Phenylacetylene (PA) was polymerised by employing (arene)Mo(CO)3/chloranil mixture as the catalyst. Preliminary kinetic studies of the polymerisation showed the presence of an induction period before commencement of polymerisation, attributable to the activation of the (arene)Mo(CO)3 by chloranil through charge-transfer. It was shown that better control over polymer molecular weight and polydispersity was achieved with prior mixing of the metal carbonyl complex with the acceptor and by delaying the addition of the monomer. Polymerisation by metathesis route was ascertained by copolymerisation, sequential addition of monomers and also by end-capping reactions. © 2007 Elsevier Ltd. All rights reserved.

N. S. Santhosh

Govindarajan Sundararajan

Carbonylation

Catalyst activity

Charge transfer

Copolymerization

Electrons

Monomers

Polydispersity

END CAPPING REACTIONS

METAL CARBONYL COMPLEX

METATHESIS POLYMERISATION

METATHESIS ROUTE

Acetylene

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

European Polymer Journal

Irradiation of W(CO)6 in CCl4 generates an 'active species' which has the ability to polymerise alkynes and strained cyclic olefins via a metathesis pathway. The precipitate formed after 2 h of irradiation is active for polymerisation. The involvement of metal carbene in the polymerisation of norbornene was proved by in situ 1H-NMR study and by the end-capping reaction. IR studies showed the presence of carbonyl and chlorine ligands around the tungsten centre. © 2000 Elsevier Science S.A.

Journal of Organometallic Chemistry

Studies on the nature of active species in W(CO)6/CCl4/hν system as applied to metathesis polymerisation reactions

Chloranil acceptor induces metathesis polymerization and block copolymerization of phenylacetylene by (arene)M(CO)3 (arene = toluene, o-xylene, or mesitylene, M = Mo or W) complexes at ambient conditions. The mechanism of catalyst activation is one of thermal electron transfer, as suggested by spectral studies.

Organometallics

Metathesis polymerization of phenylacetylene by arene metal tricarbonyl complexes promoted by chloranil acceptor

Metathesis polymerisation can be effected with many catalysts under a variety of conditions. The system described here, viz., W(CO)6/CBr4/hv, induces polymerisation by in situ generation of the active species and has not been reported in the literature so far. In this paper, optimisation studies of this system, yields obtained with various monomers and characterisation of the active species are discussed. Variation of different parameters such as the ratio of W(CO)6:CBr4, the time of photolysis and the effect of solvents as well as that of the metal carbonyls have been studied. In addition, copolymers of phenylacetylene and norbomene have been synthesised. We have also attempted to characterise the active species responsible for the polymerisation by reaction with acetophenone.

Journal of Molecular Catalysis A: Chemical

W(CO)6/CBr4/hv - A new system for metathesis polymerisation

Substituted phenylacetylenes are polymerized using in situ generated (arene) M(CO)3 complexes as catalysts. The catalytic activity of the complexes is discussed with reference to the metals and arene ligands. A ladder polymer of phenylacetylene formed via cycloaddition mechanism as a possible precursor to linear polyphenylacetylenes, in bulk polymerization conditions, has been isolated and characterized. Some of the properties of the polymers are also described. © 1995.

Journal of Molecular Catalysis. A, Chemical

Metathetical polymerization of substituted phenylacetylenes using in situ generated (arene)M(CO)3 complexes (arene = toluene, o-xylene or mesitylene, M Cr, Mo or W) as catalysts

Conjugated polymers with sidegroups such as methyl, trimethylsilyl, p-methoxy phenyl, o-methoxy phenyl, and hexyl groups on a polyphenylacetylene chain are studied in an attempt to understand the contribution of factors such as the backbone, conformation of the chain, sidegroups and polymerization catalyst on the optical nonlinearities. The results of degenerate four-wave mixing experiments at 532 nm with nanosecond pulses indicate that the substitution of an electron-donating group away from the backbone can enhance the third-order susceptibility. Some of the polymers show optical limiting action at this wavelength. The thermal contribution to the measured susceptibility is also determined. © 1993 Chapman & Hall.

Journal	European Polymer Journal
ISSN	00143057
Open Access	No