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Fabricated ferromagnetic hybrid systems consisting of a porous silicon (PS) matrix with incorporated metal nanostructures exhibit magnetic properties which can be distinguished in two ranges. A first one is related to magnetic fields below the saturation magnetization of the deposited metal and a second one to higher magnetic fields. Considering the low field region the samples show magnetic characteristics due to the metal-precipitations (geometry, distribution, kind of metal) tunable by the deposition parameters. At higher fields an additional novel non-saturating term is observed which is dependent on the temperature and differs in strength between Ni and Co. In the frame of this work this additional paramagnetic term is experimentally investigated. Index Terms--Magnetic nanocomposite, metal deposition, non-saturation, paramagnetic term.

Additive manufacturing is one of the most promising processing techniques for fabricating customized 3D objects. For the 3D printing of functional and stimuli-triggered devices, interest is steadily growing in processing materials with magnetic properties. Synthesis routes for magneto-responsive soft materials typically involve the dispersion of (nano)particles into a non-magnetic polymer matrix. Above their glass transition temperature, the shape of such composites can be conveniently adjusted by applying an external magnetic field. With their rapid response time, facile controllability, and reversible actuation, magnetically responsive soft materials can be used in the biomedical field ( e.g. drug delivery, minimally invasive surgery), soft robotics or in electronic applications. Herein, we combine the magnetic response with thermo-activated healability by introducing magnetic Fe 3 O 4 nanoparticles into a dynamic photopolymer network, which undergoes thermo-activated bond exchange reactions. The resin is based on a radically curable thiol-acrylate system, whose composition is optimized towards processability via digital light processing 3D printing. A mono-functional methacrylate phosphate is applied as a stabilizer to increase the resins' shelf life by preventing thiol-Michael reactions. Once photocured, the organic phosphate further acts as a transesterification catalyst and activates bond exchange reactions at elevated temperature, which render the magneto-active composites mendable and malleable. The healing performance is demonstrated by recovering magnetic and mechanical properties after the thermally triggered mending of 3D-printed structures. We further demonstrate the magnetically driven movement of 3D-printed samples, which gives rise to the potential use of these materials in healable soft devices activated by external magnetic fields., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)