Polymer Synthesis and Organotransition Metal Chemistry

Grubbs, Robert H.; Tumas, William

doi:10.1126/science.2645643

Cited by 479 publications

(276 citation statements)

References 86 publications

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“…90 Although early-transition-metal catalysts such as Ziegler-Natta catalysts and early-transitionmetal metallocene catalysts remain the workhorses of the polyolefin industry, significant advances have been made recently in late-transition-metal polymerization catalysts. [43][44][45][46][47][48][49] Two attributes of late-transition-metal polymerization catalysts distinguish them from early-transitionScheme 9.…”

Section: Discussionmentioning

confidence: 99%

Z. Guan, Control of polymer topology through late‐transition‐metal catalysis, J Polym Sci Part A: Polym Chem (2003), 41(22), 3680–3692

Guan

2003

J. Polym. Sci. A Polym. Chem.

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ABSTRACT:In this article, recent examples are reviewed of late-transition-metal catalysis applied to polymer topology control. By the judicious selection or design of latetransition-metal catalysts, polymers with a broad range of topologies, including linear, short-chain-branched, hyperbranched, dendritic, and cyclic topologies, have been successfully synthesized. A distinctive advantage of the catalyst approach is that polymers with complex topologies can be prepared in one pot from simple commercial monomers. A fundamental difference of the catalyst approach with respect to other approaches is that the polymer topology is controlled by the catalysts instead of the monomer structure. In our own laboratory, we have successfully used two strategies to control the polymer topology with late-transition-metal catalysts. In the first strategy, hyperbranched polymers are prepared by the direct free-radical polymerization of divinyl monomers through control of the competition between propagation and chain transfer with a cobalt chain-transfer catalyst. In the second strategy, polyethylene topology is successfully controlled by the regulation of the competition between propagation and chain walking with the Brookhart Pd II -␣-bisimine catalyst.

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Section: Discussionmentioning

confidence: 99%

Z. Guan, Control of polymer topology through late‐transition‐metal catalysis, J Polym Sci Part A: Polym Chem (2003), 41(22), 3680–3692

Guan

2003

J. Polym. Sci. A Polym. Chem.

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“…33 In contrast, the resonances due to the aromatic protons of the mesogenic biphenyl group are relatively sharp. Poly (1)(2)(3)(4)(5) containing at least 20 repeat units also displays an enantiotropic nematic mesophase. However, the nematic mesophase of the two lower molecular weight oligomers is monotropic and observable only on cooling, while a melting point is observed on heating, in addition to the glass transition.…”

Section: Polymerization Of 1-nmentioning

confidence: 99%

Synthesis of Side Chain Liquid Crystal Polymers by Living Ring Opening Metathesis Polymerization. 1. Influence of Molecular Weight, Polydispersity, and Flexible Spacer Length (n=2-8) on the Thermotropic behavior of the Resulting Polymers

Komiya¹,

Pugh²,

Schrock³

1992

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Awte'a;e I h,,ir Decr fe~orse. ABSTRACT IwI2001 ~Olds) The living ring opening metathesis polymerization of 5-carbo(n-[(4'-methoxy-4-biphenylyl)oxy]alkyl)bicyclo[2.2.1]hept-2-ene (1-n, n=2-8) by Mo(CH-t-Bu)(NAr) (0-t-Bu) 2 (Ar=2,6-C 6 H 3 -t-Pr 2 ) is described. Polymers with degrees of polymerization from 5 to 100 and narrow molecular weight distributions (Mw/Mnz1.05-1.24) were obtained in high yield. All polymers exhibit an enantiotropic nematic mesophase. Glass transition and isotropization temperatures increase with increasing molecular weight and become independent at approximately 30-50 repeat units. The change in enthalpy of isotropization is relatively independent of molecular weight. Using polymer blends, it was shown that polydispersity has no effect on either the transition temperatures or the temperature range of isotropization. Isotropization alternates in an odd-even manner up to spacer lengths of n=6, and then levels off. Reproduction in whole or in part is permitted for any purpose of the United States Government.This document has been approved for public release and sale; its distribution is unlimited. (Ar = 2,6-C 6 H3-i-Pr2) is described. Polymers with degrees of polymerization from 5 to 100 and narrow molecular weight distributions (Mw/Mn = 1.05-1.24) were obtained in high yield. All polymers exhibit an enantiotropic nematic mesophase. Glass transition and isotropization temperatures increase with increasing molecular weight and become independent at approximately 30-50 repeat units. The change in enthalpy of isotropization is relatively independent of molecular weight. Using polymer blends, it was shown that polydispersity has no effect on either the transition temperatures or the temperature range of isotropization. Isotropization alternates in an odd-even manner up to spacer lengths of n = 6, and then levels off.

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“…log(D) = -0.551og(MW) + log(C) (6) proportionality constant in eq 5. A log-log plot of the diffusion coefficient and molecular weight should yield a line with slope -0.55.…”

Section: Homopolymers and Block Copolymers That Contain Phenothiazinementioning

confidence: 99%

“…Cationic 4 or group transfer methods 5 might be more suitable than anionic methods, but again some desirable functionalities may not be tolerated. Living ring opening metathesis polymerization (ROMP) of norbornenes and norbornadienes 6 . 7 appears more promising since functionalized derivatives are relatively easy to synthesize in wide variety by Diels-Alder reactions and since well-characterized ROMP catalysts have been developed that will tolerate many functionalities.…”

Section: Introductionmentioning

confidence: 99%

Well-defined redox-active polymers and block copolymers prepared by living ring-opening metathesis polymerization

Albagli¹,

Bazan²,

Wrighton³

et al. 1992

J. Am. Chem. Soc.

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REPORT DOCUMENTATION PAGEReproduction in whole or in part is permitted for any purpose of the United States Government.This document has been approved for public release and sale; its distribution is unlimited. it is not oxidized at potentials up to 1.0 V. An analogous initiator containing a ferrocenylmethylidene ligand (ib) can be synthesized by treating la with vinylferrocene. Redoxactive derivatives of norbornene, containing ferrocene (2) or phenothiazine (3) were prepared and polymerized by la or lb to give living block copolymers containing the ring-opened norbornene derivatives. The living polymer was cleaved from the metal in a Wittig-like reaction with pivaldehyde, trimethylsilylbenzaldehyde, or octamethylferrocenecarboxaldehyde. Polydispersities for the longer block copolymers containing up to -80 monomer units was found to be as low as 1.05 by GPC. In one case the polydispersity of a homopolymer made from the ferrocenecontaining monomer was determined by FD-Mass Spectroscopy to be 1.06. DSC studies suggest that microphase formation occurs in the block copolymers, even in the case of relatively low 4 molecular weight materials. Solution voltammetric studies of homo and block copolymers showed that the redox centers were electrochemically independent, and that all centers exchanged electrons with the electrode. Neutral polymers became insoluble upon oxidation to a polycation, yielding an adsorbed polymer layer on the electrode that could then be cathodically stripped. This oxidative deposition process depended on the electrolyte and the polymer molecular weight, but also could be controlled by the size of a non-electroactive block ir the block copolymers. Problems resulting from precipitation of the redox polymers could be circumvented by employing normal pulse voltammetry. Polymers containing redox-active centers in both end groups, as well as in the polymer chain itself, have been prepared and shown in electrochemical studies to undergo the expected initiation, propagation, and termination reactions.

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Polymer Synthesis and Organotransition Metal Chemistry

Cited by 479 publications

References 86 publications

Z. Guan, Control of polymer topology through late‐transition‐metal catalysis, J Polym Sci Part A: Polym Chem (2003), 41(22), 3680–3692

Z. Guan, Control of polymer topology through late‐transition‐metal catalysis, J Polym Sci Part A: Polym Chem (2003), 41(22), 3680–3692

Synthesis of Side Chain Liquid Crystal Polymers by Living Ring Opening Metathesis Polymerization. 1. Influence of Molecular Weight, Polydispersity, and Flexible Spacer Length (n=2-8) on the Thermotropic behavior of the Resulting Polymers

Well-defined redox-active polymers and block copolymers prepared by living ring-opening metathesis polymerization

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