3D printing CuAAC D3 synthesis FDM FFF MeTHEOS N-alkyl phosphoranimines N-methylimidazole initiators POSS-Cl Piers-Rubinsztajn catalyst Piers–Chojnowski–Rubinsztajn–Kawakami reaction THEOS anionic anionic polymerization of hexamethylcyclotrisiloxane anthracyclines anticancer conjugates antimicrobial properties bidentate ligand biomimetic polymers breathable films carbosilane dendrimers chain extension by Si-H hydrolysis chain-capping agents chitosan click chemistry coatings condensation curing contact lenses coordination compounds flame retardants