CROSS-LINKING MEHTOD AND ARTICLES PRODUCED THEREBY
A method for cross-linking a styrenic polymer, the method comprising providing a partly sulphonated styrenic polymer and cross-linking the partly sulphonated styrenic polymer in the presence of a polyphosphoric acid.
1 . A method for cross-linking a styrenic polymer, the method comprising:
providing a partly sulphonated styrenic polymer, and
cross-linking the partly sulphonated styrenic polymer in the presence of a polyphosphoric acid.
2 . The method of claim 1 , wherein the styrenic polymer is selected from a group consisting of a homopolymer of a styrenic monomer, a copolymer of a styrenic monomer with one or more comonomers, and a combination thereof.
3 . The method of claim 1 , wherein the cross-linking is carried out at a temperature of about 100° C. or greater.
4 . The method of claim 1 , wherein the cross-linking is carried out at a temperature in the range from about 120° C. to about 200° C.
5 . The method of claim 1 , wherein the partly sulphonated styrenic polymer has a degree of sulfonation of about 10%-80%.
6 . The method of claim 1 , wherein the partly sulphonated styrenic polymer has a degree of sulfonation of about 20%-70%.
7 . The method of claim 1 , wherein the cross-linking is carried out by forming a composition comprising the partly sulphonated styrenic polymer to obtain a molding, and immersing the molding into the polyphosphoric acid.
8 . The method of claim 1 , wherein the molding is selected from a group consisting of a film, an ion exchange resin and a hollow fiber.
9 . The method of claim 1 , wherein the providing the partly sulphonated styrenic polymer comprises the steps of:
providing a styrenic polymer;
contacting acetic anhydride with concentrated sulfuric acid to form acetyl sulfate; and
reacting the acetyl sulfate with the styrenic polymer to obtain the partly sulphonated styrenic polymer.