Polypeptide-polysiloxane copolymers

Details Polypeptide-polysiloxane copolymers Polypeptide-polysiloxane copolymers

1999-10-15

2002-03-19

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Live hair or scalp treating compositions

Polymer containing

C424S078370, C424S078100, C528S026000, C528S028000

Reexamination Certificate

active

06358501

ABSTRACT:

RELATED APPLICATIONS
This application claims priority to German application No 198 48 002.4, filed Oct. 17, 1998, herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to polypeptide-polysiloxane copolymers, to their preparation by thermal copolymerization of amino acids with organofunctional polysiloxanes, and to their use as interface-active substances.
2. Description of the Art
Proteins are naturally occurring polypeptides and play an important role in all biological processes. They are being used increasingly in personal care products as conditioners, humectants and emollients. Proteins are natural, high molecular weight polymers and are generally hydrolyzed to low molecular weight proteins so that they are soluble in water. Although protein hydrolyzates can be incorporated more easily into formulations, the soluble proteins are less substantive on skin and hair.
Silicone is the collective term for a large number of compounds with varying properties, but which are all characterized by the silicon-oxygen bond in the siloxane chain. Like proteins, they likewise play an important role in personal care, in particular as conditioners. Polydimethylsiloxanes, for example, are substantive on skin and hair, make hair shiny and smooth and produce a pleasantly soft and silky feel on the skin. However, they are virtually insoluble in water. Although silicone polyethers are water-soluble silicone derivatives which are able to make the hair smooth, they are not very substantive.
Proteins and silicones are thus two very different classes of substances having likewise different properties and advantages which are useful in each case for cosmetic applications. The development of proteins, which also have some of the characteristic properties of silicones such as the smoothing of hair and skin, or of silicones, which have the advantages of proteins such as better solubility in water and higher substantivity, has given access to products with properties which cannot be obtained by simple mixtures of the two classes of substances.
U.S. Pat. No. 3,562,353 has already described the combination of silicones with polypeptides in the form of copolymers. These are block copolymers of the ABA or (AB)n type, which are obtained by coupling end-functionalized homopolymers. A is a polyamide moiety having a molecular mass of from 2,000 to 100,000 and B is a silicone moiety having a molecular mass of from 500 to 100,000. The compounds are thermoplastic block copolymers which are either elastic or solid and can be used as biocompatible implant materials. They are prepared by the reaction of a polyamide consisting of alpha-amino acids and having reactive end groups such as hydroxyalkyl, aminoalkyl or isocyanato groups with a silicone which carries reactive end groups such as chloroalkyl, carboxyl, isocyanato, hydroxyalkyl or aminoalkyl groups. However, the functional polyamide must first be prepared with additional synthetic expenditure including protection-group chemistry. In a first stage, the corresponding N-carboxyanhydride is prepared from the alpha-amino acid by reaction with phosgene in a solvent such as dioxane. If the alpha-amino acid is a dicarboxylic acid such as glutamic acid or aspartic acid, then one carboxyl group must first be esterified by esterification, for example, with an excess of benzyl alcohol in the presence of hydrobromic acid. If it is an alpha-amino acid containing another amino, hydroxyl or mercapto group, these must then likewise be protected in a suitable manner prior to the reaction with phosgene in order to avoid undesired side reactions. In a second stage, the protected alpha-amino acid is then reacted to give the polyamide. This multistage synthesis may be illustrated more detailed by means of the following example Starting from the N-carboxyanhydride, protected in the form of the benzyl, ester, of L-glutamic acid, N-carboxy-gamma-benzyl L-glutamate is prepared. Then this is polymerized with ethanolamine as initiator in dimethylformamide as solvent. After about 90% conversion, the N-carboxyanhydride of phenylalanine must be added so that it forms the end group of the polyamide. The polymer formed must be precipitated in water and washed with methanol. In the next step, the polyamide is heated in epsilon-caprolactone as reagent and solvent for over 50 h (!), then precipitated again in water and washed with methanol. This gives a polyamide which carries hydroxyalkyl groups at both ends. The dihydroxy-functional polyamide is then reacted in a mixture of benzene and dichlorobenzene as solvent with alpha, omega-bis(dimethylamino)poly(dimethylsiloxane) with the elimination of dimethylamine. The polymer is precipitated out with methanol and washed with hexane. Thus, to prepare the copolymers described in U.S. Pat. No. 3,562,353, a large number of reaction and work-up steps are required, including complex protection-group chemistry. In addition, some of the reagents required are very toxic, such as phosgene, and the reactions are carried out in solvents such as benzene and dimethylformamide, from which the product must be recovered. As a rule, the polypeptide moiety contains amino acids containing protective groups, such as benzylglutamic acid and nonpolar amino acids such as phenylalanine. The copolymers are thus virtually insoluble in water. On the other hand, the linking between polyamide and silicone moiety is carried out via a hydrolysis-sensitive Si—O—C bond, meaning that if the protective groups were removed, the bond between silicone and peptide moieties would be cleaved again and additionally degradation reactions on the polysiloxane would be triggered
Journal of Applied Polymer Science, 27, 1982, 139-148 likewise describes the preparation of polypeptide-polysiloxane block copolymers. These are obtained by polymerization of the N-carboxyanhydrides of phenylalanine and gamma-benzylglutamic acid with an alpha, omega-aminopropyl-functional polydimethylsiloxane as initiator. The resulting block copolymers are white, soft solids. However, as in U.S. Pat. No. 3,562,353, the preparation of the copolymers requires a large number of reaction and work-up steps, as well as protective groups and solvents. A typical reaction time for the polymerization is in the range between 100 and 200 h (!).
U.S. Pat. No. 5,100,956 claims silicone-protein copolymers in which the silicone moiety is linked to the amino group of a protein via a polyether phosphate group. Although the polyether phosphate unit makes the polymers soluble in water, they also have a very hydrolysis-sensitive phosphoric ester function, meaning that the silicone and protein moieties can again be readily cleaved from one another. In addition, it must be accepted that the polyether residues, which act as spacers and linking element between protein and silicone moieties, because of their polymer distribution and the high molecular weight character associated therewith, do not leave the properties of the product unaffected and have the property profile of hybrid silicone-polyether protein copolymers rather than act as pure silicone-protein copolymers. The silicone-protein copolymers are prepared by reacting water-soluble epoxy-functional polysil(ox)anes with hydrolyzates of natural proteins in water. The solubility of the polysiloxanes in water is here achieved by hydrosilylating addition reaction of polyethers and subsequent phosphatation of the hydroxyl group. An epoxy group, which is able to react with free amino groups of the protein, is then introduced into the silicone by reaction of the sodium salt of the silicone phosphate with epichlorohydrin. Thus synthesis route also has several stages and uses hazardous and highly toxic reagents such as phosphorus pentoxide or epichlorohydrin.
Another U.S. Patent U.S. Pat. No. 5,243,028, also describes an improved process variant for the preparation of silicone-protein copolymers. This involves firstly reacting a hydroxy-functional silicone polyether with chloroacetic acid to give the corresponding chloroaceta

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