27652
Thus , the selective H2 gas permeability for TOCN - COOH was probably due to a larger average size in free volume holes present between nanofibrils in the layer and film than those of other TOCNs with metal carboxylate groups .
 Chemical: H2; Chemical: COOH; Chemical: metal carboxylate
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: H2; Chemical: COOH; Chemical: metal carboxylate