Vinyl Addition Copolymers of Norbornylnorbornene and Hydroxyhexafluoro­isopropylnorbornene for Efficient Recovery of <i>n</i>‑Butanol from Dilute Aqueous Solution via Pervaporation

The high energy cost to recover heavier alcohols, such as <i>n</i>-butanol, from dilute aqueous solution is a significant practical barrier to their large-scale bioproduction. Membrane pervaporation offers an energy-efficient alternative, provided membrane materials can be developed which provide both good alcohol selectivity and high flux. Previous work has revealed that vinyl addition polynorbornenes bearing substituentsespecially hydroxy­hexafluoroisopropylwith an affinity for <i>n</i>-butanol have potential in this application, as their high glass transition temperature allows the formation of thin but mechanically robust selective layers in thin-film composite (TFC) membranes. In the present work, we synthesize both microphase-separated gradient copolymers, and homogeneous random copolymers, of hydroxyhexafluoro­isopropyl­norbornene (HFANB) with norbornyl­norbornene (NBANB) and evaluate their <i>n</i>-butanol/water pervaporation performance. Compared with analogous copolymers of HFANB and <i>n</i>-butyl­norbornene (BuNB), the greater <i>n</i>-butanol permeability and selectivity of PNBANB vs PBuNB lead to a more-than-2-fold increase in membrane selectivity for <i>n</i>-butanol transport; the best HFANB–NBANB copolymers show <i>n</i>-butanol selectivities and fluxes which compare favorably with those of the best commercial TFC membranes, which contain cross-linked polydimethyl­siloxane selective layers. Moreover, vinyl addition copolymers offer a straightforward route to further flux enhancement, simply by reducing the selective layer thickness

Well-Defined Ambipolar Block Copolymers Containing Monophosphorescent Dye

Well-defined ambipolar block copolymers containing carbazole, oxadiazole moieties, and only one homoleptic iridium­(III) complex between the carbazole and oxadiazole blocks were successfully synthesized by sequential living anionic polymerization with controlled molecular weights (Mw), a narrow molecular weight distribution (Mw/Mn < 1.15), and a high conversion yield (98–100%). The optimum conditions for the successful controlled synthesis of an oxadiazole-containing the homopolymer of poly­(2-phenyl-5-(6-vinylpyridin-3-yl)-1,3,4-oxadiazole) have been established by controlling the nucleophilicity strength of the carbanion. In addition, the location and concentration of the homoleptic iridium­(III) complex were controlled by linking it to 1,1-diphenylethylene, which exhibits monoaddition characteristics in the main chain of the block copolymer

Facile Preparation of Magnetite-Incorporated Polyacrylonitrile-Derived Carbons for Li-Ion Battery Anodes

A facile preparation method for magnetite (Fe3O4)-incorporated polyacrylonitrile (PAN)-derived carbon composites was developed to overcome the limitations of graphite-based materials for Li-ion batteries (LIBs), and the electrochemical performance of this material as an anode for LIBs was investigated. In this study, Fe3O4 nanoparticles (NPs) with hydrophobic surfaces and graphitizable hydrophobic PAN formed through radical polymerization were uniformly distributed in an emulsion system, and subsequently, a partially graphitic carbon composite containing Fe3O4 NPs was obtained through simple oxidation and carbonization processes. The presence of Fe3O4 NPs contributed to a slight increase in the graphitization efficiency of PAN, as well as the additional uptake of lithium ions in LIBs. As a result, when the developed composite was applied as an anode for LIBs, they exhibited increased specific capacities and stable cycle performance over more than 100 cycles. In particular, it was confirmed that the rate capability of the composite was significantly higher than that of commercial graphite. The results indicate that the developed composite is promising for applications in advanced LIBs that are specialized for high-power devices

Physical and Chemical Compatibilization Treatment with Modified Aminosilanes for Aluminum/Polyamide Adhesion

Metal/polymer bilayer composites feature high strength-to-weight ratios and low manufacturing costs despite the weak interfacial adhesion between their components. In this study, aluminum surfaces were modified to generate microporous architectures and hydroxyl moieties by various physical and chemical treatments, including thermal, plasma, anodizing, and hexafluorozirconic acid treatments to overcome the weak interfacial adhesion. The maximum shear strength of the obtained metal/polymer bilayer composites was achieved by anodizing treatment, whereas all treatment methods substantially improved the material toughness. In addition, modified compatibilizing agents with tailorable hydroxyl moieties were applied to enhance the interfacial adhesion using aminoethylaminopropyl trimethoxysilane (AEAPS) and modified AEAPS as a coupling agent. AEAPS modified by monoepoxide (glycidol) produced the strongest positive effect on the composite mechanical properties. These findings can be useful in a myriad of metal/polymer multilayer composites

Living Anionic Polymerization of <i>N</i>‑(1-Adamantyl)‑<i>N</i>‑4-vinyl­benzylidene­amine and <i>N</i>‑(2-Adamantyl)‑<i>N</i>‑4-vinyl­benzylidene­amine: Effects of Adamantyl Groups on Polymerization Behaviors and Thermal Properties

The anionic polymerization of <i>N</i>-(1-adamantyl)-<i>N</i>-4-vinylbenzylidene­amine (<b>1</b>) and <i>N</i>-(2-adamantyl)-<i>N</i>-4-vinylbenzylidene­amine (<b>2</b>) was performed using various initiators, such as oligo­(α-methylstyryl)­dipotassium, potassium naphthalenide, diphenyl­methylpotassium, and diphenyl­methyllithium, in THF at −78 °C for 1 h to investigate the effects of adamantyl groups on the polymerization behaviors and thermal properties of the resulting polymers. The well-defined poly­(<b>1</b>) and poly­(<b>2</b>) with predictable molecular weights and narrow molecular weight distributions were successfully obtained, indicating that the bulky adamantyl groups effectively protected the carbon–nitrogen double bond (CN) from the nucleophilic attack of the initiators and the propagating chain ends. The stability of the propagating chain end of poly­(<b>1</b>) was confirmed by the quantitative efficiencies in the postpolymerization and the sequential copolymerization with <i>tert</i>-butyl methacrylate. A poly­(4-formylstyrene) was quantitatively formed by the acidic hydrolysis reaction of the <i>N</i>-adamantylimino groups of the poly­(<b>1</b>). The resulting poly­(<b>1</b>) and poly­(<b>2</b>) showed significantly high glass transition temperatures (<i>T</i>_g) at 257 and 209 °C, respectively, due to the bulky and stiff adamantyl substituents. It was also found that the substituted position of adamantane unit and the linkage between polystyrene backbone and adamantyl groups played very important roles to determine the <i>T</i>_g values of the substituted polystyrenes

Well-Defined Block Copolymers with Triphenylamine and Isocyanate Moieties Synthesized via Living Anionic Polymerization for Polymer-Based Resistive Memory Applications: Effect of Morphological Structures on Nonvolatile Memory Performances

The anionic block copolymerization of 4,4′-vinylphenyl-<i>N</i>,<i>N</i>-bis­(4-<i>tert</i>-butylphenyl)­benzenamine (<b>A</b>) with <i>n</i>-hexyl isocyanate (<b>B</b>) was performed using potassium naphthalenide (K-Naph) in THF at −78 and −98 °C in the presence of sodium tetraphenylborate (NaBPh₄) to afford the well-defined block copolymers for investigating the effect of morphological structures on electrical memory performances. The well-defined functional block copolymers (P<b>BAB</b>) with different block ratios had predictable molecular weights (<i>M</i>_n = 17 700–79 100 g/mol) and narrow molecular weight distributions (<i>M</i>_w/<i>M</i>_n = 1.14–1.19). It was observed from transmission electron microscopy (TEM) that the block copolymers showed different morphological structures depending on block ratios. Although all memory devices fabricated from the resulting block copolymers with different block compositions equally exhibited nonvolatile resistive switching characteristics, which are governed by the trap-controlled space-charge-limited current (SCLC) conduction mechanism and filament formation, it was found that electrical memory performances of each device varied depending on morphological structures of the block copolymer films

Self-assembly of POSS–Polystyrene Bottlebrush Block Copolymers on an Angle-Robust Selective Absorber for Enhancing the Purity of Reflective Structural Color

A facile approach for improving color purity is explored by the introduction of an angle-robust selective absorber (ARSA) into bottlebrush block copolymer (BBCP)-based one-dimensional (1D) photonic crystals (PCs). The BBCPs of poly[(3-(12-(cis-5-norbornene-exo-2,3-dicarboximido)dodecanoylamino)propyl POSS)-block-(norbornene-graft-styrene)], Px (x = 1–4), with ultrahigh molecular weights (Mn ∼ 2260 kDa) and low dispersities (D̵ ∼ 1.07) are synthesized by ring-opening metathesis polymerization. The 1D PCs of the lamellar structure are fabricated by self-assembly of the BBCP with different periodicities for full color-generation (blue, green, and red). The optically tailored substrate (i.e., ARSA) is used to modulate the spectral line shape with selective absorption in the near-infrared range. Optical simulation proposes the optimized 1D PC structures on the ARSA, and it provides the reproducibility of the predictable color. The simulated structures are well matched with the experimental results, verifying the enhancement of color saturation even at various incident angles (0–70°)

Assessing the Range of Validity of Current Tube Models through Analysis of a Comprehensive Set of Star–Linear 1,4-Polybutadiene Polymer Blends

We blend newly synthesized nearly monodisperse four-arm star 1,4-polybutadienes with various well-entangled linear polymers, confirming the conclusions in Desai et al. [Macromolecules201649 (13)­49644977] that advanced tube models, namely, the hierarchical 3.0 and branch-on-branch models [Wang, Z.; J. Rheol.201054 (2)­223260], fail to predict the linear rheological data when the pure linear polymers have shorter relaxation times, but within 3–4 orders of magnitude of the star polymer. However, when the linear polymer has a longer relaxation time than the star, our new work, surprisingly, finds that non-monotonic dependence of terminal relaxation behavior on composition is both observed experimentally and captured by the models. Combined with previous data from the literature, we present results from over 50 1,4-polybutadiene star–linear blends, suitable for thorough testing of rheological models of entangled polymers

Challenging Tube and Slip-Link Models: Predicting the Linear Rheology of Blends of Well-Characterized Star and Linear 1,4-Polybutadienes

We compare predictions of two of the most advanced versions of the tube model, namely the “Hierarchical model” by Wang et al. [J. Rheol. 2010, 54, 223] and the BoB (branch-on-branch) model by Das et al. [J. Rheol. 2006, 50, 207], against linear viscoelastic <i>G</i>′ and <i>G</i>″ data of binary blends of nearly monodisperse 1,4-polybutadiene 4-arm star polymer of arm molar mass 24 000 g/mol with a monodisperse linear 1,4-polybutadiene of molar mass 58 000 g/mol. The star was carefully synthesized and characterized by temperature gradient interaction chromatography and by linear rheology over a wide frequency region through time–temperature superposition. We found large failures of both the Hierarchical and BoB models to predict the terminal relaxation behavior of the star/linear blends, despite their success in predicting the rheology of the pure star and pure linear polymers. This failure occurred regardless of the choices made concerning constraint release, such as assuming arm retraction in “fat” or “skinny” tubes. Allowing for “disentanglement relaxation” to cut off the constraint release Rouse process at long times does lead to improved predictions for our blends, but leads to much worse predictions for other star/linear blends described in the literature, especially those of Shivokhin et al. [Macromolecules 2014, 47, 2451]. In addition, our blends and those of Shivokhin et al. were also tested against a coarse-grained slip-link model, the “clustered fixed slip-link model (CFSM)” of Schieber and co-workers [J. Rheol. 2014, 58, 723], in which several Kuhn steps are clustered together for computational efficiency. The CFSM with only two molecular-weight- and chain-architecture-independent parameters was able to give very good agreement with all experimental data for both of these sets of blends. In light of its success, the CFSM slip-link model may be used to address the constraint release issue more rigorously and potentially help develop improved tube models