Alternating Block Copolymers Research Articles

Active Ga-catalysts for the ring opening homo- and copolymerization of cyclic esters, and copolymerization of epoxide and anhydrides.

A series of gallium complexes L12Ga4Me8 (1), L22Ga4Me8 (2), and L32Ga4Me8 (3) was synthesized by reaction of GaMe3 with Schiff base ligands L1-3H2 (L1H2 = 2,4-di-tert-butyl-6-{[(3-hydroxypropyl)imino]methyl}phenol; L2H2 = 2,4-dichloro-6-{[(3-hydroxypropyl)imino]methyl}phenol; L3H2 = 4-tert-butyl-2-{[(3-hydroxypropyl)imino]methyl}phenol) and characterized by 1H, 13C NMR, IR spectroscopy, elemental analysis and single crystal X-ray analysis (1, 2), proving their tetranuclear structure in the solid state. Complexes 1-3 showed good catalytic activity in the ring opening homopolymerization (ROP) and ring opening copolymerization (ROcoP) of lactide (LA) and ε-caprolactone (ε-CL) in the presence of benzyl alcohol (BnOH) in toluene at 100 °C, yielding polymers with the expected average molecular weights (Mn) and narrow molecular weight distributions (MWD), as well as a high isoselectivity for the ROP of rac-lactide (rac-LA), yielding isotactic-enriched PLAs with Pm values up to 0.78. Kinetic studies with complex 1 proved the first order dependence on monomer concentration, while mechanistic studies confirmed the coordination insertion mechanistic (CIM) pathway. Sequential addition of monomers gave well defined diblock copolymers of PCL-b-PLLA and PLLA-b-PCL, proving the living character of the polymerization reactions. The catalysts also showed perfect selectivity for the copolymerization of cyclohexene oxide (CHO) with both succinic anhydride (SA) and maleic anhydride (MA) in the presence of BnOH and produced >99% alternating block copolymers.

Radically Accessing D–A Type Ambipolar Copolymeric Materials with Intrinsic Electrical Conductivity and Visible–Near Infrared Absorption Via Electro‐Copolymerization

AbstractThienothiadiazole‐bisthiophene (TTDT2) and diketopyrrolo–pyrrole–bisthiophene (DPPT2) are successfully electro‐copolymerized with terthiophene (T3) as an initiator and linker at low oxidative potentials. AC impedance analysis, absorption spectroscopy, and elemental composition via SEM‐EDX support the formation of donor–acceptor (D–A) type alternating block copolymers, poly(T3‐TTDT2), and poly(T3‐DPPT2). Unique optical properties that span into the near infrared‐II(>1000 nm) region and inherent electrical conductivity at the p‐type regime, n‐type regime, and in between the two regimes (i.e., typical insulator region) are observed. This study showcases the advantages of electro‐polymerization toward tailoring of next generation opto‐electronic materials.

Copolymers of Diketopyrrolopyrrole and Benzothiadiazole: Design and Function from Simulations with Experimental Support

Alternating block copolymers consisting of diketopyrrolopyrrole and benzothiadiazole electron acceptor units linked together via aromatic five-membered donor heterocycles are studied using a combination of computer simulation techniques and experiments. Four copolymers are modeled starting from their monomers to stacked macromolecules: with two different linkers—thiophene or furan, connecting electron-withdrawing core units—and two different alkyl substituents at lactam nitrogens of diketopyrrolopyrrole—linear dodecyl and branched 2-octyldodecyl chains. In our experiments, we aim at characterization of the optical and electrochemical properties of two copolymers with branched side chains differing in the linker, since as the literature survey shows the data published on these copolymers are very sparse. These properties can be easily interpreted and later compared with theoretical predictions. The results of simulations supported by experiments show that monomers of these polymers have very similar electr...

Ion Transport Mechanisms in Single Ion Polymer Electrolytes for Application in Lithium Ion Batteries

In order to increase the energy density of lithium ion batteries, lithium metal is an attractive anode material based on its high specific capacity and low electrochemical potential. However, a major drawback of lithium metal anodes comprises dendrite growth due to unstable solid electrolyte interphase (SEI) resulting in severe safety hazards. Polymer electrolytes constitute a viable alternative to commonly utilized liquid electrolytes and are able to suppress or even avoid dendrite growth thereby providing increased safety. In particular, single ion conducting polymer electrolytes are promising for application in lithium ion or lithium metal batteries. In contrast to common dual ion conducting electrolytes, single ion conductors afford high transference numbers, hence significantly reducing polarization effects as only lithium ions are mobile whereas anions are bound at the polymer backbone. In this contribution we present various single ion conducting polymers composed of AB-type alternating block copolymers in which the lithium ions are bound to the backbone (e.g., bis(4-carboxyl benzene sulfonyl)imide moieties). Systematic variation of the constituents can control the achievable properties including the morphology, electrical and electrochemical properties of the resulting polymers. The electrolyte membranes fabricated for application in lithium meatal batteries are blends of single ion conducting aromatic polymers and a flexible linear polymer such as poly(vinylidene fluoride-co -hexafluoropropylene (PVDF-HFP). The appropriate ratio of the polymer blends is evaluated to yield membranes (swollen with thermally stable solvent solutions of ethylene carbonate and propylene carbonate (EC: PC, 1:1, v/v)), with increased ionic conductivity, reduced solvent uptake as well as sufficient flexibility and mechanical stability as well as reduced solvent uptake. We present optimized routes for the synthesis of single ion conducting polymers and suitable membrane compositions. Furthermore, feasible relations of both structural and physicochemical properties of the polymer membranes are discussed, particularly with respect to underlying ion transport properties or transport mechanisms, in this way potentially enabling controlled modification or adjustment of either the chemical structures or electrochemical properties of the polymer membranes. A morphology analysis is performed using small angle X-ray scattering (SAXS), while nuclear magnetic resonance spectroscopy (NMR) and electrochemical data including impedance as well as dielectric loss spectra are combined to unravel the major ion transport mechanisms and ion mobility in addition to ionic conductivity, complex permittivity, self-diffusion coefficients and transference numbers. Both the oxidative and reductive stability as well as cycling performance in NMC/ lithium metal cells are also presented. Profound understanding of the ion transport mechanisms and property relations in single ion conducting polymer electrolyte membranes is essential and will allow to design future electrolyte membranes having desired properties. Thereby, the requirement for different applications can be met and the application of safe and highly performing lithium metal batteries can be enabled.

Combining uretdione and disulfide reversibly degradable polyurethanes: route to alternating block copolymers

Uretdione (temperature and catalyst controlled) and disulphide (REDOX controlled) functionalised polyurethanes have been described and the reversibility of these bonds tested.

Construction of interconnected micropores in poly(arylene ether) based single ion conducting blend polymer membranes via vapor-induced phase separation

We report the construction of interconnected micropores in a poly(arylene ether) based single ion conducting blend polymer electrolyte by tuning phase separation. Bis(4-fluorine benzene sulfonyl)imide is copolymerized with bis(4-hydroxy benzene sulfonyl)imide and bisphenol A separately to form two types of AB alternating block copolymers, i.e., lithiated poly(bis(benzene sulfonyl)imide)ether (LiPBIE) and lithiated poly(bisphenol A-alt-bis(4-fluorine benzene sulfonyl)imide)ether (LiPAFE). The former is immiscible with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and the latter is well entangled with the binder upon introducing the bisphenol group. The results reveal that the LiPBIE blend film exhibits an interconnected microporous structure while the LiPAFE blend film does not. Even if the ion exchange capacity (IEC) of the LiPAFE blend film is raised to the level of the LiPBIE blend film by reducing the proportion of PVDF-HFP, the film is porous only on the surface but remains dense in its bulk. The comparative experiments confirm that the disparity of polarity and solubility between the ionomers and the binder is largely responsible for the phase separation. The microporous single ion conducting gel polymer electrolyte offers an ionic conductivity of 0.52 mS cm−1 at 25°C and its membrane displays the capability of dendrite suppression. A battery incorporating the electrolyte film exhibits excellent rate performance and electrochemical stability.

Synthesis, Morphology, and Properties of Segmented Poly(ether amide)s with Uniform Oxalamide-Based Hard Segments

The synthesis, morphology, and properties of segmented poly(ether amide)s based on flexible PTHF segments (Mn = 1.1 × 103 g mol–1) and uniform rigid oxalamide segments were investigated. The amount of oxalamide groups in the hard segment and the spacer length of bisoxalamide-based hydrogen bonded arrays were varied systematically. The segmented poly(ether amide) with single oxalamide groups connecting the polyether blocks was a sticky solid with a melting temperature of ∼25 °C. Incorporation of uniform hard segments consisting of two interconnected oxalamide units provided highly phase-separated thermoplastic elastomers with a broad temperature-independent rubber plateau. By decreasing the aliphatic spacer length separating two oxalamide units from 10 to 2 methylene groups, the melting transitions increased from 140 to 200 °C. FT-IR evidenced strongly hydrogen bonded and highly ordered bisoxalamide hard segments with degrees of ordering between 66 and 90%. AFM revealed the presence of fiber-like nanocrystals with lengths up to several hundreds of nanometers randomly dispersed in the soft PTHF matrix. The long dimension of the crystals was found parallel to the direction of the hydrogen bonds. One of the other small dimensions of the crystal approximately equals the length of the oxalamide segment, whereas the other one may correspond to the height of a stack containing ca. 10–20 hydrogen-bonded sheets. Upon heating, the crystalline phase melts over a broad temperature range to give a homogeneous melt according to temperature-dependent FT-IR, SAXS, and rheology data. Increasing the number of oxalamide groups in the hard segment to three afforded a highly phase-separated material with a melting transition above 200 °C. The segmented copolymers with two or three oxalamide groups in the hard segment show a distinct yield point and have an elastic modulus between 121 and 210 MPa, a stress at break ranging from 15 to 27 MPa, and strain at break of 150 up to 900%. The results demonstrate that alternating block copolymers with soft PTHF segments and uniform hard segments containing two or three oxalamide groups are TPEs with good thermal and mechanical properties.

Alternating block copolymers based on polyamide‐12 and polycaprolactone

AbstractA series of alternating polyester/polyamide block copolymers were prepared by sequential conversion of hydroxy‐terminated polycaprolactone and amino‐terminated polyamide‐12 with a selectively reacting coupling agent. The thermal properties of the block copolymers were investigated using differential scanning calorimetry and dynamic mechanical analysis. Mechanical properties were determined using tensile and impact tests. All polymers were phase‐separated, where the polyamide phase was semicrystalline in all compositions. Distinct crystallization of the polycaprolactone phase was observed only when the block length was greater than 2000 g mol−1. Mechanical testing showed that the polymers behave in a manner similar to that of thermoplastic elastomers. In particular, samples with a high content of polycaprolactone showed high strain and good impact behaviour. Copyright © 2011 Society of Chemical Industry

Hyperbranched alternating block copolymers using thiol–yne chemistry: materials with tuneable properties

Alternating-block hyperbranched polymers were synthesized using the highly versatile thiol-yne reaction. Dimethyl acrylamide-styrene and tert-butyl acrylate-styrene polymers were prepared, with subsequent hydrolysis of the tert-butyl ester to acrylic acid. The dimethyl acrylamide-styrene hyperbranched polymers self-assembled into large aggregates, as did the acrylic acid-styrene system at low pH. However, high pH triggers the formation of very well defined small particles in the latter system.

Poly(hydroxyether of bisphenol A) ‐alt‐polydimethylsiloxane: a novel thermally crosslinkable alternating block copolymer

AbstractBACKGROUND: An important strategy for making polymer materials with combined properties is to prepare block copolymers consisting of well‐defined blocks via facile approaches.RESULTS: Poly(hydroxyether of bisphenol A)‐block‐polydimethylsiloxane alternating block copolymers (PH‐alt‐PDMS) were synthesized via Mannich polycondensation involving phenolic hydroxyl‐terminated poly(hydroxyether of bisphenol A), diaminopropyl‐terminated polydimethylsiloxane and formaldehyde. The polymerization was carried out via the formation of benzoxazine ring linkages between poly(hydroxyether of bisphenol A) and polydimethylsiloxane blocks. Differential scanning calorimetry and small‐angle X‐ray scattering show that the alternating block copolymers are microphase‐separated. Compared to poly(hydroxyether of bisphenol A), the copolymers displayed enhanced surface hydrophobicity (dewettability). In addition, subsequent crosslinking can occur upon heating the copolymers to elevated temperatures owing to the existence of benzoxazine linkages in the microdomains of hard segments.CONCLUSION: PH‐alt‐PDMS alternating block copolymers were successfully obtained. The subsequent self‐crosslinking of the PH‐alt‐PDMS alternating block copolymers could lead to these polymer materials having potential applications. Copyright © 2008 Society of Chemical Industry

Alternating Block Copolymers Consisting of Oligo(phenylene) and Oligo(ethylene glycol) Units of Defined Length: Synthesis, Thermal Characterization, and Light-Emitting Properties

Polymers containing conjugated oligo(phenylene) segments of defined length alternating with solubilizing regions of di- to hexa(ethylene glycol) have been synthesized using a Suzuki coupling protocol. Soluble and characterizable materials with up to four benzene rings linked together have been formed without the inclusion of conjugation-disrupting solubilizing side chains. The polymers were generated with weight-averaged molecular weights as high as 158 000 g/mol as determined by GPC-LS. The thermal and luminescence properties of these materials were studied in order to determine how these properties varied with the lengths of the two types of blocks. While the terphenyl polymers were amorphous, the quaterphenyl polymers exhibited multiple transitions in their DSC thermatograms. Polarized light microscopy and X-ray diffractometry were used to investigate this behavior. All of the polymers fluoresced strongly in the blue region of the visible spectrum with a 40 nm red shift in emission between solution and solid-state spectra. UV-visible and fluorescence studies were performed at different concentrations and in solvent/nonsolvent mixtures in order to study possible causes for this spectral shift, which appears to be due to the presence of ground state aggregates.

Synthesis, Characterization, and Morphology Studies of Biodegradable Amphiphilic Poly[(R)-3-hydroxybutyrate]-alt-Poly(ethylene glycol) Multiblock Copolymers

Novel biodegradable amphiphilic alternating block copolymers based on poly[(R)-3-hydroxybutyrate] (PHB) as biodegradable and hydrophobic block and poly(ethylene glycol) (PEG) as hydrophilic block (PHB-alt-PEG) were successfully synthesized through coupling reaction. Their chemical structures have been characterized by using gel permeation chromatography, (1)H nuclear magnetic resonance, and Fourier transform infrared spectroscopy. Differential scanning calorimetry (DSC) analysis revealed that both PHB and PEG blocks in PHB-alt-PEG block copolymers can crystallize to form separate crystalline phase except in those with a short PEG block (M(n) 600) only PHB crystalline phase has been observed. However, due to the mutual interference from each other, the melting transition of both PHB and PEG crystalline phases shifted to lower temperature with lower crystallinity in comparison with corresponding pure PHB and PEG. The crystallization behavior of PHB block and PEG block has also been studied by X-ray diffraction, and the results were in good agreement with those deduced from DSC study. The surface morphologies of PHB-alt-PEG block copolymer thin films spin-coated on mica have been visualized by atomic force microscopy with tapping mode, indicating formation of laterally regular lamellar surface patterns. Static water contact angle measurement revealed that surface hydrophilicity of these spin-coated thin films increases with increasing PEG block content.

New Fluorinated Thermoplastic Elastomers, 4

AbstractSummary: The synthesis of fluorinated polyimide‐polyhybridsiloxane block copolymers (FPI‐HPHSX) was performed by polycondensation of α,ω‐dichlorosilane fluorinated polyimides (SiCl‐FPI) and α,ω‐disilanol‐polyhybridsiloxanes (SiOH‐HPHSX). The α,ω‐disilanol polyhybridsiloxanes were synthesized by polyhydrosilylation between 1,7‐octadiene and hexamethyltrisiloxane (HMTS). The resulting siloxanes exhibit a glass transition temperature close to −98 °C. The α,ω‐dichlorosilane fluorinated polyimide was prepared by hydrosilylation of α,ω‐diallyl fluorinated polyimide and dimethylchlorosilane in the presence of Karstedt's catalyst. Then a series of four FPI‐HPHSX was synthesized by polycondensation and, with tuning of the number average molecular weight ($\overline M _{\rm n}$) of the soft polyhybridsiloxane and the hard polyimide groups, they were characterized. The influence of the segment lengths on the behavior (surface tension and thermal stability) of the thermoplastic elastomer (TPE) material was studied. The FPI‐HPHSX block copolymers' thermomechanical properties are also reported and discussed.General procedure for the synthesis of alternating block copolymers FPI‐HPHSX by polycondensation.magnified imageGeneral procedure for the synthesis of alternating block copolymers FPI‐HPHSX by polycondensation.

Chemiluminescent properties of polymeric blue fluorophores containing diphenylanthracene unit

New conjugated and non-conjugated alternating block copolymers containing 9,10-diphenyl-2-chloroanthracene moieties in the main chain were synthesized via Williamson synthesis for the blue chemiluminescent fluorophore. UV-vis absorption and luminescent characteristics including chemiluminescence were measured and compared with model fluorophore 9,10-bis( p-methoxyphenyl)-2-chloroanthracene. Polymers displayed blue photoluminescence in solution with maximum around 430 nm. Tetramethyl ammonium salicylate-catalyzed reaction of hydrogen peroxide with bis(2-carbopentyloxy-3,5,6-trichlorophenyl)oxalate produced a strong chemiluminescent blue light emission with wavelength of 440 nm in the presence of the polymeric fluorophore. The chemiluminescent intensity decayed exponentially and the glow of chemiluminescence maintained more than l2 h and was visible with naked eye.

Synthesis and electroluminescent studies of blue‐emitting copolymers containing phenylene vinylene and oxadiazole moieties in the main chain

AbstractTwo statistical copolymers III and IV combining features of the two reference polymers I and II were synthesized by a Wittig reaction with the objective of raising the electron‐transport properties and fluorescence quantum yields relative to the alternating block copolymers I and II. The electroluminescent properties of single‐layer LEDs using these copolymers were studied. External quantum efficiencies of 0.035 and 0.11% were obtained from single‐layer devices on the basis of III and IV, respectively, which are higher than those of similar devices using I and II. Two single‐layer LEDs using a blend of I and II (4:1 and 1:1 wt/wt) corresponding to the compositions of copolymers III and IV, respectively, were also fabricated for comparison. Results indicated that the covalent incorporation of oxadiazole is effective in improving the efficiency of LEDs and that the molar content of oxadiazole plays an important role in the performance of the devices. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 235–241, 2002

Rigid−Flexible Alternating Block Copolymers That Contain Poly(p-phenylene) Units of Defined Length as the Rigid Blocks

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTRigid−Flexible Alternating Block Copolymers That Contain Poly(p-phenylene) Units of Defined Length as the Rigid BlocksZachary R. Wagner, Timothy K. Roenigk, and Felix E. GoodsonView Author Information Department of Chemistry, West Chester University of Pennsylvania, West Chester, Pennsylvania 19383 Cite this: Macromolecules 2001, 34, 17, 5740–5743Publication Date (Web):July 12, 2001Publication History Received6 March 2001Revised5 June 2001Published online12 July 2001Published inissue 1 August 2001https://doi.org/10.1021/ma010406bCopyright © 2001 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views362Altmetric-Citations20LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (52 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Alcohols,Aromatic compounds,Copolymers,Materials,Polymers Get e-Alerts

Selective plasticization in electroluminescent block copolymers

Differential scanning calorimetry (DSC) measurements of glass transition temperature ( T g) and of changes in heat capacity at T g have been made on a series of electro-optically active alternating block copolymers of systematically varying hard and soft block structures and of their blends with the plasticizer, 1,12-dibromododecane (DBDD) in order to assess the nature of phase separation in these copolymers.

Light-emitting copolymers of cyano-containing PPV-based chromophores and a flexible spacer

Conjugated–non-conjugated alternating block copolymers containing cyano-modified distirylbenzene units as emitting chromophores were synthesized via Knoevenagel and Wittig reactions; the non-conjugated block was an alkylene spacer. The polymers were differentiated with respect to the location of the cyano groups in the chromophoric block (double bond or phenylene ring). When photoluminescence and electroluminescence spectra of these materials were compared with those of a similar structure without the cyano group, a strong bathochromic effect was observed. A more pronounced red shift and a higher electroluminescence efficiency was observed in the polymer with the cyano group attached to the aromatic ring.

Charge carrier mobility in electroluminescent alternating block copolymers

We have investigated charge transport in two electroluminescent block copolymers, poly(1,8-octanedioxy-2,6-dimethoxy-1,4-phenylene-1,2-ethenylene-1,4-phenylene-1,2-ethenylene-3, 5-dimethoxy-1,4-phenylene) and poly(1,8-octanedioxy-2,6-dimethoxy-1,4-phenylene-1,2-ethenylene-1,4-phenylene-1,2-ethenylene1,4-phenylene-1,2-ethenylene-3,5-dimethoxy-1,4-phenylene), using current versus voltage measurements performed on metal/polymer/metal structures. The effective mobility of holes has been determined for both polymers. The characteristic charge carrier trap distribution energies of the polymers for the case of Al electrodes have also been determined.

Alternating block copolymers incorporating 3-alkyl-substituted thiophene and aniline repeat units: novel electrically conductive and fluorescent polymers

A series of alternating block copolymers incorporating 3-alkyl-substituted thiophene and aniline repeat units (PATBAs): poly{4-[2-(3-methyl)thienyl]benzenamine} (PMTBA), poly{4-[2-(3-butyl)thienyl]benzenamine} (PBTBA), poly{4-[2-(3-octyl)thienyl]benzenamine} (POTBA) and poly{4-[2-(3-dodecyl)thienyl]benzenamine} (PDTBA) were synthesized via chemical oxidative polymerization using ferric chloride as oxidant. The resulting polymers were characterized by FT-IR, UV-Vis, fluorescence spectroscopy, elemental analysis, thermogravimetry and electrical conductivity measurements. It was shown that coupling during polymerization occurred through the α-position of the thienylene ring and the amino moiety. Upon doping with iodine the polymers attained electrical conductivity ranging from 10 −4 to over 10 −3 S cm −1. The fluorescence quantum efficiency of the polymers in solution was found to decrease with increasing pendant alkyl-chain length. Scanning electron microscopy (SEM) revealed a globular morphology similar to poly[4-(2-thienyl)benzenamine] and polythiophene.