23089
To vary degradability , a co - monomer , acrylic acid ( AA ) or 2 - hydroxypropyl methacrylamide ( HPMA ) , was introduced , coupled with altering the concentration of the cross - linker and of the bioceramic .
 Chemical: acrylic acid; Chemical: 2 - hydroxypropyl methacrylamide; Chemical: HPMA
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: acrylic acid; Chemical: 2 - hydroxypropyl methacrylamide; Chemical: HPMA