Methods of forming a polymer layer on a polymer surface

Abstract

Methods of forming polymer layers on polymer surfaces using surface initiated atom-transfer radical-polymerization (ATRP) are described. The method can include functionalization steps prior to performing surface initiated ATRP, such as hydroxylation steps and/or halogenation steps. The hydroxylation step can be carried out in a solution including potassium persulfate, ammonium persulfate, or lithium hydroxide. The halogenation step can also be carried out in a solution. The methods described herein can be performed on bundles of hollow polymer fibers, including bundles of hollow polymer fibers mounted in a module.

I/We claim: 
     
         1 . A method of forming a polymer film on a polymer surface, the method comprising the steps of:
 (a) hydroxylating the polymer surface in a hydroxylation solution;   (b) halogenating the polymer surface;   (c) performing surface initiated atom-transfer radical-polymerization on the polymer surface, wherein the surface initiated atom-transfer radical polymerization forms a polymer film on the polymer surface.   
     
     
         2 . The method of  claim 1 , wherein the hydroxylation solution comprises potassium persulfate, ammonium persulfate, lithium hydroxide, or combinations thereof;
 wherein the polymer surface is a fluorinated polymer when the hydroxylation solution comprises lithium hydroxide,   
     
     
         3 . The method of  claim 2 , wherein the hydroxylation solution further comprises water. 
     
     
         4 . The method of  claim 1 , wherein the polymer surface comprises a bundle of polymer fibers. 
     
     
         5 . The method of  claim 4 , further comprising the step of mounting the bundle of polymer fibers in a module prior to performing step (a). 
     
     
         6 . The method of  claim 5 , wherein the bundle of polymer fibers comprises a bundle of hollow polymer fibers and the bundle of hollow polymer fibers is mounted in the module such that only the exterior surface of the hollow polymer fibers is exposed to the hydroxylation solution. 
     
     
         7 . The method of  claim 5 , wherein the bundle of polymer fibers comprises a bundle of hollow polymer fibers and the bundle of hollow polymer fibers is mounted in the module such that only the interior surface of the hollow polymer fibers is exposed to the hydroxylation solution. 
     
     
         8 . The method of  claim 4 , wherein:
 step (a) is performed by immersing the bundle of polymer fibers in a bath of the hydroxylation solution;   
     
     
         9 . The method of  claim 4 , wherein steps (a) is performed prior to mounting the bundle of polymer fibers in a module and steps (b) and (c) are performed after mounting the bundle of polymer fibers in a module. 
     
     
         10 . The method of  claim 4 , wherein steps (a) and (b) are performed prior to mounting the bundle of polymer fibers in a module and step (c) is performed after mounting the bundle of polymer fibers in a module. 
     
     
         11 . The method of  claim 1 , wherein the polymer surface comprises a flat sheet membrane. 
     
     
         12 . A method of forming a polymer film on a polymer surface, the method comprising the steps of:
 (a) providing a polymer surface having hydroxyl groups bonded to the polymer surface;   (b) halogenating the polymer surface in a halogenation solution, the halogenation solution comprising hydrobromic acid, hydrochloric acid, phosphorous tribromide, phosphorous trichloride, hydroiodic acid, thionyl chloride, thionyl bromide, or combinations thereof;   (c) performing surface initiated atom-transfer radical-polymerization on the polymer surface, wherein the surface initiated atom-transfer radical polymerization forms a polymer film on the polymer surface.   
     
     
         13 . The method of  claim 12 , wherein the halogenation solution further comprises water. 
     
     
         14 . The method of  claim 12 , wherein the polymer surface comprises a bundle of polymer fibers. 
     
     
         15 . The method of  claim 12 , wherein the bundle of hollow polymer fibers is mounted in a module such that only the exterior surface of the hollow polymer fibers is exposed to the halogenation solution. 
     
     
         16 . The method of  claim 12 , wherein the bundle of hollow polymer fibers is mounted in a module such that only the interior surface of the hollow polymer fibers is exposed to the halogenation solution. 
     
     
         17 . The method of  claim 12 , wherein the polymer surface comprises a flat sheet membrane. 
     
     
         18 . A method of forming a polymer layer on a bundle of hollow polymer fibers, the method comprising:
 providing a bundle of hollow polymer fibers; and   performing surface initiated atom-transfer radical-polymerization on the bundle of hollow polymer fibers, wherein the surface initiated atom-transfer radical polymerization forms a polymer film on the hollow polymer fibers.   
     
     
         19 . The method of  claim 18 , wherein the step of performing surface initiated atom-transfer radical-polymerization on the bundle of hollow polymer fibers is carried out while the bundle of hollow polymer fibers is mounted in a module. 
     
     
         20 . The method of  claim 18 , wherein the method further comprises mounting the bundle of hollow polymer fibers in a module after performing surface-initiated atom-transfer radical polymerization. 
     
     
         21 . The method of  claim 18 , wherein the method further comprises the step of hydroxylating the bundle of polymer fibers prior to performing surface initiated atom-transfer radical-polymerization. 
     
     
         22 . The method of  claim 21 , wherein hydroxylating is carried out using a hydroxylation solution. 
     
     
         23 . The method of  claim 22 , wherein the hydroxylation solution comprises potassium persulfate, ammonium persulfate, lithium hydroxide, or combinations thereof. 
     
     
         24 . The method of  claim 18 , wherein the method further comprises the step of halogenating the bundle of polymer fibers with a halogenation solution prior to performing the surface initiated atom-transfer radical-polymerization, wherein halogention solution comprises hydrobromic acid, hydrochloric acid, phosphorous tribromide, phosphorous trichloride, hydroiodic acid, thionyl chloride, thionyl bromide, or combinations thereof.