8623
The spectral changes evident in the vibrational spectra of the 3M membranes can be associated with two major phenomena : ( 1 ) dissociation of the proton from the sulfonic acid groups even in the presence of small amounts of water ; and ( 2 ) changes in the conformation or the degree of crystallinity of the poly ( tetrafluoroethylene ) hydrophobic domains both as a function of EW and membrane water content .
 Chemical: sulfonic acid; Chemical: poly ( tetrafluoroethylene )
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: sulfonic acid; Chemical: poly ( tetrafluoroethylene )