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A series of blue, green and red emitting polymers that are appropriately functionalized with alkyne and azide functional groups have been prepared and clicked together to construct bi-layered and tri-layered white emitting core-shell type nanoparticles. Here the use of these organic hetero-nanoparticles as colour converters to realize a white light-emitting diode platform acquiring a colour quality comparable to the existing phosphor-based ones was also demonstrated. © The Royal Society of Chemistry.

In the present article, we present a new and convenient optical method for the preparation of self-standing polyelectrolyte multilayer films. This method employs the disassembly of a sacrificial layer stratum composed of five poly(acrylate, merocyanine) PMC/poly(diallyldimethylammonium chloride) PDADMAC bilayers, which is triggered by the irradiation with visible light. This leads to the conversion of the zwitterionic PMC to its neutral isomer poly(acrylate, spiropyran) PSP, whereby the attractive ionic interactions between the neighboring bilayers vanish. The disassembly of the sacrificial layers in deionized water was completed within 47 s, when in-situ monitored at the maximum absorbance of PSP (λ = 360 nm), employing UV/visible spectrometry. Surprisingly, the disassembly duration of the sacrificial layers increased very little with an upper target film composed of 75 PDADMAC/PSS bilayers. The quick release of a thick target film (d ∼ 232 nm) composed of 100 (PDADMAC)/(PSS) bilayers in a large scale (7 × 18 mm(2)) could be ascribed not only to the vanished electrostatic attractive interaction between the layer pairs but also to increased hydrophobicity of the sacrificial layer element due to the photoisomerization of zwitterionic ionic PMC to neutral PSP. The unique advantages of this method as compared to the conventional approaches are demonstrated with the fast release (~2 min) of self-standing film combined with a well-defined, thin sacrificial layer (d ~ 30 nm). Moreover, harsh release conditions are also avoided, which significantly broadens the choice of materials that can be incorporated into the free-standing film.

This paper describes a pH-responsive multilayer film composed of two layered components, namely poly(allylamine hydrochloride) (PAH) and a copolymer of acrylic acid and [1,3]oxazine-modified acrylate (POA). The oxazine ring is an acidochromic chromophore and opens to form either cationic 3H-indolium or anionic hemiaminal in a pH-dependent manner. This structural transition was used to generate a net positive or negative charge on the membrane for selective ion permeation. Interestingly, the reversible oxazine ring opening and closing proceeded smoothly without significant steric hindrance in the multilayer film comprising 10 PAH/POA bilayers. The pH-responsive permselectivity for cationic and anionic probe molecules was demonstrated using a POA monolayer film adsorbed electrostatically onto an amino-functionalized ITO electrode. The origin of the excellent ion-transport selectivity in the 1 nm ultrathin POA membrane is discussed in terms of alternating charges of the aromatic amphoteric group, oxazine, in the polyeletrolyte membrane.

Toward the realization of nanoscale device control, we report a novel method for photoregulation of ion flux through a polyelectrolyte multilayer membrane by chromophore orientation that is adjusted either by illumination at normal incidence or by slantwise irradiation at an angle of 10 degrees with respect to the surface. Our results indicate that the chromophore reorientation caused by the slantwise irradiation controls the effective pore size and, consequently, the transport behavior on the nanoscale. The slantwise illumination, which includes six EZE photoisomerization cycles generated by alternately irradiating with ultraviolet (lambda = 360 nm) and visible (lambda = 450 nm) light, reversibly switches the orientation of E-azobenzene in the membrane between 53 +/- 2 degrees (high tilt) and 17 +/- 5 degrees (low tilt) with respect to the surface. The novel feature of this light-gated valve system is its extremely long-lived open-switch state; this behavior stands in contrast to that of other systems based on labile photoisomers, which tend to instantly return to the thermodynamically stable state.