23291
Using a combinatorial approach , we developed a series of biocompatible , hydrolytically degradable , elastomeric , bone - like biocomposites , comprising 60 wt % poly ( 2 - hydroxyethyl methacrylate - co - methacrylic acid ) , poly ( HEMA - co - MA ) , and 40 wt % bioceramic hydroxyapatite ( HA ) .
 poly ( 2 - hydroxyethyl methacrylate - co - methacrylic acid ), poly ( HEMA - co - MA ), hydroxyapatite
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 poly ( 2 - hydroxyethyl methacrylate - co - methacrylic acid ), poly ( HEMA - co - MA ), hydroxyapatite