15305
When compared to hysteresis of other amphiphilic diblock copolymers ( also containing PS , e . g . , polystyrene - b - poly ( ethylene oxide ) ) a general criterion can be formulated concerning the extent of hysteresis : when the hydrophobic ( PS ) block is of equal size as ( or bigger than ) the hydrophilic block , the hysteresis is maximal .
 polystyrene, poly ( ethylene oxide )
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 polystyrene, poly ( ethylene oxide )