20339
The fluorescence brightness of PFBV - Rtx single chains dispersed in a solid PMMA is very close to that expected for a chain with 100 % fluorescence quantum yield , while the unprotected PFBV chains of the same length possess 4 times lower brightness .
 PFBV, PMMA, PFBV
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 PFBV, PMMA, PFBV