Photocontrolled Release of Chemicals from Nano- and Microparticle Containers.

A benzoin-derived diol linker was synthesized and used to generate biocompatible polyesters that can be fully decomposed on demand upon UV irradiation. Extensive structural optimization of the linker unit was performed to enable the defined encapsulation of diverse organic compounds in the polymeric structures and allow for a well-controllable polymer cleavage process. Selective tracking of the release kinetics of encapsulated model compounds from the polymeric nano- and microparticle containers was performed by confocal laser scanning microscopy in a proof-of-principle study. The physicochemical properties of the incorporated and released model compounds ranged from fully hydrophilic to fully hydrophobic. The demonstrated biocompatibility of the utilized polyesters and degradation products enables their use in advanced applications, for example, for the smart packaging of UV-sensitive pharmaceuticals, nutritional components, or even in the area of spatially selective self-healing processes.

Combinatorial screening of inkjet printed ternary blends for organic photovoltaics: absorption behavior and morphology.

Inkjet printing was used for the preparation of ternary polymer/polymer/fullerene layers for organic solar cell application, as part of a combinatorial setup for the preparation and characterization of thin-film libraries. Poly(phenylene-ethynylene)-alt-poly(phenylene-vinylene) (PPE-alt-PPV) and poly(diketopyrrolopyrrole-alt-fluorene) (P(DPP-alt-F)) were systematically blended with poly(3-octylthiophene) (P3OT) and investigated by UV-vis spectroscopy to improve the photon harvesting by extending the absorption range. The blends with the broadest absorption range (20 and 40 wt % of PPE-alt-PPV and P(DPP-alt-F), respectively) were mixed with mono(1-[3-(methoxycarbonyl)propyl]-1-phenyl)-[6,6]C61 (PCBM). The blend with the low band gap polymer P(DPP-alt-F) revealed the most extended absorption, which ranges over the whole visible spectrum (350 to 750 nm). The mixing with PCBM (ratio 1/3) led to an optimal emission quenching and revealed a smooth film formation. In this contribution, we show that the combinatorial screening using inkjet printing represents an effective, time- and material-saving workflow for the investigation of polymer blend libraries, which is of high interest for the development of new materials for active layers in organic photovoltaics.