Fluorinated Styrene‐ and Carbazole‐Based Cladding Polymer Layers for EO and NLO Polymer Devices

Novel polymer cladding materials were synthesized and their potential for use in optical waveguide devices was investigated. 9‐[2‐(2,3,5,6‐Tetrafluoro‐4‐vinylphenoxy)ethyl]‐9H‐carbazole and 1‐pentafluorophenylpyrrole‐2,5‐dione were used as comonomers for preparing the acrylic cladding copolymers. These showed a low resistivity (≈2 × 10¹³ Ω · cm) at room temperature and a low optical loss (?0.6 dB · cm^?1) at a wavelength of 1.55 µm. The refractive indexes and the glass transition temperatures of the polymer cladding materials can be controlled by the composition of the copolymers. The resulting polymers are good candidates for cladding materials for practical applications in devices.

     

Rapid Synthesis and MALDI‐ToF Characterization of Poly(ethylene oxide) Multiarm Star Polymers

Multiarm PEO star polymers with a purely aliphatic polyether structure have been synthesized using hyperbranched polyglycerol (PG) with different molecular weights as a multifunctional initiator. Different degrees of deprotonation of the initiator were studied with respect to molecular weight control. The results show that the degree of deprotonation is a crucial parameter for the synthesis of well‐defined polymers with controlled molecular weights. Partial deprotonation of the PG hydroxyl groups (5–8%) was proven to represent an optimum for the synthesis of star polymers with molecular masses close to the theoretical values. Molecular weights of the stars ranged between 9 000 and 30 000 g · mol^?1. MALDI‐ToF spectra confirmed that the PEO arms in the star polymers possess homogeneous lengths.

     

Metathetic Selective Degradation of Polyisoprene: Low‐Molecular‐Weight Telechelic Oligomer Obtained from Both Synthetic and Natural Rubber

Summary: Degradation studies of cis‐1,4‐polyisoprene were carried out using first and second generation Grubbs catalysts to achieve end‐functionalized acetoxy oligomers in both an organic solvent and a latex phase at room temperature. Well‐defined acetoxy telechelic polyisoprene structures were obtained in a selective manner with a range of from 10 000 to 30 000, with a polydispersity index of around 2.5.

Structure produced by the metathetic depolymerization of hydroxy telechelic cis‐1,4‐polyisoprene.     

The Rapid Chain Extension of Anthracene‐Functional Polyesters by the Diels‐Alder Reaction with Bismaleimides

Summary: The chain extension of anthracene end‐capped oligoesters by reaction with bismaleimides constitutes a rapid route to high molecular weight polyesters. Polytransesterification of bis(2‐hydroxyethyl) terephthalate in the presence of a small amount of 2‐hydroxyethyl 2‐anthracenecarboxylate provides low molecular weight anthracene‐terminated macromers with anthracene end group functionality (f_AN) of 1.66–1.85. These are subject to rapid chain extension with di(4‐maleimidophenyl)methane by Diels‐Alder cycloadditions resulting in consumption of the anthracene and maleimide end groups to generate polymers with > 2.0 × 10⁴ g · mol⁻¹. Thus, generation of the polymeric structure is achieved rapidly by addition reactions rather than sluggish transesterification reactions in which a condensate must be removed from the viscous polymer melt.

Chain extension of low‐molecular weight 2‐anthracenecarboxylate terminated oligoesters.     

Synthesis and Electroluminescent Properties of Disubstituted Polyacetylene Derivatives Containing Multi‐Fluorophenyl and Cyclohexylphenyl Side Groups

A new series of disubstituted polyacetylene derivatives that contain multi‐fluorine atoms on the pendent phenyl ring have been synthesized and characterized. The results reveal a greater red‐shift in UV‐vis absorption and PL emission upon incorporating more fluorine atoms on the pendent phenyl ring. Among them, disubstituted polyacetylene with a difluorophenyl group ( PDPA‐2F ) showed the highest luminescent efficiency. The device performance can be promoted by blending a hole‐transporting material TM‐TPD into PDPA‐2F as the active layer or by using a light‐emitting copolymer in which PDPA‐2F was copolymerized with a carbazole group ( PDPA‐2Fcab ). A light‐emitting diode of ITO/PEDOT/ PDPA‐2Fcab /Ca/Al revealed a maximum luminescence of 4230 cd · m^?2 at 14 V and a maximum current efficiency of 3.37 cd · A^?1 at 7 V.

     

Synthesis and self‐assembly of polymers containing dicarboximide groups by living ring‐opening metathesis polymerization

Polymers with narrow molecular weight distributions and controlled architectures were generated by living ring‐opening metathesis polymerization of exo‐7‐oxabicyclo[2.2.1]hept‐5‐ene‐2,3‐dicarboximide. The dicarboximide units have been previously shown to exhibit biological activity, can selectively bind to the nucleic acid base adenine by hydrogen‐bonding, and are readily functionalizable. Block copolymers containing these moieties were generated, and underwent self‐assembly into nanoscale spherical aggregates, with surface localized molecular recognition motifs.

     

Novel Aromatic Polymer Electrolyte with Comb‐like Structure: Synthesis and Properties

Summary: A novel aromatic polymer electrolyte with pendant sulfodecyloxy groups was synthesized. The monomer 4 , bis[2‐(10′‐sulfodecyloxy)‐5‐chlorophenyl]sulfone, was synthesized from bis(2‐hydroxy‐5‐chlorophenyl)sulfide via bromoalkylation, oxidation, and sulfonation, and then polymerized via Ni‐catalyzed C C coupling polymerization to afford the title polymer electrolyte 6 . The polymer 6 was isolated as a brown powder with molecular weight of = 12 000. The high decomposition temperature of 6 (200 °C) was confirmed by TG/DTA‐MS measurement. Proton conductivity of 6 was measured using porous polyimide membrane as a supporting substrate. The pore‐filled membrane showed 1 × 10⁻⁵ S · cm⁻¹ of the proton conductivity at 80 °C and 90% RH.

Synthesis of aromatic polymer electrolyte having sulfodecyloxy groups via nickel‐catalyzed C C coupling polymerization.     

Nuclear Magnetic Resonance Spectroscopy in Macromolecular Science

A historical overview of the role of NMR spectroscopy in macromolecular science in general and its coverage in “Macromolecular Chemistry and Physics” in particular is given. In the early days physics‐application to study molecular dynamics, partial alignment of macromolecules and phase separation prevailed, deduced from broad‐line solid‐state NMR. Only somewhat later, high‐resolution NMR in solution was established as an important tool for elucidating the chain microstructure. In the future, these two aspects are expected to merge.

Side group liquid crystalline polymers: ²H NMR has elucidated alignment and dynamics of these complex materials.     

Synthesis of New Blue Anthracene‐based Conjugated Polymers and Their Applications in Polymer Light‐Emitting Diodes

A series of anthracene‐based conjugated copolymers containing 9,10‐bis(6‐bromonaphthalen‐2‐yl)‐2‐tert‐butylanthracene (BNA) and 2,7‐diphenyl substituted fluorene (DPPF) moieties are prepared via a palladium‐catalyzed Suzuki polymerization. All of the synthesized polymers emit blue light at around 450 nm and show good thermal and color stability. Their electroluminescence spectra remain unchanged at high driving voltage. The double‐layer polymer light‐emitting diode (PLED) fabricated with ITO/PEDOT:PSS/DPPFBNA3/CsF/Al, produces a maximum brightness of 1 650 cd · m^?2 and has a luminance efficiency of 0.39 cd · A^?1. The ITO/PEDOT:PSS/TFB/DPPFBNA3/CsF/Al multilayer PLED, incorporating a TFB layer to facilitate hole transportation, produces a maximum brightness of 5 371 cd · m^?2 and a luminance efficiency of 1.18 cd · A^?1.

     

An Easy Strategy for the Synthesis of Well‐Defined Aliphatic‐Aromatic Hyperbranched Polyesters

A one‐pot solution polymerization under mild conditions was adapted for the synthesis of well‐defined aliphatic‐aromatic polyesters with different degrees of branching. The esterification was performed at room temperature using 4,4‐bis(4′‐hydroxyphenyl)valeric acid (AB₂) and 3‐(4‐hydroxyphenyl)propionic acid (AB) as monomers. DPTS was used as a catalyst and DCC as a coupling agent. Polyesters with statistical, dendritic topology, controlled degree of branching and > 35 000 g · mol^?1 were obtained. The polymers were characterized by ¹H and ¹³C NMR, SEC, DSC, and TGA. A strong dependence of the degree of branching and the thermal properties of the polymers depending on the AB/AB₂ monomer ratio was observed.

     

Branched and Functionalized Polybutadienes by a Facile Two‐Step Synthesis

Anionic polymerization was used to prepare silane‐endfunctionalized polybutadiene macromonomers with different molecular weights ranging from 9 000 to 34 000 g · mol^?1. These were polymerized by a hydrosilylation reaction in bulk to obtain branched polymers, using Karstedt's catalyst. Surprisingly, the addition of monofunctional silanes during the polymerization showed only a minimal effect concerning the degree of polymerization. Furthermore, it was possible to introduce a variety of functional silanes without increasing the overall number of reaction steps by a convenient AB₂ + A type “pseudocopolymerization” method. All branched polymers were analyzed by SEC, SEC‐MALLS, SEC‐viscosimetry. ¹H NMR spectroscopy, and DSC concerning their branching ratio. The branching parameters for the branched polymers exhibited similar characteristics as for hyperbranched polymers obtained from conventional AB₂ monomers. Detailed kinetic studies showed that the polymerization occurred very rapidly in comparison to the hydrosilylation polymerization of classical AB₂ type carbosilane monomers.

     

Hydroxyl‐Functionalized Norbornene Based Co‐ and Terpolymers by Scandium Half‐Sandwich Catalyst

Copolymerization of ethylene with 5‐norbornene‐2‐methanol and terpolymerization of ethylene with norbornene and 5‐norbornene‐2‐methanol by a rare‐earth metal based catalyst, specifically the half‐sandwich bis(alkyl) scandium precursor [Sc(η⁵‐C₅Me₄SiMe₃)(η¹‐CH₂SiMe₃)₂(THF)] activated by [Ph₃C][B(C₆F₅)₄] were successfully achieved for the first time. A protocol for masking of ? OH functionality by AlⁱBu₃ to avoid catalyst poisoning was exploited. Copolymers with high molar masses and noticeable incorporation of functionalized norbornene derivative were obtained. Terpolymers with very high molar masses and with a broad range of composition were prepared with excellent yields.

     

Characterization of Carbon Monoxide Centered Triads in Poly[ethylene‐co‐(butyl acrylate)‐co‐(13C‐carbon monoxide)] by Isotopic Labeling and Two‐Dimensional NMR

Summary: Poly[ethylene‐co‐(butyl acrylate)‐co‐(carbon monoxide)] (polyEBC) samples, prepared from ¹³C‐labeled carbon monoxide, were characterized using two dimensional (2D) pulsed field gradient (PFG) 750 MHz NMR spectroscopy. To elucidate the complex mixture of structures present in this terpolymer, 2D ¹H/¹³C‐heteronuclear multiple bond correlation (HMBC) experiments were conducted by selectively exciting the enhanced peaks resulting from ¹³C‐labeling. High resolution 2D NMR combined with ¹³C‐labeling of the polymer greatly simplifies the 2D NMR spectra, selectively enhances the weak peaks from low occurrence C‐centered triad structures and aids in their resonance assignments.

     

Thickening Processes of Lamellar Crystal Monolayers of a Low‐Molecular‐Weight PEO Fraction on a Solid Surface

Using hot‐stage atomic force microscopy, the thickening processes of monolayer crystals of PEO ( = 5 000 g · mol^?1 and = 1.008) from one‐folded (FC1) to extended‐chain (EC) lamellae are experimentally monitored at three temperatures: 50, 52, and 58 °C. At 50 °C some small areas in large FC1 crystals spontaneously thicken into EC crystals. At 52 °C the spontaneously thickened area further expands so as to inductively thicken the entire FC1 lamella into EC lamella. At 58 °C EC crystals first force the adjacent FC1 crystals to melt and then absorb the melted molecules to grow laterally into large EC lamellae till all FC1 lamellae vanish. The three thickening steps express the main thickening process of lamellar crystals from a metastable state to another metastable (or equilibrium) state. The possible mechanisms are discussed in the text.

     

Synthesis and Characterization of Block Copolymers of ε‐Caprolactone and DL‐Lactide Initiated by Ethylene Glycol or Poly(ethylene glycol)

Biodegradable copolymers were prepared by ring‐opening polymerization of sequentially added ε‐caprolactone and DL ‐lactide in the presence of ethylene glycol or poly(ethylene glycol), using zinc metal as catalyst. Polymerization was performed in bulk and yielded block copolymers with predetermined PEG/PCL/PLA segments. The obtained polymers were characterized by ¹H NMR, SEC, IR, DSC, TGA, and X‐ray diffraction. Data showed that the copolymers preserved the excellent thermal behavior inherent to PCL. The crystallinity of PLA‐containing copolymers was reduced with respect to PCL homopolymer. The presence of both hydrophilic PEG and fast degrading PLA blocks should improve the biocompatibility and biodegradability of the materials, which are of interest for applications as substrate in drug delivery or as scaffolding in tissue engineering.

Block copolymerization of ε‐caprolactone and DL ‐lactide initiated by dihydroxyl PEG.     

Electroactive Polymer with Oligoanilines in the Main Chain: Synthesis,Characterization and Dielectric Properties

An electroactive polymer with well‐defined oligoanilines in the main chain has been prepared by oxidative coupling polymerization. The detailed characteristics of the polymer were systematically studied by FT‐IR, ¹H NMR, GPC and XRD. Its electrochemical behavior was explored with UV‐Vis spectra and cyclic voltammetry showing that its intrinsic electroactivity was maintained and exhibited three distinct reversible oxidative states. Its electrical conductivity is about 3.91 × 10^?4 S · cm^?1 in HCl‐doped form at room temperature. Furthermore, the polymer displays a dielectric constant of 48.4 and 13.6 at 10 and 1 MHz, respectively, mainly attributed to the improvement in delocalized charge density and electrical conductivity of the polymer by introduction of the conjugated oligoaniline segments.

     

Microwave‐Assisted Synthesis of Poly(L‐lactic acid) via Direct Melt Polycondensation Using Solid Super‐Acids

A microwave‐assisted method of synthesizing high‐molecular‐weight PLA using SSA as green catalyst was developed. Yellowish PLA with above 2.0 × 10⁴ g · mol^?1 was obtained when the reaction was run at 260 °C within 60 min under microwave irradiation with 0.4 wt.‐% SSA. This method used only 10% of the energy consumption necessary for conventional heating, and the catalyst could be used five times without losing catalytic activity. The improvement in and the decrease in the energy consumption under microwave irradiation suggested that selective heating and hot spots effects played a crucial role. The method was shown to be a time‐saving, green and a promising way to lower the cost and spread the application of PLA.

     

Synthesis of Vinylphosphonic Acid Anhydrides and their Copolymerization with Vinylphosphonic Acid

We present the synthesis and characterization of the compounds formed in a mixture of vinylphosphonic acid (VPA) and acetic anhydride used for the radical‐initiated VPA polymerization. High‐molecular‐weight PVPA with up to 109 000 g · mol⁻¹ was obtained from the polymerization of a mixture containing VPA, VPAAnh, VPADiAnh and their acetylated derivatives. Relative reactivities of these compounds were estimated. The resulting polymers were characterized by viscosimetry, light scattering and NMR measurements. The complexity of the polymer structure increases with increasing anhydride content in the reaction feed as can be concluded from the ¹H, ¹³C and ³¹P NMR spectra. This finding is in accordance with a cyclopolymerization mechanism resulting in five‐ and six‐membered anhydride rings within the polymer chain.

     

Semicontinuous Emulsion Polymerization of Butyl Methacrylate and 1, 3‐Butadiene in the Presence of Cyclodextrins and Cytocompatibility of Dicarboxylic Acid Telechelic Oligo(butyl Methacrylate)s Derived from Ozonolysis of the Latexes

Ozonolysis of unsaturated polymers produced useful telechelic oligomers that can form building blocks for networks and block copolymers. The unsaturated polymers can be prepared by semicontinuous emulsion polymerization with dienes, and here it is shown that the addition of cyclodextrins enhanced the incorporation of these comonomers. Both α‐ and β‐cyclodextrin provide copolymers with higher fractions of butadiene (BD) incorporated into the chain but α‐cyclodextrin had the highest levels of incorporation. Oxidative work up after ozonolysis produced latexes of carboxylic acid oligomers of different molar masses. A clear effect of polymer size on toxicity was observed with the oligomers with < 2 700 g · mol.^?1 proving to have similar cytotoxic effects to lactic acid. However, oligomers with above 2 700 g · mol.^?1 were cytocompatible and gave similar results to a polylactide control material.

     

Modification of Polyethylene by VUV Irradiation in the Presence of Trimethylsilane and Oxygen

The photoassisted modification of LDPE by VUV irradiation in a reactive trimethylsilane/oxygen atmosphere was investigated. The modified LDPE surface was investigated by FT‐IR, XPS, contact‐angle measurements and electron microscopy. Attachment of alkylsilyl and Si–O units to LDPE was observed. Best results were obtained using an equimolar trimethylsilane/oxygen mixture. Low‐energy surfaces were obtained after a few minutes of irradiation at an intensity of 1.7 mW · cm^?2. After prolonged irradiation, the thickness of the modified polyethylene layer is approximately 700 nm. Surface modifications of this type may be of interest to obtain protective and barrier layers on polyolefins.