Acyclic Diene Metathesis Research Articles

Near-Infinite-Chain Polymers with Ge=Ge Double Bonds.

Despite considerable interest in heteroatom-containing conjugated polymers, there are only few examples with heavier p-block elements in the conjugation path. The recently reported heavier acyclic diene metathesis (HADMET) allowed for the synthesis of a polymer containing Ge=Ge double bonds - albeit insoluble and with limited degree of polymerization. By incorporation of long alkyl chains, we now obtained soluble representatives, which exhibit degrees of polymerization near infinity according to diffusion-ordered NMR spectroscopy (DOSY) and dynamic light scattering (DLS). Analyses of the UV/Vis absorption and the NMR spectroscopic data confirm the presence of σ,π-conjugation across the silylene-phenylene linkers between the Ge=Ge double bonds. Favorable intermolecular dispersion interactions lead to ladder-like cylindrical supramolecular assemblies as confirmed by X-ray diffraction (XRD), small angle X-ray scattering (SAXS) and DLS. AFM and TEM images of deposited thin films reveal lamellar ordering of extended polymer bundles.

Anti-Ultraviolet Biobased Polyesters Synthesized by Acyclic Diene Metathesis Polymerization

Anti-Ultraviolet Biobased Polyesters Synthesized by Acyclic Diene Metathesis Polymerization

Synthesis of Polyesters Containing Long Aliphatic Methylene Units by ADMET Polymerization and Synthesis of ABA-Triblock Copolymers by One-Pot End Modification and Subsequent Living Ring-Opening Polymerization.

The synthesis of high-molecular-weight (Mn up to 62,000 g/mol) polyesters has been achieved by acyclic diene metathesis (ADMET) polymerization of α,ω-dienes prepared from biobased bis(undec-10-enoate) and diols [ethylene glycol (M1), propylene glycol (M2), 1,9-nonanediol (M3), 1,4-benzenedimethanol (M4), and hydroquinone (M5)] using ruthenium-carbene catalysts. Replacement of the solvent during the ADMET polymerization was effective for obtainment of the high-molecular-weight polymers (expressed as P1-P5). The melting temperatures (Tm) in the resultant polyesters were dependent upon the diol (middle) segment employed, and the polymer prepared from M5 exceeded 100 °C (a Tm value of 122.5 °C). The polymerization of M3 and M4 in the presence of 1,4-cis-diacetoxy-2-butene (DAB, as the chain transfer agent) afforded the telechelic polyesters [P3(OAc)2 and P4(OAc)2, respectively] containing acetoxy end groups exclusively. The resultant polymers containing hydroxy group termini [P3(OH)2 and P4(OH)2], prepared by the selective deprotection of the acetoxy end groups, were treated with AlEt3 followed by addition of ε-caprolactone to afford the ABA-type triblock copolymers exclusively, through a living ring-opening polymerization. The depolymerization (hydrolysis) under basic conditions (NaOH aqueous solution) of P3 was explored.

Synthesis of Network Biobased Aliphatic Polyesters Exhibiting Better Tensile Properties than the Linear Polymers by ADMET Polymerization in the Presence of Glycerol Tris(undec-10-enoate).

Development of biobased aliphatic polyesters with better mechanical (tensile) properties in film has attracted considerable attention. This report presents the synthesis of soluble network biobased aliphatic polyesters by acyclic diene metathesis (ADMET) polymerization of bis(undec-10-enyl)isosorbide diester [M1, dianhydro-D-glucityl bis(undec-10-enoate)] in the presence of a tri-arm crosslinker [CL, glycerol tris(undec-10-enoate)] using a ruthenium-carbene catalyst, and subsequent olefin hydrogenation using RhCl(PPh3)3. The resultant polymers, after hydrogenation (expressed as HCP1) and prepared in the presence of 1.0 mol% CL, showed better tensile properties than the linear polymer (HP1) with similar molecular weight [tensile strength (elongation at break): 20.8 MPa (282%) in HP1 vs. 35.4 MPa (572%) in HCP1]. It turned out that the polymer films prepared by the addition of CL during the polymerization (expressed as a 2-step approach) showed better tensile properties. The resultant polymer film also shows better tensile properties than the conventional polyolefins such as linear high density polyethylene, polypropylene, and low density polyethylene.

Acyclic Diene Metathesis (ADMET) Polymerization for the Synthesis of Chemically Recyclable Bio-Based Aliphatic Polyesters

The recent developments of the synthesis of bio-based long-chain aliphatic polyesters by the acyclic diene metathesis (ADMET) polymerization of α,ω-dienes, derived from plant oils and bio-based chemicals, like bis(10-undecenoate) with isosorbide, using ruthenium-carbene catalysts are reviewed. The development of subsequent (one-pot) tandem hydrogenation produced saturated polyesters under mild conditions. The polymerizations under bulk (without solvent, 80–90 °C) or in ionic liquids (50 °C) under vacuum conditions enabled the synthesis of high molar mass polymers (Mn > 30,000 g/mol). The polymerization performed by the molybdenum-alkylidene catalyst afforded the highest-molecular-weight polyesters (44,000–49,400 g/mol, in toluene at 25 °C) exhibiting promising tensile properties (strength and elongation at break) compared to polyethylene and polypropylene. Depolymerizations of these polyesters, including closed-loop chemical recycling, were also demonstrated. Catalyst developments (more active, under mild conditions) play a key role in the efficient synthesis of these materials.

Synthesis of platinum-containing oligomers utilizing ADMET chemistry and polycondensation of a bisimide with α,ω-dibromoalkanes: examination of triplet–triplet annihilation upconversion

Pt-containing oligomers synthesized by ADMET oligomerization and polycondensation phosphoresced under N2, while did not under air. They served as sensitizers of triplet–triplet annihilation upconversion with 9,10-diphenylanthracene as an emitter.

Increasingly threaded polypseudorotaxanes with reduced enthalpies of melting

We used acyclic diene metathesis (ADMET) chemistry to prepare variably threaded pseudopolyrotaxanes. We find that the melting enthalpy decreases as the number density of macrocycles is increased.

Photo- and halochromism of spiropyran-based main-chain polymers.

Advanced functional polymeric materials based on spiropyrans (SPs) feature multi-stimuli responsive characteristics, such as a change in color with exposure to light (photochromism) or acids (halochromism). The inclusion of stimuli-responsive molecules in general - and SPs in particular - as main-chain repeating units is a scarcely explored macromolecular architecture compared to side chain responsive polymers. Herein, we establish the effects of substitution patterns on SPs within a homopolymer main-chain synthesized via head-to-tail Acyclic Diene METathesis (ADMET) polymerization. We unambiguously demonstrate that varying the location of the ester group (-OCOR) on the chromophore, which is essential to incorporate the SPs in the polymer backbone, determines the photo- and halochromism of the resulting polymers. While one polymer shows effective photochromism and resistance towards acids, the opposite - weak photochromism and effective response to acid - is observed for an isomeric polymer, simply by changing the position of the ester-linker relative to the benzopyran oxygen on the chromene unit. Our strategy represents a simple approach to manipulate the stimuli-response of main-chain SP bearing polymers and highlights the critical importance of isomeric molecular constitution on main-chain stimuli-sensitive polymers as emerging materials.

Eugenol-based polyester and its bamboo fiber composite with enhanced mechanical and anti-ultraviolet properties

Eugenol (UG) is a sustainable allyl-substituted guaiacol that easily becomes the monomers for acyclic diene metathesis (ADMET) polymerization. Nevertheless, the ADMET polymers usually have a moderate molecular weight and poor...

Makromolekulare Hydrazon Hauptkettenphotoschalter

AbstractHydrazone – bestehend aus einer dynamischen Iminbindung und einem sauren NH‐Proton – haben sich in letzter Zeit aufgrund ihrer Fähigkeit zur Bildung thermisch bistabiler (Z) bzw. (E) Isomere als vielseitige Potoschalter erwiesen. In diesem Artikel stellen wir zwei lichtsensitive Homopolymere vor, die strukturell unterschiedliche Hydrazone als sich wiederholende Einheiten in der Hauptkette enthalten und durch „Kopf‐Schwanz“‐Polymerisation mittels azyklischer Dien‐METathese (ADMET) synthetisiert wurden. Der Hauptunterschied der beiden Polymere liegt dabei im Design des Hydrazon‐Photoschalters, insbesondere in der Lage des aliphatischen Arms, der den Rotor mit dem aliphatischen Polymerrückgrat verbindet. Es zeigt sich, dass sich das hydrodynamische Volumen der Polymere in verdünnter Lösung während der Photoisomerisierung (λ=410 nm) in entgegengesetzter Weise ändert. Darüber hinaus zeigt sich nach der Photoisomerisierung eine Veränderung der Glasübergangs‐temperatur (Tg) um fast 10 °C bei beiden Polymeren, unabhängig vom Design des jeweiligen Hydrazon‐Monomers. Die hier vorgestellte Designstrategie erlaubt es, makromolekulare Eigenschaften durch Strukturänderungen photochemisch zu kontrollieren.

Main-chain Macromolecular Hydrazone Photoswitches.

Hydrazones-consisting of a dynamic imine bond and an acidic NH proton-have recently emerged as versatile photoswitches underpinned by their ability to form thermally bistable isomers, (Z) and (E), respectively. Herein, we introduce two photoresponsive homopolymers containing structurally different hydrazones as main-chain repeating units, synthesized via head-to-tail Acyclic Diene METathesis (ADMET) polymerization. Their key difference lies in the hydrazone design, specifically the location of the aliphatic arm connecting the rotor of the hydrazone photoswitch to the aliphatic polymer backbone. Critically, we demonstrate that their main photoresponsive property, i.e., their hydrodynamic volume, changes in opposite directions upon photoisomerization (λ=410 nm) in dilute solution. Further, the polymers-independent of the design of the individual hydrazone monomer-feature a photoswitchable glass transition temperature (Tg ) by close to 10 °C. The herein established design strategy allows to photochemically manipulate macromolecular properties by simple structural changes.

Introducing the Reversible Reaction of CO2 with Diamines into Nonisocyanate Polyurethane Synthesis.

Nonisocyanate polyurethanes (NIPUs) are considered greener alternatives to traditional polyurethanes, and the preparation of NIPUs considerably depends on the design and synthesis of suitable monomers. Herein, we propose a toolbox for in situ capturing and conversion of CO2 into α,ω-diene-functionalized carbamate monomers by taking advantage of the facile reversible reaction of CO2 with diamines in the presence of organic superbases. The activation of CO2 into carbamate intermedia was demonstrated by NMR and in situ FTIR, and the optimal conditions to prepare α,ω-diene-functionalized carbamate monomers were established. Thiol-ene and acyclic diene metathesis (ADMET) polymerization of these monomers under mild conditions yielded a series of poly(thioether urethane)s and unsaturated aromatic-aliphatic polyurethanes with high yield and glass transition temperatures ranging from -26.8 to -1.1 °C. These obtained NIPUs could be further modified via postpolymerization oxidation or hydrogenation to yield poly(sulfone urethane) and saturated polyurethane with tunable properties.

Furandicarboxylate Polyesters: A Comprehensive ADMET Study of a Novel Class of Furan-Based α,ω-Diene Monomers.

The present research article delves into the preparation of a new class of bio-based polyesters from α,ω-diene furandicarboxylate monomers. In particular, it exploits the use of acyclic diene metathesis polymerisation (ADMET) on 2,5-furandicarboxylic acid (FDCA)-derived compounds. First, a library of furan-based α,ω-diene monomers was prepared via acid- or base-catalyzed transesterification of 2,5-furandicarboxylic acid dimethyl ester (FDME) with commercially available alcohols incorporating terminal olefins, i. e., allyl alcohol, but-3-en-1-ol, hex-5-en-1-ol and dec-9-en-1-ol. Then, the novel monomers were subjected to ADMET polymerisation employing different catalysts and reaction conditions. Interestingly, first-generation Grubbs catalyst was found to be the best promoter for ADMET polymerisation. This catalyst allowed the preparation of a new family of bio-based polyesters with molecular weights up to 26.4 kDa, with good thermal stability, and adaptable cis-trans conformations. Results also revealed that the monomer structure had a direct impact on the polymerisation efficiency and the resulting thermal properties. The effect of green bio-based solvents such as Cyrene™, dimethyl isosorbide (DMI) and γ-valerolactone (GVL) on the polymerisation process was also studied. Data collected showed that the solvent concentration influenced both the yield and length of polymers formed. Furthermore, some co-polymerisation experiments were conducted; the successful integration of different monomers in the resulting copolymer was shown to affect the glass transition temperature (Tg) of the resulting materials.

Biobased Polyethers via Acyclic Diene Metathesis Polymerization of α,ω-Diene Furanics

Biobased Polyethers via Acyclic Diene Metathesis Polymerization of α,ω-Diene Furanics

High‐Density Polyethylene with In‐Chain Photolyzable and Hydrolyzable Groups Enabling Recycling and Degradation

AbstractPolyethylenes endowed with low densities of in‐chain hydrolyzable and photocleavable groups can improve their circularity and potentially reduce their environmental persistency. We show with model polymers derived from acyclic diene metathesis polymerization that the simultaneous presence of both groups has no adverse effect on the polyethylene crystal structure and thermal properties. Post‐polymerization Baeyer–Villiger oxidation of keto‐polyethylenes from non‐alternating catalytic ethylene‐CO chain growth copolymerization yield high molecular weight in‐chain keto‐ester polyethylenes (Mn≈50.000 g mol−1). Oxidation can proceed without chain scission and consequently the desirable materials properties of HDPE are retained. At the same time we demonstrate the suitability of the in‐chain ester groups for chemical recycling by methanolysis, and show that photolytic degradation by extended exposure to simulated sunlight occurs via the keto groups.

High-Density Polyethylene with In-Chain Photolyzable and Hydrolyzable Groups Enabling Recycling and Degradation.

Polyethylenes endowed with low densities of in-chain hydrolyzable and photocleavable groups can improve their circularity and potentially reduce their environmental persistency. We show with model polymers derived from acyclic diene metathesis polymerization that the simultaneous presence of both groups has no adverse effect on the polyethylene crystal structure and thermal properties. Post-polymerization Baeyer-Villiger oxidation of keto-polyethylenes from non-alternating catalytic ethylene-CO chain growth copolymerization yield high molecular weight in-chain keto-ester polyethylenes (Mn ≈50.000 g mol-1 ). Oxidation can proceed without chain scission and consequently the desirable materials properties of HDPE are retained. At the same time we demonstrate the suitability of the in-chain ester groups for chemical recycling by methanolysis, and show that photolytic degradation by extended exposure to simulated sunlight occurs via the keto groups.

Synthesis of High Molecular Weight Biobased Aliphatic Polyesters Exhibiting Tensile Properties Beyond Polyethylene.

Synthesis of high molecular weight polyesters prepared by acyclic diene metathesis (ADMET) polymerization of bis(undec-10-enoate) with isosorbide (M1), isomannide (M2), and 1,3-propanediol (M3) and the subsequent hydrogenation have been achieved by using a molybdenum-alkylidene catalyst. The resultant polymers (P1) prepared by the ADMET polymerization of M1 (in toluene at 25 °C) possessed high Mn values (Mn = 44400-49400 g/mol), and no significant differences in the Mn values and the PDI (Mw/Mn) values were observed in the samples after the hydrogenation. Both the tensile strength and the elongation at break in the hydrogenated polymers from M1 (HP1) increased upon increasing the molar mass, and the sample with an Mn value of 48200 exhibited better tensile properties (tensile strength of 39.7 MPa, elongation at break of 436%) than conventional polyethylene, polypropylene, as well as polyester containing C18 alkyl chains. The tensile properties were affected by the diol segment employed, whereas HP2 showed a similar property to HP1.

Lamellar Ionenes with Highly Dissociative, Anionic Channels Provide Lower Barriers for Cation Transport.

Solid polymer electrolytes have the potential to enable safer and more energy-dense batteries; however, a deeper understanding of their ion conduction mechanisms, and how they can be optimized by molecular design, is needed to realize this goal. Here, we investigate the impact of anion dissociation energy on ion conduction in solid polymer electrolytes via a novel class of ionenes prepared using acyclic diene metathesis (ADMET) polymerization of highly dissociative, liquid crystalline fluorinated aryl sulfonimide-tagged ("FAST") anion monomers. These ionenes with various cations (Li+, Na+, K+, and Cs+) form well-ordered lamellae that are thermally stable up to 180 °C and feature domain spacings that correlate with cation size, providing channels lined with dissociative FAST anions. Electrochemical impedance spectroscopy (EIS) and differential scanning calorimetry (DSC) experiments, along with nudged elastic band (NEB) calculations, suggest that cation motion in these materials operates via an ion-hopping mechanism. The activation energy for Li+ conduction is 59 kJ/mol, which is among the lowest for systems that are proposed to operate via an ion conduction mechanism that is decoupled from polymer segmental motion. Moreover, the addition of a cation-coordinating solvent to these materials led to a >1000-fold increase in ionic conductivity without detectable disruption of the lamellar structure, suggesting selective solvation of the lamellar ion channels. This work demonstrates that molecular design can facilitate controlled formation of dissociative anionic channels that translate to significant enhancements in ion conduction in solid polymer electrolytes.

Cis-Selective Acyclic Diene Metathesis Polymerization of α,ω-Dienes.

The cis/trans stereochemistry of repeating alkenes in polymers provides a powerful handle to modulate the thermal and mechanical properties of these soft materials, but synthetic methods to precisely dictate this parameter remain scarce. We report herein a cis-selective acyclic diene metathesis (ADMET) polymerization of readily available α,ω-diene monomers with high functional group tolerance. Identification of a highly stereoselective cyclometalated Ru catalyst allowed the synthesis of a broad array of polymers with cis contents up to 99%. This platform was leveraged to study the impact of the cis geometry on the thermal and mechanical properties of polyalkenamers, including an ABA triblock copolymer synthesized via extension of a cis-rich telechelic polyoctenamer with d,l-lactide. These results suggest that cis-selective ADMET affords an efficient strategy to tune the properties of a variety of polymers.

Methanol-Assisted ADMET Polymerization of Semiaromatic Amides

A method for the acyclic diene metathesis polymerization of semiaromatic amides is described. The procedure uses second-generation Grubbs' catalyst and N-cyclohexyl-2-pyrrolidone (CHP), a high boiling, polar solvent capable of solubilizing both monomer and polymer. The addition of methanol to the reaction was found to significantly increase polymer molar mass although the role of the alcohol is currently not understood. Hydrogenation with hydrogen gas and Wilkinson's catalyst resulted in near-quantitative saturation. All polymers synthesized here exhibit a hierarchical semicrystalline morphology driven by ordering of aromatic amide groups via strong nonbonded interactions. Furthermore, the melting points can be tuned over a >100 °C range by precise substitution at just one of the backbone positions on each mer (<5% of the total).