Thermoreversible Attachement of Polymers to Magnetic Core-Shell Nanoparticles

Nanocomposites of inorganic nanoparticles and polymers changing their properties after the application of an external trigger have attracted great attention during the last decades. This also includes temperature-induced bond breakages of filler particles covalently connected to the polymer strands by thermo-labile crosslinking. This strategy opens a wide range of applications in the field of biomaterials, such as temperature-induced drug delivery or thermo-induced change of mechanical properties of composites. In this work, periodic mesoporous organosilica (PMO) nanoparticles having a superparamagnetic core are used to heat their surface locally by exposure to an alternating magnetic field. Complementary, this process is investigated by applying a numerical simulation. The size of the PMO shell is controlled by varying the used amount of magnetite cores. Modification of the core-shell nanoparticles with maleimide groups enables the attachment of a furan-modified P-HPMA by a thermoreversible Diels-Alder reaction. Additional fluoresceine functionalisation of the polymer allows the detection of the detached polymer after the application of an alternating magnetic field. The results show that the polymer can be detached from the nanoparticles' surface, creating an innovative stimuli-responsive nanocomposite.