Multifunctional mesoporous silica nanoparticles in poly(ethylene‐co‐vinyl acetate) for transparent heat retention films

Transparent inorganic‐polymer nanocomposite films are of tremendous current interest inemerging solar coverings including photovoltaic encapsulants and commercial greenhouse plastics, but suffer from significant radiative heat loss. This work provides a new and simple approach for controlling this heat loss by using mesoporous silica/quantum dot nanoparticles in poly(ethylene‐co‐vinyl acetate) (EVA) films. Mesoporous silica shells were grown on CdS‐ZnS quantum dot (QDs) cores using a reverse microemulsion technique, controlling the shell thickness. These mesoporous silica nanoparticles (MSNs) were then melt‐mixed with EVA pellets using a mini twin‐screw extruder and pressed into thin films of concentration variable controlled thickness. The results demonstrate that the experimental MSNs showed improved infrared and thermal wavebands retention in the EVA transparent films compared to commercial silica additives, even at lower concentrations. It was also found MSNs enhanced the quantum yield and photostability of the QDs, providing high visible light transmission and blocking of UV transmission of interest for next generation solar coatings. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 851–859     

Syntheses of biphenyl‐terminated polyhedral oligomeric octasilicate‐core dendrimers and their single‐component optical transparent free‐standing thermoplastic films

2‐Biphenylethyl and 2‐biphenylhexyl‐terminated polyhedral oligomeric octasilicate (OS)‐core polyester‐typed dendrimers, denoted as OS‐C2‐BP and OS‐C6‐BP, respectively, were prepared by ring‐opening reaction and subsequent condensation of octakis(propenyl succinicanhydrido)polyhedral octasilicate (OS‐SA) with 2‐(4‐phenylphenoxy)ethanol (BP‐C2‐OH) and 6‐(4‐phenylphenoxy)hexanol (BP‐C6‐OH), respectively. OS‐C2‐BP formed a transparent film, whereas OS‐C6‐BP formed an opaque whitish waxy film. The coating film of OS‐C2‐BP was easily peeled off from a substrate and formed a free‐standing film. The results of X‐ray diffraction and differential scanning calorimeter suggest that the film of OS‐C2‐BP was amorphous, whereas OS‐C6‐BP contained crystalline domains. Thermogravimetric analysis of OS‐C2‐BP and OS‐C6‐BP showed 5 wt % weight losses at 362 °C and 283 °C, respectively. OS‐C2‐BP offered higher thermal resistance than OS‐C6‐BP. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1437–1443     

Solvent‐free inkjet printing process for the fabrication of conductive,transparent, and flexible ionic liquid‐polymer gel structures

A new and solvent‐free process for the fabrication of inkjet printed ionic liquid‐polymer gel microstructures with high‐resolution (line widths of ～40 μm), good electrical conductivity (5–30 mS cm^?1), optical transparency, and mechanical flexibility is presented. Carrying out the printing and polymerization process in nitrogen atmosphere eliminates the inhibiting influence of oxygen and guarantees homogeneously gelled structures. Careful selection and combination of ionic liquids (ILs) and unsaturated monomers makes it possible to achieve low viscosities which are printable with commercially available inkjet printers and printheads without adding extra solvents. By using different types and amounts of ILs and monomers the resulting properties of the printed IL‐polymer gels can be controlled in terms of ionic conductivity, optical transmission, and mechanical flexibility. Higher conductivities are possible by using a bifunctional instead of a monofunctional monomer, which allows one to lower the amount of monomer without loss in mechanical strength. Cast samples make it possible to obtain data of transmission (～90% for 170‐μm thick films) and mechanical flexibility (E = 0.02–0.23 MPa) of bulk material. Comparing electrical conductivity of printed and cast samples, the higher values of printed samples indicate the conductivity enhancing influence of moisture absorbed from the surrounding atmosphere after the fabrication process. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Development of new high transparent hybrid organic–inorganic monoliths with surface engraved diffraction pattern

Flexible hybrid xerogels bringing together high optical transparency up to 96%, low shrinkage down to 5.5%, very smooth surface (average roughness of about 0.3 nm) and thermal stability up to 200 °C were achieved as a result of the optimization of sol‐gel preparative method and a new combination of sol‐gel precursors. Two types of hybrid materials (hereafter referred, respectively, as urea‐silicate and amino‐alcohol‐silicate gels) were synthesized in this work. The shrinkage and the transparency of these materials have been drastically improved by using two different derived siloxanes (3‐isocyanate propyltriethoxysilane and 3‐glycidoxypropyltrimethoxysilane) and two amine‐terminated polyether precursors with different molecular weights. A drying process was implemented to minimize yellowing of prepared samples. Under these conditions, we were able to efficiently reproduce a well‐defined imprinted pattern at materials surface by using an original casting mould. The study of the diffraction characteristics of the obtained grating revealed a good reproducibility of the imprinted grating that shows to be comparable with the original mould. The developed methodology opens the possibility to produce diffraction lenses with a wide range of forms by a simple method based on sol‐gel process. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Fully transparent nonvolatile resistive polymer memory

We present a fully transparent nonvolatile resistive polymer memory device based on an anthracene‐containing partially aliphatic polyimide along with indium tin oxide (ITO) top and bottom electrodes. High transmittance of over 90% in the wavelength range of 400 to 800 nm is accomplished with an ITO/polyimide/ITO/glass device. The device shows unipolar write‐once‐read‐many times (WORM) memory behavior with an ON/OFF current ratio of ～2 × 10³, and the ratio remained without any significant degradation for over 10⁴ s. The memory behavior of the device is considered to be governed by trap‐controlled space‐charge limited conduction (SCLC) and local filament formation. Based on molecular simulation of the polyimide, the location of energy states is different from that in the conventional charge transfer (CT) mechanism. Despite the relatively low ON/OFF current ratio, our results can give insight into the development of fully transparent memory device. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 918–925     

Flexible transparent fluorinated nanohybrid with innovative heat‐resistance property—new technology proposal for fabrication of transparent materials using “crystalline” polymer

A new technology for the production of transparent material, using a “crystalline” polymer, is proposed in this study. In addition, a heat‐resistant transparent flexible plastic film with a high hydrophobic surface and a thermal decomposition temperature near 400 °C was created. Partially fluorinated crystalline polymer with switchboard‐type lamellae results high transparency as a consequence of the formation of a high‐density amorphous structure based on high‐temperature drawing just below the melting point at 250 °C. Melt‐compounding with montmorillonite modified by the long‐chain quaternary phosphonium with high coverage induces formation of a nanohybrid that retains transparency and also results in an increase in the thermal degradation temperature by over 50 °C. Through this technology, which results in heat‐resistance, transparency, and flexibility, the nano‐micro‐millimeter structures of solid‐state polymers are hierarchically controlled, which enables the creation of new materials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1674–1690     

Design and synthesis of optically active 2‐phenylimidazolecarboxamides featuring amino acid motive

Overall sixteen new, optically active carboxamides 1‐3 have been synthesized. These compounds based on the 2‐phenylimidazole and featuring amino acid residues are linked on the 4‐position by an amidic bond. Two general methods were used for their construction. Whereas the first method employs acylchlorides as a reactive species, the second one involves a condensation of mixed anhydrides with the amino acid counterparts. Actually, the second method proved to be more efficient than the first one. Carboxamides 1‐3 were preliminarily tested as N‐chelating ligands with an application in the Henry or Aldol reactions affording either poor yields or enantiomeric excesses.     

The synthesis of optically active P‐heterocycles

Optically active 1‐alkoxy‐ and 1‐amino‐3‐phospholene oxides were synthesized by the reaction of the corresponding 1‐chloro‐3‐phospholene oxides with (1R,2S,5R)‐(–)menthol and (S)‐(–)‐α‐phenylethylamine. The 3‐methyl‐3‐phospholene oxides were subjected to dichlorocyclopropanation under liquid–liquid phase transfer catalytic conditions to afford the 3‐phosphabicyclo[3.1.0]hexane 3‐oxides as a mixture of four diastereomers. Thermolysis of the menthyl‐phosphabicyclohexane oxides led to the corresponding 1,2‐dihydrophosphinine oxide as a diastereomeric mixture of two double‐bond isomers. As a result of additional steps, the dichlorocarbene addition reaction of the 1‐menthyl‐3,4‐dimethyl‐3‐phospholene oxide resulted in eventually, the formation of a 4‐dichloromethylene‐1,4‐dihydrophosphinine oxide. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:271–277, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20599     

Synthesis of highly refractive and transparent polyimides derived from 4,4′‐thiobis[2″,6″‐dimethyl‐4″‐(p‐phenylenesulfanyl)aniline]

New sulfur‐containing aromatic diamines with methyl groups at the ortho position of amino groups have been developed to prepare highly refractive and transparent aromatic polyimides (PIs) in the visible region. All aromatic PIs derived from 4,4′‐thiobis[2″‐methyl‐4″‐(p‐phenylenesulfanyl)aniline ( 2 ), 4,4′‐thiobis[2,″6″‐dimethyl‐4″‐(p‐phenylenesulfanyl)aniline ( 5 ), and aromatic dianhydride, 4,4′‐[p‐thiobis(phenylenesulfanyl)]diphthalic anhydride ( 6 ) were prepared via a two‐step polycondensation. All PIs showed good thermal properties, such as 10% weight loss temperature in the range of 497–500 °C and glass transition temperatures above 196 °C. In addition, the PIs showed good optical properties, such as optical transparency above 75% at 450 nm with a 10‐μm film thickness, high refractive indices ranging from 1.7135 to 1.7301, and small in‐plane/out‐of‐plane birefringences between 0.0066 and 0.0076. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 656–662, 2010     

Tailored (Meth)Acrylate Shape‐Memory Polymer Networks for Ophthalmic Applications

The unique features of shape‐memory polymers enables their use in minimally invasive surgical procedures with a compact starting material switching over to a voluminous structure in vivo. In this work, a series of transparent, thermoset (meth)acrylate shape‐memory polymer networks with tailored thermomechanics have been synthesized and evaluated. Fundamental trends were established for the effect of the crosslinker content and crosslinker molecular weight on glass transition temperature, rubbery modulus and shape‐recovery behavior, and the results are intended to help with future shape‐memory device design. The prepared (meth)acrylate networks with high transparency and favorable biocompatibility are presented as a promising shape‐memory ophthalmic biomaterial.

     

Nanofiller‐reinforced polymer nanocomposites

In this work, the technology of nano‐ and micro‐scale particle reinforcement concerning various polymeric fiber‐reinforced systems including polyamides (PAs), polyesters, polyurethanes (PUs), polypropylenes (pps), and high‐performance/temperature engineering polymers such as polyimide (PI), poly(ether ether ketone) (PEEK), polyarylacetylene (PAA), and poly p‐phenylene benzobisoxazole (PBO) is reviewed. When the diameters of polymer fiber materials are shrunk from micrometers to submicrons or nanometers, there appear several unique characteristics such as very large surface area to volume ratio (this ratio for a nanofiber can be as large as 10³ times of that of a microfiber), flexibility in surface functionalities and superior mechanical performance (such as stiffness and tensile strength) compared to any other known form of the material. While nanoparticle reinforcement of fiber‐reinforced composites has been shown to be a possibility, much work remains to be performed in order to understand how nanoreinforcement results in dramatic changes in material properties. The understanding of these phenomena will facilitate their extension to the reinforcement of more complicated anisotropic structures and advanced polymeric composite systems. Copyright © 2008 John Wiley & Sons, Ltd.     

Highly soluble and optically transparent poly (ether imide)s based on 2,6‐ or 2,7‐bis(3,4‐dicarboxyphenoxy)naphthalene dianhydride and aromatic bis(ether amine)s bearing trifluoromethyl groups

Two series of novel fluorinated poly(ether imide)s (coded IIIA and IIIB ) were prepared from 2,6‐bis(3,4‐dicarboxyphenoxy)naphthalene dianhydride and 2,7‐bis(3,4‐dicarboxyphenoxy)naphthalene dianhydride, respectively, with various trifluoromethyl‐substituted aromatic bis(ether amine)s by a standard two‐step process with thermal or chemical imidization of the poly(amic acid) precursors. These fluorinated poly(ether imide)s showed good solubility in many organic solvents and could be solution‐cast into transparent, flexible, and tough films. These films were nearly colorless, with an ultraviolet–visible absorption edge of 364–386 nm. They also showed good thermal stability with glass‐transition temperatures of 221–298 °C, 10% weight loss temperatures in excess of 489 °C, and char yields at 800 °C in nitrogen greater than 50%. The 2,7‐substituted IIIB series also showed better solubility and higher transparency than the isomeric 2,6‐substituted IIIA series. In comparison with nonfluorinated poly (ether imide)s, the fluorinated IIIA and IIIB series showed better solubility, higher transparency, and lower dielectric constants and water absorption. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5909–5922, 2006     

Poly (3,4‐ethylenedioxythiophene) γ‐Fe2O3 polymer composite–super paramagnetic behavior and variable range hopping 1D conduction mechanism–synthesis and characterization

The present paper reports the preparation of poly (3,4‐ethylenedioxythiophene) (PEDOT) ferrimagnetic conducting polymer composite by incorporation of ferrite particles in the polymer matrix by emulsion polymerization. Synthesis of PEDOT–γ‐Fe₂O₃ composite was carried out by chemical oxidative polymerization of EDOT with ferrite particles in the presence of dodecylbenzenesulfonic acid (DBSA) that works as dopant as well as surfactant in aqueous medium. The resulting conducting composite possesses saturation magnetization (Ms) value of 20.56 emu/g with a conductivity of 0.4 Scm^?1, which was determined by VSM and four probe technique, respectively. B‐H curve reveals that ferrimagnetic particles of γ‐Fe₂O₃ show super‐paramagnetic behavior at room temperature which was also observed in PEDOT–γ‐Fe₂O₃ composite. The resulting conducting ferrimagnetic composite shows microwave absorption loss of 18.7–22.8 dB in the frequency range of 12.4–18 GHz. Thermogravimetric analysis of the composite revealed that the composite is thermally stable up to 230°C. The characterization of the PEDOT–γ‐Fe₂O₃ composite was carried out using XRD and FTIR spectroscopy. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of a novel phosphate‐containing highly transparent PMMA copolymer with enhanced thermal and flame retardant properties

A novel poly(methyl methacrylate) (PMMA)‐based copolymer (PMMA‐co‐BDPA) rich in aromatic rings was synthesized via radical copolymerization between a phosphorus‐containing acrylic monomer (BDPA) and methyl methacrylate (MMA). UV‐vis spectroscopy demonstrated that the copolymer had high transparency. Thermogravimetric analysis (TGA) and a differential scanning calorimeter (DSC) were used to test the thermal properties of the composites. Additionally, the PMMA‐co‐BDPA‐15 copolymer exhibited a 23% increase in the limited oxygen index (LOI) value. A cone calorimeter test indicated that the peak heat release rate (pk‐HRR) of PMMA‐co‐BDPA was reduced by 29.2% compared with that of pure PMMA, and the carbon yield of burning was obviously increased. The combined test results demonstrated that the prepared copolymer material had good transparency, thermal stability, and flame retardancy.     

High‐pressure‐synthesis of poly(isopropenyl alcohol) and its biocompatibilities

Free radical polymerization under ambient conditions gives very low‐molecular weight homopolymer of isopropenyl acetate (IPAc). On the other hand, poly (isopropenyl acetate) (PIPAc) with a weight average molecular weight over 10⁴ was found to be synthesized by high‐pressure (1 GPa) radical polymerization. Poly(isopropenyl alcohol) (PIPOH) was then derived from PIPAc by saponification. The structure and properties of PIPAc and PIPOH were investigated using X‐ray diffraction, thermal analyses, X‐ray photoelectron spectroscopy, and dynamic contact angles. Though PIPOH is insoluble in water, the surface free energy (55 mJ/m²) was comparable with that of poly(vinyl alcohol). To utilize the peculiar combination of “aqueous insolubileity and high hydrophilicity” of PIPOH, biocompatibilities of PIPOH surface was investigated. The PIPOH surface was found to show high repellencies to albumin adsorption, whole thrombogenesis, and cell adhesion. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 754–761, 2009     

Soluble and transparent polyimides with high Tg from a new diamine containing tert‐butyl and fluorene units

A novel diamine monomer 1 , 4,4'‐(9H‐fluorene‐9,9‐diyl)‐bis(2‐tert‐butylaniline), was synthesized from 9‐fluorenone and 2‐tert‐butylaniline by the condensation reaction. Then it was polymerized with several commercial aromatic dianhydrides, respectively, to produce polyimides (PIs) by the one‐pot method. The number‐averaged molecular weights of the resulting PIs are in the range of (4.54–8.82) × 10⁴ with polydispersity indices from 2.51 to 4.33 by gel permeation chromatography measurement. They are soluble in many organic solvents and can form transparent and tough films by solution‐casting. The cut‐off wavelengths of UV–vis absorption for the PI films are below 360 nm, which are much lower than that of Kapton film. The light transparency of them is above 90% in the visible light range from 400 to 760 nm. They also display relatively low dielectric constants (from 2.79 to 3.00), low water absorption rates (<1%), and high tensile strength (> 50 MPa). Their excellent solubility and transparency can be attributed to the incorporation of tert‐butyl groups and fluorene units into the rigid backbones of PIs. Simultaneously, they still maintain the high thermal stability (the 5% weight loss temperature in the range from 526 to 539 °C in nitrogen) and the high glass transition temperatures (T_g > 340 °C). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 976–984     

Solid state spectroelectrochemistry of microparticles of ruthenium diimine complexes immobilised on optically transparent electrodes

The solid state electrochemistry and solid state spectroelectrochemistry of two ruthenium complexes, ruthenium tris-(4,7-diphenyl-1,10-phenanthroline) bis-hexafluorophosphate, [Ru(dpp)₃](PF₆)₂, and ruthenium bis-(2,2′-bipyridine)(4,6-diphenyl-2,2′-bipyridine)bis-hexafluorophosphate, [Ru(bpy)₂(dpb)](PF₆)₂, is described. Microparticles of the material are immobilised on ITO electrodes, and stable voltammetric signals are obtained in contact with aqueous electrolyte solution. Spectral changes monitored during a slow cyclic voltammetric scan confirm the exhaustive oxidation of the Ru²⁺ species to the Ru³⁺ form. The derivative of the absorbance signal monitored at a single wavelength during potential cycling is morphologically identical to a cyclic voltammogram with no background current. This technique is shown to be useful when peaks of small magnitude are obscured by capacitive background or when peaks close to the solvent limit are obscured by solvent electrolysis current. The technique effectively widens the electrochemical window available for voltammetric measurements. After suitable correction of the signal, the value of the voltammetric peak height (I _p) as well as peak potential (E _p) may be obtained from the derivative absorbance signal. Chronospectrometry is demonstrated to provide the equivalent to a chronocoulometric response, but is closer to the ideal simulated response. A facile method for simulating time or potential-dependant spectroelectrochemical responses using commercial electrochemical simulation software is described. Absorbance transients monitored during the electrolysis of solid particles of [Ru(dpp)₃](PF₆)₂ show best agreement with simulated data at very short and very long timescales. This observation, in conjunction with the observations from the potential scan experiments, suggests that the absorbance, charge, or current vs. time behaviour of the system can be adequately described by a semi-infinite diffusional model at short experimental timescales and by a finite diffusional model at sufficiently long timescales. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Dedicated to the 80th birthday of Keith B. Oldham.     

Preparation of neutrally colorless,transparent polynorbornenes with multiple redox‐active chromophores via ring‐opening metathesis polymerization toward electrochromic applications

A new electrochromic norbornene derivative containing triphenylamine groups (NBDTPAC8) was synthesized using norbornene amine and bromotriphenylamine. NBDTPAC8 was used in ring‐opening metathesis polymerization to obtain poly(NBDTPAC8) using different Grubbs' catalysts and followed by hydrogen reduction to obtain poly(HNBDTPAC8). The glass transition temperatures (T_g) of poly(NBDTPAC8) and hydrogenated poly(HNBDTPAC8) were 132 and 89 °C, respectively. Poly(HNBDTPAC8) film exhibited a fluorescence maximum around 416 nm with a quantum yield of up to 60%. Hydrogenated poly(HNBDTPAC8) film showed excellent transparency (up to 93%). Poly(HNBDTPAC8) showed cyclic voltammetric and electrochromic behaviors similar to those of poly(NBDTPAC8). The cyclic voltammogram of a poly(HNBDTPAC8) film cast onto an indium tin oxide (ITO)‐coated glass substrate exhibited three reversible oxidation redox couples at 0.69, 0.94 and 1.38 V versus Ag/Ag⁺ in an acetonitrile solution. The electrochromic characteristics of poly(HNBDTPAC8) showed excellent stability and reversibility, with multi‐staged color changes from its colorless neutral form to green, light blue and dark blue upon the application of potentials ranging from 0 to 1.60 V. The color switching time and bleaching time of the poly(HNBDTPAC8) film were 6.2 s and 4.3 s at 1175 nm and 6.6 s and 4.4 s at 970 nm, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Aligned carbon cones in free‐standing UV‐Curable polymer composite

A concept where an alternating electric field (dielectrophoresis) is used to assemble and align carbon nanocone particles (CNCs) into microscopic wires in self‐supporting polymer films is demonstrated. The particle fraction is kept low (one‐tenth of the percolation threshold of isotropic mixture), which allows uniform dispersion and efficient UV curing. The alignment leads to the conductivity enhancement of three to four orders of magnitude (from ～10^?7 to ～10^?3 S/m) in the alignment direction. It does not require passing current so the material can be isolated from the alignment electrodes. This prevents electrodes attaching to the film, if the film is adhesive in nature. The alignment can be done using either in‐plane or out‐of‐plane geometries. It is proposed that this concept could be applied in areas such as electrostatic discharge applications where inexpensive conductive or dissipative materials and macroscopic uniformity are prerequisites. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011