A High‐Content Diarylethene Photochromic Polymer for an Efficient Fluorescence Modulation

Summary: A highly fluorescent photochromic polymer, poly‐BTFO4, was prepared. The fluorescence quantum yield of the poly‐BTFO4 was six times higher than that of BTFO4. Fatigue resistance of the polymer at its photostationary state was significantly enhanced compared with that of BTFO4. Importantly, the poly‐BTFO4 film also showed an efficient photochromism as well as strong fluorescence similar to the results in solution, which allow photoinduced fluorescence switching applicable to optical switches.

Improvement of fluorescence quantum yield and fatigue resistance.     

1,1‐Diphenyl Ethylene‐Mediated Radical Polymerisation: A General Non‐Metal‐Based Technique For The Synthesis Of Precise Core Cross‐Linked Star Polymers

This communication details the successful synthesis of low polydispersity core cross‐linked star (CCS) polymers via DPE‐mediated polymerisation. We demonstrate the ability to produce poly(methyl methacrylate) and poly(acrylonitrile) CCS polymers that are currently inaccessible via the two most common non‐metal‐based controlled radical polymerisation techniques (NMP and RAFT polymerisations).

     

Single‐Chain‐Particles of Poly(N‐isopropylacrylamide)

Spherical single‐chain‐particles of poly(N‐isopropylacrylamide) were prepared in aqueous solution above the lower critical solution temperature upon the addition of sodium dodecyl sulfate. The size of the single‐chain‐particles was investigated by means of transmission electron microscopy and viscosity measurements of the corresponding solutions, indicating the absence of inter‐chain entanglements among the single‐chain‐particles.

Schematic of the preparation of PNIPAM single‐chain‐globules in solution.     

A Novel Route for Fabricating Metal‐Polymer Composite Nanoparticles with Phase‐Separated Structures

Au nanoparticles (NPs) and polymer composite particles with phase‐separation structures were prepared based on phase separation structures. Au NPs were successfully synthesized in amphiphilic block‐copolymer micelles, and then composite particles were formed by a simple solvent evaporation process from Au NPs and polymer solution. The phase separated structures (Janus and Core‐shell) were controlled by changing the combination of polymers having differing hydrophobicity.

     

Solvent Resistant Honeycomb Films from Photo‐Crosslinkable Polycinnamate

Microporous films consisting of two‐dimensionally ordered void structures ‐ so‐called honeycomb films ‐ were produced by evaporation of polymer solutions under high humidity. Two types of poly(vinyl cinnamate)s were used: A newly synthesized amphiphilic poly(vinyl cinnamate) and a mixture of a commercial poly(vinyl cinnamate) and an amphiphilic polyion complex. Photo‐crosslinking of the honeycomb structure could be achieved by UV irradiation while completely retaining the film morphology. The crosslinked films showed excellent stability against organic solvents.

     

Metallo‐Supramolecular Diethylene Glycol: Water‐Soluble Reversible Polymers

Bis(2,2′:6′,2″‐terpyrid‐4′‐yl) diethylene glycol was synthesized as a monomer unit and further utilized for polymerization with FeCl₂ in order to form water‐soluble coordination polymers. Viscosity measurements and film‐forming properties indicate the formation of linear coordination polymers or larger ring structures. The terpyridine/iron(II) complexes are stable up to temperatures of 210 °C, but can be uncomplexed by the addition of an excess of a strong competitive ligand (HEDTA) under mild conditions.

     

Synthesis and Dispersion Characteristics of Multi‐Walled Carbon Nanotube Composites with Poly(methyl methacrylate) Prepared by In‐Situ Bulk Polymerization

Multi‐walled carbon nanotubes (MWNT) purified by acidic solution were processed with PMMA via an in‐situ polymerization. Experimental evidences indicate the role of radical initiator (AIBN) and MWNT, showing increases of polymerization rate and MWNT diameter. Induced radicals on the MWNT by AIBN were found to trigger the grafting of PMMA. Moreover, the solvent cast film showed a better nanoscopic dispersion of MWNT and possibilities of CNT composites in engineering applications.

Fractured surface of multi‐walled carbon nanotube composite with PMMA prepared by in‐situ bulk polymerization.     

Polyurethanes Containing Indole‐Based Non‐Linear Optical Chromophores: from Linear Chromophore to H‐Type

Two new “H” type of indole‐based chromophores were designed and successfully introduced to the polymeric system, the resultant polymers demonstrated enhanced NLO effects, good processability, thermal stability and nearly excellent transparency, indicating the advantages of “H” type chromophore moieties. And they could be promising candidates for the practical applications as new photonic materials.

     

Novel Top‐Surface Imaging Process by Selective Chemisorption of Poly(dimethyl siloxane) on Diazoketo‐Functionalized Single Component Photoresist

A novel top‐surface imaging process was successfully established using selective chemisorption of amine‐functionalized poly(dimethyl siloxane) onto the carboxylic groups formed on the surface of diazoketo‐functionalized polymer film by UV light irradiation. The chemisorbed poly(dimethyl siloxane) worked as an efficient etch mask for the subsequent oxygen plasma etching process for pattern generation. High‐resolution patterns were resolved with the new imaging process.

     

Positive‐/Negative‐, Erasable‐/Immobilized‐, Mono‐/Multi‐Color Fluorescence Image Patterning of Molecular‐Scale Porous Polymer Film via a Microcontact Printing Method Using Various Chemical Inks

Fluorescent image patterns of a substituted acetylene polymer film with a large FFV were successfully obtained by a µCP method using several kinds of chemical ink compounds. PO and SCA generated positive‐type fluorescent image patterns. On the other hand, an ethanolic solution of DNT generated a negative‐type fluorescent image pattern due to a significant quenching effect. An NMP solution of NR gave a two‐color image pattern due to an intermolecular energy transfer from PTMSDPA to NR.

     

Direct Synthesis of PVA‐g‐PDMS in Microsuspension

The synthesis of P(VA‐co‐VAc)‐graft‐PDMS copolymers has been achieved in microsuspension by direct reaction between an epoxy‐terminated PDMS and some pendant alcohol groups in P(VA‐co‐VAc). In this synthesis, the copolymer is used both as dispersant and reactant. The hydrophilic/hydrophobic character of the final material can be varied at will by incorporating various contents of epoxy‐functionalized PDMS through optimized reaction conditions. The final composition was determined by TGA and ¹H NMR. Products prepared from monofunctional PDMS were easily redispersed in water whereas a film of crosslinked materials, arising from difunctional PDMS, showed the best waterproofing as shown by contact angle analysis.

     

Supramolecular Nanocycles Comprising β‐Cyclodextrin‐click‐Ferrocene Units: Rings of Rings of Rings

We applied 1,3‐dipolar cycloaddition to bind ethynylferrocene onto 6I‐azido‐6I‐deoxycyclomaltoheptaose under microwave assisted conditions. The process was investigated by ¹H NMR, FT‐IR spectroscopy, and MALDI‐TOF mass spectrometry. The ability of the synthesized compound to self‐organize to cyclic supramolecular structures was investigated by dynamic light scattering measurements and cryo‐transmission electron microscopy.

     

Cross‐Linked Conjugated Polymers for Achieving Patterned Three‐Color and Blue Polymer Light‐Emitting Diodes with Multi‐Layer Structures

Reactions between the ethylene groups in the backbone of conjugated polymers under UV illumination and heat treatment result in the cross‐linking of the main polymer chains. The cross‐linking leads to two simultaneous results in the polymer: excellent solvent resistance and increased bandgap. Using this reaction, three‐color polymer light‐emitting diodes (PLEDs) with a multi‐layer structure can be easily realized by a dry photo‐pattern in an active‐gas‐free environment. Multi‐layer blue devices with dramatically enhanced efficiency can also be achieved conveniently.

     

Ordered Honeycomb‐Structured Films from Dendronized PMA‐b‐PEO Rod‐Coil Block Copolymers

Summary: Fabrication of honeycomb‐patterned films from amphiphilic dendronized block copolymer (PEO₁₁₃‐b‐PDMA₈₂) by ‘on‐solid surface spreading’ and ‘on‐water spreading’ method is reported. Highly ordered honeycomb films with quasi‐horizontally paralleled double‐layered structure can be fabricated by the on‐solid surface spreading method. This work raises the possibility that such structures can be formed in amphiphilic dendronized block copolymers and extends the family of source materials.

     

Polymer‐Based Rectifying Diodes on a Glass Substrate Fabricated by Ink‐Jet Printing

Summary: The fabrication of polymer diodes on a glass substrate by an ink‐jet printing technique is reported. Both an n‐type semiconductive polymer, poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐(1‐cyanovinylene)phenylene] (CN‐PPV), and a p‐type semiconductive polymer, polypyrrole (PPy) or poly(3,4‐ethylenedioxythiophene) (PEDOT), were printed through a piezoelectric ink‐jet printer. The printed CN‐PPV/PPy and CN‐PPV/PEDOT diodes showed good rectifying characteristics. These results indicate the potential of the low‐cost ink‐jet printing technique to produce polymer microelectronic devices and circuits.

Schematic diagram of the printed polymer diode     

Novel Photoactive Polymeric Multilayer Films Formed via Electrostatic Self‐Assembly

Summary: We demonstrate a novel approach for constructing photoactive multilayer films in which the aggregation of fluorescing molecules is effectively eliminated. In the films formed via a layer‐by‐layer electrostatic self‐assembly technique, the core‐shell amphiphilic copolymer, poly[(sodium 4‐styrenesulfonate)‐block‐vinylnaphthalene], was deposited. The isolated cores served as nanosized host sites for photoactive guest molecules (pyrene, perylene). The efficient energy transfer between polymeric chromophores and perylene molecules was observed.

AFM image of a nanostructured polymeric film prepared via a layer‐by‐layer technique and containing photoactive block copolymer poly[(sodium 4‐styrenesulfonate)‐block‐vinylnaphthalene]. Below is the representative height profile taken along the drawn line.