Abstract:
Disclosed are soft, high refractive index, acrylic device materials. The materials contain a multi-arm PEG macromer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119 to U.S. Provisional Patent Application No. 61/144,523, filed Jan. 14, 2009, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention is directed to improved ophthalmic and otorhinolaryngological device materials. In particular, this invention relates to soft, high refractive index acrylic device materials that comprise a multi-arm polyethylene glycol macromer. 
     BACKGROUND OF THE INVENTION 
     With the recent advances in small-incision cataract surgery, increased emphasis has been placed on developing soft, foldable materials suitable for use in artificial lenses. In general, these materials fall into one of three categories: hydrogels, silicones, and acrylics. 
     In general, hydrogel materials have a relatively low refractive index, making them less desirable than other materials because of the thicker lens optic necessary to achieve a given refractive power. Conventional silicone materials generally have a higher refractive index than hydrogels, but tend to unfold explosively after being placed in the eye in a folded position. Explosive unfolding can potentially damage the corneal endothelium and/or rupture the natural lens capsule. Acrylic materials are desirable because they typically have a high refractive index and unfold more slowly or controllably than conventional silicone materials. 
     U.S. Pat. No. 5,290,892 discloses high refractive index, acrylic materials suitable for use as an intraocular lens (“IOL”) material. These acrylic materials contain, as principal components, two aryl acrylic monomers. The IOLs made of these acrylic materials can be rolled or folded for insertion through small incisions. 
     U.S. Pat. No. 5,331,073 also discloses soft acrylic IOL materials. These materials contain as principal components, two acrylic monomers which are defined by the properties of their respective homopolymers. The first monomer is defined as one in which its homopolymer has a refractive index of at least about 1.50. The second monomer is defined as one in which its homopolymer has a glass transition temperature less than about 22° C. These IOL materials also contain a cross-linking component. Additionally, these materials may optionally contain a fourth constituent, different from the first three constituents, which is derived from a hydrophilic monomer. These materials preferably have a total of less than about 15% by weight of a hydrophilic component. 
     U.S. Pat. No. 5,693,095 discloses foldable, high refractive index ophthalmic lens materials containing at least about 90 wt. % of only two principal components: one aryl acrylic hydrophobic monomer and one hydrophilic monomer. The aryl acrylic hydrophobic monomer has the formula 
                                
wherein:
         X is H or CH 3 ;   m is 0-6;   Y is nothing, O, S, or NR, wherein R is H, CH 3 , C n H 2n+1  (n=1-10), iso-OC 3 H 7 , C 6 H 5 , or CH 2 C 6 H 5 ; and   Ar is any aromatic ring which can be unsubstituted or substituted with CH 3 , C 2 H 5 , n-C 3 H 7 , iso-C 3 H 7 , OCH 3 , C 6 H 11 , Cl, Br, C 6 H 5 , or CH 2 C 6 H 5 .
 
The lens materials described in the &#39;095 patent preferably have a glass-transition temperature (“T g ”) between about −20 and +25° C.
       

     Flexible intraocular lenses may be folded and inserted through a small incision. In general, a softer material may be deformed to a greater extent so that it can be inserted through an increasingly smaller incision. Soft acrylic or methacrylic materials typically do not have an appropriate combination of strength, flexibility and non-tacky surface properties to permit IOLs to be inserted through an incision as small as that required for silicone IOLs. 
     Polyethylene glycol (PEG) dimethacrylates are known to improve glistening resistance of hydrophobic acrylic formulations. See, for example, U.S. Pat. Nos. 5,693,095; 6,528,602; 6,653,422; and 6,353,069. Both the concentration and molecular weight of PEG dimethacrylates have an impact on glistening performance. Generally, use of higher molecular weight PEG dimethacrylates (1000 MW) yield copolymers with improved glistening performance at low PEG concentrations (10-15 wt %), as compared to lower molecular weight PEG dimethacrylates (&lt;1000 MW). However, low PEG dimethacrylate concentrations are desirable to maintain a high refractive index copolymer. Addition of PEG dimethacrylates also tends to decrease the modulus and tensile strength of the resulting copolymer. Also, higher molecular weight PEG dimethacrylates are generally not miscible with hydrophobic acrylic monomers. 
     SUMMARY OF THE INVENTION 
     Improved soft, foldable acrylic device materials which are particularly suited for use as IOLs, but which are also useful as other ophthalmic or otorhinolaryngological devices, such as contact lenses, keratoprostheses, corneal rings or inlays, otological ventilation tubes and nasal implants, have been discovered. These polymeric materials comprise a branched or “multi-arm” polyethylene glycol macromer. 
     Multi-arm PEG macromers efficiently reduce or eliminate temperature-induced glistening formation in hydrophobic acrylic copolymers of the type used in acrylic intraocular lens formulations. The subject monomers allow synthesis of glistening resistant, low equilibrium water content, high refractive index IOLs. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Unless indicated otherwise, all component amounts are presented on a % (w/w) basis (“wt. %”). 
     The device materials of the present invention are copolymers comprising a) a monofunctional acrylate or methacrylate monomer [1], b) a difunctional acrylate or methacrylate cross-linker [2], and c) a multi-arm PEG macromer [3]. The device materials may contain more than one monomer [1], more than one monomer [2], and more than one monomer [3]. Unless indicated otherwise, references to each ingredient are intended to encompass multiple monomers of the same formula and references to amounts are intended to refer to the total amount of all monomers of each formula. 
                                
wherein
         B═O(CH 2 ) n , NH(CH 2 ) n , or NCH 3 (CH 2 ) n ;   R 1 ═H, CH 3 , CH 2 CH 3 , or CH 2 OH;   n=0-12;   A=C 6 H 5  or O(CH 2 ) m C 6 H 5 , where the C 6 H 5  group is optionally substituted with —(CH 2 ) n H, —O(CH 2 ) n H, —CH(CH 3 ) 2 , —C 6 H 5 , —OC 6 H 5 , —CH 2 C 6 H 5 , F, Cl, Br, or I; and   m=0-22;       

                                
wherein
         R 2 , R 3  independently=H, CH 3 , CH 2 CH 3 , or CH 2 OH;   W, W′ independently=O(CH 2 ) d , NH(CH 2 ) d , NCH 3 (CH 2 ) d , O(CH 2 ) d C 6 H 4 , O(CH 2 CH 2 O) d CH 2 , O(CH 2 CH 2 CH 2 O) d CH 2 , O(CH 2 CH 2 CH 2 CH 2 O) d CH 2 , or nothing;   J=(CH 2 ) a , O(CH 2 CH 2 O) b , O, or nothing, provided that if W and W′=nothing, then J≠nothing;   d=0-12;   a=1-12;   b=1-24;       

                                
wherein:
         k=2-75;   s=0 or 1;   t=0-4;   Y independently=H, C(O)CCH 2 R 4 , CH 2 CH 2 NH 2 , CH 2 CH 2 NHC(O)CCH 2 R 4 , CH 2 CH 2 CH(OH)CH 2 OC(O)CCH 2 R 4 , CH 2 CH 2 NHC(O)NHCH 2 CH 2 OC(O)CCH 2 R 4 , C(O)NHCH 2 CH 2 OC(O)CCH 2 R 4 , or CH 2 CH 2 SH; and   R 4 ═H, CH 3 , CH 2 CH 3 , or CH 2 OH.
 
Preferred monomers of formula [1] are those wherein:
   B═O(CH 2 ) n ;   R 1 ═H or CH 3 ;   n=1-4; and   A=C 6 H 5 .
 
Preferred monomers of formula [2] are those wherein:
   R 2 , R 3  independently=H or CH 3 ;   W, W′ independently=O(CH 2 ) d , O(CH 2 ) d C 6 H 4 , or nothing;   J=O(CH 2 CH 2 O) b  or nothing, provided that if W and W′=nothing, then J≠nothing;   d=0-6; and   b=1-10.
 
Preferred monomers of formula [3] are those wherein:
   k=8-55;   s=0 or 1;   t=0 or 4;   Y independently=H, C(O)CCH 2 R 4 , CH 2 CH 2 NH 2 , CH 2 CH 2 NHC(O)CCH 2 R 4 , or C(O)NHCH 2 CH 2 OC(O)CCH 2 R 4 ; and   R 4 ═H, CH 3 , CH 2 CH 3 , or CH 2 OH.
 
Most preferred monomers of formula [3] are those wherein
   k=11-35;   s=1;   t=0;   Y═H, C(O)CCH 2 R 4 , CH 2 CH 2 NH 2 , or CH 2 CH 2 NHC(O)CCH 2 R 4 ; and R 4 ═H or CH 3 .       

     Monomers of formula [1] are known and can be made by known methods. See, for example, U.S. Pat. Nos. 5,331,073 and 5,290,892. Many monomers of formula [1] are commercially available from a variety of sources. Preferred monomers of formula [1] include benzyl methacrylate; 2-phenylethyl methacrylate; 3-phenylpropyl methacrylate; 4-phenylbutyl methacrylate; 5-phenylpentyl methacrylate; 2-phenoxyethyl methacrylate; 2-(2-phenoxyethoxy)ethyl methacrylate; 2-benzyloxyethyl methacrylate; 2-(2-(benzyloxy)ethoxy)ethyl methacrylate; and 3-benzyloxypropyl methacrylate; and their corresponding acrylates. 
     Monomers of formula [2] are known and can be made by known methods, and are commercially available. Preferred monomers of formula [2] include ethylene glycol dimethacrylate (“EGDMA”); diethylene glycol dimethacrylate; triethylene glycol dimethacrylate; 1,6-hexanediol dimethacrylate; 1,4-butanediol dimethacrylate; 1,4-benzenedimethanol dimethacrylate; and their corresponding acrylates. Most preferred is 1,4-butanediol diacrylate. 
     Macromers of formula [3] can be made from commercially available starting materials using known methods. For example, the general schemes below may be used. 
     
       
                 
         
             
             
         
      
     
     
       
                 
         
             
             
         
      
     
     Macromers of formula [3] have number average molecular weights (M n ) of 1,000-10,000 Daltons. M n  is determined by gel permeation chromatography (GPC) {size exclusion chromatography (SEC)} using THF as solvent, and relate to polystyrene calibration standards. 
     The copolymeric materials of the present invention contain a total amount of monomer [1] from 75 to 97%, preferably from 80 to 95%, and most preferably from 80-93%. The difunctional cross-linker [2] concentration is generally present in an amount from 0.5-3%, and preferably 1-2%. 
     The materials of the present invention have at least one macromer of [3]. The total amount of macromer [3] depends on the desired physical properties for the device materials. The copolymeric materials of the present invention contain a total of at least 1% and can contain as much as 8% of macromer [3]. Preferably, the copolymeric device materials will contain from 2 to 7% of macromer [3]. Most preferably, the device materials will contain from 3 to 5% of macromer [3]. 
     The copolymeric device material of the present invention optionally contains one or more ingredients selected from the group consisting of a polymerizable UV absorber and a polymerizable colorant. Preferably, the device material of the present invention contains no other ingredients besides the monomers of formulas [1] and [2], the macromer [3], and the optional polymerizable UV absorbers and colorants. 
     The device material of the present invention optionally contains reactive UV absorbers or reactive colorants. Many reactive UV absorbers are known. A preferred reactive UV absorber is 2-(2′-hydroxy-3′-methallyl-5′-methylphenyl)benzotriazole, commercially available as o-Methallyl Tinuvin P (“oMTP”) from Polysciences, Inc., Warrington, Pa. UV absorbers are typically present in an amount from about 0.1-5%. Suitable reactive blue-light absorbing compounds include those described in U.S. Pat. No. 5,470,932. Blue-light absorbers are typically present in an amount from about 0.01-0.5%. When used to make IOLs, the device materials of the present invention preferably contain both a reactive UV absorber and a reactive colorant. 
     In order to form the device material of the present invention, the chosen ingredients [1], [2], and [3], along with any of the optional ingredients, are combined and polymerized using a radical initiator to initiate polymerization by the action of either heat or radiation. The device material is preferably polymerized in de-gassed polypropylene molds under nitrogen or in glass molds. 
     Suitable polymerization initiators include thermal initiators and photoinitiators. Preferred thermal initiators include peroxy free-radical initiators, such as t-butyl (peroxy-2-ethyl)hexanoate and di-(tert-butylcyclohexyl) peroxydicarbonate (commercially available as Perkadox® 16 from Akzo Chemicals Inc., Chicago, Ill.). Particularly in cases where the materials of the present invention do not contain a blue-light absorbing chromophore, preferred photoinitiators include benzoylphosphine oxide initiators, such as 2,4,6-trimethyl-benzoyldiphenyl-phosphine oxide, commercially available as Lucirin® TPO from BASF Corporation (Charlotte, N.C.). Initiators are typically present in an amount equal to about 5% or less of the total formulation weight, and more preferably less than 2% of the total formulation. As is customary for purposes of calculating component amounts, the initiator weight is not included in the formulation weight % calculation. 
     The particular combination of the ingredients described above and the identity and amount of any additional components are determined by the desired properties of the finished device material. In a preferred embodiment, the device materials of the present invention are used to make IOLs having an optic diameter of 5.5 or 6 mm that are designed to be compressed or stretched and inserted through surgical incision sizes of 2 mm or less. For example, the macromer [3] is combined with at least one mono-functional acrylate or methacrylate monomer [1] and a multifunctional acrylate or methacrylate cross-linker [2] and copolymerized using a radical initiator in a suitable lens mold. 
     The device material preferably has a refractive index in the hydrated state of at least about 1.50, and more preferably at least about 1.53, as measured by an Abbe&#39; refractometer at 589 nm (Na light source) and 25° C. Optics made from materials having a refractive index lower than 1.50 are necessarily thicker than optics of the same power which are made from materials having a higher refractive index. As such, IOL optics made from materials with comparable mechanical properties and a refractive index lower than about 1.50 generally require relatively larger incisions for IOL implantation. 
     The proportions of the monomers to be included in the copolymers of the present invention should be chosen so that the copolymer has a glass transition temperature (T g ) not greater than about 37° C., which is normal human body temperature. Copolymers having glass transition temperatures higher than 37° C. are not suitable for use in foldable IOLs; such lenses could only be rolled or folded at temperatures above 37° C. and would not unroll or unfold at normal body temperature. It is preferred to use copolymers having a glass transition temperature somewhat below normal body temperature and no greater than normal room temperature, e.g., about 20-25° C., in order that IOLs made of such copolymers can be rolled or folded conveniently at room temperature. T g  is measured by differential scanning calorimetry at 10° C./min., and is determined at the midpoint of the transition of the heat flux curve. 
     For IOLs and other applications, the materials of the present invention must exhibit sufficient strength to allow devices made of them to be folded or manipulated without fracturing. Thus the copolymers of the present invention will have an elongation of at least 80%, preferably at least 100%, and most preferably between 110 and 200%. This property indicates that lenses made of such materials generally will not crack, tear or split when folded. Elongation of polymer samples is determined on dumbbell shaped tension test specimens with a 20 mm total length, length in the grip area of 4.88 mm, overall width of 2.49 mm, 0.833 mm width of the narrow section, a fillet radius of 8.83 mm, and a thickness of 0.9 mm. Testing is performed on samples at ambient conditions using an Instron Material Tester (Model No. 4442 or equivalent) with a 50 Newton load cell. The grip distance is set at 14 mm and a crosshead speed is set at 500 mm/minute and the sample is pulled until failure. The elongation (strain) is reported as a fraction of the displacement at failure to the original grip distance. Since the materials to be tested are essentially soft elastomers, loading them into the Instron machine tends to make them buckle. To remove the slack in the material sample a pre-load is placed upon the sample. This helps to reduce the slack and provide a more consistent reading. Once the sample is pre-loaded to a desired value (typically 0.03 to 0.05 N) the strain is set to zero and the test begun. The modulus is calculated as the instantaneous slope of the stress-strain curve at 0% strain (“Young&#39;s modulus”), 25% strain (“25% modulus”) and 100% strain (“100% modulus). 
     IOLs made of the ophthalmic device materials of the present invention are more resistant to glistenings than other materials. Glistenings are measured according to the following test. The presence of glistenings is measured by placement of a lens or disk sample into a vial or sealed glass chamber and adding deionized water or a balanced salt solution. The vial or glass chamber is then placed into a water bath preheated to 41° C. Samples are to be maintained in the bath for a minimum of 16 hours and preferably 24±2 hours. The vial or glass chamber is then immediately placed in a water bath preheated to 35° C. and allowed to equilibrate at 35° C. for a minimum of 30 minutes and preferably 30 to 60 minutes. The sample is inspected visually in various on angle or off angle lighting to evaluate clarity while at 35° C. Visualization of glistenings is carried out at 35° C. with light microscopy using a magnification of 50 to 200×. A sample is judged to have many glistenings if, at 50-200× magnification, there are approximately 50 to 100% as many glistenings as observed in control samples based on 65 weight % PEA, 30 weight % PEMA, 3.2 weight % BDDA, and 1.8 weight % OMTP. Similarly, a sample is judged to have few glistenings if there are approximately 10% or more glistenings relative to the quantity observed in control samples. A sample is judged to have very few glistenings if there are approximately 1% or more glistenings relative to a control sample. A sample is judged to be free of glistenings if the number of glistenings detected in the eyepiece is zero. A sample is judged to be substantially free of glistenings if the number of glistenings detected in the eyepiece is less than about 2/mm 3 . It is often very difficult to detect glistenings, especially at surfaces and edges where more defects and debris have formed, so the sample is rastered throughout the entire volume of the lens, varying the magnification levels (50-200×), the aperture iris diaphragm, and the field conditions (using both bright field and dark field conditions) in an attempt to detect the presence of glistenings. 
     The copolymers of the present invention preferably have an equilibrium water content (EWC) of 0.5 to 3 weight %. EWC is measured by placing one rectangular 0.9×10×20 mm slab in a 20 ml scintillation vial filled with deionized water and subsequently heating in a 35° C. water bath for a minimum of 20 hours and preferably 48±8 hours. The slab is blotted dry with lens paper and the % water content is calculated as follows: 
     
       
         
           
             
               % 
               ⁢ 
               
                   
               
               ⁢ 
               water 
               ⁢ 
               
                   
               
               ⁢ 
               content 
             
             = 
             
               
                 
                   ( 
                   
                     
                       wet 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       weight 
                     
                     - 
                     
                       dry 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       weight 
                     
                   
                   ) 
                 
                 
                   wet 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   weight 
                 
               
               × 
               100 
             
           
         
       
     
     IOLs constructed of the device materials of the present invention can be of any design capable of being stretched or compressed into a small cross section that can fit through a 2-mm incision. For example, the IOLs can be of what is known as a one-piece or multi-piece design, and comprise optic and haptic components. The optic is that portion which serves as the lens and the haptics are attached to the optic and are like arms that hold the optic in its proper place in the eye. The optic and haptic(s) can be of the same or different material. A multi-piece lens is so called because the optic and the haptic(s) are made separately and then the haptics are attached to the optic. In a single piece lens, the optic and the haptics are formed out of one piece of material. Depending on the material, the haptics are then cut, or lathed, out of the material to produce the IOL. 
     In addition to IOLs, the materials of the present invention are also suitable for use as other ophthalmic or otorhinolaryngological devices such as contact lenses, keratoprostheses, corneal inlays or rings, otological ventilation tubes and nasal implants. 
     The invention will be further illustrated by the following examples, which are intended to be illustrative, but not limiting. 
     The following abbreviations are used throughout the Examples and have the following meanings. 
     
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                   
                 BzA 
                 benzyl acrylate 
                   
               
               
                   
                 BzMA 
                 benzyl methacrylate 
                   
               
               
                   
                 BDDA 
                 1,4-butanediol diacrylate 
                   
               
               
                   
                 THF 
                 tetrahydrofuran 
                   
               
               
                   
                 AIBN 
                 azobisisobutyronitrile 
                   
               
               
                   
                 OMTP 
                 2-(2H-benzo[d][1,2,3]triazol-2-yl)-4- 
                   
               
               
                   
                   
                 methyl-6-(2-methylallyl)phenol 
               
               
                   
               
             
          
         
       
     
     EXAMPLE 1 
     Synthesis of Partially Methacrylated 2000 M n  4-Arm PEG, Batch #1 
     Commercially-available 4-arm polyethylene glycol was degassed at 70° C. for 4 days then dissolved in ˜100 ml THF. Triethylamine and p-methoxyphenol (˜50 mg) were added and the mixture was cooled to 0° C. Methacryloyl chloride was added dropwise. Triethylamine-HCl salts immediately began to form. The mixture was stirred at ambient temperature for 72 hours and then filtered through a silica plug using a fritted glass funnel with medium porosity. The silica was rinsed with methylene chloride so the total volume of filtrate was ˜500-700 ml. The solvent was removed by rotary evaporation and the product was dried under vacuum for 3-4 days to yield a light yellow liquid (60% yield). 
     Reaction table showing synthesis of 4-arm PEG using 1.5 eq methacryloyl chloride 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                   
                 4 arm 
                 Methacryloyl 
                   
                   
               
               
                   
                 PEG2000 
                 chloride 
                 TEA 
                 Product 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 F.W. 
                 2000 
                 104.53 
                 101.2 
                 ~2250 
               
               
                 g (used) 
                 100.372 
                 8.197 
                 15 ml (12 g) 
                 112.9 
               
               
                 mmol (used) 
                 50.19 
                 78.42 
                 120 
                 50.19 
               
               
                 eq 
                 1 
                 1.6  
                 2.3 
                 1 
               
               
                   
                   
                 per molecule 
                   
                   
               
               
                   
               
             
          
         
       
     
     EXAMPLE 2 
     Synthesis of Partially Methacrylated 2000 M n  4-Arm PEG, Batch #2 
     Procedure: same as Example 1. Light yellow liquid (˜60% yield). 
     Reaction table showing synthesis of 4-arm PEG using 3.5 eq methacryloyl chloride 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                   
                 4 arm 
                 Methacryloyl  
                   
                   
               
               
                   
                 PEG2000 
                 chloride 
                 TEA 
                 Product 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 F.W. 
                 2000 
                 104.53 
                 101.2 
                 ~2250 
               
               
                 g (used) 
                 68.406 
                 12.401 
                 20 ml (16 g) 
                 77.0 
               
               
                 mmol (used)  
                 34.203 
                 118.6 
                 150 
                 34.203 
               
               
                 eq 
                 1 
                 3.5  
                 4.4 
                 1 
               
               
                   
                   
                 per molecule 
                   
                   
               
               
                   
               
             
          
         
       
     
     EXAMPLE 3 
     IOL Formulations 
     Multi-arm PEG derivatives from Examples 1 and 2 were formulated as shown in Tables 1 and 2. Test samples measuring 0.9 mm in thickness were thermally cured at 70° C. for 1 hour and 110° C. for 2 hours. Samples were extracted in acetone for 20 hours at 55° C. and then dried slowly at ambient temperature for 20 hours, followed by vacuum (0.1 mm Hg) for a minimum of 20 hours at 70° C. Weight percent extractables, equilibrium water content (EWC), refractive index (R.I.), and slab appearance of hydrated samples that were subjected to a 45-22° C. delta T test are shown in Table 3. Mechanical and thermal properties of select compositions are shown in Table 4. 
     
       
         
               
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                   
                 Example (% w/w) 
               
             
          
           
               
                 Component 
                 3A 
                 3B 
                 3C 
               
               
                   
               
             
          
           
               
                 Macromer of Ex. 1 
                 3.14 
                 4.00 
                 5.02 
               
               
                 BzA 
                 83.3 
                 82.6 
                 81.7 
               
               
                 BzMA 
                 10.2 
                 10.1 
                 9.97 
               
               
                 BDDA 
                 1.53 
                 1.51 
                 1.50 
               
               
                 3-(3-tert-butyl-4-hydroxy-5- 
                 1.83 
                 1.81 
                 1.80 
               
               
                 (5-methoxy-2H- 
                   
                   
                   
               
               
                 benzo[d][1,2,3]-triazol-2- 
                   
                   
                   
               
               
                 yl)phenoxy)propyl 
                   
                   
                   
               
               
                 methacrylate 
                   
                   
                   
               
               
                 N-2-(3-(2- 
                 0.021 
                 0.020 
                 0.020 
               
               
                 methylphenylazo)-4- 
                   
                   
                   
               
               
                 hydroxyphenyl)ethyl- 
                   
                   
                   
               
               
                 methylacrylamide 
                   
                   
                   
               
               
                 AIBN 
                 0.5 
                 0.5 
                 0.5 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                   
                 Example (% w/w) 
               
             
          
           
               
                 Component 
                 3D 
                 3E 
                 3F 
               
               
                   
               
             
          
           
               
                 Macromer of Ex. 2 
                 2.98 
                 4.12 
                 5.12 
               
               
                 BzA 
                 83.5 
                 82.5 
                 81.6 
               
               
                 BzMA 
                 10.2 
                 10.1 
                 9.96 
               
               
                 BDDA 
                 1.53 
                 1.51 
                 1.50 
               
               
                 3-(3-tert-butyl-4-hydroxy-5-(5- 
                 1.83 
                 1.81 
                 1.79 
               
               
                 methoxy-2H-benzo[d][1,2,3]- 
                   
                   
                   
               
               
                 triazol-2-yl(phenoxy)propyl 
                   
                   
                   
               
               
                 methacrylate 
                   
                   
                   
               
               
                 N-2-(3-(2-methylphenylazo)- 
                 0.021 
                 0.020 
                 0.020 
               
               
                 4-hydroxy- 
                   
                   
                   
               
               
                 phenyl)ethylmethylacrylamide 
                   
                   
                   
               
               
                 AIBN 
                 0.5 
                 0.5 
                 0.5 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Sample 
                 Glis- 
               
               
                   
                 % 
                   
                   
                   
                 Appearance 
                 tenings 
               
               
                   
                 Extract- 
                 EWC 
                 EWC 
                   
                 After 
                 Per 
               
               
                 Ex- 
                 ables 
                 (35° C.) 
                 (45° C.) 
                 R.I. 
                 Delta T 
                 Test 
               
               
                 ample 
                 (N = 8) 
                 (wt. %) 
                 (wt. %) 
                 (35° C.)  
                 Test 
                 Sample 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 3A 
                 3.1 
                 0.6 
                 0.7 
                 1.556 
                   1 Clear 
                 0 
               
               
                 3B 
                 3.4 
                 1.2 
                 1.1 
                 1.557 
                   1 Clear 
                 0 
               
               
                 3C 
                 3.6 
                 1.6 
                 1.4 
                 1.555 
                   1 Clear 
                 0 
               
               
                 3D 
                 2.8 
                 0.6 
                 0.7 
                 1.557 
                   1 Clear 
                 0 
               
               
                 3E 
                 2.5 
                 0.8 
                 0.8 
                 1.556 
                   1 Clear 
                 0 
               
               
                 3F 
                 2.6 
                 1.1 
                 0.9 
                 1.555 
                   1 Clear 
                 0 
               
               
                   
               
               
                   1 Sample was equilibrated in deionized water for 9 days at 45° C., then cooled to ambient temperature and inspected by an optical microscope 1-2 hours later using a 10X lens objective 
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                   
                   
                   
                   
                 25% 
                 100% 
               
               
                   
                 Stress At  
                 Strain  
                 Young&#39;s 
                 Secant 
                 Secant 
               
               
                   
                 Break 
                 At 
                 Modulus 
                 Modulus 
                 Modulus 
               
               
                 Example 
                 (MPa) 
                 Break (%) 
                 (MPa) 
                 (MPa) 
                 (MPa) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 3A 
                 9.3 
                 148 
                 121 
                 16.2 
                 5.8 
               
               
                 3B 
                 10.2 
                 161 
                 115 
                 15.7 
                 5.6 
               
               
                 3C 
                 9.4 
                 162 
                 86 
                 12.6 
                 4.9 
               
               
                 3D 
                 10.6 
                 151 
                 137 
                 17.9 
                 6.4 
               
               
                 3E 
                 10.5 
                 156 
                 100 
                 14.7 
                 5.8 
               
               
                 3F 
                 11.0 
                 164 
                 73 
                 11.9 
                 5.1 
               
               
                   
               
             
          
         
       
     
     This invention has been described by reference to certain preferred embodiments; however, it should be understood that it may be embodied in other specific forms or variations thereof without departing from its special or essential characteristics. The embodiments described above are therefore considered to be illustrative in all respects and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description.