Biomacromolecules and Bio‐Related Macromolecules

The present article briefly reviews research developments in the area of biomacromolecules and bio‐related macromolecules, whose research papers have been published for several decades preferably in the Macromolecular Journals. The area covers the important classes of macromolecules, polysaccharides (cellulose, amylose, chitin, etc.), polyesters (poly(lactic acid), poly(hydroxyalkanoate)s, etc.), and phenolic polymers (lignin, urushi, etc.). These polymers and their derivatives are very important for scientific interests as well as for industrial applications. Their synthesis, structure, reactions, and properties are mainly mentioned, and important topics of the target polymers are selected and mostly chronologically reviewed.

     

Synthesis of Polyphenylene Ether Derivatives: Estimation of Their Dielectric Constants

A series of poly(2‐alkyl‐6‐phenylphenylene ether)s were prepared by the oxidative polymerization of 2‐alkyl‐6‐phenylphenols. Their dielectric constants were approximately 2.5, whereas it was found that the phenyl group at the 6‐position clearly increased the Q factor of the polymer compared with poly(2,6‐dimethylphenylene ether), PPE. These values were qualitatively predicted from the polarizability and the molar volume calculated by the theoretical analysis of the unit structure at the HF/6‐31G* level.

     

Temperature Dependence of the Oxygen Solubility in Acrylates and its Effect on the Induction Period in UV Photopolymerization

Summary: The influence of temperature on the kinetics of the UV photopolymerization of two diacrylates carried out under air was studied by real‐time FTIR‐ATR spectroscopy. In the temperature range up to 100 °C, the rate of polymerization obeys the Arrhenius law. The induction period was found to decrease with increasing temperature. It was shown that this decay is exclusively due to the decreasing solubility of oxygen in the acrylate. Moreover, from the induction period and the oxygen solubility, quantum yields of the α‐cleavage of some photoinitiators were estimated.

Induction period calculated from the solubility of oxygen in TPGDA in comparison with experimental data from RT‐FTIR measurements.     

Macromol. Chem. Phys. 21/2009

Alternating copolymers of maleimides containing pyrenyl and alkynylpyrenyl moieties with isobutene (IB) were synthesized as a new class of heat‐resistant and fluorescent polymers. N‐(1‐Pyrenyl)maleimide (1) and N‐[4‐(1‐pyrenylethynyl)phenyl]maleimide (2) were copolymerized with IB in the presence and absence of N‐methylmaleimide (3) . The obtained maleimide/IB copolymers showed excellent thermal stability and high glass transition temperatures, and were soluble in common organic solvents. The copolymers including the alkynylpyrenyl fluorophore emitted strong fluorescence with a high quantum efficiency (Φ = 0.83) even in the presence of air and upon heating. Solid‐state fluorescence in transparent films was also investigated.

     

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.

     

Polyrotaxanes of Pyrene–Triazole Conjugated Azomethine and α‐Cyclodextrin with High Fluorescence Properties

The paper reports on the preparation of a new 2‐rotaxane monomer through an acid coupling reaction between 1‐pyrenecarboxaldehyde and α‐CD/3,5‐diamino‐1,2,4‐triazole inclusion complex. Pyrenyl groups are large enough to provide a blocking effect toward cyclodextrin de‐threading. The oxidative C? C coupling of 2‐rotaxane in the presence of RuCl₃ catalyst afforded conjugated azomethine polyrotaxanes. The expected modifications of the solubility, morphology, film forming ability for rotaxane polymer were proved. As shown by fluorescence and UV‐vis spectroscopy, a material with optical properties appropriate for use in photonics was obtained.

     

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.

     

Negatively Birefringent Polymer Films

Polymer films exhibiting large negative birefringence, suitable for compensating residual positive birefringence of liquid crystal displays, have been achieved for syndiotactic polystyrene. Procedures involving axial stretching at different draw ratios of unoriented films, followed by different crystallization routes, have been compared. The control of the polymer polymorphic behavior, i.e., of the formation of crystalline and co‐crystalline (with low‐molecular‐mass guest molecules) phases, allows to control the negative birefringence up to Δn = n_? ? n_|| = 0.17.

     

Morphology and Phase Characteristics of High‐Density Polyethylene Probed by NMR Spin Diffusion and Second Moment Analysis

Summary: A dipolar filter pulse sequence combined with cross‐polarization‐MAS is applied to characterize the phase distribution, morphology, and spin diffusion within a high‐density polyethylene sample. A new method to obtain quantitative ¹³C NMR by combining cross‐polarization‐MAS and spin diffusion NMR is presented. The derived crystallinity is consistent with the corresponding crystallinity obtained by ¹H NMR.

Illustration of the pulse sequence(s) applied in the present work.     

Synthesis,Electrochemical and Photovoltaic Properties of Multi‐Armed Polythiophenes with Triphenylamine Trivinylene as Conjugated Linker

Three polythiophenes with 5%, 10% and 15% triphenylamine trivinylene (TPAV) as bridge linker, PT‐TPAV5, PT‐TPAV10 and PT‐TPAV15, were synthesized. The Wittig‐Horner‐Emmons reaction and the Stille method were employed to synthesize these polymers. The polythiophenes were subsequently used in bulk‐heterojunction polymer solar cells (PSCs) as donor materials. The polymers exhibited a striking and reversible color change after the oxidation of the polymer films. The power conversion efficiencies of the PSCs based on PT‐TPAV5, PT‐TPAV10 and PT‐TPAV15 as donors and PCBM as acceptor were 0.17%, 0.50%, and 0.35%, respectively, under the illumination of AM 1.5, 100 mW · cm^?2.

     

“One‐pot” Synthesis of 1‐Vinyl‐2‐pyrrolidone with Protic Functional Groups in 3‐Position

A synthetic route that allows modification of 1‐vinyl‐2‐pyrrolidone with an alcohol or thiol group in its 3‐position in a one‐pot reaction without using protecting groups is described. The strategy used to achieve this goal is the reaction of the carboxamide anion of 1‐vinyl‐2‐pyrrolidone with cyclic precursors of these functionalities. It is furthermore shown that VP‐monomers functionalized with OH groups are suitable for the preparation of the corresponding copolymers with pure VP. As a second application of the new compounds, we also describe the synthesis of the first asymmetric crosslinker based on VP.

     

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.

     

Aniline‐Based Disulfide/Aniline Copolymers as a High Energy‐Storage Material

Aniline‐based disulfide, 5‐amino‐1,4‐dihydrobenzo[d]‐1′,2′‐dithiadiene (DTAn), was synthesized through a new route. The DTAn/aniline copolymers [P(DTAn‐co‐An)] were prepared by chemical oxidative polymerization. The results show that the polymerization activity of the DTAn is obviously lower than that of aniline, and the degree of polymerization increases with the increasing feed ratio of aniline and oxidant dosage. The cyclic voltammograms of the copolymers indicate that intramolecular self‐catalyzed effects occurred between the conducting backbone and the S‐S side chain. The charge–discharge tests of Li/P(DTAn‐co‐An) cell show an initial specific capacity of 262 mAh · g⁻¹, which suggests that P(DTAn‐co‐An) may be a promising cathode material in secondary lithium batteries.

     

Unique Effects of Cyclodextrins on the Formation and Colorimetric Transition of Polydiacetylene Vesicles

Summary: The effects of cyclodextrins (CDs) on the formation and color changes of polymerized 10,12‐pentacosadiynoic acid (PCDA) vesicles have been investigated. The strategy used in this study focuses on three different stages in which the CDs can play a role. Among the cyclodextrins investigated, α‐CD had most prominent effect on the perturbation of the ordered structures of the PCDA vesicles. Solid precipitates, formed by the PCDA vesicles in the presence of α‐CD were shown to be PCDA ‐ α‐CD inclusion complexes by using DSC, FTIR and ¹H NMR analysis. The results of studies using 4‐nitrophenol as an inhibitor and the consideration of inner and outer diameters of cyclodextrins have led to the conclusion that the color induced by the cyclodextrins is due to the formation of inclusion complexes with the polydiacetylene.

Photograph of the polydiacetylene liposomes after 1 h in the presence of 10 mM of the three different cyclodextrins in a HEPES buffer solution.     

4‐Alkylphenoxymethyl‐Substituted Polystyrenes for Liquid Crystal Alignment Layers

We synthesized a phenoxymethyl‐substituted polystyrene (PHP) and a series of 4‐alkylphenoxymethyl‐substituted polystyrenes, where the alkyl group is ? (CH₂)_nH (n = 1, 2, 4, 6, and 8), using polymer analogous reactions, in order to study the effect of the phenoxymethyl and 4‐alkylphenoxymethyl side groups on the liquid crystal (LC) alignment properties. The LC cell fabricated with the rubbed PHP film exhibited homogeneous planar and perpendicular LC alignment with respect to the rubbing direction. On the contrary, the LC cells made from the 4‐alkylphenoxymethyl‐substituted polystyrenes showed homeotropic LC alignment behaviors even at a very high rubbing density of 250, regardless of the length of the alkyl groups. Previously, n‐alkylsulfonylmethyl‐substituted polystyrenes with alkyl groups having more than 8 carbons (n > 8) showed homeotropic LC alignment behavior. Therefore, the additional phenoxy group in the side chain was found to improve the homeotropic LC aligning ability of the polystyrene derivatives.

     

Photoinduced Polymerization of Thiophene Using Iodonium Salt

Summary: Thiophene was polymerized by means of UV irradiation using diphenyliodonium hexafluorophosphate as a photoinitiator. An initiation mechanism involving electron transfer from photochemically generated onium radical cations to thiophene was proposed. N‐Ethoxy‐2‐methylpyridinium hexafluorophosphate and triphenylsulfonium hexafluorophosphate were also found to be effective in facilitating the polymerization of thiophene. Polymerization is accompanied with the film formation on the surface of the reaction tube. The photochemically obtained polymers were characterized by FT‐IR, DSC, and SEM analyses and compared with those obtained by oxidative and electrochemical means. Electrical conductivities of the samples were measured by four‐probe technique.

Photograph of the polymerization mixture containing thiophene and iodonium salt in CH₂Cl₂ before (a), after 5 min of irradiation (b), and dried film (c).     

Structural Reasons for Restricted Backbone Motion in Poly(n‐alkyl methacrylates): Degree of Polymerization,Tacticity and Side‐Chain Length

Summary: The complex dynamics of poly(n‐alkyl methacrylates) is studied by advanced ¹³C NMR spectroscopy as well as mechanical and dielectric relaxation. Extended backbone conformations are identified as the molecular units involved in structural relaxation. From the variation in the degree of polymerization and a comparison with the presence of stereoregular sequences in the sample, the length of the extended units is determined to involve about five, at most ten monomeric units. Syndiotactic and isotactic sequences behave similarly. These findings are indicative of locally structured polymer melts.

     

Preparation of Inclusion Complexes between Amylose and Ester‐Containing Polymers by Means of Vine‐Twining Polymerization

This paper reports the preparation of inclusion complexes of amylose with synthetic polymers by means of enzymatic polymerization of α‐D ‐glucose 1‐phosphate monomer (Glc‐1‐P). The synthetic polymers, employed as the guests, are poly(ε‐caprolactone), poly(δ‐valerolactone), and poly(ester‐ether), containing ester groups in the main chains. The formation of the inclusion complexes was carried out by the enzymatic polymerization of Glc‐1‐P catalyzed by phosphorylase in the presence of the guest polymers.

     

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.

     

Novel Light Emitting Diode Using Organic Electroluminescence Microcapsules

Novel light emitting diodes (LEDs) were prepared using electroluminescence (EL) material/polymer microcapsules (ELC). N‐vinylcarbazole as a hole‐transporting component and methyl methacrylate (MMA) were copolymerized for producing the seed particles using dispersion polymerization. An oxadiazole derivative, synthesized as a electron‐transporting component, and tris(8‐hydroxyquinolinato) aluminium(III) (Alq₃) were incorporated into the polymer particles by using the solute co‐diffusion method (SCM). The LEDs for the EL characterization were fabricated in a thin sandwich configuration: Al anode/ELC/ITO cathode. The surface imaging of the LED prepared using ELC was performed by atomic force microscopy (AFM). The EL characteristics of the ELC were investigated by UV, photoelectron and luminescence spectroscopy, and the current‐voltage and the light‐voltage characteristics for the LED were determined.

Encapsulation procedure using solute co‐diffusion method (SCM).