26319
The data reveal that the pore structures and surface energy can be controlled by varying the concentration and molecular weight of PEO and using different cooling rates during thermo - reversible gelation .
 Chemical: PEO
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: PEO 
Answer:
 Chemical: PEO