Polyalcoxyamines obtained from &bgr;-substituted nitroxides

Details Polyalcoxyamines obtained from &bgr;-substituted nitroxides Polyalcoxyamines obtained from &bgr;-substituted nitroxides

2002-03-15

2003-12-02

Truong, Duc (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Nitrogen-containing reactant

C528S425000, C528S398000, C525S333800

Reexamination Certificate

active

06657043

ABSTRACT:

The present invention relates to polyalkoxyamines obtained from &bgr;-substituted nitroxides, which may be used especially as free-radical polymerization initiators.
Recent developments in controlled free-radical polymerization have revealed the value of polyalkoxyamines as described in Accounts of Chemical Research, 1997, 30, pages 373-382.
These polyalkoxyamines, under the action of heat, in the presence of an olefin which may undergo free-radical polymerization, initiate the polymerization while at the same time allowing it to be controlled.
The mechanism for this control may be represented diagrammatically as below:
with M representing a polymerizable olefin and P representing the growing polymer chain.
The key to the control is associated with the constants K
deact
, k
act
and k
p
(T. Fukuda and A. Goto, Macromolécules 1999, 32, pages 618 to 623). If the ratio k
deact
/k
act
is too high, the polymerization is blocked, whereas when the ratio k
p
/k
deact
is too high, when the ratio k
deac
/k
act
is too low though, the polymerization is uncontrolled.
It has been found (P. Tordo et al., Polym. Prep. 1997, 38, pages 729 and 730; and C. J. Hawker et al., Polym. mater. Sci. Eng., 1999, 80, pages 90 and 91) that &bgr;-substituted alkoxyamines make it possible to initiate and control efficiently the polymerization of several types of monomers, whereas TEMPO-based alkoxyamines [such as (2′,2′,6′,6′-tetramethyl-1′-piperidyloxy-)methylbenzene mentioned in Macromolecules 1996, 29, pages 5245-5254] control only the polymerizations of styrene derivatives.
The Applicant has now found that, starting with polyoxyamines of the general formula (I):
in which n≧2,
A represents a polyfunctional core and R
L
represents a radical with a molar mass of greater than 15, A and R
L
will be defined more fully later, it can synthesize polymers and copolymers with well defined architecture.
Starting with a dialkoxyamine of formula. (I) in which n=2, it is possible to synthesize triblock copolymers, each block being derived from monomers as different as alkyl acrylates and/or styrene derivatives, with excellent control of the polymerization and the polydispersity and with very short polymerization reaction times.
Thus, for example, it is possible to polymerize successively 2 monomers M1 and M2:
By way of example, M1=alkyl acrylate and M2=styrene.
Starting from a trialkoxyamine, “star-shaped” polymers will be obtained.
One subject of the invention is thus polyalkoxyamines of general formula (I):
in which: n≧2,
A represents a divalent or polyvalent structure which may be chosen from the structures given below in a nonlimiting manner:
in which R
1
and R
2
, which may be identical or different, represent a linear or branched alkyl radical containing a number of carbon atoms ranging from 1 to 10, phenyl or thienyl radicals optionally substituted with a halogen atom such as F, Cl or Br, or a linear or branched alkyl radical containing a number of carbon atoms ranging from 1 to 4, or alternatively with nitro, alkoxy, aryloxy, carbonyl or carboxyl radicals; a benzyl radical, a cycloalkyl radical containing a number of carbon atoms ranging from 3 to 12, a radical comprising one or more unsaturations; B represents a linear or branched alkylene radical containing a number of carbon atoms ranging from 1 to 20; m is an integer ranging from 1 to 10;
in which R
3
and R
4
, which may be identical or different, represent aryl, pyridyl, furyl or thienyl radicals optionally substituted with a halogen atom such as F, Cl or Br, or with a linear or branched alkyl radical containing a number of carbon atoms ranging from 1 to 4, or alternatively with nitro, alkoxy, aryloxy, carbonyl or carboxyl radicals; D represents a linear or branched alkylene radical containing a number of carbon atoms ranging from 1 to 6, a phenylene radical or a cycloalkylene radical; p ranging from 0 to 10;
in which R
5
, R
6
and R
7
, which may be identical or different, have the same meanings as R
1
and R
2
of formula (II), q, r and s are integers ranging from 1 to 5;
in which R
8
has the same meaning as R
3
and R
4
of formula (III), t is an integer ranging from 1 to 4, u is ≧2 and ≦6;
in which R
9
has the same meaning as the radical R
8
of formula (V) and v is ≧2 and ≦6;
in which R
10
, R
11
and R
12
, which may be identical or different, represent a phenyl radical, optionally substituted with a halogen atom such as Cl or Br, or with a linear or branched alkyl radical containing a number of carbon atoms ranging from 1 to 10; W represents an oxygen, sulfur or selenium atom, and w is equal to zero or 1;
in which R
13
has the same meaning as R
1
of formula (II), and R
14
has the same meaning as R
3
or R
4
of formula (III);
in which R
15
and R
16
, which may be identical or different, represent a hydrogen atom, a linear or branched alkyl radical containing a number of carbon atoms ranging from 1 to 10, or an aryl radical, optionally substituted with a halogen atom or a hetero atom,
R
L
has a molar mass of greater than 15; the monovalent radical R
L
is said to be in a &bgr; position relative to the nitrogen atom, the remaining valencies on the carbon atom and on the nitrogen atom in formula (1) may be linked to various radicals such as a hydrogen atom, a hydrocarbon-based radical, for instance an alkyl, aryl or aralkyl radical containing from 1 to 10 carbon atoms, the carbon atom and the nitrogen atom in formula (1) may also be linked together via a divalent radical so as to form a ring; preferably, however, the remaining valencies on the carbon atom and on the nitrogen atom of formula (I) are linked to monovalent radicals; preferably, the radical R
L
has a molar mass of greater than 30, the radical R
L
may have, for example, a molar mass of between 40 and 450; by way of example, the radical R
L
may be a radical comprising a phosphoryl group, said radical R
L
preferably being represented by the formula:
in which R
17
and R
18
, which may be identical or different, may be chosen from alkyl, cycloalkyl, alkoxy, aryloxy, aryl, aralkyloxy, perfluoroalkyl and aralkyl radicals and may contain from 1 to 20 carbon atoms; R
17
and/or R
18
may also be a halogen atom, for instance a chlorine or bromine or fluorine or iodine atom; the radical R
L
may also comprise at least one aromatic ring such as the phenyl radical or naphthyl radical, said radical possibly being substituted, for example with an alkyl radical containing from 1 to 10 carbon atoms.
According to the present invention, the monovalent radicals linked to the carbon atom bearing the radical R
L
, which may be identical or different, may be a hydrogen atom, a linear or branched alkyl radical containing a number of carbon atoms ranging from 1 to 12, a phenyl radical, or an aralkyl radical containing, for example, from 1 to 10 carbon atoms. By way of illustration of such monovalent radicals, mention will be made of ethyl, butyl, tert-butyl and isopropyl radicals.
According to the present invention, the alkoxyamines of formula (I) in which n=2 and in which at least one of the remaining valencies on the carbon atom bearing R
L
is linked to a hydrogen atom, are most particularly preferred.
The two remaining valencies on the carbon atom may also be linked to a divalent radical so as to form a ring including the carbon atom bearing the radical R
L
, said ring possibly containing a number of carbon atoms ranging from 3 to 10 and possibly containing a hetero atom such as N, O or S.
The remaining valency on the nitrogen atom may also be linked to a group —C(CH
3
)
2
Z with Z=—COOalkyl, —COOH, —CH
3
, —CN, —CH
2
OH, —CH
2
OSi(CH
3
)
3
.
The polyalkoxyamines of formula (I) may be prepared according to methods known in the literature. The method most commonly used involves the coupling of a carbon-based radical with a nitroxide radical. The coupling may be performed using a halo derivative A(X)
n
in the presence of an organometallic system, for instance CuX/ligand (X=Cl or

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