Method of making functionalized substrates

Abstract

Functionalized substrates, methods of making functionalized substrates, and methods of using functionalized substrates are disclosed.

1 . A method of making a functionalized substrate, the method comprises the steps of:
 providing a porous base substrate having interstitial and outer surfaces;   imbibing the porous base substrate with a first solution to form an imbibed porous base substrate, the first solution comprising at least one grafting monomer having (a) a free-radically polymerizable group and (b) an additional functional group comprising an ethylenically unsaturated group, epoxy group, azlactone group, isocyanate group, or combination thereof, and (c) optionally a grafting monomer having a free-radically polymerizable group and an alkylene oxide group;   exposing the imbibed porous base substrate to a controlled amount of electron beam radiation so as to form a first functionalized substrate comprising grafted species attached to the surfaces of the porous base substrate, wherein at least one of the grafted species comprises the epoxy group, azlactone group, isocyanate group,   imbibing the first functionalized substrate with a second solution comprising at least one nucleophilic compound comprising at least one nucleophilic group; and   exposing the first imbibed functionalized substrate to a controlled amount of heat so as to react the nucleophilic compound with the epoxy group, azlactone group, isocyanate group, or combination thereof.   
   
   
       2 . The method of  claim 1 , wherein the first imbibing solution comprises a grafting monomer having a free-radically polymerizable group and an alkylene oxide group. 
   
   
       3 . The method of  claim 1 , wherein the porous base substrate is microporous. 
   
   
       4 . The method of  claim 1 , wherein the porous base substrate is selected from a porous membrane, porous non-woven web, or porous fiber. 
   
   
       5 . The method of  claim 1 , wherein the porous base substrate is a microporous membrane or a nonwoven web that is hydrophobic. 
   
   
       6 . The method of  claim 1 , wherein the porous base substrate is hydrophobic and the functionalized substrate is hydrophilic. 
   
   
       7 . The method of  claim 1 , further comprising the step of exposing the functionalized substrate to a heat cycle at 30° C. or higher. 
   
   
       8 . The method of  claim 1 , wherein the grafting monomer having a free-radically polymerizable group and an alkylene oxide group comprises a polyalkylene glycol di(methacrylate). 
   
   
       9 . The method of  claim 1 , wherein the imbibing solution comprises a polyalkylene glycol di(meth)acrylate and a glycidyl (meth)acrylate, isocyanatoalkyl (meth)acrylate, or vinyl azlactone. 
   
   
       10 . The method of  claim 1 , wherein the nucleophilic compound comprises a nucleophilic group comprising at least one primary amino group, secondary amino group, hydroxy or combination thereof. 
   
   
       11 . The method of  claim 10 , wherein the nucleophilic compound has a plurality of nucleophilic groups that react to crosslink at least two grafted species. 
   
   
       12 . The method of  claim 11 , wherein the nucleophilic compound comprises at least two primary amino groups and a polyalkylene oxide group. 
   
   
       13 . The method of  claim 1  comprising the step of imbibing the porous bases substrate with a grafting monomer having (a) a free-radically polymerizable group and (b) an ionic group. 
   
   
       14 . The method of  claim 1  comprising the step of imbibing the porous bases substrate with a grafting monomer having (a) a free-radically polymerizable group and (b) an ethylenically unsaturated group. 
   
   
       15 . The method of  claim 1 , wherein the porous base substrate is a hydrophobic microporous membrane having an initial average pore size and the functionalized substrate is hydrophilic microporous membrane having a final average pore size that is larger than the initial average pore size of the porous base substrate. 
   
   
       16 . The method of  claim 15 , wherein the hydrophobic microporous membrane is formed by a thermally-induced phase separation (TIPS) method. 
   
   
       17 . The method of  claim 16 , wherein the hydrophobic microporous membrane comprises poly(vinylidene fluoride) formed by a thermally-induced phase separation (TIPS) method. 
   
   
       18 . The method of  claim 1 , wherein the controlled amount of electron beam radiation exposure comprises a dosage of 20 kGy to 40 kGy. 
   
   
       19 . A method of making a functionalized substrate, the method comprises the steps of:
 providing a porous base substrate having interstitial and outer surfaces;   imbibing the porous base substrate with a first solution to form an imbibed porous base substrate, the first solution comprising at least one grafting monomer having (a) a free-radically polymerizable group and (b) an additional functional group comprising an ethylenically unsaturated group, epoxy group, azlactone group, isocyanate group, or combination thereof, and (c) optionally a grafting monomer having a free-radically polymerizable group and an alkylene oxide group;   positioning the imbibed porous base substrate between a removable carrier layer and a removable cover layer to form a multilayer structure;   exposing the multilayer structure to a controlled amount of electron beam radiation so as to form a functionalized substrate positioned between the removable carrier layer and the removable cover layer, the functionalized substrate comprising grafted species attached to the surfaces of the porous base substrate, wherein at least one of the grafted species comprises the additional functional group; and   removing the carrier layer and cover layers from the multilayer structure.