The Structure of Water in PEO‐Based Segmented Block Copolymers and its Effect on Transition Temperatures

The effect of water on block copolymers that contain hydrophilic PEO flexible segments is studied. The polyether phase consisted of either PEO or mixtures of PEO and hydrophobic PTMO, monodisperse crystallisable T6T6T was used as hard segments. Water absorption as a function of relative humidity and PEO content were studied. The PEO melting temperature and crystallinity were strongly reduced when the copolymer absorbed water, while the PTMO phase remained unaffected by its presence. Freezing water was present in the PEO‐based copolymers when the PEO phase contained ≈30 vol.‐% water, its relative amount being almost independent of PEO concentration and molecular weight and the presence of hydrophobic PTMO segments.

     

Synthesis and Micellization of Star‐Shaped Poly(ethylene glycol)‐block‐Poly(ε‐caprolactone)

Summary: The relationship between the architecture of block copolymers and their micellar properties was investigated. Diblock, 3‐arm star‐shaped and 4‐arm star‐shaped block copolymers based on poly(ethylene glycol) and poly(ε‐caprolactone) were synthesized. Micelles of star‐shaped block copolymer in an aqueous solution were then prepared by a solvent evaporation method. The critical micelle concentration and the size of the micelles were measured by the steady‐state pyrene fluorescence method and dynamic light scattering, respectively. The CMC decreased in the order di‐, 3‐arm star‐shaped and 4‐arm star‐shaped block copolymer. The size of the micelles increased in the same order as the CMC. Theory also predicts that the formation of micelles becomes easier for 4‐arm star‐shaped block copolymers than for di‐ and 3‐arm star‐shaped block copolymers, which qualitatively agrees with the experiments.

     

Fluorene‐Based Single‐Chain Copolymers for Color‐Stable White Light‐Emitting Diodes

Fluorene‐based single‐chain copolymers with a white light emitter consisting of a blue and an orange chromophore have been synthesized and their photophysical and electroluminescent properties are investigated. The experimental results suggest that only a relatively small fraction of the orange‐emitting units incorporated into the fluorene is needed to achieve efficient white light emission by controlled incomplete energy transfer. A device from a copolymer with 0.02% DDQ content showed the highest external quantum efficiency of 2.64% with a luminance efficiency of 4.06 cd · A^?1 with CIE coordinates (0.28, 0.24). The EL emissions are extremely stable over a wide range of current densities.

     

Double‐Gyroid Morphology of a Polystyrene‐block‐Poly(ferrocenylethylmethylsilane) Diblock Copolymer: A Route to Ordered Bicontinuous Nanoscale Architectures

A polystyrene‐block‐poly(ferrocenylethylmethylsilane) diblock copolymer, displaying a double‐gyroid morphology when self‐assembled in the solid state, has been prepared with a PFEMS volume fraction ?_PFEMS = 0.39 and a total molecular weight of 64 000 Da by sequential living anionic polymerisation. A block copolymer with a metal‐containing block with iron and silicon in the main chain was selected due to its plasma etch resistance compared to the organic block. Self‐assembly of the diblock copolymer in the bulk showed a stable, double‐gyroid morphology as characterised by TEM. SAXS confirmed that the structure belonged to the Ia d space group.

     

Synthesis of Defined Poly(silsesquioxane)s: Fast Polycondensation of Trialkoxysilanes in a Continuous‐Flow Microreactor

The polycondensation of trialkoxysilanes to PSSQs in a microreactor setup is demonstrated. While continuous‐flow processes involving microreactors found various applications in chain growth polymerization, their influence on step‐growth polymerization is less explored, and the polycondensation of multifunctional monomers has not been studied in detail. We found significantly increased yields and a decreased polydispersity of the obtained polymers in comparison to the batch process. By variation of the residence time molecular weights could be adjusted reproducibly ranging from = 1 900 to 11 000 g · mol^?1. Thus, the microreactor setup offers for the first time the possibility to synthesize PSSQ with adjustable properties.

     

Synthesis and Characterization of New Acrylate and Methacrylate Monomers with Pendant Pyridine Groups

To overcome some drawbacks of polyvinylpyridines, new monomers of acrylate and methacrylate type with pendant pyridine groups i.e., 4‐(3‐methacryloylpropyl)pyridine 1a and 4‐(3‐acryloylpropyl)pyridine 1b were successfully prepared, although it turned out to be challenging work to synthesize the acrylate monomer 1b . First polymerization studies showed that the new monomers could be polymerized easily by atom transfer radical polymerization (ATRP). The new polymers show excellent characteristics, such as very good solubility, low glass‐transition temperature, and easy quaternization.

Design and structure of new monomers 1a and 1b .     

Rod‐Length Dependent Aggregation in a Series of Oligo(p‐benzamide)‐Block‐Poly(ethylene glycol) Rod‐Coil Copolymers

Summary: The synthesis of a series of rod‐coil diblock copolymers with flexible poly(ethylene oxide) chains ( = 5 000 g · mol⁻¹) and rod blocks consisting of monodisperse oligo(p‐benzamide)s is described. The formation of defined supramolecular aggregates in solution as well as the solid state has been analyzed. The length of the oligo(p‐benzamide)s has been systematically varied from n = 1 to 7 units. The influence of n on aggregation in chloroform and aqueous solution was investigated by GPC as well as UV‐vis spectroscopy. A critical aggregation length was found for chloroform (n = 5) and water (n = 4), below which no aggregation is observed under otherwise identical experimental conditions. Aggregation of the polymers in chloroform solution can be chemically reversed by the addition of PCl₅, resulting in conversion of the aromatic amides into imidoyl chlorides. Such amide‐protected block copolymers show no aggregation in NMR and GPC experiments. Imidoyl chloride formation was shown to be reversible, i.e., addition of water regenerated the oligo(p‐benzamide) blocks.

Conversion of aramide block copolymer into molecularly dissolved form using PCl₅.     

Dendronized Polymers: Recent Progress in Synthesis

This article divides the synthetic routes leading to dendronized polymers into two main categories (attach‐to and macromonomer) and compares their respective advantages and disadvantages. It gives a comprehensive overview on the kind of structures presently available and also spans the bridge between both polymers and molecular objects, decorated with only a few dendrons, and the structurally related, but less well defined polymers with hyperbranched side chains.

A coiled polymer backbone's stretching through the attachment of increasingly sterically demanding dendrons: a) no dendrons; b) dendrons of the first generation; c) second generation; d) third generation.     

Synthesis of Amphiphilic and Double‐Hydrophilic Block Copolymers Containing Poly(vinyl amine) Segments by RAFT Polymerization of N‐Vinylphthalimide

We report on the controlled synthesis of amphiphilic and double‐hydrophilic block copolymers having poly(vinyl amine) segments by the reversible addition–fragmentation chain transfer (RAFT) polymerization of N‐vinylphthalimide (NVPI), followed by deprotection. The block copolymer poly(NVPI)‐b‐poly(N‐isopropylacrylamide) with a controlled molecular weight and low molecular mass distribution was obtained by the polymerization of N‐isopropylacrylamide (NIPAAm) using dithiocarbamate‐terminated poly(NVPI). The chain extension from the dithiocarbamate‐terminated polystyrene to NVPI could be controlled well under suitable conditions, and provided the block copolymer, polystyrene‐b‐poly(NVPI). We also investigated the thermoresponsive and optoelectronic properties and the aggregation behavior of double hydrophilic and amphiphilic block copolymers obtained after deprotection.

     

Characterization of Linear and 3‐Arm Star Block Copolymers by Liquid Chromatography at Critical Conditions

Summary: LCCC for polyMA homopolymers was established in order to analyze the polyMA‐polySt linear and star block copolymers. The validity of the assumption that under the LCCC for polyMA, the polyMA segment in the polyMA‐containing block copolymer is chromatographically “invisible” was verified. It was found that within the scale of investigation ( ), the molecular weight and architecture of the polyMA segments had no evident influence on the retention behavior of the polySt‐polyMA block copolymers and the polyMA block in the copolymer was “invisible”. The critical conditions of polyMA were used for quantitative analysis of the polySt block in the linear and 3‐arm star polyMA‐polySt block copolymers, which were synthesized by AGET ATRP in miniemulsion. It was shown that the copolymer had completely different elution peak from its MI. The calculated molecular weights of polySt blocks in the block copolymers were similar to those obtained from normal SEC analysis. Transferring the eluates from the LCCC (the first dimension) column to a SEC column (the second dimension) produced LCCC × SEC two‐dimensional chromatogram, which contained information on both chemical composition and molecular weight of the synthesized copolymers. The combination of these liquid chromatography methods clearly confirmed the high initiation efficiency of the polyMA MIs during the synthesis of block copolymers and the presence of a byproduct formed by radical‐radical coupling.

     

Evidence of Intramolecular Cyclization in Copolymerization of Ethylene with 1,3‐Butadiene: Thermal Properties of the Resulting Copolymers

Summary: Ethylene and butadiene were copolymerized with a silylene‐bridged bis(fluorenyl) complex {[Me₂Si(C₁₃H₈)₂]NdCl} ( 1 ) in combination with various alkylating agents (BuLi/AlH(iBu)₂, (Bu)MgCl, Mg(Bu)(Oct)). Copolymers have a unique microstructure since they contain 1,2‐cyclohexane rings and unsaturations along the polymer chain. An intramolecular mechanism was proposed for the formation of six‐membered rings. The influence of these cyclic structures on thermal properties of the copolymers has been investigated.

Proposed mechanism for formation of 1,2‐cyclohexane rings.     

Synthesis and Characterization of Oxetane‐Functionalized Phosphorescent Ir(III)‐Complexes

In order to incorporate iridium(III) complexes covalently into an oxetane‐bearing hole‐transporting matrix, a new oxetane‐equipped acetoacetate derivative was introduced as an ancillary ligand. Model complexes with an analogical nonpolymerizable ligand were also prepared in order to perform comparative investigations. Therefore, a series of bis‐cyclometalated Ir(III) complexes, showing orange (C?N‐ligand, coumarin 6) and green (C?N‐ligand, phenylpyridine) emission were synthesized and fully characterized. The emission maxima are 569 nm for the orange and 518 nm for the green‐emitting Ir(III) complexes. Entirely solution processed devices, based on crosslinkable hole‐conductors, partially doped with the described orange and green Ir(III) emitters, respectively, were fabricated and tested.

     

Proton Conductivity of Acid Doped Styrene‐Maleic Imide Copolymer With Benzimidazole Side Group

Summary: Styrene‐maleic imide copolymer with benzimidazole side group was prepared from 2‐amino‐benzimidazole and styrene‐maleic anhydride copolymer. The structures of the new styrene‐maleic imide copolymers from both random and alternating styrene‐maleic anhydride copolymer were characterized by FTIR, DSC, and gel permeation chromatography (GPC). Styrene‐maleic imide copolymer has good solubility, excellent film forming ability, and is easy to prepare, though the solubility of styrene‐maleic imide copolymer decreases a little with increasing maleic imide. The proton conductivity of phosphoric acid doped styrene‐maleic imide copolymer was studied. The temperature dependence of proton conductivity in H₃PO₄ doped a‐styrene‐maleic imide copolymer can be fitted by a simple Arrhenius equation very well, while H₃PO₄ doped r‐styrene‐maleic imide copolymer has somewhat deviation from Arrhenius equation. The structure of alternating copolymer is more favorable for proton transport contributed by hopping mechanism. The proton conductivity of phosphoric acid doped styrene‐maleic imide copolymer can be improved by increasing the acid doping level or the imidazole content.

     

Linear Terpyridine‐Ruthenium(II) Poly(ethylene glycol) Coordination Polymers

In the present contribution, we synthesized linear coordination polymers based on oligo(ethylene glycol)s as well as poly(ethylene glycol)s and terpyridine ruthenium(II) complexes. The reaction conditions, e.g., solvent, concentration, were varied to obtain well‐soluble, high molecular weight polymers. The resulting compounds were characterized by UV‐vis and NMR spectroscopy. The viscosity of the materials was also investigated with and without salt addition. Finally, the polymers were characterized with DSC and AFM. AFM revealed a lamellar morphology.

     

Synthesis of Ethylene/Acrylonitrile Composite Elastomers with Nanosized Polyacrylonitrile Domains Using α‐Dimine‐[N,N] Nickel Dichloride/EASC

A series of ethylene and acrylonitrile composite elastomers were prepared using (1,4‐bis(2,6diisopropylphenyl)‐acenaphtenediimine‐nickel(II))‐dichloride/ethylaluminum sesquichloride (EASC). The xylene‐soluble polymer fraction showed nitrile bands in infrared spectroscopy at 2 245 and 2 214 cm^?1 and polyacrylonitrile‐enriched structures were detected in the xylene‐insoluble fraction by¹H and ¹³C NMR. In addition, TEM detected nanosized polyacrylonitrile domains dispersed in the polyethylene matrix. Differential scanning calorimetry scans conducted from ?70 to 350 °C measured exothermic bands corresponding to the cyclization and aromatization of the nitrile groups dispersed in the polyethylene matrix.

     

Synthesis and Characterization of an Amphiphilic Blue‐Light‐Emitting Glycosylated Poly(naphthalene/phenylene) Copolymer

The preparation and self‐assembly of poly(2‐glucopyranosyl‐1,6‐naphthalene‐1,4‐phenylene), P16NP2Glu , an amphiphilic, blue‐light‐emitting copolymer, is reported. The copolymer is soluble in polar solvents such as methanol/THF mixtures and even in water. The emission spectrum of P16NP2Glu shows a maximum at ≈400 nm for solutions containing the above solvents. Owing to the highly polar nature of the glucopyranose rings of P16NP2Glu , the formation of aggregates is observed. Uniform‐size nanospheres capable of emitting blue light are prepared in the solid phase. The critical micelle concentration and micelle sizes are determined by light‐scattering measurements. It is found that the emission maximum and fluorescence quantum yields depend on the aggregate formation of the copolymer.

     

Computer Simulations of the “Hairy Rod” Model

Summary: Using extensive Molecular Dynamics simulations we study the behavior of very rigid polyelectrolytes with hydrophobic side chains that are known to form cylindrical micelles in aqueous solution. We investigate the stability of such micelles with respect to hydrophobicity, Coulomb interaction, and micellar size. We show that for the parameter range relevant for poly(p‐phenylene sulfonate)s (PPP) one finds a stable finite micellar size close to the experimental parameter region. We also point out that our model has some similarities to DNA solutions with added condensing agents, hinting to the possibility that the size of DNA aggregates is under certain circumstances thermodynamically limited.

DNA‐like morphologies of the polyelectrolytes.     

Tailor‐Made Soluble Polymer Supports: Synthesis of a Series of ATRP Initiators Containing Labile Wang Linkers

A series of functional initiators for atom transfer radical polymerization (ATRP) was prepared. These structures contain an ATRP initiating site, a labile p‐alkoxybenzyl ester Wang linker and a functional end‐group (i.e., ? COOH, ? N₃, ? OH, ? C?CH, or ? NHFmoc). These novel initiators can be utilized for synthesizing well‐defined soluble polymer supports. For instance, the azide‐, alcohol‐, alkyne‐, and NHFmoc‐ derivatives were tested as initiators for the bulk ATRP of styrene. SEC, MALDI‐TOF‐MS, and NMR measurements indicated that well‐defined polystyrene samples with defined end‐groups have been synthesized in this process. Moreover, it was demonstrated that the labile Wang linkers could be easily cleaved with a mild trifluoroacetic acid treatment.

     

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.     

Preparation of Carboxyl‐Functionalized Polystyrene/Silica Composite Nanoparticles

Summary: This paper describes the synthesis of carboxyl‐functionalized polystyrene/silica (PS/SiO₂) composite nanoparticles with various contents of poly(methacrylic acid) (PMAA) on the surface by post‐addition of methacrylic acid (MAA) via emulsion polymerization. High yields and binding efficiencies (around 90%) are achieved by an optimal procedure mainly involving the appropriate addition of MAA and amounts of surfactant and silica. The kinetics investigated indicates that the polymerization follows a mechanism different than that found in some earlier studies. The amount of grafted PMAA was determined by titration and FT‐IR, and altered in a wide range (1–40 wt.‐% to PS). Transmission electron microscopy (TEM) photographs show that the composite nanoparticles are about 60 nm in spherical shape and have a multi‐layered core‐shell structure with a cluster of primary silica beads as the core and PMAA as the outmost shell. There are approximately 4 to 21 primary silica beads in one composite nanoparticle, depending on the amount of silica added.

Preparation of carboxyl‐functionalized polystyrene(PS)/silica composite nanoparticles.