Highly fluorinated nanostructured polymer foams for producing super-repellent surfaces

Abstract

The present invention relates to a highly fluorinated nanostructured polymer foam as well as to its use as a super-repellent coating of substrates. Furthermore, the present invention relates to a composition and to a method for producing the highly fluorinated nanostructured polymer foam.

1 . A highly fluorinated nanostructured polymer foam with a density of at most 2.2 g/mL, an absolute foam expansion of at least 1% as well as a free surface energy of at most 12 mN/m, wherein the fluorine content is at least 20 mol % and wherein cavities with dimensions of at most 5 pm are homogeneously distributed throughout the entire volume of the polymer foam. 
     
     
         2 . The highly fluorinated nanostructured polymer foam according to  claim 1 , wherein at least 20% of the fluorine content is present as CF 3  groups. 
     
     
         3 . The highly fluorinated nanostructured polymer foam according to  claim 1 , wherein the polymer foam has a transmission of at least 50% within the wavelength range between 400 and 800 nm at a thickness of 0.25 mm. 
     
     
         4 . A composition for producing the highly fluorinated nanostructured polymer foam according to  claim 1 , comprising the following components:
 at least one monomer which can be polymerized by supplying heat or light, wherein the fluorine content of the at least one monomer is at least 20 mol %;   a polymerization initiator which initiates the polymerization of the at least one monomer by supplying heat or light; and   a non-polymerizable porogen.   
     
     
         5 . The composition according to  claim 4 , wherein the volume percentage of the non-polymerizable porogen in the composition is at least 5%. 
     
     
         6 . The composition according to  claim 4 , wherein the at least one monomer is a diacrylate derivative, represented by the following general formula (I): 
       
         
           
           
               
               
           
         
         wherein X 1  is independently selected from the group consisting of hydrogen, methyl, monofluoromethyl, difluoromethyl and trifluoromethyl and Y 1  is a fluorinated saturated hydrocarbon residue which optionally comprises one or more ether groups, or a monoacrylate derivative, represented by the following general formula (II): 
       
       
         
           
           
               
               
           
         
         wherein X 2  is selected from the group consisting of hydrogen, methyl, monofluoromethyl, difluoromethyl and trifluoromethyl and Y 2  is a fluorinated saturated hydrocarbon residue which optionally comprises one or more ether groups. 
       
     
     
         7 . A method for producing the highly fluorinated nanostructured polymer foam, comprising the following steps:
 (a) curing the composition according to  claim 4  by supplying heat or light, optionally on a substrate to be coated;   (b) optionally dipping the polymer foam obtained in this manner into a solvent; and   (c) drying the polymer foam treated in this manner,
 wherein the steps (a) to (c) are optionally repeated at least once, 
 wherein the polymer foam has a density of at most 2.2 g/mL, an absolute foam expansion of at least 1% as well as a free surface energy of at most 12 mN/m, wherein the fluorine content is at least 20 mol % and wherein cavities with dimensions of at most 5 μm are homogeneously distributed throughout the entire volume of the polymer foam. 
   
     
     
         8 . The method according to  claim 7 , wherein the polymer foam is dipped into an alcohol at step (b). 
     
     
         9 . The method according to  claim 7 , wherein the drying of the polymer foam at step (c) is carried out at a temperature within the range of 50 to 100° C. 
     
     
         10 . (canceled) 
     
     
         11 . The method according to  claim 7 , wherein the volume percentage of the non-polymerizable porogen in the composition is at least 5%. 
     
     
         12 . The method according to  claim 7 , wherein the at least one monomer is a diacrylate derivative, represented by the following general formula (I): 
       
         
           
           
               
               
           
         
         wherein X 1  is independently selected from the group consisting of hydrogen, methyl, monofluoromethyl, difluoromethyl and trifluoromethyl and Y 1  is a fluorinated saturated hydrocarbon residue which optionally comprises one or more ether groups, or a monoacrylate derivative, represented by the following general formula (II): 
       
       
         
           
           
               
               
           
         
         wherein X 2  is selected from the group consisting of hydrogen, methyl, monofluoromethyl, difluoromethyl and trifluoromethyl and Y 2  is a fluorinated saturated hydrocarbon residue which optionally comprises one or more ether groups. 
       
     
     
         13 . A super-repellent substrate coating comprising the highly fluorinated nanostructured polymer foam according to  claim 1 .