Disclosed is a fluorinated polymer of the formula: R—S—P, wherein R is a fluorocarbyl group, S is sulfur, and P is: (i) polyglycerol; (ii) poly(allyl glycidyl ether); (iii) a copolymer of glycidol and allyl glycidyl ether, the copolymer having one or more allyl groups; or (iv) poly(allyl glycidyl ether) or copolymer of glycidol and allyl glycidyl ether, wherein one more of the allyl groups have been replaced with a functional group as described herein. Also disclosed is a method of preparing the fluorinated polymer. The fluorinated polymer finds use in improving the hydrophilicity of porous hydrophobic membranes such as PTFE and PVDF.