18396
Ultrastrong , transparent , conductive and printable nanocomposites were successfully prepared by mixing single - walled carbon nanotubes ( CNTs ) with 2 , 2 , 6 , 6 - tetramethylpiperidine - 1 - oxyl ( TEMPO ) - oxidized cellulose nanofibrils ( TOCNs ) with abundant sodium carboxyl groups on the crystalline nanocellulose surfaces .
 carbon, 2 , 2 , 6 , 6 - tetramethylpiperidine - 1 - oxyl, TEMPO, sodium carboxyl
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 carbon, 2 , 2 , 6 , 6 - tetramethylpiperidine - 1 - oxyl, TEMPO, sodium carboxyl