Tapered Multiblock Star Copolymers: Synthesis, Selective Hydrogenation, and Properties

Two series of well-defined multiblock four-arm tapered star copolymers with “arms” of the type poly(styrene)-block-poly(isoprene-grad-styrene), (SI/S)₄, were synthesized on a multigram scale with short reaction times. Targeted molecular weight (M) values ranged from 80 to 240 kg mol–¹ with polystyrene (PS) compositions of 40 and 60 wt %. Narrowly distributed (Đ = 1.04–1.12) copolymers were obtained regardless of M and without additional purification beyond precipitation. At sufficiently high M, members of the 40 wt % PS series possessed either a cylindrical or bicontinuous morphology, whereas the 60 wt % PS series yielded lamellae. The star copolymers outperformed their corresponding linear…

Tapered Multiblock Copolymers Based on Isoprene and 4-Methylstyrene: Influence of the Tapered Interface on the Self-Assembly and Thermomechanical Properties

The synthesis of tapered multiblock copolymers by statistical living anionic copolymerization of a mixture of isoprene (I) and 4-methylstyrene (4MS) in cyclohexane is based on vastly different reac...

Tetrahydrofuran: More than a “Randomizer” in the Living Anionic Copolymerization of Styrene and Isoprene: Kinetics, Microstructures, Morphologies, and Mechanical Properties

The statistical anionic copolymerization of isoprene (I) and styrene (S) is commonly used to synthesize tapered block copolymers, enabling control of the phase behavior by adjusting the order–disor...

Orientation and Dynamics of ZnO Nanorod Liquid Crystals in Electric Fields.

ZnO nanorod polymer hybrids (i.e., ZnO nanorods coated with a block copolymer with a short anchor block (dopamine) and a longer solubilizing block of polystyrene (PS)) form liquid crystalline (LC) phases if they are dispersed at high concentration e.g., in a PS oligomer matrix. Due to the high mobility of the low T(g)-matrix the nanorod polymer hybrids show a switching behavior under an applied AC electric field. Hence, the orientation of the nanorod mesogens can be changed from planar (parallel to the substrate) to homeotropic (perpendicular) in full analogy to the switching of low molecular liquid crystals in an electric field. Dielectric measurements show that such a switching is mainly …

Polymerized Ionic Liquids with Polythiophene Backbones: Self-Assembly, Thermal Properties, and Ion Conduction

Single ion conductors, based on polymerized ionic liquids (PILs) with a polythiophene backbone bearing imidazolium salts with butyl, hexyl, octyl, and decyl side groups and six different counterani...

Dipolar Relaxation in Functionalized Poly-p-phenylenes Bearing Ultrastrong Dipoles Perpendicular to the Backbone

Local polymer dynamics are studied in polymers bearing dipoles rigidly attached to the backbone. The compounds are based on cyano-substituted dihydrobenzimidazoles bearing ultrastrong dipole moments (∼12 D per repeat unit) incorporated in a poly-p-phenylene backbone, giving rise to polymers with rigid dipoles perpendicular to the chain. They belong to type B polymers according to the Stockmayer classification. They are ideal model systems for studying rotational isomers in the gas phase and the self-assembly and local dynamics in the solid state. Gas phase calculations (DFT) provided the dipole moments, the energetic barriers, and the backbone conformation as a function of the dipole streng…

Local and Subchain Relaxation of Polyisoprene in Multiblock Copolymers with a Tapered Interface

We report on the local and (sub-) chain dynamics in a new class of tapered multiblock copolymers synthesized by the repeated statistical living anionic copolymerization of a mixture of isoprene and...

Hexasubstituted Benzenes with Ultrastrong Dipole Moments

Hexasubstituted benzenes have been synthesized with the highest known dipole moments, as determined by dielectric spectroscopy and DFT methods. Based on the preparation of 4,5-diamino-3,6-dibromophthalonitrile, combined with a novel method to synthesize dihydrobenzimidazoles, these benzene derivatives have dipole moments in excess of 10 debye. Such dipole moments are desirable in ferroelectrics, nonlinear optics, and in organic photovoltaics. Structure determination was achieved through single-crystal X-ray crystallography, and the optical properties were determined by UV/Vis absorption and fluorescence spectroscopy.

Capillary Imbibition, Crystallization, and Local Dynamics of Hyperbranched Poly(ethylene oxide) Confined to Nanoporous Alumina

The crystallization and dynamics of hyperbranched poly(ethylene oxide) (hbPEO), obtained from the direct random copolymerization of EO and glycidol (PEO-co-PG), are studied both in bulk and within nanoporous alumina (AAO). Copolymerization decreases the degree of crystallinity and lowers the crystallization and melting temperatures as compared to linear PEO. The dynamics of capillary imbibition within AAO followed the t1/2 prediction but is slower than predicted by the classical Lucas–Washburn equation. The most prominent effect of confinement is the change in nucleation mechanism—from heterogeneous nucleation in bulk to homogeneous nucleation inside AAO. The homogeneous nucleation temperat…

The Next 100 Years of Polymer Science

International audience; The year 2020 marks the 100th anniversary of the first article on poly merization, published by Hermann Staudinger. It is Staudinger who realized that polymers consist of long chains of covalently linked building blocks. Polymers have had a tremendous impact on the society ever since this initial publication. People live in a world that is almost impossible to imagine without synthetic polymers. But what does the future hold for polymer science? In this article, the editors and advisory board of Macromolecular Chemistry and Physics reflect on this question.

Structure Formation of Polymeric Building Blocks: Complex Polymer Architectures

This chapter describes macromolecules with a complex structure, their defined aggregation in solution, their adsorption to surfaces, and their possible aggregation on surfaces. The term “complex structure” implies that the macromolecules show different, distinct structural elements or building blocks on a supra-atomic length scale. Key to understanding the complex structure of macromolecules, their aggregation, and adsorption to surfaces are intra- and intermolecular interactions such as van der Waals, electrostatic, π–π interactions, and hydrogen bonds.

Building Bridges by Blending: Morphology and Mechanical Properties of Binary Tapered Diblock/Multiblock Copolymer Blends

Hexasubstituierte Benzolderivate mit ultrastarken Dipolmomenten

Tapered Multiblock Copolymers Based on Farnesene and Styrene: Impact of Biobased Polydiene Architectures on Material Properties

The reactivity of the biobased monomer β-farnesene in the statistical anionic copolymerization with styrene and the effect of the bottlebrush-like polyfarnesene structure on the phase separation be...

Towards bio-based tapered block copolymers: the behaviour of myrcene in the statistical anionic copolymerisation

To explore the potential of myrcene (Myr) as a bio-based monoterpene comonomer for styrenic copolymers and to establish its general applicability for the carbanionic copolymerisation, several statistical copolymerisations of myrcene and common monomers like isoprene (I), styrene (S) and 4-methylstyrene (4MS) were carried out in cyclohexane and monitored by in situ1H NMR spectroscopy. Real-time NMR kinetic studies permitted the determination of the reactivity ratios and the composition profile for each monomer combination. While the copolymerisation of Myr/I yielded a gradient copolymer and reactivity ratios of moderate disparity (rMyr = 4.4; rI = 0.23), the statistical copolymerisation of M…

Isoprene/Styrene Tapered Multiblock Copolymers with up to Ten Blocks: Synthesis, Phase Behavior, Order, and Mechanical Properties

The living anionic copolymerization of isoprene and styrene in cyclohexane affords tapered block copolymers due to the highly disparate reactivity ratios of rI = 12.8 and rS = 0.051. Repeated addit...

Dicyanobenzothiadiazole Derivatives Possessing Switchable Dielectric Permittivities

Benzothiadiazoles are important electron acceptors and are frequently employed as electron-deficient components of donor-acceptor polymers. We report the effect of nitrile functionalities on the reactivity, steric hindrance, optoelectronic properties, and dielectric permittivity in dicyanobenzothioadiazole (DCNBT). Dielectric spectroscopy in the bulk and in solution assisted by DFT-calculations revealed that these molecules can be engineered to engender maximum values of the dipole moment and of dielectric permittivity due to the strong electron-withdrawing effect of the nitrile groups. The self-assembly in the bulk was investigated by X-ray scattering performed on single crystals, fibers (…

CCDC 1421613: Experimental Crystal Structure Determination

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CCDC 1533973: Experimental Crystal Structure Determination

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CCDC 1533972: Experimental Crystal Structure Determination

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CCDC 1421614: Experimental Crystal Structure Determination

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CCDC 1421615: Experimental Crystal Structure Determination

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CCDC 1533971: Experimental Crystal Structure Determination

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CCDC 1421617: Experimental Crystal Structure Determination

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CCDC 1533733: Experimental Crystal Structure Determination

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CCDC 1533970: Experimental Crystal Structure Determination

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CCDC 1814647: Experimental Crystal Structure Determination

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CCDC 1533734: Experimental Crystal Structure Determination

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CCDC 1814646: Experimental Crystal Structure Determination

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CCDC 1421616: Experimental Crystal Structure Determination

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CCDC 1814648: Experimental Crystal Structure Determination

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