20385
The structural characterization of the oligo ( hydroxyalkanoate ) diols was conducted using NMR and ESI - mass spectrometry analyses , which confirmed that oligomers that were terminated by two hydroxyl end groups were formed .
 oligo ( hydroxyalkanoate ) diols, hydroxyl
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 oligo ( hydroxyalkanoate ) diols, hydroxyl