Mechanistic Investigations on the Formation of Supramolecular Cylindrical Shaped Oligomers and Polymers by Living Ring Opening Metathesis Polymerization of a 7-Oxanorbornene Monomer Substituted with Two Tapered Monodendrons

Percéc, Virgil; Schlueter, D.

doi:10.1021/ma970157k

Cited by 132 publications

(84 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Metathesis polymerizations have been used to synthesize sidechain liquid-crystalline polymers using molybdenum 34 or ruthenium initiators 35,36 . Other very important materials accessible by ROMP are monolithic supports, reported by Buchmeiser and co-workers, which were used for the chromatography of biological samples, polymers and DNA fragments 37,38 .…”

mentioning

confidence: 99%

Catalytic living ring-opening metathesis polymerization

Nagarkar

Kilbinger

2015

Nature Chem

View full text Add to dashboard Cite

In living ring-opening metathesis polymerization (ROMP), a transition-metal-carbene complex polymerizes ring-strained olefins with very good control of the molecular weight of the resulting polymers. Because one molecule of the initiator is required for each polymer chain, however, this type of polymerization is expensive for widespread use. We have now designed a chain-transfer agent (CTA) capable of reducing the required amount of metal complex while still maintaining full control over the living polymerization process. This new method introduces a degenerative transfer process to ROMP. We demonstrate that substituted cyclohexene rings are good CTAs, and thereby preserve the 'living' character of the polymerization using catalytic quantities of the metal complex. The resulting polymers show characteristics of a living polymerization, namely narrow molecular-weight distribution, controlled molecular weights and block copolymer formation. This new technique provides access to well-defined polymers for industrial, biomedical and academic use at a fraction of the current costs and significantly reduced levels of residual ruthenium catalyst. In olefin metathesis reactions, olefinic bonds are rearranged with the help of a transition-metal catalyst 1,2 . In the early days following the discovery of this reaction, ill-defined catalysts 3 were used to carry out this transformation. After Herisson and Chauvin 4 had proposed a reaction mechanism, the olefin metathesis reaction was better understood and soon gained much popularity. Typical catalysts used for olefin metathesis reactions include those based on ruthenium (developed mainly by the Grubbs group 5 ), tungsten and molybdenum (developed mainly by the Schrock group 6 ). Owing to the low oxophilicity of ruthenium compared to those of molybdenum and tungsten, the ruthenium metathesis catalysts (commonly known as Grubbs' catalysts) are more tolerant towards many polar functional groups and residual impurities, as well as to water 7 . Therefore, these catalysts are the catalysts of choice in highly functional organic chemistry transformations as well as for the majority of metathesis polymerizations carried out today. Catalysts G1 (first generation) and G3 (third generation) are the most widely used ruthenium initiators for ring-opening metathesis polymerization (ROMP). In comparison to the G1 initiator, the third-generation catalyst G3 exhibits very fast initiation and propagation rates, and thereby gives polymers with very narrow dispersities and an excellent control over their molecular weights. Owing to its superior stability as well as the favourable polymerization kinetics, the third-generation Grubbs' catalyst G3 was used for this work. ROMP is a polymerization technique that uses the metathesis of cyclic olefins to synthesize linear polymers. Depending on the structure of the monomer, such polymerizations can be controlled perfectly to give polymers with a narrow molecular weight distribution and a controlled average molecular weight. Ring-strained monomers, li...

show abstract

mentioning

confidence: 99%

Catalytic living ring-opening metathesis polymerization

Nagarkar

Kilbinger

2015

Nature Chem

View full text Add to dashboard Cite

show abstract

“…[32,33] For this, new triazine triamides 8 e and 8 f with terminal olefinic groups were designed and prepared (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

An Enantiomeric Nanoscale Architecture Obtained from a Pseudoenantiomeric Aggregate: Covalent Fixation of Helical Chirality Formed in Self‐Assembled Discotic Triazine Triamides by Chiral Amplification

Ishi‐i

Kuwahara

Takata

et al. 2006

Chemistry A European J

View full text Add to dashboard Cite

Covalent fixation of a chiral helical structure which is created in a self-assembling system by a chiral-amplification method based on the sergeants/soldiers principle is reported. Disk-shaped triazine triamides self-assembled to form columnar-type helical aggregates through pi-stacking interactions among the central triphenyltriazine moieties, hydrogen-bonding interactions among the amide groups, and van der Waals interactions among the alkyl groups in nonpolar solvents such as hexane, octane, toluene, and p-xylene. When the achiral triazine triamide soldier component is mixed with a tiny amount of the chiral triazine triamide sergeant component, control of the intrinsic supramolecular helicity of the self-assembled soldier component by the sergeant component leads to chiral amplification and formation of a pseudoenantiomeric aggregate with only one handedness of the helix. The helicity can be preserved by ring-closing olefin metathesis polymerization mediated by Grubbs catalyst when an achiral component with terminal olefinic groups forms the pseudoenantiomeric aggregate in the presence of a tiny amount of the chiral component without olefinic groups. After polymerization and removal of the chiral component, the polymeric architecture obtained from the achiral soldier component is optically active and thus can be regarded as an enantiomeric object in which the chiral information transferred from the chiral sergeant component is preserved. The nanoscale chiral structure is fixed perfectly, as indicated by CD spectroscopic evidence obtained in a polar THF medium at high temperature and low concentration. AFM and TEM observations show a nanoscale fibrous structure with a diameter of 2-4 nm, which corresponds to the molecular size of the triazine triamide monomer.

show abstract

“…[23] However, advances occurred to achieve the homopolymerization of these dendrons by several research groups. [24][25][26][27][28][29][30] The main requirement to undergo homopolymerization is to sustain high monomer concentration during the polymerization.…”

Section: Homopolymerizationmentioning

confidence: 99%

“…Molarity of the monomer in solution is around 1-2 M limits. Reasons of this homo polymerization could be a preorganization of dendrons prior to polymerization, so that the polymerizable units were kept at short distance [23] or dense packing of dendrons in bulk leading to anchoring of bulky dendrons to the backbone. [29] The first-generation dendron ACTES, bearing an acrylate group, radically homopolymerized in dioxane with benzoyl peroxide as radical initiator.…”

Section: Homopolymerizationmentioning

confidence: 99%

Synthesis and characterization of linear dendritic homo and copolymers acrylated behera amine

Esen

2015

Designed Monomers and Polymers

View full text Add to dashboard Cite

A co-polymerizable dendron of first generation synthesized from behera amine was homopolymerized and copolymerized with commercial monomers such as styrene, methyl methacrylate, and N-vinyl pyrrolidone. Characterization of the co-polymers was performed and it was found with the help of FT-IR and proton and carbon NMR that copolymerizable dendron, ACTES (ACrylated TriESter, first-generation dendron of acrylated behera amine) was incorporated in the co-polymer chains. Besides, the reactivity ratio pairs of the ACTES monomer with both styrene and n-vinyl pyrrolidone were determined. The reactivity ratio pair for ACTES and MMA could not be determined by neither gravimetrically nor with NMR. After experiments and calculations, the reactivity ratio pair for styrene and ACTES was found to be r st = 0.27 and r ac = 0.44 and for NVP and ACTES r nvp = 0.36 and r ac = 1.01. By utilization of the reactivity ratio of ACTES, "Q" and "e" values were determined in order to be able to draw some conclusions about the reactivity behavior during copolymerizations. "Q" = 1.152 and "e" = 0.66 were found with respect to styrene as reference. These values indicates the steric effect of ACTES was more dominant in copolymerizations.

show abstract

Mechanistic Investigations on the Formation of Supramolecular Cylindrical Shaped Oligomers and Polymers by Living Ring Opening Metathesis Polymerization of a 7-Oxanorbornene Monomer Substituted with Two Tapered Monodendrons

Cited by 132 publications

References 39 publications

Catalytic living ring-opening metathesis polymerization

Catalytic living ring-opening metathesis polymerization

An Enantiomeric Nanoscale Architecture Obtained from a Pseudoenantiomeric Aggregate: Covalent Fixation of Helical Chirality Formed in Self‐Assembled Discotic Triazine Triamides by Chiral Amplification

Synthesis and characterization of linear dendritic homo and copolymers acrylated behera amine

Contact Info

Product

Resources

About