Current Organic Chemistry, Volume 6, No. 2, 2002
Polymer
Chemistry
From Atom Transfer Radical Addition to Atom
Transfer Radical Polymerization
Pp.67-82
Krzysztof
Matyjaszewski
The Prediction of Reactivity in Radical
Polymerisation Pp.83-107
A.D.
Jenkins
Chemo-, Regio-, Stereo- and
Chrono-Selectivity Control in Polymerization and Organic Processes
by Catalytic Coordination
Aggregates:A"Topochemistry" in Solution? Pp.109-119
R.
Jérôme and Ph. Teyssié
Relation Between Reactivities of Vinyl
Monomers andTheir NMR Spectra
Pp.121-153
Koichi
Hatada, Tatsuki Kitayama, Takafumi Nishiura and Wataru Shibuya
Linking Chemistry and Anionic Polymerization Pp.155-176
N. Hadjichristidis, S. Pispas, H. Iatrou and M. Pitsikalis
New Aspects of Catalysis in Polycondensation Pp.177-208
E.
Marechal
In Vitro Polyester Synthesis via Enzymatic
Polymerization Pp.209-222
Shiro
Kobayashi and Hiroshi Uyama
[Back to top] From Atom Transfer Radical Addition to Atom
Transfer Radical Polymerization
Krzysztof Matyjaszewski
This review
provides a survey of Atom Transfer Radical Addition (ATRA) and Atom Transfer
Radical Polymerization (ATRP) with the special emphasis on the copper mediated
processes. Mechanistic features of these techniques are reviewed together with
the major components of ATRP and examples of materials prepared by ATRP.
[Back to top] The Prediction of Reactivity in Radical
Polymerisation
A.D. Jenkins
The essential reactions in radical polymerisation involve the addition of a radical to a molecule. In the propagation process, the radical is typically a polymer and the molecule is a monomer; in transfer, the molecule is a transfer agent and, in initiation, the radical is a species of low molar mass. It is now possible to predict the reactivity of both the radicals and the molecules by means of a revised form of the Patterns Scheme, and a review is presented here of the historical development of the state of understanding of reactivity in the various component steps in a polymerisation process propagated by radicals.
[Back to top] Chemo-, Regio-, Stereo- and
Chrono-Selectivity Control in Polymerization and Organic Processes by Catalytic
Coordination Aggregates:A"Topochemistry" in Solution?
R. Jérôme and Ph. Teyssié
Soluble
coordination aggregates are usually multinuclear-multiligand entities (MxLyXz)n
hold together by m-type of bonds, often said
electron-deficient. A number of results scattered in the last three decades
literature indicate that the size and shape of these aggregates, when used as
catalysts, are factors controlling reactions selectivity with unexpected
efficiency. This review aims at collecting and discussing a number of such
examples in polymer-organic chemistry, including anionic polymerization of
(meth)acrylates, ring-opening polymerization of lactones and oxiranes,
coordination polymerization of diolefins and lithiation of alkyl aromatics.
Under careful control of kinetic and thermodynamic conditions, those processes
may exhibit remarkable chemo-, regio-, stereo- and even chrono-selectivity,
provided a fine tailoring of the catalytic aggregate structural
characteristics. Moreover, some of the examples strongly suggest the occurrence
of a "topochemical" control in solution, a behaviour usually typical
of solid surfaces. Due to the huge potential variety of such aggregates,
extension of these ideas as a general and unifying concept is certainly
possible, particularly if more sophisticated physical methods are used for the
precise characterization of those entities 3D structure.
[Back to top] Relation Between Reactivities of Vinyl Monomers
andTheir NMR Spectra
Koichi
Hatada, Tatsuki Kitayama, Takafumi Nishiura and Wataru Shibuya
The 13C-NMR
chemical shifts of b-carbon (dCb) in the
vinyl group of various monomers, which depend on the p-electron density on the carbon, were
correlated with their reactivity parameters in polymerization reactions. The relations were studied
between the dCb and the
e-value of the monomer and direct evidences were obtained for the validity of
Q-e scheme. The meaning of Q-value was discussed in some detail from the
careful examination of the correlations between the Q-values of homologous
monomers and their 13C- or 1H-NMR chemical
shifts and coupling constants for the vinyl groups. The method to estimate the
monomer reactivity ratios for the copolymerizations of homologous monomers are
proposed. The relative reactivities of monomers which were represented by the
log(1/r1) were correlated with the dCb values in cationic copolymerizations of
styrene derivatives; the b-carbon
resonates at the higher field, the higher the reactivity is. The reverse was
the case in anionic polymerizations. The correlations for the cationic
polymerization of alkyl vinyl ethers and the coordinated anionic
polymerizations of a-olefines were rather
complex and the mechanisms of polymerizations were discussed from the results.
The 1H-NMR chemical shifts of vinyl groups of
monomers could also be correlated with the reactivities of monomers,
particularly among the homologous monomers. These results revealed that the NMR
chemical shift of monomer can be used as a measure of reactivity of monomer and
is an important tool for the examination of mechanism of polymerization.
[Back to top] Linking Chemistry and Anionic Polymerization
N. Hadjichristidis, S. Pispas, H. Iatrou and M.
Pitsikalis
This review
summarizes the most popular linking agents (chlorosilanes, chloro(bromo)
methylbenzenes, divinylbenzenes, diphenylethylene derivatives), which in
combination with anionic polymerization lead to a plethora of macromolecular
architectures i.e., symmetric and asymmetric star, a,w-branched,
exact comb and cyclic polymers, etc. Depending on the nature of their reaction
product with living macroanions, linking agents can be characterized either as
non-living (neutralization of active centers) or living (creation of a new
anionic active center). The chlorosilanes and chloro(bromo)methylbenzenes
belong to the first category, whereas divinylbenzenes and diphenylethylene
derivatives in the second. The most important examples of both categories will
be discussed in this review.
[Back to top] New Aspects of Catalysis in Polycondensation
E. Marechal
This article
concerns the catalysis of polycondensations and polyadditions; its scope is
limited to the use of metal derivatives and enzymes. Palladium, nickel,
ruthenium and copper derivatives are studied as catalysts of carbon-carbon
forming polycondensations when applied to polymeric systems and models; side
reactions are analyzed. Palladium-derivatives mainly concern Heck and Suzuki
polycondensations. The influence of the nature of the catalyst on reactivity is
also an important part of this article; it is not limited to carbon-carbon
forming reactions but also to other polycondensations such as polyesterifications.
Some examples concern systems activited by Ni(0), CsF and rhodium complexes as
activators. A general bibliography of enzyme-catalyzed polycondensations is
given; however only polyesterifications are studied, particularly aliphatic,
unsaturated and aromatic polyesters; side reactions and linear chains/cycles
equilibriums are particularly studied.
[Back to top] In Vitro Polyester Synthesis via Enzymatic
Polymerization
Shiro Kobayashi and Hiroshi Uyama
Recent topics on in vitro synthesis of polyesters by mainly lipase catalysis are reviewed. Lipase, an enzyme catalyzing an ester bond-cleavage reaction by water in living cells, induces the reverse reaction of hydrolysis, leading to polymer production by a bond-forming reaction. Polyester synthesis has been achieved from various monomer combinations, typically oxyacids or their esters, dicarboxylic acids or their derivatives/glycols, and lactones under mild reaction conditions. Lipase catalyzes ring-opening polymerization of lactones and their enzymatic polymerizability is quite specific in comparison with that by conventional chemical catalysts. Enzymatic synthesis of end-functional polyesters by facile procedures has been developed. By utilizing characteristic catalytic function of lipases, regio- and enantioselective polymerizations proceed to give functional polymers, many of which are difficult to be synthesized by conventional methodologies.