Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-06-07
2004-10-26
Zalukaeva, Tatyana (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S213000, C526S214000, C526S222000, C526S307700, C526S318000, C526S318300, C526S319000
Reexamination Certificate
active
06809164
ABSTRACT:
The present invention relates to a novel method for “controlled” or “live” radical polymerisation leading to polymers, especially block copolymers.
Block polymers are normally prepared by ionic polymerisation. That type of polymerisation has the disadvantage of permitting the polymerisation of only specific types of non-polar monomer, especially styrene and butadiene, and of requiring a particularly pure reaction medium and temperatures often lower than the ambient temperature in order to minimise parasitic reactions, thus giving rise to major implementation constraints.
Radical polymerisation has the advantage of being easy to implement without respecting excessive conditions of purity and at temperatures equal to or higher than the ambient temperature. However, until recently, there was no radical polymerisation method enabling block polymers to be obtained.
Since then, a novel radical polymerisation method has been developed: the method involved is so-called “controlled” or “live” radical polymerisation. Radical polymerisation proceeds by growth by propagation of macro-radicals. Those macro-radicals, which have a very short life, recombine irreversibly by coupling or dismutation. When polymerisation takes place in the presence of several comonomers, the variation in the composition of the mixture is extremely slight considering the life of the macro-radical, so that the chains have a random chain formation from the monomer units and not a block chain formation.
Recently, techniques for controlled radical polymerisation have been developed in which the ends of polymer chains can be reactivated into the form of a radical by homolytic bond cleavage (for example C—O, or C-Halogen).
Controlled radical polymerisation therefore has the following distinctive aspects:
1. The number of chains is fixed throughout the duration of the reaction,
2. The chains all grow at the same rate, which translates into:
a linear increase in the molar masses with the conversion,
a narrow mass distribution,
3. The average molar mass is controlled by the molar ratio of the monomer to the chain precursor,
4. The possibility of preparing block copolymers.
The controlled character is all the more marked because the rate of reactivation of the chains into radical form is very high considering the rate of growth of the chains (propagation). There are cases in which this is not always true (i.e. the rate of reactivation of the chains into radical form is higher than or equal to the rate of propagation) and conditions 1 and 2 are not observed. Nevertheless, it is still possible to prepare block copolymers.
WO 98/58974 describes a live radical polymerisation method enabling block copolymers to be obtained by a method without UV irradiation, by using xanthate compounds, the properties of which are:
That radical polymerisation enables block polymers to be prepared in the absence of a UV source, using any type of monomer. The polymers obtained do not contain metallic impurities which would militate against their use. They are functionalised at the end of the chain and have a low index of polydispersion of less than 2 and even less than 1.5.
One object of the present invention is to propose a novel polymerisation method using novel precursors of the xanthate type.
Another object is to propose a polymerisation method using precursors of the xanthate type, in the course of which the number-average molar masses M
n
of the polymers obtained are well controlled, that is to say, close to the theoretical values M
n th
, this being throughout the polymerisation reaction.
Another object is to propose a polymerisation method using precursors of the xanthate type for the synthesis of block copolymers and homopolymers having a polydispersion index (M
w
/M
n
) which is low, that is to say, close to 1.
The work of the inventors has resulted in a method for radical polymerisation in which block copolymers or homopolymers can be prepared in accordance with a process having remarkable and substantially greater control than the methods known hitherto.
This method uses xanthates of a particular type which themselves constitute novel molecules.
The invention therefore relates to a method for the preparation of polymers, characterised in that there are brought into contact with one another:
at least one ethylenically unsaturated monomer,
at least one source of free radicals, and
at least one compound (I) of the general formula (IA), (IB) or (IC):
in which:
R
2
and R
2
′, which may be identical or different, represent a group of the formula:
in which:
R
3
and R
4
, which may be identical or different, are selected from a halogen group, —NO
2
, —SO
3
R, —NCO, CN, R, —OR, —SR, —NR
2
, —COOR, O
2
CR, —CONR
2
, —NCOR
2
, C
n
F
2n+1
with n being 1 to 20, preferably 1,
in which the groups R, which may be identical or different, represent H or a group selected from:
alkyl,
alkenyl,
alkynyl,
cycloalkenyl,
cycloalkynyl,
aryl, optionally fused to an aromatic or non-aromatic heterocycle,
alkaryl,
aralkyl,
heteroaryl,
which are optionally substituted by one or more identical or different groups selected from halogen, ═O, ═S, OH, alkoxy, SH, thioalkoxy, NH
2
, mono- or di-alkylamino, CN, COOH, ester, amide, C
n
F
2n+1
(n being 1 to 20), and/or optionally interrupted by one or more atoms selected from O, S, N, P,
or a heterocyclic group optionally substituted by one or more groups such as defined above,
or R
3
and R
4
, together with the carbon atom to which they are attached, form a group ═O or ═S or a hydrocarbon ring or a heterocycle,
R
5
and R
6
, which may be identical or different, represent a group such as defined above for R,
or R
5
and R
6
together form a C
2
-C
4
hydrocarbon chain optionally interrupted by a hetero atom selected from O, S, N and P,
R
1
and R
1
′, which may be identical or different, represent a group such as defined above for R
3
or R
4
,
p represents an integer from 2 to 10.
According to the invention, the term “alkyl” denotes a linear or branched hydrocarbon radical containing from 1 to 20 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, isobutyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl or icosyl.
“Alkenyl” means a linear or branched hydrocarbon chain of from 2 to 20 carbon atoms comprising one or more double bonds. Examples of particularly preferred alkenyl groups are alkenyl groups carrying a single double bond, such as —CH
2
—CH
2
—CH═C(CH
3
)
2
, vinyl or allyl.
“Alkynyl” means a linear or branched hydrocarbon chain of from 2 to 20 carbon atoms comprising one or more triple bonds. Examples of particularly preferred alkynyl groups are alkynyl groups carrying a single triple bond, such as —CH
2
—CH
2
—C≡CH.
The term “cycloalkyl” denotes saturated hydrocarbon groups which may be monocyclic or polycyclic and which comprise from 3 to 12 carbon atoms, preferably from 3 to 8 carbon atoms. Monocyclic cycloalkyl groups, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl and cyclododecyl are more particularly preferred.
According to the invention, “cycloalkenyl” means a group derived from a cycloalkyl group as defined above, having one or more double bonds, preferably one double bond.
According to the invention, “cycloalkynyl” means a group derived from a cycloalkyl group as defined above, having one or more triple bonds, preferably one triple bond.
The term “aryl” represents an aromatic monocyclic or bicyclic hydrocarbon group comprising from 6 to 10 carbon atoms, such as phenyl or naphthyl.
“Alkaryl” means an aryl group as defined above, substituted by an alkyl group.
“Aralkyl” means an alkyl group as defined above, substituted by an aryl group.
“Alkoxy” means an O-alkyl group generally having from 1 to 20 carbon atoms, especially methoxy, ethoxy, propoxy and butoxy.
“Halogen” means a fluorine, chlorine, bromine or iodine atom.
When the alkyl group is optionally hal
Charmot Dominique
Destarac Mathias
Gauthier-Gillaizeau Isabelle
Zard Samir
Burns Doane Swecker & Mathis L.L.P.
Rhodia Chimie
Zalukaeva Tatyana
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