2729718 POSS-MA polyhedral oligomeric silsesquioxane methacryl substituted 7 2729716 POSS-MA polyhedral oligomeric silsesquioxane 4 2729721 POSS-MA POSS-methacryl substituted 2 2729719 POSS-MA Polyhedral oligomeric silsesquioxane containing methacrylate units 1 2729720 POSS-MA Polyhedral Oligomeric Silsesquioxanes 1 2729717 POSS-MA substituted-polyhedral oligomeric silsesquioxane 1