Novel Polymeric Thin Films from Labile Lactic Acid by a Dry Process

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A novel approach of fabricating white phosphorescent polymers for light‐emitting diodes (LEDs) was successfully developed via processes of plasma polymerization and complex chelation. Direct injection of high concentrations of aromatic monomer, 1,10‐phenanthroline (Ph), into plasma reaction chamber allowed the polymerization to take place in high yields with excellent retention of desired monomer functionalities. Constructed by conjugated segments of various lengths in their backbones, the synthesized polymer emitted broad‐band photoluminescence spectra from 380 to 600 nm. Subsequent refluxing with the transition metal iridium (Ir) resulted Ir–polymer complexes that manifested broad‐band fluorescence from 400 to 600 nm and phosphorescence from 450 to 700 nm. The phosphorescent emissions were assigned to a combination of triplet ligand‐centered π–π* and metal‐to‐ligand (ML) charge transfer emissions. Between electrodes, the polymer–Ir complexes emanated full‐spectral white‐light emissions that are composed of ligand‐centered π–π* emission with maxima at 435 nm and ML charge transfer emission with maxima at 605 nm. The devices exhibited voltage‐stable white luminescence with the Commission Internationale de l'Enclairage (CIE) coordinates of (0.25, 0.26), a maximum luminance efficiency of 7.44 cd · A−1, and a maximum luminance of 4 486 cd · m−2. This simple approach offers great potential for the synthesis and engineering of white organic LED phosphorescent materials.

Section: Methodsmentioning

confidence: 99%

White Luminescent Polymers by Plasma Polymerized Iridium Complexes from 1,10‐Phenanthroline

Chang

Wang

Chen

et al. 2011

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One‐step Fabrication of π‐Conjugated Polymer Thin Films from Naphthalenes via Plasma Polymerization for Efficient Optoelectronic Devices: White Polymer Light‐emitting Diodes

Chang

Hwang

et al. 2011

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We describe a facile one‐step fabrication process of thin film conjugated polymers for efficient optoelectronic devices from naphthalenes by plasma polymerization through a new monomer feeding method. The resulting 3‐D aromatic chain networks of the polymerized films were in good agreement with the predictions based on monomer bond rupture routes analysis. The photoluminescence (PL) spectra of plasma‐polymerized films featured short‐lived inter‐molecular emissions arising from self‐assembly of the naphthalene units in the crosslinked architectures. When functioning between the electrodes for light emitting, the plasma films manifested electroluminescence (EL) spectra that showed a steep rise at the threshold wavelength red‐shifted relative to the PL spectra, indicating prevailing charge tunneling to lower excited states by the accumulated interfacial charges. The wide distribution of conjugation lengths in the plasma films provided the subsequent energy transfer routes and gave rise to the broad EL emission band that produced stable pure white light of CIE coordinates of (0.34, 0.33) with excellent efficiencies. This dry deposition process allows the use of multiple monomers for property tailoring and may be used for large‐area depositions.

Surface Modification of Biodegradable Poly(L‐Lactic Acid) by Argon Plasma: Fibroblasts and Keratinocytes in the Spotlight

Rimpelová

Peterková

Kasálková

et al. 2014

Poly(L-lactic acid) [PLLA] is a biodegradable polymer of growing importance for applications in tissue engineering. This work deals with PLLA tuned by Ar plasma treatment (3 W) with the aim to enhance its wettability and cytocompatibility. Changes in surface properties of PLLA caused by plasma treatment were studied in relation to adhesion, proliferation, and metabolic activity of mouse embryonic fibroblasts (NIH 3T3) and human keratinocytes (HaCaT) in vitro. Plasma treatment of PLLA significantly improved adhesion and proliferation of both cell lines when compared to pristine PLLA. Changes in expression of adhesion molecules, talin 1 and vinculin, were also examined. The amount of both proteins in cells cultivated on modified PLLA matrices was lower than in cells grown on pristine PLLA after 24 h of incubation.