Thermosensitive and control release behavior of poly(N-isopropylacrylamide-co-acrylic acid)/nano-Fe3O4 magnetic composite latex particle that is synthesized by a novel method

In this study, a novel method was used to synthesize the poly(N-isopropylacrylamide-co-acrylic acid)/Fe3O4 (poly(NIPAAm-AA)/Fe3O4) magnetic composite latex. The crosslinked poly(NIPAAm-AA) polymer latex particles were first synthesized by the method of soapless emulsion polymerization, then Fe2+ and Fe3+ ions were introduced to bond with the –COOH groups of AA segments in poly(NIPAAm-AA) polymer latex particles. Further by a reaction with NH4OH, Fe3O4 nanoparticles were generated in situ. The concentrations of acrylic acid (AA), crosslinking agent (N,N′-methylene bisacrylamide (MBA)), and Fe3O4 nanoparticles were important factors to influence the morphology and lower critical solution temperature (LCST) of poly(NIPAAm-AA)/Fe3O4 magnetic composite latex particles. The poly(NIPAAm-AA)/Fe3O4 latex particles were used as a thermosensitive drug carrier to load caffeine. The control release of caffeine was studies. Morphology-based schematic models were proposed to explain the control release behavior of the composite particles with different compositions. Moreover, the protein (albumin, acetylated from bovine serum (BSA)) was bound on the surface of poly(NIPAAm-AA)/Fe3O4 composite latex particles. The effects of AA, crosslinking agent and Fe3O4 contents on the amount of BSA binding were investigated at different temperatures and pH values. The composition–morphology–BSA conjugation relationship was established.