Sulfonated polymers and method of sulfonating polymers

A method of imparting hydrophilic character to a shaped polymer, the method comprising:

• contacting the shaped polymer with a gaseous mixture consisting essentially of sulfur dioxide and an oxygen donating gas, in which the mixture has a mole ratio of sulfur dioxide to the oxygen donating gas which is equal to or greater than a stoichiometric ratio;
• and
• continuously exposing the shaped polymer and gaseous mixture to ultraviolet light while the shaped article is in contact with the gaseous mixture;
• wherein contacting and exposing are carried out at a pressure of less than 1 atmosphere and the oxygen donating gas is nitrous oxide, nitrogen dioxide, or a halogen dioxide.

A method of sulfonating a polymer, the method comprising:

• continuously exposing a gaseous mixture consisting essentially of sulfur dioxide and an oxygen donating gas to ultraviolet light, in which the mixture has a mole ratio of sulfur dioxide to the oxygen donating gas which is equal to or greater than a stoichiometric ratio;
• and
• contacting the polymer with the exposed gaseous mixture;
• wherein exposing and contacting are carried out at a pressure of less than 1 atmosphere, continuous exposure is carried out for as long as the exposed gaseous mixture is in contact with the polymer, and the oxygen donating gas is nitrous oxide nitrogen dioxide, or a halogen dioxide.