Bio-olefins via condensation metathesis chemistry

Hopkins, Thomas S.

doi:10.1016/j.molcata.2003.11.024

Cited by 10 publications

(4 citation statements)

References 35 publications

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“…The synthesis of linear EAA copolymers required the preparation of unsaturated monomers for both the ADMET and ROMP reactions. Symmetrical acid bearing dienes and an acid-functionalized cyclooctene were prepared by previously reported methods. , Prior to polymerization, acid monomers were protected with a unique hemiacetal ester moiety to prevent metathesis catalyst decomposition and allow for conversion back to the free carboxylic acid either by thermal deprotection or during the subsequent polymer hydrogenation reaction. This protection scheme is key to the formation of high molecular weight, high strength materials where preliminary mechanical measurements reveal tensile strengths in excess of 4500 psi and elongations to break in excess of 450% for a sample of melt-cast polymer 14 .…”

Section: Resultsmentioning

confidence: 99%

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Synthesis and Morphology of Well-Defined Poly(ethylene-co-acrylic acid) Copolymers

et al. 2007

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We report the detailed characterization of strictly linear ethylene-co-acrylic acid (EAA) copolymers synthesized via two modes of olefin metathesis polymerization, where control of the polymer microstructure leads to the generation of unique polymer morphologies based on distribution of carboxylic acid moieties along the polymer backbone. Acyclic diene metathesis (ADMET) was used to prepare three high molecular weight, high strength EAA materials bearing pendant carboxylic acid groups along the copolymer backbone precisely placed every 9th, 15th, and 21st carbon, and ring-opening metathesis polymerization (ROMP) was used to create EAA materials of equimolar acid concentrations with irregularly distributed pendant groups along the linear copolymer backbone. Primary structure characterization using FT-IR and NMR techniques are discussed as well as secondary structure analysis via DSC and X-ray scattering. Thermal analysis indicates significant effects of functional group placement on melting temperatures and enthalpies illustrating the importance of ethylene sequence lengths and distributions on polymer crystallization. X-ray scattering reveals broad scattering peaks with evidence of orthorhombic polyethylene-like crystallization in all irregular copolymers except the most highly functionalized, fully amorphous material. The precise carboxylic acid copolymers have X-ray scattering peaks indicative of acid−acid spacing along all-trans polyethylene segments of the polymer chain. Only the regularly functionalized EAA copolymer with the lowest acid content is semicrystalline with evidence of orthorhombic polyethylene-like crystallization, while higher concentrations of acids groups lead to amorphous materials. Drawing the semicrystalline ADMET acid copolymer produces an anisotropic morphology, indicating that the acid−acid spacing is parallel to the polyethylene chain axis.

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Section: Resultsmentioning

confidence: 99%

“…First generation Grubbs' catalyst was a gift from Materia, Inc., and was used as received. Preparation of 2-(4-cyclooctenyl)acetic acid, 2-(4-pentenyl)-6-hepteneoic acid, 2-(7-octenyl)-9-deceneoic acid, and 2-(10-undecenyl)-12-trideceneoic acid was performed as previously reported.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Morphology of Well-Defined Poly(ethylene-co-acrylic acid) Copolymers

et al. 2007

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“…The newly formed metal alkylidenes react further with a second terminal olefin molecule producing growing polymers. The ADMET reaction is fully reversible at each step, and therefore constantly removing ethylene condensates pushes the reaction equilibrium toward the chain growth. − In contrast to randomly functionalized copolymers, these precise polymers exhibit remarkably uniform nanoscale morphologies that enable us to understand the morphological effect on mechanical properties or ion transport. ,,− In conjunction with experimental studies, both coarse-grained (CG) and all-atom (AA) molecular dynamics (MD) simulations have been used to investigate the morphologies and dynamics of these precise ionomers. ,,,− The CG and AA MD simulation results in these precise PE-based ionomers show excellent agreement with X-ray scattering data and further reveal various ion aggregate morphologies including compact-isolated, branched-stringy, and percolated morphologies as the PE-segment length decreases or the neutralization level increases. ,, Further MD studies show that percolated ionic aggregate morphologies exhibit higher conductivities in comparison with the discrete aggregates , and the ion diffusivity within the aggregates exhibits superionic transport that is decoupled from polymer segmental dynamics as evidenced by various CG and AA MD simulations. , Therefore, producing percolated ionic aggregates within single-ion conducting polymers is a promising route to decouple the ion transport from the polymer segmental dynamics and to increase ionic conductivity without compromising mechanical properties . Although the PE-based precise ionomers produce well-defined nanoscale morphologies and even percolated aggregates for efficient ion pathways, the ADMET synthesis currently imposes severe constraints on polymer quantities that impedes further experimental investigations.…”

Section: Introductionmentioning

confidence: 99%

Ionomers from Step-Growth Polymerization: Highly Ordered Ionic Aggregates and Ion Conduction

Hoang

Winey

2020

Macromolecules

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Precisely controlling the position of ionic groups along neutral polymer backbones in ionomers has led to novel nanoscale morphologies and promising properties, although the synthetic routes can be quite demanding. Here, we report a series of Li + -containing ionomers directly synthesized from step-growth polymerization of commercially available diol monomers (x = 6 or 12) and dianhydride monomers followed by neutralization with various amounts of lithium salts. The results are nearly precise linear polymers wherein nonpolar segments have precisely 6 or 12 methylene groups, as determined by the diol. The functional segment has two carboxylic acid pendant groups and 6−8 backbone atoms depending on the dianhydride addition. From X-ray scattering, these segmented ionomers exhibit well-defined nanostructures in contrast to the conventional random ionomers. The nearly precise nature of these segmented ionomers does not compromise the morphological ordering. The temperature-dependent ionic conductivities exhibit a systematic increase with Li + neutralization level, as expected in a single-ion conductor. Notably, the ionic conductivities in these amorphous ionomers at high neutralization levels (≥65%) exhibit Arrhenius behavior even at T > T g , suggesting that ion mobility is decoupled from polymer segmental motion and largely within the aggregates; this finding could be a promising design strategy for solid polymer electrolytes. The synthetic scheme reported here provides a readily accessible suite of nearly precise ionomers by which to build fundamental correlations between polymer microstructures, nanoscale ionic aggregate morphologies, and ionic conductivities that are currently lacking.

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“…Recently, a family of sequenced EP copolymers with exact chemical repeat units were synthesized through a metathesis polymerization/hydrogenation approach. , First, acyclic diene metathesis (ADMET) produces an unsaturated copolymer with absolute control over alkyl branch identity and frequency along the polymer backbone; − subsequently, exhaustive hydrogenation of this material yields sequenced ethylene−α-olefin copolymer analogues unattainable through standard chain copolymerization techniques. Approaching ethylene−α-olefin copolymer synthesis in this fashion has yielded ethylene−propylene (EP), ,, ethylene−1-butene, and ethylene−1-octene materials exhibiting pristine microstructures with exact ethylene sequence length between branches.…”

Section: Introductionmentioning

confidence: 99%

Sequenced Ethylene−Propylene Copolymers: Effects of Short Ethylene Run Lengths

2006

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Two sequenced ethylene-propylene (EP) copolymers possessing methyl groups every fifth (EP5) or seventh (EP7) carbon have been prepared using an olefin metathesis polycondensation/hydrogenation strategy, thus generating methyl branched polyolefins with short ethylene run lengths of 4 or 6 carbons, respectively. Precise spacing of methyl branches along both copolymer backbones imparts pristine microstructure and targeted comonomer ratios in the copolymer. Extensive NMR spectral data are presented detailing polymer microstructure, branching analysis, and end-group identification. Thermal analysis using differential scanning calorimetry revealed multiple low-temperature relaxations for EP7 and glass transition temperature of -63 °C for EP5, and FT-IR analysis suggests no crystallinity under ambient conditions. A new ADMET monomer synthesis is also reported for the development of highly functionalized polyolefins or sequenced ethylene copolymers.

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Bio-olefins via condensation metathesis chemistry

Cited by 10 publications

References 35 publications

Synthesis and Morphology of Well-Defined Poly(ethylene-co-acrylic acid) Copolymers

Synthesis and Morphology of Well-Defined Poly(ethylene-co-acrylic acid) Copolymers

Ionomers from Step-Growth Polymerization: Highly Ordered Ionic Aggregates and Ion Conduction

Sequenced Ethylene−Propylene Copolymers: Effects of Short Ethylene Run Lengths

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