该混合边值问题化为奇异积分方程组，通过数值求解获得 应力强度因子. 考察了材料梯度变化形式、结构几何尺寸和材料梯度参数对裂纹应力强度因子的影响，发现 功能梯度材料涂层尺寸、裂纹长度以及材料梯度参数均对应力强度因子有显著影响.