Block copolymers and preparation thereof

Details Block copolymers and preparation thereof Block copolymers and preparation thereof

1999-11-18

2001-10-09

Moore, Margaret G. (Department: 1712)

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

Synthetic resins

From silicon reactant having at least one...

C528S031000, C528S025000, C528S026000, C556S445000

Reexamination Certificate

active

06300452

ABSTRACT:

The invention relates to new polysiloxane based block copolymers and to the preparation thereof.
Silicones, or polyorganosiloxanes, represent a broad spectrum of synthetic silicon based polymers of formula (R′R″SiO)
n
, where R′ and R″ represent alkyl groups, usually methyl, ethyl, propyl, or phenyl groups. In the literature, various methods for the preparation of siloxanes are known, for example, Walter Noll, Chemistry and Technology of Silicones, Academic Press, Orlando, 1968, 190-245, and John C Saam, in John M Zeigler and F W Gordon Fearon, ed., Silicon-Based Polymer Science, A Comprehensive Resource, Advances in Chemistry Series, American Chemical Society, Washington, D.C., 1990, 71-90.
Polysiloxanes, particularly poly(dimethyl siloxanes), are used extensively as such in technical applications.
Copolymers of polysiloxane and poly(alkylene oxide) are known. Known copolymers of this type are useful as emulsifiers and stabilizers. The preparation of such copolymers by hydrosilylation has been reported in the literature (Polysiloxane Copolymers/Anionic Polymerization, Springer-Verlag Berlin Heidelberg 1988, pp. 46-47; H W Haesslin & H F Eicke, Makromol Chem 185, 2625-2645, (1984); H W Haesslin, Makromol Chem 186, 357-366 (1985), and M Galin & A Mathis, Macromolecules 1981, 14, 677-683. The preparation of block copolymers AB, ABA and (AB)n, where A represents poly(ethylene oxide) (PEO) and B is poly(dimethyl siloxane), by hydrosilylation of mono- or diallyl-terminated PEO-oligomers and Si-H-terminated PDMS oligomers with hexachloroplatinic acid as a catalyst, was reported by Haesslin. The molecular weight of PDMS-oligomer was 1000 g/mol and the molecular weight of ternary block copolymers (ABA) was between 1550 g/mol and 1800 g/mol.
Haesslin & Eike describe ternary block copolymers PEO-PDMS-PEO, where the molecular weight of PDMS is 1000 g/mol and the molecular weight of PEO-block is between 100 g/mol and 750 g/mol.
Galin & Mathis describe the preparation of ternary PDMS-PEO-PDMS block copolymers. The molecular weight of PDMS was between 1000 g/mol and 4700 g/mol and the molecular weight of PEO was between 6200 g/mol and 10,700 g/mol.
European Patent Publication EP 545,002 describes grafted polysiloxanes prepared by hydrosilylation of polysiloxanes with polyalkylene oxides of formula CH
2
═CHCH
2
O(CHRCH
2
O)
m
CH
2
CH═CH
2
. In these polymers, the polyether moieties are linked to the alkyl substituent of silicon instead of being linked to the stem.
OBJECT OF THE INVENTION
This invention is directed to providing new alkylene terminated polysiloxane-poly(alkylene oxide)-based block copolymers of controlled polarity for the preparation of elastomers, either as such or as a component in the elastomeric structure or as a component in the mixture of an elastomeric composition. The new copolymers must satisfy the following criteria:
1. In the preparation of elastomers, the copolymer should be capable of crosslinking, for example by hydrosilylation. Thus the copolymer should include an alkenyl-terminated polyalkylene oxide block at both of its ends to allow crosslinking by hydrosilylation. The copolymers described in Galin & Mathis do not satisfy this condition.
2. The ternary block copolymers described in Haesslin and Haesslin & Eicke are rather small. The polymers described in these publications do not either end up in alkylene terminated polyalkylene oxide blocks. Moreover, it is of importance for the present invention that polysiloxane and polyalkylene oxide blocks are linked to each other by silicon-carbon bonds.
3. The copolymer can exist in one phase. If the molecular weight of the polyalkylene block is too high in relation to the molecular weight of the polysiloxane unit, phase separation will occur.
SUMMARY OF THE INVENTION
Thus, the invention is directed to a new polysiloxane-based block copolymer of formula
T(AB)
x
(AT)  (I)
wherein
A=—(SiR′R″O)
n
SiR′R″—, wherein R′ and R″ are the same or different and represent a lower alkyl group or a phenyl group, where said alkyl or phenyl group may be substituted or unsubstituted;
B is polyalkylene oxide of formula
wherein
R is hydrogen, lower alkyl, or phenyl,
R
1
is hydrogen or lower alkyl,
y is 2-6,
m is 1-30,
n is 1-3000, and
x is 0-100.
The term “lower alkyl” represents C
1
-C
6
alkyl groups.
The substituents R′ and R″ of formula (I) are preferably both methyl groups.
The number y is preferably 2.
R is preferably hydrogen, methyl, or phenyl.
According to a preferred embodiment, the B in the formula (I) is
The invention is also directed to a method for the preparation of new compounds of formula (I). The method is characterized in that the polysiloxane of formula (II)
wherein R′ and R″ are the same, or different, lower alkyl or phenyl groups, where said alkyl or phenyl group may be substituted or unsubstituted, is reacted, in the presence of a catalyst, with a polyalkylene oxide of formula (IIIa) or (IIIb)
where R, R
1
, n, and m are the same as above.
Preferred compounds of the group IIIa include vinyl or allyl terminated polyethylene glycol. A preferred compound of the group IIIb is, for example, methacryl terminated polyethylene glycol.
A preferred catalyst is a noble metal catalyst, most generally a platinum complex in alcohol, xylene, divinyl siloxane, or cyclic divinyl siloxane. An especially preferred catalyst is Pt(0)divinyl tetramethyl siloxane complex.
In order to prepare the &agr;,&ohgr;-alkylene terminated PEO(PDMS-PEO)
n
copolymer, the compound of formula (IIIa) or (IIIb) must be used in excess in relation to the compound of formula (II). Preferably, the molar ratio
compound of formula (IIIa) or (IIIb)
compound of formula (II)
is between 1.05 and 2.0.


REFERENCES:
patent: 3836560 (1974-09-01), Prokai et al.
patent: 6187891 (2001-02-01), Rautschek et al.

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