High refractive index monomers for optical applications

Abstract

The present invention includes optical coatings containing ultraviolet curable monomers employing a bromine substituted fluorene structure. The fluorene backbone of the monomers of the present invention may also be functionalized with one or more polymerizable or reactive functionalities, and most readily at the 9 position. Compositions of the present invention include the reactive bromosubstituted fluorenes combined with inorganic nanoparticles, particularly nanoparticles with reactive surface modifiers exhibiting polymerizable functionality. Reactive high index nanoparticles such as surface modified zirconia are contemplated.

1 . An optical coating comprising: 
 a monomer containing a substituted fluorene structure wherein said fluorene structure is a bromo-substituted fluorene; and    surface modified inorganic nanoparticles dispersed within said fluorene, wherein said optical coating has a refractive index of at least 1.58.    
     
     
         2 . The coating of  claim 1  wherein said bromo-substituted fluorene is selected from the group of monomers defined by the following formulas:  
       
         
           
           
               
               
           
         
       
     
     
         3 . The coating of  claim 2  wherein said bromo substituted fluorene monomer is selected from the group consisting of acrylic acid 3-[9-(3-acryloyloxy-propyl)-2,3,7-tribromo-9H-fluoren-9-yl]-propyl ester, acrylic acid 3-{9-[3-acyloyloxy-propoxy)-propyl]-2,3,7-tribromo-9H-fluoren-9-yl}-propyl ester, 3-[9-(3-acryloyloxy-propyl)-2,7-dibromo-9H-fluoren-9-yl]-propyl ester, and 2-[9-(2-acryloyloxy-ethyl)-2,7-dibromo-9H-fluoren-9-yl]-ethyl ester.  
     
     
         4 . The coating of  claim 1  wherein said bromo-substituted fluorene is functionalized with one or more polymerizable functionalities.  
     
     
         5 . A display system comprising the coating of  claim 1 .  
     
     
         6 . The display system of  claim 5  further comprising a photoinitiator within said coating.  
     
     
         7 . The coating of  claim 1  wherein said surface modified inorganic nanoparticle comprises nanoparticles selected from the group consisting of titanium, antimony, silica, zirconia, mixed metal oxides, and mixtures thereof.  
     
     
         8 . The coating of  claim 1  wherein said nanoparticles are selected from the group consisting of surface modified crystalline zirconia, surface modified amorphous zirconia, and functionalized silica.  
     
     
         9 . A nanocomposite coating comprising: 
 a polymer matrix formed from bromo-substituted fluorene; and    surface modified zirconia nanoparticles dispersed within said polymer matrix.    
     
     
         10 . A coating comprising: 
 a polymeric substrate;    a hard coat layer fixed to the polymeric substrate;    a high refractive index optical layer fixed to the hard coat layer, said high refractive index optical layer comprising a bromine substituted fluorene structure; and    an optional low refractive index optical layer fixed to the high refractive index optical layer,    wherein said high refractive index optical layer has a refractive index of at least 1.6 and said optional low refractive index layer has a refractive index less than 1.5.    
     
     
         11 . The coating of  claim 10  wherein said fluorene structure is bromine substituted at one or more of the 2, 3, and 7 positions.  
     
     
         12 . The coating of  claim 10  wherein said high refractive index optical layer further comprises surface modified zirconia nanoparticles.  
     
     
         13 . The coating of  claim 10  wherein said high refractive index optical layer further comprises surface modified inorganic nanoparticles selected from the group consisting of nanoparticles formed from titanium, antimony, silica, zirconia, mixtures of metal oxides, and mixtures thereof.  
     
     
         14 . The coating of  claim 10  wherein said high refractive index optical layer further comprises a photoinitiator prior to curing.  
     
     
         15 . The coating of  claim 10  wherein said high refractive index optical layer comprises a polymer containing a bromine fluorene monomer substituted with a polymerizable functionality.  
     
     
         16 . The coating of  claim 15  wherein said polymerizable functionality is an acrylate group substituted at the 9-position of the fluorene monomer.  
     
     
         17 . A display system comprising the coating of  claim 10.