Hydrophilic porous substrates

Abstract

Hydrophilic porous substrates, methods of making hydrophilic porous substrates from hydrophobic polymers are disclosed.

1 . A method of making a functionalized substrate, the method comprises the steps of:
 1) providing a porous base substrate having interstitial and outer surfaces;   2) imbibing the porous base substrate with a first solution to form an imbibed porous base substrate, the first solution comprising (a) at least one grafting monomer having an acrylate group and a photoinitiator group and (b) one or more monomers having at least one acrylate group and at least one additional ethylenically unsaturated, free-radically polymerizable group; and optionally (c) one or more additional monomers having at least one ethylenically unsaturated, free-radically polymerizable group and a hydrophilic group; wherein at least one of (b) or (c) monomers are hydrophilic.   3) exposing the imbibed porous base substrate to a controlled amount of electron beam radiation so as to form a first functionalized substrate comprising grafted photoinitiator group attached to the surfaces of the porous base substrate, and   4) exposing the porous base substrate comprising grafted photoinitiator groups to a controlled amount of UV radiation to crosslink the remaining ethylenically unsaturated, free-radically polymerizable groups.   
   
   
       2 . The method of  claim 1 , wherein the porous base substrate is microporous. 
   
   
       3 . The method of  claim 1 , wherein the porous base substrate is selected from a porous membrane, porous non-woven web, or porous fiber. 
   
   
       4 . The method of  claim 1 , wherein the monomer (b) comprises a poly(alkylene oxide) di(meth)acrylate. 
   
   
       5 . The method of  claim 1  wherein said monomers (b) having two or more free-radically polymerizable groups comprises a first acrylate group for grafting to said porous base substrate and a second methacrylate group for subsequent UV crosslinking. 
   
   
       6 . The method of  claim 1 , wherein said first solution comprises (c) one or more additional monomers monomer having a free-radically polymerizable group and a hydrophilic group. 
   
   
       7 . The method of  claim 2 , wherein the microporous base substrate is formed by a thermally-induced phase separation (TIPS) method. 
   
   
       8 . The method of  claim 7 , wherein the microporous base substrate comprises propylene polymer membrane formed by a thermally-induced phase separation (TIPS) method. 
   
   
       9 . The method of  claim 1 , wherein the controlled amount of electron beam radiation exposure comprises a dosage of less than 10 kGy. 
   
   
       10 . A method of making a functionalized substrate, the method comprises the steps of:
 1) providing a porous base substrate having interstitial and outer surfaces;   2) imbibing the porous base substrate with a first solution to form an imbibed porous base substrate, the first solution comprising (a) at least one grafting monomer having an acrylate group and a photoinitiator group and (b) one or more monomers having at least one acrylate group and at least one additional ethylenically unsaturated, free-radically polymerizable group; and optionally (c) one or more additional monomers monomer having at least one ethylenically unsaturated, free-radically polymerizable group and a hydrophilic group; wherein at least one of (b) or (c) monomers are hydrophilic,   3) positioning the imbibed porous base substrate between a removable carrier layer and a removable cover layer to form a multilayer structure;   4) 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 photoinitiator groups attached to the surfaces of the porous base substrate;   5) exposing the multilayer structure to UV radiation to initiate polymerization of the ungrafted ethylenically unsaturated groups; and   6) removing the carrier layer and cover layers from the multilayer structure.   
   
   
       11 . An article comprising a porous base substrate having interstitial and outer surfaces and grafted photoinitiator groups extending from the surfaces of the porous base substrate. 
   
   
       12 . The article of  claim 11  further comprising grafted ethylenically unsaturated groups extending from the surfaces of the porous base substrate. 
   
   
       13 . The article of  claim 11  further comprising grafted hydrophilic groups extending from the surfaces of the porous base substrate. 
   
   
       14 . The article of  claim 11  further comprising the polymerization reaction product of: (b) one or more monomers having at least one acrylate group and at least one additional ethylenically unsaturated, free-radically polymerizable group; and optionally (c) one or more additional monomers monomer having at least one ethylenically unsaturated, free-radically polymerizable group and a hydrophilic group; wherein at least one of (b) or (c) monomers are hydrophilic. 
   
   
       15 . The article of  claim 12  wherein the grafted ethylenically unsaturated groups are derived from one or more monomers having at least one acrylate group and at least one additional ethylenically unsaturated, free-radically polymerizable group. 
   
   
       16 . The article of  claim 14  derived from a poly(alkylene oxide) di(meth)acrylate. 
   
   
       17 . The article of  claim 11 , wherein the porous base substrate is microporous. 
   
   
       18 . The article of  claim 11 , wherein the porous base substrate comprises a porous membrane, a porous nonwoven web, or a porous fiber. 
   
   
       19 . The article of  claim 11 , wherein the porous base substrate comprises a microporous, thermally-induced phase separation membrane. 
   
   
       20 . The article of  claim 19 , wherein the thermally-induced phase separation membrane comprises a propylene polymer. 
   
   
       21 . The article of  claim 11 , wherein the grafted photoinitiator comprises the reaction product of a monomer having an acrylate group and a photoinitiator group upon exposure to electron beam irradiation. 
   
   
       22 . The article of  claim 11 , wherein the grafted ethylenically unsaturated groups comprises the reaction product of di(meth)acrylate poly(alkylene oxide) with the surfaces of the porous base substrate upon exposure to an electron beam. 
   
   
       23 . The article of  claim 11 , wherein the article comprises (a) a first grafted species comprising the reaction product of a monomer having a free-radically polymerizable group and a photoinitiator group; and (b) a second grafted species comprising the reaction product of a partially acrylated polyol upon exposure to an electron beam irradiation. 
   
   
       24 . The article of  claim 11  comprising the crosslinked reaction product of the unreacted ethylenically unsaturated groups on exposure to UV radiation.