Synthesis and characterization of hydrophilic polyester‐PEO networks with shape‐memory properties

Shape‐memory polyester‐polyethylene oxide networks are synthesized through photopolymerization of hydrophobic poly[(D,L‐lactide)‐co‐glycolide]tetraacrylate (PLGATA) and hydrophilic poly(ethylene glycol) dimethacrylate (PEGDMA). The materials can recover their original shape either quickly by heating stimulus or slowly upon immersion in water. The wettability, mechanical properties, and transition temperature of the polymer networks could be conveniently adjusted by variation of the compositions of PLGATA and PEGDMA. The hydrophilicity of PEGDMA could prospectively improve blood compatibility of polymer networks. They offer a high potential for biomedical applications such as smart implants, drug delivery systems, or medical devices. Copyright © 2010 John Wiley & Sons, Ltd.     

Preparation and characterization of polymer‐stabilized cholesteric texture cells using (+)‐bornylmethacrylate 1

Chiral monomeric (+)‐bornyl methacrylate (BMA) was synthesized from (+)‐camphor. The normal mode of polymer‐stabilized cholesteric texture (PSCT) liquid crystal cells was fabricated using 97.3 wt% of liquid crystal (E48/CB15 = 92/8) and 2.7 wt% of various compositions of chiral and achiral monomers. BMA was used as a chiral monomer and, 4,4′‐bis[6‐(acryloyloxy)hexyloxy]biphenyl and ethyleneglycol dimethacrylate were used as achiral difunctional monomers. The electro‐optical characteristics and the morphology of the PSCT cells with chiral and achiral polymer materials were investigated. The effects of monomer concentration and polymerization conditions of the chiral (+)‐bornyl methacrylate on the electro‐optical characteristics and morphology of PSCT cells were also investigated. It was found that the electro‐optical characteristics of PSCT cells were improved by using the chiral monomer of (+)‐bornyl methacrylate effectively. A PSCT cell was fabricated, and the reversible turbid and transparent changes were examined by applying a 15 V electric field. Copyright © 2000 John Wiley & Sons, Ltd.     

Low loss second‐order non‐linear optical crosslinked polymers based on a phosphorus‐containing maleimide

A series of crossslinked organic and organic/inorganic polymers based on maleimide chemistry have been investigated for second‐order non‐linear optical (NLO) materials with excellent thermal stability and low optical loss. Two reactive chromophores (maleimide‐containing azobenzene dye and alkoxysilane‐containing azobenzene dye) were incorporated into a phosphorus‐containing maleimide polymer, respectively. The selection of the phosphorus‐containing maleimide polymer as the polymeric matrices provides enhanced solubility and thermal stability, and excellent optical quality. Moreover, a full interpenetrating network (IPN) was formed through simultaneous addition reaction of the phosphorus‐containing maleimide, and sol‐gel process of alkoxysilane dye (ASD). Atomic force microscopy (AFM) results indicate that the inorganic networks are distributed uniformly throughout the polymer matrices on a nano‐scale. The silica particle sizes are well under 100 nm. Using in situ contact poling, the r₃₃ coefficients of 2.2–17.0 pm/V have been obtained for the optically clear phosphorus‐containing NLO materials. Excellent temporal stability (100°C) and low optical loss (0.99–1.71 dB/cm; 830 nm) were also obtained for these phosphorus‐containing materials. Copyright © 2004 John Wiley & Sons, Ltd.     

Referenced Dual Pressure‐ and Temperature‐Sensitive Paint for Digital Color Camera Read Out

The first fluorescent material for the referenced simultaneous RGB (red green blue) imaging of barometric pressure (oxygen partial pressure) and temperature is presented. This sensitive coating consists of two platinum(II) complexes as indicators and a reference dye, each of which is incorporated in appropriate polymer nanoparticles. These particles are dispersed in a polyurethane hydrogel and spread onto a solid support. The emission of the (oxygen) pressure indicator, PtTFPP, matches the red channel of a RGB color camera, whilst the emission of the temperature indicator [Pt^II(Br‐thq)(acac)] matches the green channel. The reference dye, 9,10‐diphenylanthracene, emits in the blue channel. In contrast to other dual‐sensitive materials, this new coating allows for the simultaneous imaging of both indicator signals, as well as the reference signal, in one RGB color picture without having to separate the signals with additional optical filters. All of these dyes are excitable with a 405 nm light‐emitting diode (LED). With this new composite material, barometric pressure can be determined with a resolution of 22 mbar; the temperature can be determined with a resolution of 4.3 °C.     

Synthesis of polymers containing regularly distributed tetrathia‐[7]‐elicene units along the backbone

A tetrathia‐[7]‐helicene bearing in the 2 and 13 positions cyanovinyl groups was used as comonomer in the Michael‐type polyaddition reaction with N,N′‐bis(β‐mercaptoethyl)piperazine. This led to a new polymer bearing tetrathia‐[7]‐helicene units regularly distributed along the polymer backbone, which may be regarded as the first example of a new family of potentially useful nonlinear optical materials. All products were structurally characterized by ¹H and ¹³C NMR spectroscopy. Differential scanning calorimetry characterizations revealed the presence, in both monomeric and polymeric helicenes, of glass‐transition like temperatures, associated to some conformational variation of the helicene units. The optical properties, the film formation and the morphology of the polymer‐containing tetratia‐[7]‐helicenes were also investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Refractive index increase of acrylate‐based polymers by adding soluble aromatic guest‐molecules

This work presents the influence of dopants on viscosity in an uncured liquid state as well as on refractive index, Abbe number, optical loss, and glass transition temperature of different polymer compositions. The base material consists of Genomer 2263, a bisphenol, an epoxy diacrylate as matrix polymer, and benzyl methacrylate as comonomer. As dopants, the soluble aromatic guest‐molecules 9‐bromophenantrene and 9‐vinylcarbazole are investigated. The viscosity can be adjusted by different mixtures of the matrix polymer and comonomer from 3000 down to 4 mPa sec. Depending on the type and content of the dopants, the refractive index, Abbe number, and the glass transition temperature can be adjusted. The refractive indices increase linear at 589 nm and 20°C from 1.572 to 1.638 by doping, with Abbe numbers between 20 and 30. At this wavelength, the optical losses were determined to be around 2 dB · cm^?1. The glass transition temperature can be tailored between 50 and 98°C. A way to use high amounts of optical dopants is presented, which opens up the way for different shaping technologies like inkjet printing of optical components. Copyright © 2016 John Wiley & Sons, Ltd.     

Photo‐induced thiol‐ene polysulfide‐crosslinked materials with tunable thermal and mechanical properties

Photo‐induced thiol‐ene crosslinked polymeric networks have been extensively explored in constructing a variety of new materials with enhanced mechanical properties for optical, biomedical, and sensing applications. Toward the broad applications, however, tunable mechanical properties are greatly desired. Here, an effective approach utilizing high‐molecular‐weight methacrylate copolymers having pendant thiol and vinyl groups (MCPsh and MCPenes) to modulate thermal and mechanical properties of photo‐induced thiol‐ene crosslinked materials is reported. The MCP copolymers are synthesized by an industrially friendly polymerization method, followed by post‐modification including either a facile coupling reaction or reductive cleavage. Upon UV irradiation, thiol‐ene reactive blends of MCPsh and MCPenes yield highly crosslinked materials through the formation of flexible sulfide linkages. These polysulfide‐crosslinked materials based on rigid MCP backbones exhibit enhanced mechanical properties. Further, their thermal and mechanical properties are tuned by modulating monomer compositions of MCPs as well as varying numbers of pendant SH or vinyl groups (i.e., extent of crosslinking densities). This approach is versatile and effective for development of high performance polymeric materials. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3060–3068     

Poly(difluorophosphazene) as the First Deep‐Ultraviolet Nonlinear Optical Polymer: A First‐Principles Prediction

A novel concept to obtain the deep‐ultraviolet (DUV) nonlinear optical (NLO) materials is proposed based on the assembling of one‐dimensional (1D) polar motifs into quasi‐1D polymer patterns. Based on the first‐principles calculations, we have successfully discovered an excellent DUV NLO polymer, i.e., poly(difluorophosphazene), with the chemical formula of (PNF₂)_n. Calculations reveal that PNF₂ has a larger band gap, a stronger second harmonic generation effect, a larger birefringence, and a shorter phase‐matching cutoff than KBe₂BO₃F₂. These findings not only demonstrate that the PNF₂ is the first reported DUV NLO polymer, but also could open a new direction to discover novel DUV NLO materials in polymer systems.     

An Aqueous Conducting Redox‐Polymer‐Based Proton Battery that Can Withstand Rapid Constant‐Voltage Charging and Sub‐Zero Temperatures

Electrodes based on organic matter operating in aqueous electrolytes enable new approaches and technologies for assembling and utilizing batteries that are difficult to achieve with traditional electrode materials. Here, we report how thiophene‐based trimeric structures with naphthoquinone or hydroquinone redox‐active pendent groups can be processed in solution, deposited, dried and subsequently polymerized in solid state to form conductive (redox) polymer layers without any additives. Such post‐deposition polymerization offers efficient use of material, high mass loading (up to 10 mg cm^?2) and good flexibility in the choice of substrate and coating method. By employing these materials as anode and cathode in an acidic aqueous electrolyte a rocking‐chair proton battery is built. The battery shows good cycling stability (85 % after 500 cycles), withstands rapid charging, with full capacity (60 mAh g^?1) reached within 100 seconds, allows for direct integration with photovoltaics, and retains its favorable characteristics even at ?24 °C.     

Disposable Injection‐Moulded Cell‐on‐a‐Chip Microfluidic Devices with Integrated Conducting Polymer Electrodes for On‐Line Voltammetric and Electrochemiluminescence Detection

This work reports the construction and characterization of plastic electrochemical micro‐flow‐cells with integrated injection‐moulded polymer electrodes. The three electrodes (working, auxiliary, and reference) were fabricated by injection‐moulding from a conducting grade of polystyrene loaded with carbon fibers. On‐chip reference electrodes were prepared by coating one of the conducting polymer electrodes with a Ag/AgCl layer (implemented either by e‐beam evaporation of Ag followed by electrochemical formation of AgCl or by applying a Ag/AgCl paste). Working electrodes were either polymer electrodes coated with Au by e‐beam evaporation or bare conducting polymer electrodes. The electrodes were integrated into the micro‐flow‐cells by an over‐moulding process followed by ultrasonic welding. The devices were characterized by optical and electrochemical techniques. Studies by cyclic voltammetry (CV), anodic stripping voltammetry (ASV) and electrochemiluminescence (ECL) demonstrate ‘proof–of‐principle’ of the micro‐flow‐cells as electrochemical sensors.     

Solvent‐assisted prototyping of microfluidic and optofluidic microsystems in polymers

Due to their low‐cost and processing simplicity, polymers have made a substantial impact on everyday life and scientific discoveries. Such discoveries include the use of microanalysis and optical microsystems, which—albeit simpler to prototype than their inorganic counterparts—still require dedicated procedures at high temperatures and pressures. Here, recent developments in microsystem prototyping are highlighted, based on solvent‐assisted polymer stimulation. These developments—largely inspired by the earlier demonstration of solvent‐assisted micromolding (SAMIM) for nanoimprinting—enable micronscale imprinting, but also bonding to substrates and three‐dimensional chemical functionalization via strict benchtop procedures. These solvent‐assisted strategies are categorized into two groups: those based on solvent immersion and those based on complete polymer dissolution. Recent embodiments within each group are discussed and compared in performance. Solvent‐assisted prototyping further narrows the gap of processing complexity and costs between the PDMS elastomer and thermoplastic polymer microfluidics, and also enables novel architectures and thus new opportunities in microscale Life Sciences and Chemistry investigations. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1681–1686     

A facile approach to prepare soluble side‐chain polyimides for second‐order nonlinear optics

A simple and generally applicable new synthetic method to prepare second‐order nonlinear optical (NLO) polyimides has been developed. In this approach, side‐chain‐substituted polyimides were synthesized via isocyanato‐terminated prepolymers prepared directly from NLO chromophore‐containing diols Disperse Red 19. Using this technique, the tedious synthesis of the classical diamine monomers and harsh imidization process associated with polyamic acid prepolymers are avoided. The resulting polymers possessed good solubility and high glass‐transition (171–211 °C) and thermal‐decomposition temperatures. The polymers also exhibited excellent film‐forming properties, and good optical‐quality films were easily obtained by spin coating. The second‐order NLO activities of the polymer films were also studied, and several factors that might determine the growth of the second‐order NLO activity were proposed. The polymers obtained exhibit a large second‐order NLO activity (34–52.5 pm/V at 1064 nm). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2189–2195, 2001     

Second‐order non‐linear optical polymers

In this article we discuss the state of the art in the field of second‐order non‐linear optical polymers. More specifically, we highlight those results that we think made an important contribution to the field, combined with some of our own results. We start with a general overview of all the aspects involved in characterizing second‐order non‐linear optical polymers, from thin film formation and poling to second‐harmonic generation and electro‐optic measurements on such systems. Next, we review the second‐order non‐linear optical properties of selected polymer systems such as poly(vinyl ether)s, polystyrenes, polymethacrylates, main‐chain polymers and high T_g polymers like polyimides and polymaleimides. Finally, we discuss some new polymer systems that might become important in the field of non‐linear optics in the near future.     

Synthesis,optical and photoconducting properties of platinum poly‐yne polymers functionalized with electron‐donating and electron‐withdrawing bithiazole units

By virtue of the electron‐donating and electron‐withdrawing properties of the thiazole ring, a new soluble rigid‐rod organometallic polymer containing electron‐donating and electron‐withdrawing trans‐[‐Pt‐(PBu₃)₂‐C≡C—R—C≡C—]_n (R = bithiazolediyl) groups is prepared by CuI‐catalyzed dehydrohalogenation. The thermal properties and the optical absorption and photoluminescence spectra of the polymer are reported. The polymer is luminescent with a singlet emission peak at 539 nm and photoconducting in a single‐layer sandwich structure photocell. The optical gap of the polymer is reduced compared to that for the oligothienyl analogue.     

In vitro antibacterial and antifungal assay of poly‐(ethylene oxamide‐N,N′‐diacetate) and its polymer–metal complexes

A new polyester, poly‐(ethylene oxamide‐N,N′‐diacetate) (PEODA), containing glycine moiety was synthesized by the reaction of oxamide‐N,N′‐diacetic acid and ethylene glycol and its polymer–metal complexes were synthesized with transition metal ions. The monomer oxamide‐N,N′‐diacetic acid was prepared by the reaction of glycine and diethyl oxalate. The polymer and its metal complexes were characterized by elemental analysis and other spectroscopic techniques. The in vitro antibacterial activities of all the synthesized polymers were investigated against some bacteria and fungi. The analytical data revealed that the coordination polymers of Mn(II), Co(II) and Ni(II) are coordinated with two water molecules, which are further supported by FTIR spectra and TGA data. The polymer–metal complexes showed excellent antibacterial activities against both types of microorganisms; the polymeric ligand was also found to be effective but less so than the polymer–metal complexes. On the basis of the antimicrobial behavior, these polymers may be used as antifungal and antifouling coating materials in fields like life‐saving medical devices and the bottoms of ships. Copyright © 2007 John Wiley & Sons, Ltd.     

Crown‐ether and azobenzene‐containing liquid crystalline polymers: An influence of macromolecular architecture on optical properties and photo‐orientation processes

A series of novel crown ether‐containing photochromic comb‐shaped liquid crystalline polyacrylates with different macromolecular structure of side groups were synthesized and investigated. Phase behavior, optical and photo‐optical properties of thin spin‐coated films of these polymers were studied. A special attention was paid to a comparative study of the photo‐orientation phenomena occurring in the polymer films under a polarized light action. It was shown that complex formation with the potassium ions results in the decrease in degree of the photoinduced order that can be used for the creation of new materials for sensor devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Self‐Immolative Poly(4,5‐dichlorophthalaldehyde) and its Applications in Multi‐Stimuli‐Responsive Macroscopic Plastics

End‐capped poly(4,5‐dichlorophthalaldehyde) (PCl₂PA), which is a new self‐immolative CD_r polymer with the unique capability of depolymerizing continuously and completely in the solid state when an end cap is cleaved from the polymer by reaction with a specific molecular signal, is described. End‐capped poly(4,5‐dichlorophthalaldehyde) is sufficiently stable to enable patterning of three‐dimensional macroscopic polymeric materials by selective laser sintering. These unique materials are capable of 1) autonomously amplifying macroscopic changes in the material in response to specific molecular inputs, and 2) altering their responses depending on the identity of the applied signal. Thus, not only does end‐capped PCl₂PA provide new and unique capabilities compared to the small subset of existing CD_r polymers, but it also provides access to a new class of stimuli‐responsive materials.     

Dual‐emissive polydiphenylsilane nanocomposite: effect of N,N′‐bis(4‐hydroxysalicylidene)‐1,2‐phenylenediamine‐Zn complex

The fluorescence properties of polysilane can be strongly influenced by creating new excited states that involve electronic transitions and the relaxation to the ground state. This work presents the optical effects obtained by doping a specially designed polydiphenylsilane copolymer with Zn complex of N,N′‐bis(4‐hydroxysalicylidene)‐1,2‐phenylenediamine. The nanocomposites have been prepared in solution by mixing the polymer with low amounts of Zn–salophen and using tetrahydrofuran as solvent. The ultraviolet–visible spectrum has shown the occurrence of an intermolecular charge transfer between polysilane and the metal complex. Photoluminescence studies have revealed an interesting dual emission profile of nanocomposite. The origin of this phenomenon has been evidenced by molecular modeling and simulation of the electronic transitions. The modeling results have unveiled a new low‐lying excited state due to intermolecular interactions. The thin films of nanocomposites have been drop‐casted from solutions. The obtained films have been studied by Transmission Electron Microscopy (TEM)‐Scanning Transmission Electron Microscopy (STEM)‐Energy Dispersive X‐ray analysis (EDX) to gain information on the film‐forming capacity and surface morphology. The results have revealed a high potential of such materials for fluorescence sensing applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis of novel hydrocarbon polymers containing 6‐membered rings in the main chain: living anionic polymerization of 1,3‐cyclohexadiene

The n‐butyllithium (n‐BuLi)/N,N,N',N'‐tetrametylethylene‐diamine (TMEDA) system (the molar ratio of TMEDA to n‐BuLi higher than 4/4) has been found to polymerize 1,3‐cyclohexadiene (1,3‐CHD) to produce “living” polymer having narrow molecular weight distribution with well‐controlled polymer chain length. Binary and ternary block copolymers with narrow molecular weight distribution could be synthesized from 1,3‐cyclohexadiene, styrene, and butadiene with very high efficiency. These polymers and their hydrogenated derivatives have excellent thermal, mechanical, chemical, and optical properties for the new industrial materials.     

SEM and RBS characterization of a cobalt‐based conversion coating process on AA2024‐T3 and AA7075‐T6

Samples of aluminium alloys AA2024‐T3 and AA7075‐T6 were treated with a chromate‐based deoxidizer, then conversion coated with a commercial cobalt‐based solution and finally sealed with a commercial vanadate‐based product. The alloy specimens were examined using scanning electron microscopy, transmission electron microscopy and Rutherford backscattering spectroscopy. The thickness of the cobalt‐based conversion coating increased rapidly up to 5 min of immersion but more slowly for longer times. Sealing resulted in penetration of vanadium through the oxide and a small increase in thickness due to the deposition of a thin sealing coating within the pores and on the external surface of the cobalt‐containing coating. Copyright © 2004 John Wiley & Sons, Ltd.