Nontoxic polyethoxysiloxane material or the production of biologically resorbable and/or bioactive articles containing polyethoxysiloxane material, the production thereof, and the use thereof
The present invention relates to a polyethoxysiloxane (PES) material to be obtained in that (a) a first hydrolysis condensation reaction of a maximum of one group X of one or more different Si compounds of the formula (I) SiX4 (I) in which the groups X are the same or different and represent hydroxy, hydrogen, or ethoxy (EtO), are catalyzed in an acidic fashion at an initial pH value of 0 to ≦7, is conducted in the presence of ethanol (EtOH) or an ethanol-water mixture as a solvent over a time period of 1 to 24 hours at a temperature of 0° C. to 78° C, (b) a second hydrolysis condensation reaction of the material obtained in step (a) is conducted while simultaneously removing the solvent by successive evaporation in a gas diffusion-tight container at a pressure of 100 to 1013 mbar, preferably at a slight negative pressure of 300 mbar to 800 mbar and a temperature of 50-78° C. until a drastic increase in viscosity (at a shear rate of 10 s −1 at 4° C.) to 0.5 to 2 Pa·s until a constant weight is attained and a cyclotetrasiloxane of the general formula ((SiO(OH) 0,75 (OEt) 1,25 × 1/64H 2 O) 4 and a molar mass of 4*approx. 114 g=approx. 456 g; (c) said PES material is cooled in a closed container over a time period from a few minutes to a few hours, and (d) the PES material obtained from step (c) is converted into an rPES material by a third hydrolysis condensation reaction.
1. A polyethoxysiloxane (PES) material obtained by
(a) performing a first hydrolysis-condensation reaction (HCR) of an X radical of one or more different silicon compounds of formula I
SiX 4 (I),
where the X radicals are the same or different and each represent hydroxyl, hydrogen or ethoxy, acid catalyzed, in the presence of water and in the presence of ethanol or of an ethanol-water mixture as solvent, for a period of 1 to 24 h at a temperature of 0° C. to 78° C.,
(b) performing a second HCR of the material obtained in step (a) while at the same time removing the solvent by gradual evaporation in a gas diffusion tight container at a pressure of 100 to 1013 mbar, and a temperature of 50-78° C., until an increase in viscosity to 0.5-2Pa·s, until weight constancy and until formation of a cyclotetrasiloxane of the formula ((SiO(OH) 0.75 (OEt) 1.25 × 1/64 H 2 O) 4 and of molar mass of about 456 g;
(c) cooling the polyethoxysiloxane material obtained in step (b) in a closed container over a period of from 2 to 5 minutes to 0.2 to 5 hours, to form a sol and, optionally;
(d) converting the polyethoxysiloxane material obtained from (c) into an rPES material via a third HCR.
2. The material according to claim 1 , wherein the pH of 0 to ≦7 in step (a) is set with dilute nitric acid or with an acidic mixture suitable for producing NO or NO 2 in situ or solution of (i) a physiologically tolerable acid and (ii) a substrate of nitroxide synthase (NOS).
3. The material according to claim 2 , wherein the dilute nitric acid is used in a molar ratio of silicon compound(s) of formula (I) to nitric acid in the range from 90:1 to 110:1.
4. The material according to claim 1 , wherein the acid strength is reduced in step (b), by evaporating NO 2 or by means of a Tris solution.
5. The polyethoxysiloxane material according to claim 1 , wherein the polyethoxysiloxane material in step (c) is cooled down to −20° C. to +10° C.
6. The material according to claim 1 , wherein the conversion of the polyethoxysiloxane to an rPES in step (d) is effected at a temperature of −20° C. to 10° C.
7. The material according to claim 1 , wherein step (d) is performed until a viscosity of the material in the range from 30 to 55 Pa·s.
8. The material according to claim 1 , wherein the silicon compound used in step (a) is tetraethoxysilane (TEOS).
9. Bioabsorbable or bioactive material comprising the polyethoxysiloxane material of claim 1 .
10. Bioabsorbable or bioactive material according to claim 9 , wherein said polyethoxysiloxane material is a fiber, a fibrous nonwoven web, powder, monolith or coating solution.
11. The Bioabsorbable or bioactive material according to claim 10 , wherein the fiber, fibrous nonwoven web, powder, monolith or coating solution is watered immediately before use.
12. The material of claim 2 , wherein said nitroxide synthase (NOS) is arginine.
13. The material of claim 2 , wherein said physiologically tolerable acid is selected from the group consisting of citric, succinic, tartaric, acetic and ascorbic acids.