Colloidal crystal (CC) thin films that produce structural colours over a wide visible spectrum have been self-assembled from silica nanoparticles (SNPs) using a natural sedimentation method. A series of colloidal suspensions containing uniform SNPs (207-350 nm) were prepared using the Stöber method. The prepared silica suspensions were directly subjected to natural sedimentation at an elevated temperature. The SNPs were deposited under the force of gravity and selfassembled into an ordered array. The solid CC thin films produced structural colours over a wide visible spectrum from red to violet. Visual inspection and colorimetric measurements indicated that the structural colour of the CC thin film is tuneable by varying the SNPs diameters and the viewing angles. The closely packed face-centred cubic (fcc) structure of the CC thin film was confirmed using SEM imaging and was in agreement with the intense colour observed from the film surface.
In this work, the Stöber process was applied to produce uniform silica nanoparticles (SNPs) in the meso-scale size range. The novel aspect of this work was to control the produced silica particle size by only varying the volume of the solvent ethanol used, whilst fixing the other reaction conditions. Using this one-step Stöber-based solvent varying (SV) method, seven batches of SNPs with target diameters ranging from 70 to 400 nm were repeatedly reproduced, and the size distribution in terms of the polydispersity index (PDI) was well maintained (within 0.1). An exponential equation was used to fit the relationship between the particle diameter and ethanol volume. This equation allows the prediction of the amount of ethanol required in order to produce particles of any target diameter within this size range. In addition, it was found that the reaction was completed in approximately 2 h for all batches regardless of the volume of ethanol. Structurally coloured artificial opal photonic crystals (PCs) were fabricated from the prepared SNPs by self-assembly under gravity sedimentation.
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Electronic supplementary materialThe online version of this article (doi:10.1007/s11051-016-3691-8) contains supplementary material, which is available to authorized users.
A short study has been conducted to examine the efficiency of different alkaline reduction‐clearing conditions on Ingeo [poly(lactic acid)] fibres, dyed with disperse dyes. The results indicate that the preferred conditions are 15 min at 60 °C in the presence of 2 g/l sodium carbonate and 2 g/l ‘hydros’, conditions which avoid any significant change of shade by colour loss and lead to optimised wash fastness.
The interaction between water and fibers is critical in the physiological comfort of garments, especially inner wears. Antigravity directional water transport and ultrafast evaporation are the two key indicators to be expected of a high‐performance moisture management textile. However, it is practically still challenging to make the textiles with continuous directional liquid moisture transport and outstanding prevention of water penetration in the reverse direction. In this work, a Janus functional textile achieved by graphene oxide (GO) coating is developed, with the GO coating side on the textile working as the outer side for its good moisture absorbing and spreading features and the reduced GO coating side serving as the inner layer because of its hydrophobicity. Performance of the as‐prepared textile is characterized by moisture management tester, exhibiting remarkable accumulative one‐way transport index R (1145%) and a desired overall moisture management capacity (0.77) within 120 s, the negative R value (−690.4%) indicates an ultrahigh directional liquid moisture transport capacity. The Janus textile can provide a source of inspiration for the development of more adaptive textiles and garments to maximize personal comfort in demanding situations under hot and humid environments.
The reflectance spectra of natural and man‐made surfaces are highly constrained. Statistical analyses have been conducted that confirm that the surface reflectance spectra form a set of band‐limited functions with a frequency limit of approximately 0.02 cycles/nm. The reflectance spectra can be represented by a linear‐model framework and are adequately described by 6‐12 basis functions. However, the spectral properties of surfaces are not so constrained as to allow the human visual system to recover the surface properties from cone excitations. Furthermore, trichromatic colour devices such as scanners and cameras can only capture illumination‐specific colour information.
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