Organic compounds -- part of the class 532-570 series – Organic compounds – Silicon containing
Reexamination Certificate
2000-07-06
2001-09-04
Shaver, Paul F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Silicon containing
C556S450000, C556S453000, C556S459000, C556S460000, C556S461000, C528S012000, C528S014000
Reexamination Certificate
active
06284906
ABSTRACT:
This invention concerns new cyclotrisiloxanes, new hyperbranched or linear siloxane polymers, and their preparation.
BACKGROUND OF THE INVENTION
The publications and other materials used herein to illuminate the background of the invention, and in particular, cases to provide additional details respecting the practice, are incorporated by reference.
Organosilicon dendritic and hyperbranched polymers are well known. The dendrirner core is usually prepared from tetraallyl- or -vinylsilane, which is then derivatized by hydrosilylation reaction (1, 2). On the other hand, hyperbranched polycarbosilanes are commonly prepared from vinyltris(dimethylsiloxy)silane via hydrosilylation reactions. Typically, 8-10 mol-% starting material cyclizes in a side reaction (3). See Scheme 1.
There are few examples of hyperbranched or dendritic polysiloxanes, eg. polymers, whose backbone consist only of —SiRR′—O— linkages. Probably the most significant paper is by Uchicda et al. (4) which describes a multistep pathway for highly regular third generation dendritic polysiloxanes with molecular weight of about 15,000 g/mol. See Scheme 2.
Rebrov (5) used a different approach. He let MeSiCl
3
react with three equivalents of NaOSiMe(OEt)
2
. Ethoxy groups were then converted quantitatively into chlorines by reaction with thionyl chloride. Treatment of the resulting product again with NaOSiMe(OEt)
2
, followed by conversion of the Si—OEt into Si—Cl groups repeatedly gave a fourth generation polymer in >75% yield. See Scheme 3.
Morikowa (6) utilized easily cleavageable Si—Ph bond in his synthesis. The core was prepared from a compound having three Si-phenyl groups which were converted into Si—Br by treatmnent of Br
2
. Reaction with HNMe
2
gave Si—N functionalities, which in turn could be reacted with silanols bearing Si-phenyl groups. This cycle was repeated two times to give a 3
rd
generation dendrimer in 32% yield, with a molecular weight of about 4,800 g/mol. See Scheme 4.
OBJECTS AND SUMMARY OF THE INVENTION
The aim of this invention is to provide convenient methods for the preparation of hyperbranched siloxane polymers by anionic polymerization of a cyclotrisiloxane having the functional group Si—OH, and for the preparation of linear siloxane polymers by cationic or anionic polymerization of a cyclotrisiloxane having a vinyl terminal functional group. A further object of this invention is to provide novel cyclotrisiloxanes useful for the preparation of the aforementioned polymers.
Thus, according to one aspect, this invention concerns a novel cyclotrisiloxane of the formula (I)
wherein Y is OSi(R)
2
H, OSi(R)
2
OH, or O—Si(R)
2
—OSi(R)
2
—CH═CH
2
, and the R substituents can be the same or different, any R substituent being selected from the group consisting of phenyl, an unsubstituted or substituted alkyl of 1 to 6 carbon atoms, wherein the optional substituent is a phenyl or one or more fluoro atoms, provided that the alpha or beta position of the alkyl chain cannot be fluorosubstituted.
According to another aspect, the invention concerns a method for the preparation of hyperbranched siloxane polymer, wherein a compound of formula (II)
wherein Y is OH or OSi(R)
2
OH, and the R substituents can be the same or different, any R substituent being selected from the group consisting of phenyl, an unsubstituted or substituted alkyl of 1 to 6 carbon atoms, wherein the optional substituent is a phenyl or one or more fluoro atoms, provided that the alpha or beta position of the alkyl chain cannot be fluorosubstituted
is subjected to anionic polymerization, in bulk or in a suitable solvent, e.g. TBF, to give a hyperbranched polymer, which has the formula (IIIa1, IIIa2, IIIa3) or (IIIb1, IIIb2, IIIIb3)
wherein the substituents R are as defined above and where each Z in IIIa1-a3 is one of the groups IIIa1--a3, and each Z in IIIb1-b3 is one of the groups IIIb1-b3, or Z is an endcapping group. Said endcapping group, which can be the same or different, can be hydrogen obtained by neutralization, or a radical derived from a halosilane or a halosiloxane, e.g. chlorosilane or chlorosiloxane, wherein said halosilane or halosiloxane can bear functional or non-functional groups. As examples of said functional or non-functional group can be mentioned hydrogen, vinyl, the substituent R as defined before, amino, alkoxy or polyalkylene oxide. The endcapping of the polymer can also be carried out by using a mixture of different compounds. By proper choice of endcapping group the surface of the polymer can be modified in desired ways.
According to a further aspect, the invention concerns a method for the preparation of a linear siloxane polymer, wherein a compound of the formula (IV)
wherein Y is O—Si(R)
2
—OSi(R)
2
—CH═CH
2
, and the R substituents can be the same or different, any R substituent being selected from the group consisting of phenyl, an unsubstituted or substituted alkyl of 1 to 6 carbon atoms, wherein the optional substituent is a phenyl or one or more fluoro atoms, provided that the alpha or beta position of the alkyl chain cannot be fluorosubstituted, is subjected to cationic or anionic polymerization to give a linear polymer, which has the formula (V)
wherein the substituents R are the same as in compound (IV) and m is 3 to 9000.
The invention also concerns the novel hyperbranched or linear siloxane polymers.
DETAILED DESCRIPTION OF THE INVENTION
According to a preferred embodiment, each R-substituent in the cyclotrisiloxane of formula (I) is the same and is an alkyl of 1 to 4 carbon atoms. Most preferably, each R -substituent is methyl.
The anionic polymerization of the Si—OH functionalized cyclotrisiloxane (compound (II)) can be carried out in the presence of a lithium containing base, for example an alkyl lithium such as n-butyl lithium or triphenylmethyl lithium, or lithium diisopropyl amide. The polymerization can be carried out in bulk or in a suitable solvent. As an example of a suitable solvent can be mentioned THF.
Alternatively, the anionic polymerization can be carried out by subjecting the Si—OH functionalized cyclotrisiloxane to a catalytic amount of superbase such as a phosphazene. A particularly useful superbase is phosphazene base P
4
-t-Bu [1-tert-Butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)-phosphoranyliden-amino]-2&lgr;
5
, 4&lgr;
5
-catenadi(phosphazene)].
The preparation of linear siloxane polymers can be carried out by cationic polymerization initiated by an acid such as trifluoromethane sulfonic acid (triflic acid) or by anionic polymerization initiated by bases such as dilithium diphenylsilanolate or dilithium tetramethylsiloxanediolate.
REFERENCES:
patent: 5246703 (1993-09-01), Durfee
patent: 5700899 (1997-12-01), Aoki et al.
patent: 5852153 (1998-12-01), Sugo et al.
Jyri K. Paulasaari and William P. Weber, “Preparation and polymerization of 1,3,3,5,5-pentamethyl-1-(2′-perfluorophenyl-1′,1′,2′,2′-tetrahydroethyl)cyclotrisiloxane (I). Comparison of anionic and cationic polymerization of I”, 39Polym. Prepr., 583-584 (1998) (Abstract).
Jyri K. Paulasaari and William P. Weber, “Preparation and Orthogonal Polymerizations of 1-Hydrido-1-vinyldimethylsiloxy-3,3,5,5-tetramethylcyclotrisiloxane”, 32Macromolecules5217-5221 (1999) (Abstract).
Jyri K. Paulasaari and William P. Weber, “Polymerizations of 1-Hydrido-1-vinyldimethylsiloxy-3,3,5,5-tetramethylcyclotrisiloxane”, 40Polym. Prepr.801-802 (1999) (Abstract).
Jyri K. Paulasaari and William P. Weber, “Preparation of Highly Regular Poly(1-Hydrido-1,3,3,5,5-pentamethyltrisiloxane) and Its Chemical Modification by Hydroxsilylation”, 32Macromolecules6574-6577 (1999) (Abstract).
Paulasaari Jyri Kalevi
Weber William P.
Lydon James C.
Shaver Paul F.
University of Southern California
LandOfFree
Cyclotrisiloxanes, new siloxane polymers and their preparation does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cyclotrisiloxanes, new siloxane polymers and their preparation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cyclotrisiloxanes, new siloxane polymers and their preparation will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2493005