CA2243869A1 - Non-fouling, wettable coated devices - Google Patents

Abstract

A device, and its production method, the device has a substrate and a coating composition, the coating composition being formed by the gas phase or plasma polymerization of a gas comprising at least one organic compound or monomer. The polymerization is carried out using a pulsed discharge having a duty cycle of less than about 1/5, in which the pulse-on time is less than about 100 msec and the pulse-off time is less than about 2000 msec. The duty cycle can also be varied, thus the coating composition can be gradient layered accordingly. The device has a coating composition which is uniform in thickness, pin-hole free, optically transparent in the visible region of the magnetic spectrum, permeable to oxygen, abrasive resistant, wettable and biologically non-fouling.

Description

NON-FOUI,~G~ WETTARI ~ COATED DEVICES

The US Government has certain rights in the present invention pursuant to the National Tn.ititlltes of Health under Grant R01 AR43186-5 01 and by the State of Texas through the Texas Higher F.duc~tion Coolrli~ g Board ATP Program under Grant 003656-137.
This application claims the benefit of U. S. Provisional Application Serial No. 60/055,260 filed on August 8, 1997, and entitled "NON-FOULl~G WETTABLE COATED DEVICES7" commonly ~igned with 10 the present invention and incorporated herein by reference.
This is a continuation-in-part application of prior U.S. Patent Application Serial No. 08/632,935, filed April 16, 1996, the entire content of which is hereby incorporated by reference.

This invention relates to devices having gas-phase deposited coatings and their methods of production. More specifically, this invention relates to devices, and their method of production, having gas-phase deposited coatings which are non-fouling and wettable.
BACKGROUND
The chemical composition of surfaces plays a pivotal role in dictating the overall efficacy of many devices. Some devices require non-fouling, and wettable surfaces in order for the devices to be useful for 25 their inten-led purposes. For example, many biomedical devices such as catheters, stents, implants, interocular lenses and contact lenses require surfaces which are biologically non-fouling, which means that proteins, lipids, and cells will not adhere to the surfaces of the devices. In some cases materials for devices are developed which have all the necess~ry 30 attributes for their intended purposes, such as, strength, optimal tr~n~mi~ion, flexibility, stability, and gas transport except that the surfaces of the materials will foul when in use. In these cases either new materials for the devices are developed or an attempt to change the surface characteristics of the materials is made.
In the specific case of contact or interocular lenses, particularly contact lenses, although many polymeric materials possess the necessary mechanical, oxygen permeation and optical pl Op~l lies required for lens m~nllf~r,ture, many potential contact lens materials are subject to rapid biological fouling due to the adhesion of proteins, lipids, and other 10 molecules present in the tear fluid surrounding the lens, and/or the surface energies of the materials are too low making the contact lenses too hydrophobic, and therefore not wettable by the tear fluid.
In light of the above considerations, a common approach utilized by various leseal ~;h~l ~ is to attempt to improve the biocompatibility of the 15 potential contact lens materials by application of a thin coating to these substrates. In theory such a coating would take advantage of the inherent favorable bulk mechanical, gas transport and optical properties of the polymer with the applied coating providing the required hydrophilicity and non-fouling properties. However, despite the plethora of such studies, it 20 is significant to note that, at present, not a single contact lens m~n~lf~lrer offers commercial products having coatings applied for this express purpose. Obviously, although the concept of simply applying a surface coating to remedy physical property deficiencies of a given polymer substrate has theoretical appeal, this has proven to be a totally 25 illusive goal in actual practice. The previous failures reflect the fact that, to be commercially viable, a c~lccessfill contact lens coating procedure must satisfy a myriad of rather stringent requirements. These requirements, as a minim~lm, include the following criteria: the coatings must be uniform and, ideally, pin-hole free; the coatings must be both 30 wettable and non-biologically fouling; the coatings should be e~nti~lly devoid of extractables and they must exhibit long-term chemical stability in aqueous saline solution, the coatings must exhibit excellent optical transparency in the visible region of the electromagnetic spectrum; the coatings must not co~ roll~ise the oxygen permeability (i.e., the so-called 5 DK value) ofthe po~mer substrate; and, in the case of reusable lenses, the coatings must exhibit sufficient abrasion reci.~t~n~e and chemical stability to with.~t~n-l repeated cle~ning~. In the latter case, cleaning procedures would include both exposure to harsh chemical cle~n~in~ agents and to mechanical rubbing actions.
European Patent Application 93810399.1, filed June 2, 19937 describes a complicated multi-step process to alter the surface of a contact lens material. The process requires a plasma treatment of the surface to generate surface free radicals, which are reacted with oxygen to form hydroperoxy groups, to which are graft polymerized an ethylenically 15 unsaturated monomer plus cross-linking agent, followed by a solution extraction period to remove unreacted monomers. This complex process requires the presence of inhibition agents during the monomer coupling reactions to prevent the homopolymerization of the ethylene monomers by free radicals generated during the thermal decomposition of the 20 hydroperoxy groups.
The plasma deposition of triethylene glycol monoallyl ether is reported in the German patent application DE19548152.6. Although it did not deal with contact lenses, it centered on surface modifications to reduce the adsorption of biological compounds. Coatings of such type 25 would be useful in re(l~lcing non-specific protein adsorption on certain biosensor surfaces. In this work, substrates for coating were located outside the plasma discharge zone and exceptionally low RF power densities were employed in an attempt to ..,il~i,..i,ç fragmentation ofthe polyethylene oxide units present in this monomer. Not unexpectedly, coatings deposited in the relatively non-energetic region upstream of the 5 plasma discharge and outside the luminous discharge zone were only weakly attache~ to the underlying substrates. Another problem encountered in this work was the low volatility of the monomer. This resulted in a req~ e~cnl for monomer heating to provide sufficient vapor for the plasma deposition process. However, even with heating, the vapor 10 pressures obtainable without initiating thermal decomposition of the monomer were too low to provide any sort of flow rate and/or reactor pressure controllability. Additionally~ the llnll.sll~lly low vapor pressure resulted in exceptionally low film depo~ition rates with accompanying film non-ul. r~ y. The co~tin~c obtained were not tested for adhesion under 15 flow conditions, nor were they subjected to any abrasive cleaning or rubbing actions. Simple soaking of the coating substrates in distilled water for relatively short periods (e.g., less than 48 hours) resulted in measurable changes in the chemical compositions of the coatings as revealed by XPS surface analysis of these coatings before and after the 20 simple water immersion test.
US Patents 3,008,920 and 3,070,573 reveal the use of plasma surface treatments to generate free radicals for subsequent peroxy group formation followed by the grafting of vinylic monomers to the polymer substrate. The control of the depth unlrol Illily and density of the grafted 25 coatings is a difficult problem encountered in these grafting experiments.

PCT/US90/05032 (Int. Publication #W091/04283) discloses increasing the wettability of polymeric contact lens materials synthesized from specific hydroxy acrylic units and vinylic siloxane monomers by grafting other molecules to the surface. The only examples of the 5 proposed grafting procedure described in this patent involve attachment of specific polyols by wet chemical procedures, but this patent does suggest that hydroxy acrylic units may be grafted to the specific hydroxy acrylic/siloxane polymeric materials by radiation methods. Additionally, radiation induced atta~hment by gaseous hydroxyl acrylic units was described in US Patent 4,143,949 as a means of improving surface hydrophilic character.
US Patent 4,143,949 discloses a process for putting a hydrophilic coating on a hydrophoic contact lens. The polymerization is achieved by subjecting a monomer, in gaseous state, to the influence of 15 electromagnetic energy, of a frequency and power sufficient to cause an electrodeless glow discharge of the monomer vapor.
US Patent 4,693,799 describes a process for producing a plasma polymerized film by pulse discharging. The process comprises forming a plasma pol~ e--~ed film on the surface of a substrate placed in a reaction 20 zone by subjecting an organic compound co..la~ -g gas to plasma polymerization utili~ing low temperature plasma formed by pulse discharging, in which the time of non-discharging condition is at least 1 msec, and the voltage rise time for gas breakdown is not longer than 100 msec. Specifically, the patent disclosed a process employing an 25 alternating current ("AC") electrical discharge operated in a pulsed mode to provide films having small coefficients of friction and high lubricity for use on m~gnetic tapes and discs. Althol1gh various c ,~l~elil,lental sets were carried out at di~lenl AC frequencies (from 2 to 2 Khz), all experiments within a given set were reportedly conducted at fixed plasma on to plasma off times. However, it provides no mention of the film compositional 5 control available via changes in the ratio of plasma on to plasma offtimes during pulsed plasma polymerization of an organic monomer; nor is any mention made of the adhesion of the deposited films with respect to soaking or abrasive cleaning actions.
US Patents 3,854,982 and 3,916,033 describe the use of liquid 10 coating techniques to improve the wettability of contact lens polymers.
In these procedures free radical polymerizable precursors, including hydroxy alkyl methacrylates, are attached to contact lenses by exposure to high energy radiation. However, these solution attachment processes provide poor control of the film thickness and these films exhibit poor~5 abrasion resistance, particularly when attached to polysilicone substrates.
The direct plasma treatment to improve the wettability of contact lenses is described in US Patent 3,925,178 in which an electrical or radio frequency discharge in water vapor is employed for that purpose. This non-coating treatment results in a relatively unstable hydrophilic surface 20 in which the wettability of the contact lens substrate decreases rapidly in time.
US Patent 57153,072 describes a method of controlling the chemical structure of polymeric films by plasma deposition and films produced thereby. The focus of this invention involves controlling the 25 telllpel~lure ofthe substrate and the reactor so as to create a temperature differential between the substrate and reactor such that the precursor CA 02243869 l998-07-22 molecules are plere~e~ ally adsorbed or condensed on the substrate either during plasma deposition or between plasma deposition steps.
Yasuda et al., "Some Aspects of Plasma Polymerization Investig~ted by Pulsed R.F. Discharge," Journal of Polymer Science:
Polymer Chemistry Edition, Vol. 15, pp. 81-97 (1977), discloses the polymerization of organic compounds in glow discharge (plasma polymerization) by using pulsed RF discharge ( 100 microsec. on, and 900 microsec. of ~. The effect of pulsed d;s~ ,e on polymer deposition rate, pressure change in plasma, ESR signals of free spins in both plasma polymer and substrate, and the contact angle of water on the plasma polymer surface were investaged for various organic compounds.
N~ etal., "PlasmaPolyrnerization of Tetrafluoroethylene,"
Journal of Applied Polymer Science, Vol. 23,pp. 2627-2637(1979), describes the plasma polymerization of tetrafluoroethylene in both continuous wave and pulsed radio frequency ("RF") discharges They reported that both polymer deposition rates and polymer structures were e~nti~lly identical when using continuous wave and pulsed RF discharge.
Lopez et al., "Glow discharge plasma deposition of tertraethylene glycol dimethyl ether for fouling-res;31alll biomaterial surfaces," Jozlrnal of BiomeG~calMaterialsResearch, Vo].26,pp 415-439(1992), discloses the glow discharge plasma deposition of tetraethylene glycol dimethyl ether onto glass, polytetrafluoroethylene and polyethylene. The monomer required heating, and low power to retain the ethylene oxide content of the plasma deposited coatings. As a result, no monomer flow rate controllability was available, and the films deposited at the lower RF
powers exhibited low stability to even simple overnight soaking in water.

The film adhesion to the polymeric substrate could be improved by carrying out the plasma deposition at higher power but this improved adhesion was achieved at the ~,Apense of loss of ethylene oxide fflm content and thus poorer non-fouling properties.
The need still remains for a composition which can be applied to the surface of a substrate to provide a film of coating that is uniform in thickness, pin-hole free7 optically ~l~nspa.cllL in the visible region of the magnetic spectrum7 perrneable to oxygen7 biologically non-fouling, relatively abrasive resict~nt, and wettable (hydrophilic).
SUM:MARY
The present invention provides a device Col~ g a substrate and a coating composition7 the coating composition being formed by the gas phase or plasma polymerization of a gas comprising at least one organic 15 compound or monomer7 the organic compound having the following structure:

Rl F13 R4 R6 C_~Y ) 0--C--C ~8 m l I
R2 ~ R5 R7 Jn m = 0-1; n = 0-67 25 where Y represents C=0;
Rl7 R27 R3, R4, R5, R6 and R' each independently represents:

OH, halogen, Cl- C4 alkyl, Cl - C4 alkene, Cl- C4 diene, Cl- C4 alkyne, C,- C4 alkoxy, or 0 C,- C4 alkyl halide;
and R8 represents:
H, halogen, C, - C4 alkyl, Cl- C4 alkene, C,- C4 diene, C,- C4 alkyne, Cl- C4 alkyl halide, Cl - C4 aldehyde, Cl- C4 ketone, Cl- C4 epoxide, Cl- C4 carboxylic acid, C,- C4 ester, -CH = CHR9, where R9 is H, halogen7 C, - C4 alkyl, C, -C4 alkyl halide, C, - C4 aldehyde, C, - C4 ketone, Cl-C4 alkoxyl, Cl - C4 epoxide, Cl - C4 carboxylic acid, or C, - C4 ester, or -ORI~, where Rl~ is H, halogen, C~ - C4 alkyl, Cl - C4 alkene, Cl - C4 diene, C, - C4 alkyne, C~ - C4 alkyl halide, Cl - C4 aldehyde, C~ - C4 ketone, Cl - C4 epoxide, Cl - C4 carboxylic acid, or C~ - C4 ester.
The polymerization of the present invention can be carried out using a pulsed discharge having a duty cycle of less than about 1/5, in 10 which the pulse-offtime is less than about 2000 msec and the pulse-on time is less than about 100 msec. The duty cycle can also be varied, thus the coating composition can be gradient layered accordingly.
The compound generally has low molecular weight, one or more ether link~es and at least one unsaturated carbon-carbon bond.
The devices of this invention have coating compositions which are uniform in thickness, pin-hole free, optically transparent in the visible region ofthe m~n.-.tic spectrum, permeable to oxygen, abrasive resi~t~nt, wettable and biologically non-fouling; therefore, making it possible to use substrates which, except for their surface characteristics, are well suited for their intended uses. In the specific case of contact or interocular lenses, particularly contact lenses, substrates which are not wettable by the tear fluid, which are subject to rapid biological fouling7 and/or have surface energies which are too low can be made useful when coated with the coating compositions of this invention.
The co~ting.C of the present invention are deposited on the surface of a solid substrate via plasma polymerization of at least one selected monomer. The plasma deposition of the present invention is achieved by either continuous wave ("CW") or pulsed plasmas. In the pulsed mode, the deposition is carried out of a fixed plasma duty cycle or, alternately, using a variable duty cycle pulsed plasma deposition.

BRI~,F DF.SCRIPTION OF THE DRAWINGS
Fig. 1 is an illustration of the variation in coating wettability with changes in RF duty cycles employed during deposition, while all other plasma reaction variables were being held constant.
Figs. 2 (a-d) are illustrations of the variation in coating composition with changes in RF duty cycles employed during deposition of plasma polymerized EO2V film at 200 watts, while all other plasma reaction variables were being held constant. The numerator given below denotes the plasma-on time, and the denominator given below denotes the plasma-off time, both in the unit of msec. High resolution C (1s) XPS
spectra are shown for films deposited at RF on/off ratio (in msec) of: (a) 1/20; (b) 1/50; (c) 1/100; and (d) 1/200.
Fig. 3 is an illustration of the variation in coating wettability with changes in RF peak power employed during deposition, at a constant plasma on/off ratio of 10/200 msec, all other plasma reaction variables were held constant.
Figs. 4 (a-b) are illustrations of the stability of EO2V plasma films to prolonged exposure to air. The EO2V plasma film was deposited at a plasma-on time of 10 msec and a plasma-offtime of 200 msec at 50 watts.
The spectra shown are C (1s) XPS results of these films: (a) after exposure to air for 10 months; and (b) fresh film.

Figs. 5 (a-e) are illustrations of XPS high resolution C ( 1 s) spectra of plasma polymerized EO2V films obtained from a series of runs carried out at a fixed plasma-on to plasma-offratio of 1 to 20 at 50W but with varying actual plasma-on and plasma-offpulse width: (a) 100 msec on and 2000 msec off; (b) 10 msec on and 200 msec off; (c) 1 msec on and 20 msec off; (d) 0.1 msec on and 2 msec off; and (e) 0.01 msec on and 0.2 msec off.

DET~l,F.n DESCRIPTION
The devices of this invention comprise non-fouling coating compositions. The coating compositions provide surfaces which are uniform, pin-hole free, wettable, devoid of extractables, and chemically stable. Further, the coatings exhibit excellent optical transparency in the visible region ofthe electromagnetic spectrum, are oxygen permeable, and 15 are abrasion resistant. These are desirable characteristics particularly for biomedical devices, such as stents, implants, catheters, etc., and particularly for contact or interoccular lenses. The coating of the present invention is also suitable for surface coating of magnetic recording media, m~gn~.tic tapes, m~n~ic discs, cell cultivation bed, carriers for diagnostic 20 reagents, biosensors, and artificial organs, such as artificial blood vessels, artificial bones, and others.
The substrates for the devices of this invention can comprise polymers, plastic, ceramics, glass, ~ilpni7ed glass, fabrics, paper, metals7 sil~ni7ed metals, silicon, carbon, silicones and hydogels. Some of the 25 more prere-l~d materials include those that are likely to be used for biomedical devices, such as silicone and silicone cont~ining compositions, (mixed blends and copolymers), polyurethanes, and hydrogels, and mixtures ofthese materials. The most plerer~ed substrate materials are those polymers used to make contact lenses, which do not support a stable tear film on the surface, such as silicones? silicone mixed blends, 5 alkoxylated methyl glucosides, silicone hydrogels, polyurethane-silicone hydrogels, and polysulfones. Illustrative silicones are polydimethylsiloxane polydimethyl-co-vinylmethylsiloxane, silicone rubbers described in US
Patent No. 3,228,741, silicone blends such as those described in US
Patent 3,341,490, and silicone compositions such as described in US
Patent 3,518,324. Useful silicone materials are the cross linked polysiloxanes obtained by cross linking siloxane prepolymers by means of hydrosilylation, cocondensation and by free radical mech~ni~m~.
Particularly suitable substrate materials are organopolysilioxane polymer mixtures which readily undergo hydrosilylation. Such prepolymers will 15 comprise vinyl radicals and hydride radicals which serve as cros~linking sites during chain extension and crosslinking reaction and are of the general formulation comprising polydihydrocarbyl-co-vinylhydrocarbylsiloxane and polydihydrocarbyl-co-hydrocarbylhydrogensiloxanes wherein the hydrocarbyl radicals are 20 monovalent hydrocarbon radicals such as alkyl radicals having 1-7 carbon atoms, such as, methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl; aryl radicals, such as phenyl, tolyl, xylyl, biphenyl; haloaryl, such as chlorophenyl and cycloalkyl radicals such as cyclopentyl, cyclohexyl, etc.
The more preferred materials are silicone hydrogels, particularly silicone-25 hydrogels formed from monomer mixtures comprising an acrylic-capped polysiloxane prepolymer, a bulky polysiloxanylalkyl (meth)acrylate monomer and hydrophilic monomers as described in US Patents 5,387,632; 5,358,995; 4,954,586; 5,023,305; 5,034,461; 4,343,927; and 4,780,515. Other p.~r~ d substrate materials comprise cyclic polyols of alkoxylated glucose or sucrose like those described in 5,196,458 and 5,304,584, and US Patent Application Serial No. 08/712,657, filed September 13, 1996. All of the patents cited above are incorporated herein by reference.
The pl~r~--ed coating compositions comprise gas phase deposited low molecular weight, high volatility organic compounds cont~inin~ one 10 or more ether linkages. Preferably, the molecules contain at least one unsaturated carbon-carbon bond in the molecule to assist in achieving polymerization, particularly under low energy gas-phase deposition methods. The groups having unsaturated carbon-carbon bonds are preferably vinyl compounds. The coating compositions are stable, and 15 adherent to a wide range of substrates while m~int~ining maximum integrity of the ether linkages present in these monomers. The weight average molec ll~r weights ofthe compounds are preferably less than 400, more preferably less than 300, and most preferably less than 200.

The p- ere - ed coating compositions are formed by the gas phase deposition and polymerization of a linear or branched organic compound or monomer having the following structure:

R1 R3 R4 R~

C G~Y ) O--C--C R~
m F ~2 ~ R5 R~ Jn ~0 m = 0-1; n = 0-6, where Y represents C=0;
Rl, R2, R3, R4, R5, R6 and R' each independently represents:
H, OH, halogen, Cl- C4 alkyl, Ct- C4 alkene, Cl- C4 diene, Cl - c4alkyne~
Cl- C4 alkoxy, or C,- C4~kyl halide;
and R8 represents:
H, halogen, Cl- C4 alkyl, Cl- C4 alkene, Cl- C4 diene, S C,- C4 alkyne, C,- C4 alkyl halide, C,- C4 aldehyde, C,- C4 ketone, Cl- C4 epoxide, 0 C,- C4 carboxylic acid, Cl- C4 ester, -CH = CHR9, where R9 is H, halogen, Cl - C4 alkyl, Cl -C4 alkyl halide, C, - C4 aldehyde, C, - C4ketone1 C,-C4 alkoxyl, C, - C4 epoxide, Cl - C4 carboxylic acid, or C, - C4 ester, or -ORI~, where R'~ is H, halogen, C, - C4 alkyl, C, - C4 alkene, C, - C4 diene, C,- C4 alkyne, C, - C4 alkyl halide, Cl - C4 aldehyde, C, - C4 ketone, C, - C4 epoxide, Cl - C4 carboxylic acid, or C, - C4 ester.
Examples of usable organic compounds include the following structures:
R'C(R")=C(R" ')-(OCH2CH2)n-OR
R'C(R'')=C(R''')-(OcH2cH2)n-R
R'C(R")=C(R" ')-C(O)-(OcH2cH2)n-oR~ " ' and R'C(R")=C(R"')-C(O)-(OCH2CH2)n-R""
where R', R", R"', and R"" independently represent H, a linear or branched alkyl having I to 4 carbons; preferably methyl or H; more preferably H; and n is 1 to 6; preferably 1 to 5; more preferably 2 or 3 5 For specifically ~l~r~lled monomers having the above structural formulas R', R", R"'~ and R"" are H; or R', R", R"' are H, and R"" is CH3; and n is 2 or 3, more preferably 2.
Example of more specific usable organic compounds include:

1 0 CH2=CH-(OCH2CH2)n-OH
CH2=CH-(OCH2CH2)n-OCH3 CH2=CH-(OCH2CH2)n-OCH=CH2 Other examples of usable organic compounds in the coating composition of this invention include:
di(ethylene glycol) divinyl ether (H2C=CHOcH2CH2)2O
di(ethylene glycol) vinyl ether H2C=CH(OCH2CH2)2OH
di(ethylene glycol) methyl vinyl ether H2C=CH(OCH2CH2)2OCH3 di(ethylene glycol) diacrylate (H2C=CHcO2cH2CH2)2O
di(ethylene glycol) ethyl ether acrylate H2C=CHC(O)(OCH2CH2)20c2H5 trimethylolpropane diallyl ether C2H5c(cH2ocH2cH=cH2)2cH2oH

tetra(ethylene glycol) propyl ether methacrylate H2C=C(CH3)CO2(0CH2CH2)4CH2CH2CH3 hexa(ethylene glycol) methyl ether methacrylate H2C=C(CH3)C02(0CH2CH2)6CH3 The more plerelled organic compounds include di(ethylene 5 glycol) divinyl ether, di(ethylene glycol) methyl vinyl ether, di(ethylene glycol) ethyl ether acrylate, and trimethylolpropane diallyl ether. The most plt;re.led compound is di(ethylene glycol) vinyl ether.
The coating compositions can comprise the polymerization of substantially a single organic compound or of a mixture of organic 10 compounds with or without the addition of cross-linking agents. The single and the mixture of organic compounds p~ere,~ly are selected from the organic compounds described above.
The selection of compounds and method of application of the compounds to the surface of the substrate preferably provide a coating 15 composition in which the outermost layer of the coating has a ratio of carbon-oxygen bonds to carbon-carbon bonds of greater than 1:1, more p.er~.~bly greater than 1.5:1, and most preferably greater than 2:1, even more prer~;--ed is greater than 2.5:1. The coating compositions having a higher ratio of carbon-oxygen bonds to carbon-carbon bonds are 20 prere~ed, because of improved non-fouling and higher wettability characteristics.
One method for depositing the coating compositions on the substrates is by gas phase deposition, because it provides uniform coating compositions. Gas phase deposition means by any method the gaseous 25 monomers are attached to the solid substrate as a surface coating. Gas phase depositions include plasma and photochemical induced CA 02243869 l998-07-22 ~ 19 polymerizations. Plasma induced polymerizations or plasma depositions are polymerizations due to the generations of free radicals caused by passing an electrical discharge through a gas. The electrical discharge can be caused by high voltage methods, either alternating current ("AC") 5 or direct current ("DC"), or by electromagnetic methods, such as, radio frequency ("RF") and microwave. Alternatively, the coating process can be carried out using photochemical inlluced polymerizations as provided by direct absorption of photons of sufficient energy to create free radicals and/or electronically excited species capable of initiation of the 10 polymerization process.
One preferred method of one-step gas phase deposition is by plasma polymerization, particularly radio frequency plasma polymerization, in which the coating is deposited on the surface of the substrate via direct monomer polymerization. This process will be 15 described herein. It is more fully described in U. S. Patent Application Serial No. 08/632,935, incorporated herein by reference. Additional descriptions can be found in PanchPling~m et al., "Molecular Surface Tailoring of Biomaterials Via Pulsed RF Plasma Discharges,"
J.Biomater. Sci. Polymer Edn., Vol. 5, pp. 131-145 (1993), and 20 Panr.h~ling~nn et al, "Molecular Tailoring of Surfaces Via Pulsed RF
Plasma Depositions," Journal of Applied Science: Applied Polymer Symposium, 54, 123-141 (1994), incorporated herein by reference. In this method, coatings are deposited on solid substrates via plasma poly~ ion of selected monomers under controlled conditions. The 25 plasma is driven by RF radiation using coaxial external RF electrodes located around the exterior of a cylindrical reactor. Substrates to be coated are preferably located in the reactor between the RF electrodes;
however, substrates can be located either before or after the electrodes.
The reactor is evac~l~ted to background pressure using a rotary vacuum pump. A fine metering valve is opened to permit vapor of the monomer 5 (or monomer mixtures) to enter the reactor. The pressure and flow rate of the monomer through the reactor is controlled by adjustments of the metering valve and a butterfly control valve (connected to a pressure controller) located dowl~lJ eam of the reactor. In general, the monomer reactor pressures employed range from applox~,.a~ely 50 to 200 mili-10 torr, although values outside this range can also be utilized. It isplere..ed that the compounds have sufficiently high vapor pressures so that the compounds do not have to be heated above room temperature (from about 20 to about 25~C) to vaporize the compounds. Although the electrodes are located exterior to the reactor, the process of the 15 invention works equally well for electrodes located inside the reactor (i.e.
a capacitively coupled system).
The chemical composition of a film obtained during plasma deposition is a strong function of the plasma variables employed, particularly the RF power used to initiate the polymerization processes.
20 It is pr~re~ed to operate the plasma process under pulsed conditions, coml)ared to continuous wave ("CW") operation, because it is possible to employ reasonably large peak powers during the plasma on initiation step while m~int~ining a low average power over the course of the coating process. Pulsing means that the power to produce the plasma is 25 turned on and off. The average power under pulsing is defined as:

..

AveragePower = pl~m~-ontime X PeakPower plasma-on time + plasma-off time For example, a plasma deposition carried out at a RF duty cycle of 10 msec on and 200 msec offand a peak power of 25 watts corresponds to an average power of 1.2 watts. The Peak Power is preferably between about 10 and about 300 watts.
The formal definition of duty cycle is defined as the ratio of the plasma on time (i.e. discharge time) to a sum of the plasma-on time and the plasma-offtime (i.e. non-discharge time), as represented below:

plasma-on time Duty cycle plasma-ontime + plasma-offtime However, for convenience, the plasma on to plasma off times are frequently cited herein as a simple ratio of on to off time, both times employing the same scale (i.e. milli~econds or microseconds).
The workable range of duty cycle is less than about 1/5, the preferred range is between about 1/10 and about 1/1000, and the more plere--ed range is between about 1/10 and about 1/30. The plasma-on time should be larger than about 1 ,usec, preferably in the range of between about 10 ,(lsec and about 100 msec, and more preferably in the range of between about 100 ,~sec and about 10 msec. The plasma offtime, i.e. the non-discharge time, should be larger than about 4 ,usec, preferably in the range of between about 100 ,usec and 2000 msec, and more preferably in the range of between about 200 ,~sec and about 100 msec. The total deposition time varies depending on the monomer and the conditions used. Typically, the deposition time can vary from about 0.5 min to about 3 hours.
Pulsed plasma deposition permits use of relatively high peak powers while simlllt~neously I~lAil~l~ining relatively low average powers which provides for the retention of monomer functional groups. Coating compositions deposited under low average power pulsed conditions tend to be more adhesive to a given substrate when compared to films 10 deposited at the same average power but under CW operation. For a given average power7 the momentary high peak power available under pulsed conditions appal e,.~ly assists in obtaining a stronger grafting of the film to the substrate than that obtained under the same average power CW conditions.
For a given RF peak power, an increased retention of the ether content (C-O functionality) of the plasma generated coating is observed as the plasma duty cycle is reduced when working with a given monomer. Alternatively, the chemistry of the coating composition can be varied under pulsed conditions by working at a single plasma duty cycle but varying peak powers. There is an increased incorporation of C-O functionality in coating compositions as the peak power is decreased. Surprisingly, the plasma generated film composition can be varied by ch~nging the plasma on to plasma offpulse widths, at a fixed ratio of plasma on to plasma off times and at a fixed RF peak power.
Although the film deposition mode described is one of RF plasma polymerization, those familiar in the art will recognize that other poly~ fi~lion methods (e.g., microwave plo~m~ photo-polymerization, ionizing radiation, electrical discharges, etc.) could also be adapted for this purpose.
The chemical composition of the films of this invention can be varied during pulsed plasma deposition, by varying the peak power and/or the duration ofthe plasma on and plasma offpulse widths. This excellent film chemistry controllability is achieved without recourse to mod~ tin~ the temperature of the substrate during the actual coating process. To produce a coating composition with the prerel I ed ratio of 10 C-O functionality to C-C functionality, it is prere.-ed that the average power of the pulsed plasma deposition is less than 100 watts, more prere- ably less than 40 watts, most preferably less than 10 watts. The highest ratios of C-O functionality to C-C functionality can be obtained when the average power is 1 watt and less which provides the most non-15 fouling and wettable coating compositions.
However, as those skilled in the art will recognize, the actual effect of peak power input on film composition is dependent on the reactor volume (i.e. power density). In the present invention, the reactor volume is approximately 2 liters. Obviously, if a smaller reactor were 20 employed, the same film compositioned changes reported herein would be achieved at lower peak power inputs. Other reaction variables which would infll~ence peak power inputs are reactor pressure and monomer(s) flow rates. If larger reactor volumes were employed, the same film compositional variations could be achieved using higher power input.
The use of lower average power conditions increases the presence of functional groups, e.g. ether units, in the coatings, but the less energetic deposition conditions at lower average power may result in poorer adhesion of the polymer film to the underlying substrate. Thus, the plasma coating process involves somewhat of a compromise between retention of monomer integrity in the plasma generated film and the 5 strength ofthe adhesion between the coating and the solid substrate. In the case of biomedical devices and contact lenses, the adhesion and overall stability of the coating composition to the lens substrate is an extremely important consideration.
One method of applying the coating compositions to the substrate 10 of the present invention is by pulsed plasma coupled with gradient layering. The duty cycle can be varied? thus creating variable duty cycle.
The method can be used to maximize the adhesion of the coating composition and the functionalities present in the coating composition.
Films deposited under low average power pulsed conditions tend to be 15 more adhesive to a given substrate when compared to films deposited at the same average power but under CW operation. For a given average power, the momentary high peak power available under pulsed conditions assists in obtaining a stronger grafting of the film to the substrate than that obtained under the same average power CW
20 condition. This stronger grafting under pulsed conditions is repeated with each plasma on cycle. The better grafting of the film to the substrate ~l~ ed under pulsed conditions can be even further enhanced by combining the pulsed deposition with a gradient layering technique.
This method is described further in U. S. Patent Application 08/632,93 5, 25 which is incorporated herein by reference. In this process, an initial high power, high plasma duty cycle is employed to graft the plasma generated coating composition tightly to the underlying substrate. The plasma duty cycle is subsequently progressively decreased in a systematic manner, with each decrease reslllting in an increased retention of the C-O
functionality in the coating. In this way, the successive plasma deposited S films are tightly bonded to each other. The process is tern in~ted when the exterior film layer has reached the desired composition. The succession of thin layers, each differing slightly in composition in a progressive fashion from the p,c;cedin~ one, results in a significantly more adhesive composite coating composition bonded to the substrate than 10 coatings deposited without adjusting the deposition conditions under a relatively lower plasma duty cycle Gas-phase deposition, particularly plasma depositions, provide coating compositions of s~ tially uniform thickness. The thicknesses of the coating composition could be between 5 A and 5 ,L~m, more pl~rt;l~bly between 50 A and 1 ,~m, and most preferably between 100 A
and 0.1 ,~lm. The uniform film thickness and controllability of the deposition method can be contrasted with thickness controllability problems encountered using previously disclosed methods. Using the RF
pulsed plasma deposition provides linearity of the thickness of the 20 coating composition with deposition time for a given plasma duty cycle and fixed monomer pressure and flow rate.
The coatings of this invention increase the hydrophilic character ofthe surface ofthe substrates, particularly with substrates that are more hydrophobic (e.g., polysiloxanes). The extent of hydrophilicity 25 introduced during the plasma process was observed to increase as the oxygen content of the plasma generated coating compositions increased.

The wettabilities of the substrates employed were measured before and after plasma coating using both static and dynamic water contact angle measurements. In general, the coatings applied serves to increase the hydrophilic character of the surface, particularly with 5substrates that are more hydrophobic (e.g., polysiloxanes). The extent of hydrophilicity introduced during the plasma process was observed to increase as the oxygen content of the plasma generated films increased.
The stability of the surface wettability was examined in several ways, including exposure to aqueous solution flow and to abrasive 10r~le~n:ng and rubbing tests. Additional s~lcces~fill stability testing of the coated substrates involved autoclaving for five cycles at 121~ C for 30 minutes each cycle. The examples below include the results of these tests.
The non-fouling character of the coating compositions were 15measured using adsorption studies with radioactively labeled proteins, as well as by total protein assay. In general, decreases in protein adsorption were observed for coated polymer substrates as compared to uncoated polymer substrate as shown in the examples which follow.
The optical transparency of the coating compositions was 20measured spectrophotometrically at wavelengths ranging from 800 to 200 nm. The plasma coating compositions of the invention exhibited consistent excellent transparency over the entire region of the visible spectrum (i.e., from 780 to 380 nm) with photon absorption be~inning to occur around 370 nm in the near W region. The absorption increases 25sharply over the interval from 370 to 200 nm, as revealed by samples deposited on quartz plates.

The oxygen permeability was measured using the Fatt Method (Patt, I. et al, International Contact Lens Clinic, 9(2), pp. 76-88 1992).
In general, the oxygen permeabilities (reported as DK values) of the polymeric substrates were not measurably decreased by the presence of 5 the plasma film on the surface.
The substrates with coating compositions of this invention are suited for contact lenses and other biomedical devices. The coating compositions exhibit good adhesion, high wettability, high oxygen permeability, and excellent transparency in the visible region of the 10 electromagnetic spectrum when deposited on polymer substrates. The adhesion ofthe coating compositions to these substrates are sufficiently strong to resist del~min~tion.
Thus the coating composition applied by a one-step and all-dry process of this invention satisfies the stringent criteria listed above to 15 improve the biocon-phlibility of contact lenses. The emphasis in this invention has been placed on the contact lenses; however, those skilled in the art will recognize that the highly wettable, biologically non-fouling, transparent coatings of this invention are useful for various other applications (e.g., biomedical devices, biosensors, detectors deployed in 20 marine en~ nel.Ls, membranes, tissue culture growth, implants, etc.).
A particularly surprising result obtained in the present study is the lt;lll~uk~bly stable and good biologically non-fouling properties ofthese coatings despite the very low molecular weights of the monomers employed to form the coating compositions. This observation is contrary 25 to many previous studies which conclude that relatively large polymeric molecules cont~ining ether linkages are required in order to observe the non-fouling effect.
The approach of the present invention represents an ~Imlsll~lly simple, one-step coating process which could be conveniently coupled 5 with a plasma based sterilization procedure to provide large scale fabrication polyethyleneglycol ("PEG") modified surfaces. Additional il~he~ L advantages of a plasma based approach would include successful surface modifications being less dependent on the composition and geometry of the solid substrates. Tetraethylene glycol dimethyl ether, CH3O(CH2CH2O)4CH3, and tri(ethylene glycol) monoallyl ether, CH2 =
CHCH2(OCH2CH2)3OH, were studied as potential monomers for plasma polymerized PEG surfaces. For example, tetraethylene glycol dimethyl ether was plasma deposited to yield surfaces with high short-term rÇc~ n~e to biomolecular absorption, as demonstrated with both plasma 15 protein and cellular adsorption studies. However, simple overnight soaking of plasma coated substrates in water resulted in major chemical compositional changes as revealed by XPS analysis of surfaces before and after soaking. Similarly, plasrna polymerization of tri(ethylene glycol) monoallyl ether produced coatings having good short term 20 resi~t~nce to biofouling but poor stability towards soaking or exposure to flowing aqueous solutions. Adhesion of the plasma films to the polymeric substrates could theoretically be improved by carrying out the plasma deposition at higher power but this improved adhesion was achieved at the expense of loss of ethylene oxide film content and thus 25 poorer non-fouling properties.

Although not wishing to be bound by any particular postulate, it is speculated that the gas phase deposition process, particularly the pulsed plasma deposition process of the present invention results in an lmllsl~lly efficient stacking of ether 1 ~'-~ec on the substrate surface thus 5 providing a high surface density of such groups. This high surface density is, in turn, extremely effective in preventing the adsorption of biological molecules onto the surface while simultaneously creating a relatively polar environment to adsorb water molecules, thus providing high surface wettability. When the coating process is used for contact 10 lenses, the coating composition on the contact lens substrate should provide a low water contact angle. For contact lenses, it is preferred that the coating compositions have an advancing sessile drop water contact angle of less than 85 ~, more pl~rela~ly less than 65 ~, most preferably less than 45~.
15 Example 1 Di(ethylene glycol) vinyl ether (EO2V) was plasma deposited on a DacronTM polyester substrate under pulsed plasma deposition conditions using an RF on/off cycle of 10 msec on and 200 msec off at 100 W peak power. A 1000 A thick film was deposited during the 20 20 minute run. X-ray photoelectron spectroscopy (XPS) analysis of this film revealed significantly more carbon atoms bonded to oxygen than to other carbon atoms. A sample prepared in this manner was then subjected to 65 hours of a constant 40 ml/min flow of phosphate buffer solution (PBS) at pH of 7.4. The sample was subsequently vacuum dried 25 and re-analyzed by XPS. The relative concentration of C-O to C-C
groups present on the surface had actually increased slightly revealing negligible surface modification during the buffer flow7 indicating the durability of the coating composition.
Example 2 A sample prepared as described in Example 1 was deposited on 5 a silicone contact lens substrate. The advancing water contact angle was measured on the polysiloxane before and after plasma treatment. The advancing sessile drop water contact angle of 98~ observed on the untreated surface had decreased to 58~ a~[er surface coating by the plasma, indicating an increased wettability due to the coating 10 composition. Subsequent soaking of the coated sample in PBS buffer solution for several days resulted in essent~ y negligible change in the advancing water contact angles, indicating the durability of the coating composition. See, TABLE I. The ratio 10/200 in TABLE I indicates 10 msec plasma-on time and 200 msec plasma-offtime.
TABLE I
Contact Angle Vari~tion for EO2V Films on Silicone Contact Lenses as a Function of Soakin~ T;me in PBS Ruffer Solution 20Coating Condition Fresh 5 hrs 10 hrs 48 hrs 96 hrs 240 hrs Film 10/200, lOOw, 15 min 58 60 66 63 60 60 10/200, lOOw, 30min 58 62 58 62 60 60 Example 3 Samples were prepared as described in Example 1 on a polyethylene substrate, but at various plasma on/off cycles of on-time in msec/off-time in msec of 1/20, 1/50, 1/100, and 1/200 at a peak power 5 of 200 watts. Analysis ofthese films by water contact angle goniometry revealed progressively lower advancing water contact angles corresponding to lower RF plasma duty cycles employed during the coating procedure. (Fig. 1) The increased wettability observed with decreasing average power during film formation is correlated with high 10 resolution C (1s) XPS spectra ofthese films which show increasing C-O
versus C-C film content with decreasing RF duty cycle employed during film formation. (Figs. 2 (a-d)).
Another set of samples were prepared as described in Example I
on a DacronTM substrate but at various plasma peak power of 100 watts, 50 watts, 25 watts and 10 watts and at a cycle of 10 msec on and 200 msec off. Analysis of these films by water contact angle goniometry revealed progressively lower advancing water contact angles corresponding to lower RF plasma peak power employed during the coating procedure. (Fig. 3). The increased wettability observed with 20 decreasing average plasma energy correlated with XPS analysis of these films which showed increasing C-O versus C-C film content with decreasing RF peak power employed during film formation.
Example 4 The monomer CH2=CH-(OCH2CH2)2OCH3 (Methyl EO2V) was 25 plasma deposited on a polysiloxane substrate using the same RF duty cycle and peak power employed in Example 1. The resulting film revealed slightly higher C-O content relative to C-C bonds than obtained in Example 1. Additionally, these films exhibited an advancing water contact angle which was approximately 5~ less (i.e., more hydrophilic) than that obtained in Example 2.
5 Example 5 A coating was prepared from the monomer di(ethylene glycol) divinyl ether [(H2C=CHOCH2CH2)20] using the same plasma deposition conditions employed in Fx~mples 1 and 4. The advancing water contact angle for this sample was virtually identical to that obtained for the 10 methoxy compound of Example 4. Both the methoxy and divinyl samples of Examples 4 and 5 revealed less hysteresis in terms of advancing versus receding water contact angles than observed for the sample of Example 2, indicating that the surface molecules are less mobile, and therefore less likely to foul. Further, the contact angles 15 indicate that the surfaces are wettable.
Example 6 A sample was prepared in which the monomer of Example 1 was plasma deposited onto a DacronTM sample using an RF on/offcycle of 10 msec on and 200 msec off and a peak power of 50 watts. Protein 20 adsorption using l25I-labeled albumin and fibrinogen was conducted using uncoated and plasma coated DacronTM samples. The protein adsorption on the coated samples was dr~ tic~lly reduced (i.e., by a factor in excess of 20) when compared to adsorption on the uncoated DacronTM
control. The differences were particularly acute in contrasting protein 25 retained on these surfaces after gently washing with 1% sodiumdodecyl sulfate (SDS) solution. The retained protein was barely detect~ble on the plasma treated surfaces, being several orders of magnitude less than that retained on the uncoated DacronTM controls. This example indicates both the durability and non-fouling properties of the coating composition of the invention Another sample was prep~ed in which the monomer of Example 1 was plasma deposited onto a DacronTM sample using an RF duty cycle of 10 msec on and 50 msec offand a peak power of 100 watts. The protein adsorption on the coated samples was increased (i.e. by a factor of about 1.2) when compared to adsorption on the uncoated DacronTM
10 control. This ~x~ le shows that the non-fouling properties of coatings made at high RF duty cycle (1/5) are not as desirable as those coatings made at low RF duty cycle.
Example 7 Samples were prepared as described in Example 1. These 15 samples were then subjected to abrasive cleaning processes using standard commercial contact lens cleansers following the lens cleaning instructions provided by the m~nllf~cturers. Negligible changes in surface wetting were observed in comparing coated samples before and after the abrasive cleaning processes as measured by the repeated 20 dynamic water content angle method.
Example 8 Samples were prepared as described in Example I and were deposited on a silicone contact lens. These samples were subjected to water vapor autoclaving at 121 ~C for 5 successive sterilizing cycles, each 25 of 30 mim~tes duration. Negligible ch~n~s in the surface wettabilities were observed in comparing samples before and after autoclaving, indicating the durability of the coating compositions.
Example 9 Silicone contact lens substrates were coated using a gradient 5 layering technique. In this process an initially high duty cycle plasma deposition was carried out for 30 seconds at a power of 100 watts and plasma on/offcycle of 10 msec on and 20 msec off. Subsequently the plasma offtime was increased sequentially to values of 50, 100, 150 and 200 msec. At each onloffcycle, the plasma deposition was operated for several mimltes with the final 10/200 deposition being carried out for 5 minutes. The resl lltin~ gradient layered film structure exhibited exceptional abrasion resistance and stability towards long term (i.e., 15 days) soaking under rapid (40 ml/min) flow conditions in PBS buffer at a pH of 7.2. XPS (X-ray Photoelectron Spectroscopy) analysis of the surface composition of this layered structure revealed a high resolution C(ls) spectrum having ei~ctollti~lly the same composition as that observed from a direct 10 msec plasma on and 200 msec plasma offdeposition at 100 watts peak power.
Example 10 The increased wettability of substrates having the coating composition of this invention are shown by this example.
Water contact angle measurements were measured using both static (sessile drop) and dynamic (modified Wilhelmy plate) methods for coated and uncoated substrates. Static measurements were made using distilled water and a Rame'-Hart goniometer. Dynamic measurements were made using substrates immersed in succession in three solutions, namely: saline; protein; and then again in saline. The protein solution contained a mixture of albumen, Iysozyme and immunoglobin.
Advancing and receding contact angles were measured under both static and dynamic conditions. In the static 1~pel i"lents, the advancing contact 5 angles were measured at 4 ',lL volume intervals as the water droplet was increased from 4 to 16 ~L. Receding angles were recorded as the droplet size was reduced from 16 to 4 ',lL, again at 4 IlL intervals. The dynamic measulemellts were each repeated four times as the sample was cycled up and down, with the average value being recorded for these four I0 measurements.
Hydrophobic polymeric substrates (e.g. polyethylene;
polyethylene terephth~l~te) having static water contact angles in excess of 85~ were employed. After plasma coating with coating compositions of this invention, the wettability of the surfaces increased, evidenced by 15 the large decreases in the water contact angles. No substrate dependence was observed in achieving the improved wettabilities.
Table II provides results of static sessile drop water contact angles observed after tre~tm~nt of an initially hydrophobic polymeric substrate with plasma deposited films by plasma deposition of di(ethylene 20 glycol) vinyl ether monomer. As show in Table II, all samples revealed a decrease in water contact angles from the uncoated substrate whose advancing angle was in excess of 85~ Also as shown in Table II, the exact extent of increased surface wettability is a function of the plasma deposition conditions, with the wettability generally increasing as the 25 average power employed during coating was reduced , . , , ~v ,.

TABLE II
STATIC CONTACT ANGLES

Plasma RF CyclePealc Average Advaslcing Receding S Coated Du~ TimesPower Power Angle Angle ON, msec OFF,msec (W) (W) Yes 10 200 100 4.76 60 33 Yes 10 200 50 2.38 46 30 Yes 10 200 25 1.~9 3() 15 Yes 1 20 2009.52 60 48 1 0 Yes 1 50 200 3.92 46 33 Yes 1 100 200 1.98 33 22 Yes 1 200 200 0.995 32 23 No >85 The dynamic (i.e. modified Wilhelmy plate) contact angle measurements are listed in Table III for samples prepared by plasma deposition of di(ethylene glycol) vinyl ether as described above, using an RF on/off cycle of 10 msec on and 200 msec off and 100 watts peak power. The advancing and receding contact angles are shown for measurements in the three separate solutions7 with these measurements being carried out in succession. As in the static measurements, the dynamic studies reveal con~i~tçntly lower contact angles for the coated substrates with the surface wettability being appreciably higher for samples immersed in the protein co~ inin~ solutions.
Overall, the water contact angle measurements illustrate the L~ r~ ion ofthe initial hydrophobic polymer surface to a hydrophilic wettable surface as provided by the plasma deposited coatings.

TABLE III
DYNAMIC CONTACT ANGLES

Solution Advancing Angle Receding Angle Saline 61 43 Protein in Solution 25 2 Saline 45 43 Example 11 Static (sessile drop) water contact angles, both advancing and receding, were measured on polymeric substrates, plasma coated with different monomers. The monomers employed were diethylene glycol vinyl ether (EO2V), diethylene glycol rnethyl vinyl ether (Methyl EO2V), diethylene glycol divinyl ether (Divinyl EO2V), and diethylene glycol 15 ethyl ether acrylate (Acrylate EO2V). These four coatings are given in the table which follows. All plasma films were deposited under the irl~nti~l RF on/offcycle of 10 msec on and 200 msec offand 100 watts peak power. In each case, the uncoated hydrophobic polymeric surface (initially an advancing angle in excess of 85~) was transformed to a highly 20 wettable hydrophilic surface by the plasma deposition. As shown in Table IV, the hydrophilicity of the res--lting surfaces were relatively constant with each of these monomers, with the degree of hysteresis between advancing and receding contact angles being significantly reduced for the two monomers not terminated in -OH groups (i.e. Methyl 25 EO2V and Divinyl EO2V).

The results obtained clearly illustrate the utility of employing the coatings ofthis invention to ll~n~roll~ the surface ofthe substrate from hydrophobic to hydrophilic.

TABLE IV
STATIC CONTACT ANGLES

MonomerAdvancing Angle Receding Angle Methyl EO2V 53 47 Divinyl EO2V 55 49 Acrylate EO2V 65 47 These examples show that the coating compositions of this invention can 15 be used to provide non-fouling and hydrophilic surfaces to substrates, which have bulk properties which are well-suited for particular applications. These coatings are particularly suited for biomedical applications and in particular for contact or interoccular lenses.
The invention has been described in detail with particular 20 reference to pl~rel-ed embodiments thereof, but it will be understood that variations and modifications can be effected with the spirit and scope of the invention.
Example 12 A sample on a silicon substrate was prepared from the monomer 25 of Example 1 using plasma deposition conditions of an RF on/off cycle of 10 msec on and 200 msec offa peak power of 50 watts. XPS analysis of this film revealed significantly more carbon atoms bonded to oxygen ., .. . ., . .. "", , ,.,, . . ,. . . . . . .. I ~.. ,. ~ . . .. . ......

than to other carbon atoms. A sample prepared in this manner was then exposed to air for 10 months for a long term stability experiment. The sample was then re-analyzed by XPS. The relative concentration of C-O
to C-C groups present on the surface had actually increased slightly 5 revealing negligible surface modification during air exposure, indicating the durability of the coating composition. (Figs. 4 (a-b)).
Example 13 Samples were prepared as described in Example I on quartz substrate. Analysis of these films by UV-VIS spectrometry showed 10 complete light tr~n~mi~sion over the entire visible region of the electromagnetic spectrum, 380 to 800 nm.
Example 14 Samples were prepared as described in Example 1 on DacronTM
substrates at a fixed plasma-on to plasma-off ratio of l to 20 but with 15 actual plasma-on and plasma-off pulse widths varying from 100 msec to 10 ~lsec and 2000 msec to 200 ~Isec, respectively. All runs were carried out at a peak power of 50 watts and at constant flow rate and reactor pressure of the EO2V monomer. XPS high resolution C(l s) spectra showed that a variation in the percent retention of the ether content of 20 the plasma generated films was observed in these experiments with dilIelel-l plasma-on and plasma-offpulse widths but all runs carried out at a constant average power of 2.4 watts. (Figs. 5 (a-e)).
Example 15 Samples are prepared as described in Example 1 using a 10 ~Isec 25 plasma-on time and a 400 ~lsec plasma-offtime. Again, highly wettable surfaces can be obtained cont~ining high C-O bonds relative to C-C

bonds, thus illustrating the production of usable films under ultrashort (i.e. microsecond) pulse times.

Claims (22)

What is Claimed:

1. A device comprising a substrate and a coating composition, said coating composition being formed by the gas phase polymerization of a gas comprising at least one organic compound, said gas phase polymerization being pulsed, having a duty cycle of less than about 1/5, in which the pulse-on time is less than about 100 msec and the pulse-off time is less than about 2000 msec, and said organic compound having the following structure:

m = 0-1 ; n = 0-6, where Y represents C=0;
R1, R2, R3, R4, R5, R6 and R7 each independently represents:
H, OH:, halogen, C1 - C4 alkyl, C1 - C4 alkene, C1 - C4 diene, C1 - C4 alkyne, C1 - C4 alkoxy, or C1 - C4 alkyl halide;
and R8 represents:
H, halogen, C1 - C4 alkyl, C1 - C4 alkene, C1 - C4 diene, C1 - C4 alkyne, C1 - C4 alkyl halide, C1 - C4 aldehyde, C1 - C4 ketone, C1 - C4 epoxide, C1 - C4 carboxylic acid, C1 - C4 ester, -CH = CHR9, where R9 is H, halogen, C1 - C4 alkyl, C1 - C4 alkyl halide, C1 - C4 aldehyde, C1 - C4 ketone, C1 - C4 alkoxyl, C1 - C4 epoxide, C1 - C4 carboxylic acid, or C1 - C4 ester, or -OR10, where R10 is H, halogen, C1 - C4 alkyl, C1 - C4 alkene, C1 - C4 diene, C1 - C4 alkyne, C1 - C4 alkyl halide, C1 - C4 aldehyde, C1 - C4 ketone, C1 - C4 epoxide, C1 - C4 carboxylic acid, or C1 - C4 ester.

2. The device of claim 1, wherein said organic compound is selected from the group of consisting of the following structural formulas:
R'C(R'')=C(R''')-(OCH2CH2)n-OR'''' and R'C(R'')=C(R''')-(OCH2CH2)n-R'''' where R', R'', R''', and R'''' each independently represents H, a linear or branched alkyl having 1 to 5 carbons; and n is 1 to 5.

3. The device of claim 1, wherein said duty cycle is from about 1/10 to about 1/1000, and the pulse-on time is from about 1 µsec to about 100 msec, and the pulse-off time is from about 10 µsec to about 2000 msec.

4. The device of claim 1, wherein said organic compound is di(ethylene glycol) vinyl ether, di(ethylene glycol) divinyl ether, or di(ethylene glycol) methyl vinyl ether.

5. The device of claim 1, wherein said substrate is a contact lens.

6. The device of claim 1, wherein said gas phase polymerization is high voltage discharge, radio frequency, microwave;
ionizing radiation induced plasma polymerization; or photo induced polymerization, or a combination thereof.

7. The device of claim 1, wherein said coating composition is gradient layered by systematically decreasing the duty cycle of said gas phase polymerization.

8. A device comprising a substrate and a coating composition, said coating composition being formed by the gas phase polymerization of a gas comprising at least one organic compound, said gas phase polymerization being pulsed, having a variable duty cycle each being of less than about 1/5, in which the pulse-on time is less than about 100 msec and the pulse-off time is less than about 2000 msec, and said organic compound having the following structure:

m = 0-1; n = 0-6, where Y represents C=0;
R1, R2, R3, R4, R5, R6 and R7 each independently represents:
H, OH, halogen, C1 - C4 alkyl, C1- C4 alkene, C1- C4 diene, C1- C4 alkyne C1- C4 alkoxy, or C1- C4 alkyl halide;
and R8 represents:
H, halogen, C1 - C4 alkyl, C1 - C4 alkene, C1 - C4 diene, C1 - C4 alkyne, C1 - C4 alkyl halide, C1- C4 aldehyde, C1 - C4 ketone, C1 - C4 epoxide, C1 - C4 carboxylic acid, C1 - C4 ester, -CH = CHR9, where R9 is H, halogen, C1 - C4 alkyl, C1 - C4 alkyl halide, C1 - C4 aldehyde, C1 - C4 ketone, C1 - C4 alkoxyl, C1 - C4 epoxide, C1 - C4 carboxylic acid, or C1 - C4 ester, or -OR10, where R10 is H, halogen, C1- C4 alkyl, C1 - C4 alkene, C1 - C4 diene, C1 - C4 alkyne, C1 - C4 alkyl halide, C1 - C4 aldehyde, C1 - C4 ketone, C1 - C4 epoxide, C1 - C4 carboxylic acid, or C1 - C4 ester.

9. The device of claim 8, wherein said organic compound is selected from the group of consisting of the following structural formulas:
R'C(R'')=C(R''')-(OCH2CH2)n-OR'''' and R'C(R'')=C(R''')-(OCH2CH2)n-R'''' where R', R'', R''', and R'''' each independently represents H, a linear or branched alkyl having 1 to 5 carbons; and n is 1 to 5.

10. The device of claim 8, wherein said duty cycles vary from about 1/10 to about 1/1000, and the pulse-on time varies from about 1 µsec to about 100 msec, and the pulse-offtime varies from about 10 µsec to about 2000 msec.

11. The device of claim 8, wherein said organic compound is di(ethylene glycol) vinyl ether, di(ethylene glycol) divinyl ether, or di(ethylene glycol) methyl vinyl ether.

12. The device of claim 8, wherein said substrate is a contact lens.

13. The device of claim 8, wherein said gas phase polymerization is high voltage discharge, radio frequency, microwave;
ionizing radiation induced plasma polymerization; or photo induced polymerization; or a combination thereof.

14. The device of claim 8, wherein said coating composition is gradient layered by systematically decreasing the duty cycle of said gas phase polymerization.

15. A method for plasma depositing a coating to a solid substrate, said method comprising: subjecting an organic compound having carbon, hydrogen and oxygen elements and a vinyl moiety to a gas phase polymerization utilizing a pulsed discharge having a duty cycle of less than about 1/5, in which the pulse-on time is less than about 100 msec and the pulse-offtime is less than about 2000 msec.

16. The method of claim 15, wherein said duty cycle is from about 1/10 to about 1/1000, and the pulse-on time is from about 1 µsec to about 100 msec, and the pulse-of time is from about 10 µsec to about 2000 msec.

17. The method of claim 15, wherein said organic organic compound is di(ethylene glycol) vinyl ether, di(ethylene glycol) divinyl ether, or di(ethylene glycol) methyl vinyl ether.

18. The method of claim 15, wherein said substrate is a contact lens.

19. The method of claim 15, wherein said gas phase polymerization is high voltage, radio frequency, microwave, ionizing radiation induced plasma polymerization; or photo induced polymerization; or a combination thereof.

20. The method of claim 15, wherein said pulsed discharge comprises a series of variable duty cycle.

21. The method of claim 15, wherein said organic compound further having a halogen element.

22. The device prepared by the method of claim 15.