30294
Water uptake of the polymer was only 2 . 8 and 0 . 2 % for PEC with the MW of 200 kDa ( PEC200 ) and PEC with the MW of 41 kDa ( PEC41 ) , respectively .
 PEC, PEC200, PEC, PEC41
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 PEC, PEC200, PEC, PEC41