Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/38—Polysiloxanes modified by chemical after-treatment
  • C08G77/382—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon
  • C08G77/388—Polysiloxanes modified by chemical after-treatment containing atoms other than carbon, hydrogen, oxygen or silicon containing nitrogen
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
  • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
  • G02B1/041—Lenses
  • G02B1/043—Contact lenses

Definitions

• This application is directed toward improved methods of synthesizing cationic siloxane prcpolymers as well as a specific cationic siloxane prepolymer having improved compatibility with monofunctional siloxanyl methacrylate monomers and medical devices containing the cationic siloxane prepolymer.
• n is an integer from 1 to about 300.
• the method comprises, in one embodiment, reacting bis-bromobutyl polydimethylsiloxane with 2-(methylamino)ethanol in polar solvent such as dioxane to provide a first reaction product.
• the first reaction product is then reacted with methacryloyl chloride or methacrylic anhydride in the presence of triethylamine in polar solvent such as chloroform to provide a second reaction product.
• the second reaction product is then reacted with iodomethane in tetrahydrofuran to provide the third reaction product as a cationic functionalized siloxane prepolymer.
• T he improved cationic siloxane prepolymer is a monomer having the following formula (IVj:
• n is from 0 to 200.
• the method comprises reacting a bis-halide polysiloxane such as bis-bromobutyl poiydimethylsiloxane with an alkyl functionalized hydroxy secondary amine such 2-(methylamino)ethanol to provide a first reaction product.
• a bis-halide polysiloxane such as bis-bromobutyl poiydimethylsiloxane
• an alkyl functionalized hydroxy secondary amine such 2-(methylamino)ethanol
• alkyl functionalized hydroxy secondary amines would include 2- (ethylamino) ethanol, 2-(propylamino) ethanol, 2-(butylamino) ethanol.
• the reaction is conducted in a polar solvent.
• Polar solvents are selected because they are able to dissolve the reactants and increase the reaction rate. Examples of polar solvents would include ethyl acetate, dioxane, THF, DMF, chloroform, etc.
• the first reaction product is then reacted with a methacrylating agent to pro ⁇ ide a second reaction product having vinyl polymerizable endgroups on the polysiloxane.
• methacrylating agents would include methacryloyl chloride, methacrylic anhydride, 2-isocyanatoethyl methacrylate, itaconic acid and itaconic anhydride.
• an acid scavenger such as triethylamine, triethanolamine, or 4-dimethylaminopyridine is used to reduce the amount of HCl formed during the synthesis.
• acid scavenger refers to a material that reacts with any acid that is otherwise formed during the synthesis to prevent the degradation of the reaction product.
• an alkyl halide such as iodomethane is used as a quaternizing agent to provide the final third reaction product.
• the final product is isolated by removal of the solvent and any residual alkyl halide from the reaction mixture.
• This new synthetic route divides the synthesis into three steps and differs dramatically from the previous procedure in that the quat functionality is formed at the last step of the reaction.
• This change in synthetic route allows lor easy removal of unreacted starting materials and significantly reduces the occurrence of premature polymerization.
• Use of lower levels of polymerization inhibitor in the synthesis of the cationic siloxane prepolymer is also able to be achieved.
• reaction product ( 1) after isolation.
• the structure of (1 ) was verified by NMR analysis.
• Product (1 ) with chlorofo ⁇ n as a solvent, was then allowed to react with methacryloyl chloride in the presence of triethylamine at ambient temperature to afford reaction product (2) after isolation.
• the structure of product (2) was also verified by NMR analysis.
• the final step of the synthesis was the quaternization of (2) with iodomethane, using THF as a solvent, to afford reaction product (3) after 15 hours at 45 0 C.
• the structure of the final product, (3) was verified by NMR, SEC, and Mass Spectrometry analyses.
• the method is particularly useful for synthesizing the following prepolymer which has desirable properties for forming a medical device.
• n is from 0 to 200.
• a preferred monomer is shown below wherein n equals 39.
• the invention includes articles formed of device forming monomer mixes comprising the prepolymers of formula (IV).
• the article is the polymerization product of a mixture comprising the aforementioned cationic siloxane prepolymer of formula (II) and at least a second monomer.
• Preferred articles are optically clear and useful as a contact lens.
• Useful articles made with these materials may require hydrophobic, possibly silicon containing monomers.
• Preferred compositions have both hydrophilic and hydrophobic monomers.
• the invention is applicable to a wide variety of polymeric materials, either rigid or soft.
• Especially preferred polymeric materials are lenses including contact lenses, phakic and aphakic intraocular lenses and cornea! implants although all polymeric materials including biomaterials are contemplated as being w ithin the scope of this invention.
• Especially preferred are silicon containing hydrogels.
• the present imention also provides medical devices such as heart valves and films, surgical devices, vessel substitutes, intrauterine devices, membranes, diaphragms, surgical implants, blood vessels, artificial ureters, artificial breast tissue and membranes intended to come into contact with body fluid outside of the body, e.g., membranes for kidney dialysis and heart/lung machines and the like, catheters, mouth guards, denture liners, ophthalmic devices, and especially contact lenses.
• medical devices such as heart valves and films, surgical devices, vessel substitutes, intrauterine devices, membranes, diaphragms, surgical implants, blood vessels, artificial ureters, artificial breast tissue and membranes intended to come into contact with body fluid outside of the body, e.g., membranes for kidney dialysis and heart/lung machines and the like, catheters, mouth guards, denture liners, ophthalmic devices, and especially contact lenses.
• Silicon containing hydrogels are prepared by polymerizing a mixture containing at least one silicon-containing monomer and at least one hydrophilic monomer.
• the silicon-containing monomer may function as a crosslinking agent (a crosslinker being defined as a monomer having multiple polymerizable functionalities) or a separate crosslinker may be employed.
• Lenses are made from poly(organosiloxane) monomers which are ⁇ , ⁇ terminally bonded through a divalent hydrocarbon group to a polymerized activated unsaturated group.
• Various hydrophobic silicon-containing prepolymers such as l ,3-bis(methacryloxyalkyl)- poh siloxanes were copolymerized with known hydrophilic monomers such as 2- hydrox ⁇ ethyl methacrylate (HEMA).
• U.S. Pat. No. 5,358,995 (Lai et al) describes a silicon containing hydrogel which is comprised of an acrylic ester-capped polysiloxane prepolymer, polymerized with a bulky polysiloxanylalkyl (meth)acrylate monomer, and at least one hydrophilic monomer.
• Lai et al is assigned Io Bausch & Lomb Incorporated and the entire disclosure is incorporated herein b) reference.
• the acrylic ester-capped polysiloxane prepolymer, commonly known as M? D N consists of two acrylic ester end groups and "x" number of repeating dimethylsiloxane units.
• the preferred bulky polysiloxanylalkyl (meth)acrylate monomers are TRIS-type (methacryloxypropyl tris(trimethylsiloxy)silane) with the hydrophilic monomers being either acrylic- or vinyl-containing.
• silicon-containing monomer mixtures which may be used with this invention include the following: vinyl carbonate and vinyl carbamate monomer mixtures as disclosed in U.S. Pat. Nos. 5,070,215 and 5,610,252 (Bambury et al); fluorosilicon monomer mixtures as disclosed in U.S. Pat. Nos. 5,321, 108; 5,387.662 and 5,539,016 (Kunzler et al); fumarate monomer mixtures as disclosed in U.S. Pat. Nos. 5.374.662; 5,420,324 and 5,496,871 (Lai et al) and urethane monomer mixtures as disclosed in U.S. Pat. Nos.
• non-silicon hydrophobic materials include alkyl acrylates and methacrylates.
• the cationic siloxane prepolymer may be copolymerized with a wide variety of hydrophilic monomers to produce silicon hydrogel lenses.
• hydrophilic monomers include: unsaturated carboxylic acids, such as methacrylic and acrylic acids; acrylic substituted alcohols, such as 2-hydroxyethylmethacrylate and 2- hydroxyethylacrylate; vinyl lactams, such as N-vinyl pyrrolidone (NVP) and 1 - vinylazonam-2-one; and acrylamides, such as methacrylamide and N, N- dimethylacrylamide (DMA).
• hydrophilic vinyl carbonate or vinyl carbamate monomers disclosed in U.S. Pat. Nos. 5.070.215
• hydrophilic oxazolone monomers disclosed in U.S. Pat. No. 4,910,277.
• Other suitable hydrophilic monomers will be apparent to one skilled in the art.
• Hydrophobic cross-linkers would include methacrylates such as ethylene glycol dimethacrylate (EGDMA) and allyl methacrylate (AMA).
• EGDMA ethylene glycol dimethacrylate
• AMA allyl methacrylate
• the monomer mixtures containing the quaternized siloxane prepolymer of the invention herein are relatively water soluble. This feature provides advantages over traditional silicon hydrogel monomer mixtures in that there is less risk of incompatibility phase separation resulting in hazy lenses and the polymerized materials are extractable with water.
• traditional organic extraction methods may also be used.
• the extracted lenses demonstrate a good combination of oxygen permeability (Dk) and low modulus, properties known to be important to obtaining desirable contact lenses.
• lenses prepared with the quaternized siloxane prepolymers of the invention herein are wettable even without surface treatment, provide dry mold release, do not require solvents in the monomer mix (although solvents such as glycerol may be used) the extracted polymerized material is not cytotoxic and the surface is lubricious to the touch.
• solvents such as glycerol may be used
• the polymerized monomer mix containing the quaternized siloxane prepolymers of the invention herein do not demonstrate a desirable tear strength
• toughening agents such as TBE (4-/-butyl-2- hydroxycyclohexyl methacrylate) may be added to the monomer mix.
• Other strengthening agents are well known to those of ordinary skill in the art and may also be used when needed.
• an organic diluent may be included in the initial monomelic mixture.
• the term "organic diluent” encompasses organic compounds which minimize incompatibility of the components in the initial monomelic mixture and are substantially nonreactive with the components in the initial mixture. Additionally, the organic diluent serves to minimize phase separation of polymerized products produced by polymerization of the monomelic mixture. Also, the organic diluent will generally be relatively non- inflammable.
• Contemplated organic diluents include / ⁇ ?/7-butanol (TBA); diols, such as ethylene glycol and propylene glycol; and polyols, such as glycerol.
• TSA / ⁇ ?/7-butanol
• diols such as ethylene glycol and propylene glycol
• polyols such as glycerol.
• the organic diluent is sufficiently soluble in the extraction solvent to facilitate its removal from a cured article during the extraction step.
• the organic diluent is included in an amount effective to provide the desired effect. Generally, the diluent is included at 5 to 60% by weight of the monomeric mixture, with 10 to 50% by weight being especially preferred.
• the monomeric mixture comprising at least one hydrophilic monomer, at least one cationic siloxane prepolymer and optionally the organic diluent, is shaped and cured by conventional methods such as static casting or spincasting.
• Lens formation can be by free radical polymerization such as azobisisobutyronitrile (AIBN) and peroxide catah sts using initiators and under conditions such as those set forth in U.S. Pat. No. 3,808,179. incorporated herein by reference.
• Photo initiation of polymerization of the monomer mixture as is well known in the art may also be used in the process of forming an article as disclosed herein. Colorants and the like may be added prior to monomer polymerization.
• non-polymerized monomers into the eye upon installation of a lens can cause irritation and other problems.
• non-flammable solvents including water may be used for the extraction process.
• the biomaterials formed from the polymerized monomer mix containing the cationic siloxane prepolymers monomers disclosed herein are formed they are then extracted to prepare them for packaging and eventual use. Extraction is accomplished by exposing the polymerized materials to various solvents such as water, tert-butanol, etc. for varying periods of time. For example, one extraction process is to immerse the pol) merized materials in water for about three minutes, remove the water and then immerse the polymerized materials in another aliquot of water for about three minutes. remove that aliquot of water and then autoclave the polymerized material in water or buffer solution.
• various solvents such as water, tert-butanol, etc.
• the shaped article for example an RGP lens
• the machining step includes lathe cutting a lens surface, lathe cutting a lens edge, buffing a lens edge or polishing a lens edge or surface.
• the present process is particularly advantageous for processes wherein a lens surface is lathe cut, since machining of a lens surface is especially difficult when the surface is tacky or rubbery.
• NMR ⁇ -Nuclear Magnetic Resonance
• SEC Size Exclusion Chromatography
• ESI-TOF MS The electrospray (ESI) time of flight (TOF) MS analysis was performed on an Applied Biosystems Mariner instrument. The instrument operated in positive ion mode. The instrument is mass calibrated with a standard solution containing lysine, angiotensinogen, bradykinin (fragment 1 -5) and des-Pro bradykinin. This mixture provides a seven-point calibration from 147 to 921 m/z. The applied voltage parameters are optimized from signal obtained from the same standard solution.
• Modulus and elongation tests are conducted according Io ASTM D- 1708a, employing an Instron (Model 4502) instrument where the hydrogel film sample is immersed in borate buffered saline; an appropriate size of the film sample is gauge length 22 mm and width 4.75 mm, where the sample further has ends forming a dog bone shape to accommodate gripping of the sample with clamps of the Instron instrument, and a thickness of 200+50 microns.
• Instron Model 4502
• Oxygen permeability (also referred to as Dk) is determined by the following procedure. Other methods and/or instruments may be used as long as the oxygen permeability values obtained therefrom are equivalent to the described method.
• the oxygen permeability of silicone hydrogels is measured by the polarographic method (ANSI Z80.20-1998) using an 02 Permeometer Model 20 IT instrument (Createch, Albany, California USA) having a probe containing a central, circular gold cathode at its end and a silver anode insulated from the cathode. Measurements are taken only on pre- inspected pinhole-free, flat silicone hydrogel film samples of three different center thicknesses ranging from 150 to 600 microns.
• Center thickness measurements of the film samples may be measured using a Rehder ET-I electronic thickness gauge.
• the film samples have the shape of a circular disk. Measurements are taken with the film sample and probe immersed in a bath containing circulating phosphate buffered saline (PBS) equilibrated at 35°C+/- 0.2°. Prior to immersing the probe and film sample in the PBS bath, the film sample is placed and centered on the cathode premoistened with the equilibrated PBS, ensuring no air bubbles or excess PBS exists between the cathode and the film sample, and the film sample is then secured to the probe with a mounting cap, with the cathode portion of the probe contacting only the film sample.
• PBS circulating phosphate buffered saline
• Teflon polymer membrane e.g.. having a circular disk shape
• the Teflon membrane is first placed on the pre-moistened cathode, and then the film sample is placed on the Teflon membrane, ensuring no air bubbles or excess PBS exists beneath the Teflon membrane or film sample.
• R2 correlation coefficient value
• Any film samples hydrated with solutions other than PBS are first soaked in purified water and allowed to equilibrate for at least 24 hours, and then soaked in PHB and allowed to equilibrate for at least 12 hours.
• the instruments are regularly cleaned and regularly calibrated using RGP standards. Upper and lower limits are established by calculating a +/- 8.8% of the Repository values established by William J. Benjamin, et ak, The Oxygen Permeability of Reference Materials, Optom Vis Sci 7 (12s): 95 (1997), the disclosure of which is incorporated herein in its entirety:
• n is about 11
• Liquid monomer solutions containing cationic end-capped poly(dimethylsiloxane) prepolymers from examples below, along with other additives common to ophthalmic materials (diluent, initiator, etc.) are clamped between silanized glass plates at various thicknesses and polymerized using thermal decomposition of the free-radical generating additive by heating 2 h at 100 0 C under a nitrogen atmosphere.
• Each of the formulations affords a transparent, tack-free, insoluble film.
• This example details the synthetic procedure for the production of the intermediate, 1 ,3-bis(4-bromobutyl (tetramethyldisiloxane.
• a 5 L 3 -neck round bottom Morton flask is equipped with a Teflon bladed mechanical stirring system and a condenser.
• a silica gel column (2 kg silica gel, column 3.5 inches in diameter and 30 inches long) is prepared by slurry packing with heptane.
• the yellow silicone liquid is placed on the silica gel chromatography column with heptane (20Og). 0. Elutc with 1.5 L 100% heptane, 1 L 100% heptane. 1 L 80% heptane 20% methylene chloride, then 1 L 60% heptane 40% methylene chloride until done. 1. Start collecting after the first 1 L collected as Fraction ""0". The organic fractions 1 (65.6 g), 2, 3 (343 g), 4, 5, 6 (33 g).
• Flasks 1000 ml round bottom (x3), 3-neck 1000 niL round bottom. 500 mL pressure flask (round bottom)
• Glass microfiber filter paper (retains samples down to 0.7 ⁇ m)
• Trifluoromethanesulfonic acid ( 1 .25 g, 0.25 w/w %) is added and stirred 24 hours at room temperature.
• the mixture is stirred magnetically and stripped for at least 4 hours at 80 0 C and ⁇ 1.3 mbar using a vacuum pump and acetone/dry ice trap, or until collection of residual octamethylcyclotctrasiloxane is essentially complete (no further collection of liquid) to afford the product as a transparent, colorless, viscous liquid (426 g. 85% yield).
• Silicone product from Step 2.9 was redissolved in anhydrous chloroform (3.0 mL/g silicone) and transferred to 1000 mL round bottom jlask (dried with heat gun) with magnetic stir bar.
• Triethylamine (6 mol eq.) was added to the reaction, along with 250 ppm BH I inhibitor.
• reaction vessel sealed and allowed to stir in a 45 0 C oil bath for 15 hours protected from light (wrapped in Al foil).
• thermocouple Thermometer or thermocouple
• a 5 L 3-neck round bottom Morton flask is equipped with a Teflon b laded mechanical stirring s ⁇ stem and a condenser.
• a silica gel column (2 kg silica gel, column 3.5 inches in diameter and 30 inches long) is prepared by slurry packing with heptane.
• the yellow silicone liquid is placed on the silica gel chromatography column with heptane (20Og).
• BHT 2,6-Di-tert-butyl-methylphenoS
• Flasks 1000 mL round bottom (1-neck), 1000 mL round bottom (2-neck). 2000
• Trifluoromethanesulfonic acid 1 .25 g, 0.25 w/w %) is added and stirred 24 hours at room temperature. 3. To the reaction is added sodium bicarbonate (7 g) and the mixture is allowed to stir at a moderate rate for an additional 24 hours at room temperature.
• the mixture is then filtered w ith slight positive nitrogen pressure through a pressure filter system equipped with 5 ⁇ m PTFE filter and a celite pad into a 100OmL round bottom flask.
• the mixture is stirred with a magnetic stir bar and stripped for at least 4 hours at 80 0 C and ⁇ 1.3 mbar using a vacuum pump and acetone/dry ice trap, or until collection of residual octamethylcyclotetrasiloxane is essentially complete (no further collection of liquid) to afford the product as a transparent, colorless, viscous liquid (426 g, 85% yield).
• Step 3 Methacrylation with methacrylic anhydride.
• Silicone product from Step 2.9 (450.8 g) was re-dissoh ed in drous chloroform (450 mL, 1 mL/g silicone) and transferred to a minimum of a 2-neck 2000 mL round bottom flask (dried with heat gun) equipped with a overhead mechanical stirrer.
• Isolated product layer was washed with 2000 mL 50/50 brine/10% NaHCCG (x2). followed by 2000 mL 50/50 brine/water.
• UV blocker 969 1.50 vaso-64 N/A 0.50
• Example 9 Properties of films of Example 7

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• 2008
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